Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

7 files changed, 2539 insertions, 0 deletions

diff --git a/drivers/bus/mhi/ep/Kconfig b/drivers/bus/mhi/ep/Kconfig
new file mode 100644
index 0000000000..90ab3b0406
--- /dev/null
+++ b/drivers/bus/mhi/ep/Kconfig
@@ -0,0 +1,10 @@
+config MHI_BUS_EP
+	tristate "Modem Host Interface (MHI) bus Endpoint implementation"
+	help
+	  Bus driver for MHI protocol. Modem Host Interface (MHI) is a
+	  communication protocol used by a host processor to control
+	  and communicate a modem device over a high speed peripheral
+	  bus or shared memory.
+
+	  MHI_BUS_EP implements the MHI protocol for the endpoint devices,
+	  such as SDX55 modem connected to the host machine over PCIe.
diff --git a/drivers/bus/mhi/ep/Makefile b/drivers/bus/mhi/ep/Makefile
new file mode 100644
index 0000000000..aad85f180b
--- /dev/null
+++ b/drivers/bus/mhi/ep/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_MHI_BUS_EP) += mhi_ep.o
+mhi_ep-y := main.o mmio.o ring.o sm.o
diff --git a/drivers/bus/mhi/ep/internal.h b/drivers/bus/mhi/ep/internal.h
new file mode 100644
index 0000000000..a2125fa5fe
--- /dev/null
+++ b/drivers/bus/mhi/ep/internal.h
@@ -0,0 +1,218 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2022, Linaro Ltd.
+ *
+ */
+
+#ifndef _MHI_EP_INTERNAL_
+#define _MHI_EP_INTERNAL_
+
+#include <linux/bitfield.h>
+
+#include "../common.h"
+
+extern struct bus_type mhi_ep_bus_type;
+
+#define MHI_REG_OFFSET				0x100
+#define BHI_REG_OFFSET				0x200
+
+/* MHI registers */
+#define EP_MHIREGLEN				(MHI_REG_OFFSET + MHIREGLEN)
+#define EP_MHIVER				(MHI_REG_OFFSET + MHIVER)
+#define EP_MHICFG				(MHI_REG_OFFSET + MHICFG)
+#define EP_CHDBOFF				(MHI_REG_OFFSET + CHDBOFF)
+#define EP_ERDBOFF				(MHI_REG_OFFSET + ERDBOFF)
+#define EP_BHIOFF				(MHI_REG_OFFSET + BHIOFF)
+#define EP_BHIEOFF				(MHI_REG_OFFSET + BHIEOFF)
+#define EP_DEBUGOFF				(MHI_REG_OFFSET + DEBUGOFF)
+#define EP_MHICTRL				(MHI_REG_OFFSET + MHICTRL)
+#define EP_MHISTATUS				(MHI_REG_OFFSET + MHISTATUS)
+#define EP_CCABAP_LOWER				(MHI_REG_OFFSET + CCABAP_LOWER)
+#define EP_CCABAP_HIGHER			(MHI_REG_OFFSET + CCABAP_HIGHER)
+#define EP_ECABAP_LOWER				(MHI_REG_OFFSET + ECABAP_LOWER)
+#define EP_ECABAP_HIGHER			(MHI_REG_OFFSET + ECABAP_HIGHER)
+#define EP_CRCBAP_LOWER				(MHI_REG_OFFSET + CRCBAP_LOWER)
+#define EP_CRCBAP_HIGHER			(MHI_REG_OFFSET + CRCBAP_HIGHER)
+#define EP_CRDB_LOWER				(MHI_REG_OFFSET + CRDB_LOWER)
+#define EP_CRDB_HIGHER				(MHI_REG_OFFSET + CRDB_HIGHER)
+#define EP_MHICTRLBASE_LOWER			(MHI_REG_OFFSET + MHICTRLBASE_LOWER)
+#define EP_MHICTRLBASE_HIGHER			(MHI_REG_OFFSET + MHICTRLBASE_HIGHER)
+#define EP_MHICTRLLIMIT_LOWER			(MHI_REG_OFFSET + MHICTRLLIMIT_LOWER)
+#define EP_MHICTRLLIMIT_HIGHER			(MHI_REG_OFFSET + MHICTRLLIMIT_HIGHER)
+#define EP_MHIDATABASE_LOWER			(MHI_REG_OFFSET + MHIDATABASE_LOWER)
+#define EP_MHIDATABASE_HIGHER			(MHI_REG_OFFSET + MHIDATABASE_HIGHER)
+#define EP_MHIDATALIMIT_LOWER			(MHI_REG_OFFSET + MHIDATALIMIT_LOWER)
+#define EP_MHIDATALIMIT_HIGHER			(MHI_REG_OFFSET + MHIDATALIMIT_HIGHER)
+
+/* MHI BHI registers */
+#define EP_BHI_INTVEC				(BHI_REG_OFFSET + BHI_INTVEC)
+#define EP_BHI_EXECENV				(BHI_REG_OFFSET + BHI_EXECENV)
+
+/* MHI Doorbell registers */
+#define CHDB_LOWER_n(n)				(0x400 + 0x8 * (n))
+#define CHDB_HIGHER_n(n)			(0x404 + 0x8 * (n))
+#define ERDB_LOWER_n(n)				(0x800 + 0x8 * (n))
+#define ERDB_HIGHER_n(n)			(0x804 + 0x8 * (n))
+
+#define MHI_CTRL_INT_STATUS			0x4
+#define MHI_CTRL_INT_STATUS_MSK			BIT(0)
+#define MHI_CTRL_INT_STATUS_CRDB_MSK		BIT(1)
+#define MHI_CHDB_INT_STATUS_n(n)		(0x28 + 0x4 * (n))
+#define MHI_ERDB_INT_STATUS_n(n)		(0x38 + 0x4 * (n))
+
+#define MHI_CTRL_INT_CLEAR			0x4c
+#define MHI_CTRL_INT_MMIO_WR_CLEAR		BIT(2)
+#define MHI_CTRL_INT_CRDB_CLEAR			BIT(1)
+#define MHI_CTRL_INT_CRDB_MHICTRL_CLEAR		BIT(0)
+
+#define MHI_CHDB_INT_CLEAR_n(n)			(0x70 + 0x4 * (n))
+#define MHI_CHDB_INT_CLEAR_n_CLEAR_ALL		GENMASK(31, 0)
+#define MHI_ERDB_INT_CLEAR_n(n)			(0x80 + 0x4 * (n))
+#define MHI_ERDB_INT_CLEAR_n_CLEAR_ALL		GENMASK(31, 0)
+
+/*
+ * Unlike the usual "masking" convention, writing "1" to a bit in this register
+ * enables the interrupt and writing "0" will disable it..
+ */
+#define MHI_CTRL_INT_MASK			0x94
+#define MHI_CTRL_INT_MASK_MASK			GENMASK(1, 0)
+#define MHI_CTRL_MHICTRL_MASK			BIT(0)
+#define MHI_CTRL_CRDB_MASK			BIT(1)
+
+#define MHI_CHDB_INT_MASK_n(n)			(0xb8 + 0x4 * (n))
+#define MHI_CHDB_INT_MASK_n_EN_ALL		GENMASK(31, 0)
+#define MHI_ERDB_INT_MASK_n(n)			(0xc8 + 0x4 * (n))
+#define MHI_ERDB_INT_MASK_n_EN_ALL		GENMASK(31, 0)
+
+#define NR_OF_CMD_RINGS				1
+#define MHI_MASK_ROWS_CH_DB			4
+#define MHI_MASK_ROWS_EV_DB			4
+#define MHI_MASK_CH_LEN				32
+#define MHI_MASK_EV_LEN				32
+
+/* Generic context */
+struct mhi_generic_ctx {
+	__le32 reserved0;
+	__le32 reserved1;
+	__le32 reserved2;
+
+	__le64 rbase __packed __aligned(4);
+	__le64 rlen __packed __aligned(4);
+	__le64 rp __packed __aligned(4);
+	__le64 wp __packed __aligned(4);
+};
+
+enum mhi_ep_ring_type {
+	RING_TYPE_CMD,
+	RING_TYPE_ER,
+	RING_TYPE_CH,
+};
+
+/* Ring element */
+union mhi_ep_ring_ctx {
+	struct mhi_cmd_ctxt cmd;
+	struct mhi_event_ctxt ev;
+	struct mhi_chan_ctxt ch;
+	struct mhi_generic_ctx generic;
+};
+
+struct mhi_ep_ring_item {
+	struct list_head node;
+	struct mhi_ep_ring *ring;
+};
+
+struct mhi_ep_ring {
+	struct mhi_ep_cntrl *mhi_cntrl;
+	union mhi_ep_ring_ctx *ring_ctx;
+	struct mhi_ring_element *ring_cache;
+	enum mhi_ep_ring_type type;
+	u64 rbase;
+	size_t rd_offset;
+	size_t wr_offset;
+	size_t ring_size;
+	u32 db_offset_h;
+	u32 db_offset_l;
+	u32 ch_id;
+	u32 er_index;
+	u32 irq_vector;
+	bool started;
+};
+
+struct mhi_ep_cmd {
+	struct mhi_ep_ring ring;
+};
+
+struct mhi_ep_event {
+	struct mhi_ep_ring ring;
+};
+
+struct mhi_ep_state_transition {
+	struct list_head node;
+	enum mhi_state state;
+};
+
+struct mhi_ep_chan {
+	char *name;
+	struct mhi_ep_device *mhi_dev;
+	struct mhi_ep_ring ring;
+	struct mutex lock;
+	void (*xfer_cb)(struct mhi_ep_device *mhi_dev, struct mhi_result *result);
+	enum mhi_ch_state state;
+	enum dma_data_direction dir;
+	u64 tre_loc;
+	u32 tre_size;
+	u32 tre_bytes_left;
+	u32 chan;
+	bool skip_td;
+};
+
+/* MHI Ring related functions */
+void mhi_ep_ring_init(struct mhi_ep_ring *ring, enum mhi_ep_ring_type type, u32 id);
+void mhi_ep_ring_reset(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring);
+int mhi_ep_ring_start(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
+		      union mhi_ep_ring_ctx *ctx);
+size_t mhi_ep_ring_addr2offset(struct mhi_ep_ring *ring, u64 ptr);
+int mhi_ep_ring_add_element(struct mhi_ep_ring *ring, struct mhi_ring_element *element);
+void mhi_ep_ring_inc_index(struct mhi_ep_ring *ring);
+int mhi_ep_update_wr_offset(struct mhi_ep_ring *ring);
+
+/* MMIO related functions */
+u32 mhi_ep_mmio_read(struct mhi_ep_cntrl *mhi_cntrl, u32 offset);
+void mhi_ep_mmio_write(struct mhi_ep_cntrl *mhi_cntrl, u32 offset, u32 val);
+void mhi_ep_mmio_masked_write(struct mhi_ep_cntrl *mhi_cntrl, u32 offset, u32 mask, u32 val);
+u32 mhi_ep_mmio_masked_read(struct mhi_ep_cntrl *dev, u32 offset, u32 mask);
+void mhi_ep_mmio_enable_ctrl_interrupt(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_disable_ctrl_interrupt(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_enable_cmdb_interrupt(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_disable_cmdb_interrupt(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_enable_chdb(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id);
+void mhi_ep_mmio_disable_chdb(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id);
+void mhi_ep_mmio_enable_chdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl);
+bool mhi_ep_mmio_read_chdb_status_interrupts(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_mask_interrupts(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_get_chc_base(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_get_erc_base(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_get_crc_base(struct mhi_ep_cntrl *mhi_cntrl);
+u64 mhi_ep_mmio_get_db(struct mhi_ep_ring *ring);
+void mhi_ep_mmio_set_env(struct mhi_ep_cntrl *mhi_cntrl, u32 value);
+void mhi_ep_mmio_clear_reset(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_reset(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_get_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state *state,
+			       bool *mhi_reset);
+void mhi_ep_mmio_init(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_mmio_update_ner(struct mhi_ep_cntrl *mhi_cntrl);
+
+/* MHI EP core functions */
+int mhi_ep_send_state_change_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state state);
+int mhi_ep_send_ee_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ee_type exec_env);
+bool mhi_ep_check_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state cur_mhi_state,
+			    enum mhi_state mhi_state);
+int mhi_ep_set_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state mhi_state);
+int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl);
+int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl);
+int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl);
+void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl);
+
+#endif
diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
new file mode 100644
index 0000000000..582d5c166a
--- /dev/null
+++ b/drivers/bus/mhi/ep/main.c
@@ -0,0 +1,1670 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MHI Endpoint bus stack
+ *
+ * Copyright (C) 2022 Linaro Ltd.
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/dma-direction.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/mhi_ep.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include "internal.h"
+
+#define M0_WAIT_DELAY_MS	100
+#define M0_WAIT_COUNT		100
+
+static DEFINE_IDA(mhi_ep_cntrl_ida);
+
+static int mhi_ep_create_device(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id);
+static int mhi_ep_destroy_device(struct device *dev, void *data);
+
+static int mhi_ep_send_event(struct mhi_ep_cntrl *mhi_cntrl, u32 ring_idx,
+			     struct mhi_ring_element *el, bool bei)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	union mhi_ep_ring_ctx *ctx;
+	struct mhi_ep_ring *ring;
+	int ret;
+
+	mutex_lock(&mhi_cntrl->event_lock);
+	ring = &mhi_cntrl->mhi_event[ring_idx].ring;
+	ctx = (union mhi_ep_ring_ctx *)&mhi_cntrl->ev_ctx_cache[ring_idx];
+	if (!ring->started) {
+		ret = mhi_ep_ring_start(mhi_cntrl, ring, ctx);
+		if (ret) {
+			dev_err(dev, "Error starting event ring (%u)\n", ring_idx);
+			goto err_unlock;
+		}
+	}
+
+	/* Add element to the event ring */
+	ret = mhi_ep_ring_add_element(ring, el);
+	if (ret) {
+		dev_err(dev, "Error adding element to event ring (%u)\n", ring_idx);
+		goto err_unlock;
+	}
+
+	mutex_unlock(&mhi_cntrl->event_lock);
+
+	/*
+	 * Raise IRQ to host only if the BEI flag is not set in TRE. Host might
+	 * set this flag for interrupt moderation as per MHI protocol.
+	 */
+	if (!bei)
+		mhi_cntrl->raise_irq(mhi_cntrl, ring->irq_vector);
+
+	return 0;
+
+err_unlock:
+	mutex_unlock(&mhi_cntrl->event_lock);
+
+	return ret;
+}
+
+static int mhi_ep_send_completion_event(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
+					struct mhi_ring_element *tre, u32 len, enum mhi_ev_ccs code)
+{
+	struct mhi_ring_element *event;
+	int ret;
+
+	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
+	if (!event)
+		return -ENOMEM;
+
+	event->ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(*tre));
+	event->dword[0] = MHI_TRE_EV_DWORD0(code, len);
+	event->dword[1] = MHI_TRE_EV_DWORD1(ring->ch_id, MHI_PKT_TYPE_TX_EVENT);
+
+	ret = mhi_ep_send_event(mhi_cntrl, ring->er_index, event, MHI_TRE_DATA_GET_BEI(tre));
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
+
+	return ret;
+}
+
+int mhi_ep_send_state_change_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state state)
+{
+	struct mhi_ring_element *event;
+	int ret;
+
+	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
+	if (!event)
+		return -ENOMEM;
+
+	event->dword[0] = MHI_SC_EV_DWORD0(state);
+	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_STATE_CHANGE_EVENT);
+
+	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
+
+	return ret;
+}
+
+int mhi_ep_send_ee_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ee_type exec_env)
+{
+	struct mhi_ring_element *event;
+	int ret;
+
+	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
+	if (!event)
+		return -ENOMEM;
+
+	event->dword[0] = MHI_EE_EV_DWORD0(exec_env);
+	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_EE_EVENT);
+
+	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
+
+	return ret;
+}
+
+static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ev_ccs code)
+{
+	struct mhi_ep_ring *ring = &mhi_cntrl->mhi_cmd->ring;
+	struct mhi_ring_element *event;
+	int ret;
+
+	event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache, GFP_KERNEL | GFP_DMA);
+	if (!event)
+		return -ENOMEM;
+
+	event->ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(struct mhi_ring_element));
+	event->dword[0] = MHI_CC_EV_DWORD0(code);
+	event->dword[1] = MHI_CC_EV_DWORD1(MHI_PKT_TYPE_CMD_COMPLETION_EVENT);
+
+	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
+
+	return ret;
+}
+
+static int mhi_ep_process_cmd_ring(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_result result = {};
+	struct mhi_ep_chan *mhi_chan;
+	struct mhi_ep_ring *ch_ring;
+	u32 tmp, ch_id;
+	int ret;
+
+	ch_id = MHI_TRE_GET_CMD_CHID(el);
+
+	/* Check if the channel is supported by the controller */
+	if ((ch_id >= mhi_cntrl->max_chan) || !mhi_cntrl->mhi_chan[ch_id].name) {
+		dev_dbg(dev, "Channel (%u) not supported!\n", ch_id);
+		return -ENODEV;
+	}
+
+	mhi_chan = &mhi_cntrl->mhi_chan[ch_id];
+	ch_ring = &mhi_cntrl->mhi_chan[ch_id].ring;
+
+	switch (MHI_TRE_GET_CMD_TYPE(el)) {
+	case MHI_PKT_TYPE_START_CHAN_CMD:
+		dev_dbg(dev, "Received START command for channel (%u)\n", ch_id);
+
+		mutex_lock(&mhi_chan->lock);
+		/* Initialize and configure the corresponding channel ring */
+		if (!ch_ring->started) {
+			ret = mhi_ep_ring_start(mhi_cntrl, ch_ring,
+				(union mhi_ep_ring_ctx *)&mhi_cntrl->ch_ctx_cache[ch_id]);
+			if (ret) {
+				dev_err(dev, "Failed to start ring for channel (%u)\n", ch_id);
+				ret = mhi_ep_send_cmd_comp_event(mhi_cntrl,
+							MHI_EV_CC_UNDEFINED_ERR);
+				if (ret)
+					dev_err(dev, "Error sending completion event: %d\n", ret);
+
+				goto err_unlock;
+			}
+		}
+
+		/* Set channel state to RUNNING */
+		mhi_chan->state = MHI_CH_STATE_RUNNING;
+		tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[ch_id].chcfg);
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_RUNNING);
+		mhi_cntrl->ch_ctx_cache[ch_id].chcfg = cpu_to_le32(tmp);
+
+		ret = mhi_ep_send_cmd_comp_event(mhi_cntrl, MHI_EV_CC_SUCCESS);
+		if (ret) {
+			dev_err(dev, "Error sending command completion event (%u)\n",
+				MHI_EV_CC_SUCCESS);
+			goto err_unlock;
+		}
+
+		mutex_unlock(&mhi_chan->lock);
+
+		/*
+		 * Create MHI device only during UL channel start. Since the MHI
+		 * channels operate in a pair, we'll associate both UL and DL
+		 * channels to the same device.
+		 *
+		 * We also need to check for mhi_dev != NULL because, the host
+		 * will issue START_CHAN command during resume and we don't
+		 * destroy the device during suspend.
+		 */
+		if (!(ch_id % 2) && !mhi_chan->mhi_dev) {
+			ret = mhi_ep_create_device(mhi_cntrl, ch_id);
+			if (ret) {
+				dev_err(dev, "Error creating device for channel (%u)\n", ch_id);
+				mhi_ep_handle_syserr(mhi_cntrl);
+				return ret;
+			}
+		}
+
+		/* Finally, enable DB for the channel */
+		mhi_ep_mmio_enable_chdb(mhi_cntrl, ch_id);
+
+		break;
+	case MHI_PKT_TYPE_STOP_CHAN_CMD:
+		dev_dbg(dev, "Received STOP command for channel (%u)\n", ch_id);
+		if (!ch_ring->started) {
+			dev_err(dev, "Channel (%u) not opened\n", ch_id);
+			return -ENODEV;
+		}
+
+		mutex_lock(&mhi_chan->lock);
+		/* Disable DB for the channel */
+		mhi_ep_mmio_disable_chdb(mhi_cntrl, ch_id);
+
+		/* Send channel disconnect status to client drivers */
+		if (mhi_chan->xfer_cb) {
+			result.transaction_status = -ENOTCONN;
+			result.bytes_xferd = 0;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+		}
+
+		/* Set channel state to STOP */
+		mhi_chan->state = MHI_CH_STATE_STOP;
+		tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[ch_id].chcfg);
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_STOP);
+		mhi_cntrl->ch_ctx_cache[ch_id].chcfg = cpu_to_le32(tmp);
+
+		ret = mhi_ep_send_cmd_comp_event(mhi_cntrl, MHI_EV_CC_SUCCESS);
+		if (ret) {
+			dev_err(dev, "Error sending command completion event (%u)\n",
+				MHI_EV_CC_SUCCESS);
+			goto err_unlock;
+		}
+
+		mutex_unlock(&mhi_chan->lock);
+		break;
+	case MHI_PKT_TYPE_RESET_CHAN_CMD:
+		dev_dbg(dev, "Received RESET command for channel (%u)\n", ch_id);
+		if (!ch_ring->started) {
+			dev_err(dev, "Channel (%u) not opened\n", ch_id);
+			return -ENODEV;
+		}
+
+		mutex_lock(&mhi_chan->lock);
+		/* Stop and reset the transfer ring */
+		mhi_ep_ring_reset(mhi_cntrl, ch_ring);
+
+		/* Send channel disconnect status to client driver */
+		if (mhi_chan->xfer_cb) {
+			result.transaction_status = -ENOTCONN;
+			result.bytes_xferd = 0;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+		}
+
+		/* Set channel state to DISABLED */
+		mhi_chan->state = MHI_CH_STATE_DISABLED;
+		tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[ch_id].chcfg);
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_DISABLED);
+		mhi_cntrl->ch_ctx_cache[ch_id].chcfg = cpu_to_le32(tmp);
+
+		ret = mhi_ep_send_cmd_comp_event(mhi_cntrl, MHI_EV_CC_SUCCESS);
+		if (ret) {
+			dev_err(dev, "Error sending command completion event (%u)\n",
+				MHI_EV_CC_SUCCESS);
+			goto err_unlock;
+		}
+
+		mutex_unlock(&mhi_chan->lock);
+		break;
+	default:
+		dev_err(dev, "Invalid command received: %lu for channel (%u)\n",
+			MHI_TRE_GET_CMD_TYPE(el), ch_id);
+		return -EINVAL;
+	}
+
+	return 0;
+
+err_unlock:
+	mutex_unlock(&mhi_chan->lock);
+
+	return ret;
+}
+
+bool mhi_ep_queue_is_empty(struct mhi_ep_device *mhi_dev, enum dma_data_direction dir)
+{
+	struct mhi_ep_chan *mhi_chan = (dir == DMA_FROM_DEVICE) ? mhi_dev->dl_chan :
+								mhi_dev->ul_chan;
+	struct mhi_ep_cntrl *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct mhi_ep_ring *ring = &mhi_cntrl->mhi_chan[mhi_chan->chan].ring;
+
+	return !!(ring->rd_offset == ring->wr_offset);
+}
+EXPORT_SYMBOL_GPL(mhi_ep_queue_is_empty);
+
+static int mhi_ep_read_channel(struct mhi_ep_cntrl *mhi_cntrl,
+				struct mhi_ep_ring *ring,
+				struct mhi_result *result,
+				u32 len)
+{
+	struct mhi_ep_chan *mhi_chan = &mhi_cntrl->mhi_chan[ring->ch_id];
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	size_t tr_len, read_offset, write_offset;
+	struct mhi_ep_buf_info buf_info = {};
+	struct mhi_ring_element *el;
+	bool tr_done = false;
+	u32 buf_left;
+	int ret;
+
+	buf_left = len;
+
+	do {
+		/* Don't process the transfer ring if the channel is not in RUNNING state */
+		if (mhi_chan->state != MHI_CH_STATE_RUNNING) {
+			dev_err(dev, "Channel not available\n");
+			return -ENODEV;
+		}
+
+		el = &ring->ring_cache[ring->rd_offset];
+
+		/* Check if there is data pending to be read from previous read operation */
+		if (mhi_chan->tre_bytes_left) {
+			dev_dbg(dev, "TRE bytes remaining: %u\n", mhi_chan->tre_bytes_left);
+			tr_len = min(buf_left, mhi_chan->tre_bytes_left);
+		} else {
+			mhi_chan->tre_loc = MHI_TRE_DATA_GET_PTR(el);
+			mhi_chan->tre_size = MHI_TRE_DATA_GET_LEN(el);
+			mhi_chan->tre_bytes_left = mhi_chan->tre_size;
+
+			tr_len = min(buf_left, mhi_chan->tre_size);
+		}
+
+		read_offset = mhi_chan->tre_size - mhi_chan->tre_bytes_left;
+		write_offset = len - buf_left;
+
+		buf_info.host_addr = mhi_chan->tre_loc + read_offset;
+		buf_info.dev_addr = result->buf_addr + write_offset;
+		buf_info.size = tr_len;
+
+		dev_dbg(dev, "Reading %zd bytes from channel (%u)\n", tr_len, ring->ch_id);
+		ret = mhi_cntrl->read_from_host(mhi_cntrl, &buf_info);
+		if (ret < 0) {
+			dev_err(&mhi_chan->mhi_dev->dev, "Error reading from channel\n");
+			return ret;
+		}
+
+		buf_left -= tr_len;
+		mhi_chan->tre_bytes_left -= tr_len;
+
+		/*
+		 * Once the TRE (Transfer Ring Element) of a TD (Transfer Descriptor) has been
+		 * read completely:
+		 *
+		 * 1. Send completion event to the host based on the flags set in TRE.
+		 * 2. Increment the local read offset of the transfer ring.
+		 */
+		if (!mhi_chan->tre_bytes_left) {
+			/*
+			 * The host will split the data packet into multiple TREs if it can't fit
+			 * the packet in a single TRE. In that case, CHAIN flag will be set by the
+			 * host for all TREs except the last one.
+			 */
+			if (MHI_TRE_DATA_GET_CHAIN(el)) {
+				/*
+				 * IEOB (Interrupt on End of Block) flag will be set by the host if
+				 * it expects the completion event for all TREs of a TD.
+				 */
+				if (MHI_TRE_DATA_GET_IEOB(el)) {
+					ret = mhi_ep_send_completion_event(mhi_cntrl, ring, el,
+								     MHI_TRE_DATA_GET_LEN(el),
+								     MHI_EV_CC_EOB);
+					if (ret < 0) {
+						dev_err(&mhi_chan->mhi_dev->dev,
+							"Error sending transfer compl. event\n");
+						return ret;
+					}
+				}
+			} else {
+				/*
+				 * IEOT (Interrupt on End of Transfer) flag will be set by the host
+				 * for the last TRE of the TD and expects the completion event for
+				 * the same.
+				 */
+				if (MHI_TRE_DATA_GET_IEOT(el)) {
+					ret = mhi_ep_send_completion_event(mhi_cntrl, ring, el,
+								     MHI_TRE_DATA_GET_LEN(el),
+								     MHI_EV_CC_EOT);
+					if (ret < 0) {
+						dev_err(&mhi_chan->mhi_dev->dev,
+							"Error sending transfer compl. event\n");
+						return ret;
+					}
+				}
+
+				tr_done = true;
+			}
+
+			mhi_ep_ring_inc_index(ring);
+		}
+
+		result->bytes_xferd += tr_len;
+	} while (buf_left && !tr_done);
+
+	return 0;
+}
+
+static int mhi_ep_process_ch_ring(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
+	struct mhi_result result = {};
+	u32 len = MHI_EP_DEFAULT_MTU;
+	struct mhi_ep_chan *mhi_chan;
+	int ret;
+
+	mhi_chan = &mhi_cntrl->mhi_chan[ring->ch_id];
+
+	/*
+	 * Bail out if transfer callback is not registered for the channel.
+	 * This is most likely due to the client driver not loaded at this point.
+	 */
+	if (!mhi_chan->xfer_cb) {
+		dev_err(&mhi_chan->mhi_dev->dev, "Client driver not available\n");
+		return -ENODEV;
+	}
+
+	if (ring->ch_id % 2) {
+		/* DL channel */
+		result.dir = mhi_chan->dir;
+		mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+	} else {
+		/* UL channel */
+		result.buf_addr = kmem_cache_zalloc(mhi_cntrl->tre_buf_cache, GFP_KERNEL | GFP_DMA);
+		if (!result.buf_addr)
+			return -ENOMEM;
+
+		do {
+			ret = mhi_ep_read_channel(mhi_cntrl, ring, &result, len);
+			if (ret < 0) {
+				dev_err(&mhi_chan->mhi_dev->dev, "Failed to read channel\n");
+				kmem_cache_free(mhi_cntrl->tre_buf_cache, result.buf_addr);
+				return ret;
+			}
+
+			result.dir = mhi_chan->dir;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+			result.bytes_xferd = 0;
+			memset(result.buf_addr, 0, len);
+
+			/* Read until the ring becomes empty */
+		} while (!mhi_ep_queue_is_empty(mhi_chan->mhi_dev, DMA_TO_DEVICE));
+
+		kmem_cache_free(mhi_cntrl->tre_buf_cache, result.buf_addr);
+	}
+
+	return 0;
+}
+
+/* TODO: Handle partially formed TDs */
+int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct mhi_ep_chan *mhi_chan = mhi_dev->dl_chan;
+	struct device *dev = &mhi_chan->mhi_dev->dev;
+	struct mhi_ep_buf_info buf_info = {};
+	struct mhi_ring_element *el;
+	u32 buf_left, read_offset;
+	struct mhi_ep_ring *ring;
+	enum mhi_ev_ccs code;
+	size_t tr_len;
+	u32 tre_len;
+	int ret;
+
+	buf_left = skb->len;
+	ring = &mhi_cntrl->mhi_chan[mhi_chan->chan].ring;
+
+	mutex_lock(&mhi_chan->lock);
+
+	do {
+		/* Don't process the transfer ring if the channel is not in RUNNING state */
+		if (mhi_chan->state != MHI_CH_STATE_RUNNING) {
+			dev_err(dev, "Channel not available\n");
+			ret = -ENODEV;
+			goto err_exit;
+		}
+
+		if (mhi_ep_queue_is_empty(mhi_dev, DMA_FROM_DEVICE)) {
+			dev_err(dev, "TRE not available!\n");
+			ret = -ENOSPC;
+			goto err_exit;
+		}
+
+		el = &ring->ring_cache[ring->rd_offset];
+		tre_len = MHI_TRE_DATA_GET_LEN(el);
+
+		tr_len = min(buf_left, tre_len);
+		read_offset = skb->len - buf_left;
+
+		buf_info.dev_addr = skb->data + read_offset;
+		buf_info.host_addr = MHI_TRE_DATA_GET_PTR(el);
+		buf_info.size = tr_len;
+
+		dev_dbg(dev, "Writing %zd bytes to channel (%u)\n", tr_len, ring->ch_id);
+		ret = mhi_cntrl->write_to_host(mhi_cntrl, &buf_info);
+		if (ret < 0) {
+			dev_err(dev, "Error writing to the channel\n");
+			goto err_exit;
+		}
+
+		buf_left -= tr_len;
+		/*
+		 * For all TREs queued by the host for DL channel, only the EOT flag will be set.
+		 * If the packet doesn't fit into a single TRE, send the OVERFLOW event to
+		 * the host so that the host can adjust the packet boundary to next TREs. Else send
+		 * the EOT event to the host indicating the packet boundary.
+		 */
+		if (buf_left)
+			code = MHI_EV_CC_OVERFLOW;
+		else
+			code = MHI_EV_CC_EOT;
+
+		ret = mhi_ep_send_completion_event(mhi_cntrl, ring, el, tr_len, code);
+		if (ret) {
+			dev_err(dev, "Error sending transfer completion event\n");
+			goto err_exit;
+		}
+
+		mhi_ep_ring_inc_index(ring);
+	} while (buf_left);
+
+	mutex_unlock(&mhi_chan->lock);
+
+	return 0;
+
+err_exit:
+	mutex_unlock(&mhi_chan->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mhi_ep_queue_skb);
+
+static int mhi_ep_cache_host_cfg(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	size_t cmd_ctx_host_size, ch_ctx_host_size, ev_ctx_host_size;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int ret;
+
+	/* Update the number of event rings (NER) programmed by the host */
+	mhi_ep_mmio_update_ner(mhi_cntrl);
+
+	dev_dbg(dev, "Number of Event rings: %u, HW Event rings: %u\n",
+		 mhi_cntrl->event_rings, mhi_cntrl->hw_event_rings);
+
+	ch_ctx_host_size = sizeof(struct mhi_chan_ctxt) * mhi_cntrl->max_chan;
+	ev_ctx_host_size = sizeof(struct mhi_event_ctxt) * mhi_cntrl->event_rings;
+	cmd_ctx_host_size = sizeof(struct mhi_cmd_ctxt) * NR_OF_CMD_RINGS;
+
+	/* Get the channel context base pointer from host */
+	mhi_ep_mmio_get_chc_base(mhi_cntrl);
+
+	/* Allocate and map memory for caching host channel context */
+	ret = mhi_cntrl->alloc_map(mhi_cntrl, mhi_cntrl->ch_ctx_host_pa,
+				   &mhi_cntrl->ch_ctx_cache_phys,
+				   (void __iomem **) &mhi_cntrl->ch_ctx_cache,
+				   ch_ctx_host_size);
+	if (ret) {
+		dev_err(dev, "Failed to allocate and map ch_ctx_cache\n");
+		return ret;
+	}
+
+	/* Get the event context base pointer from host */
+	mhi_ep_mmio_get_erc_base(mhi_cntrl);
+
+	/* Allocate and map memory for caching host event context */
+	ret = mhi_cntrl->alloc_map(mhi_cntrl, mhi_cntrl->ev_ctx_host_pa,
+				   &mhi_cntrl->ev_ctx_cache_phys,
+				   (void __iomem **) &mhi_cntrl->ev_ctx_cache,
+				   ev_ctx_host_size);
+	if (ret) {
+		dev_err(dev, "Failed to allocate and map ev_ctx_cache\n");
+		goto err_ch_ctx;
+	}
+
+	/* Get the command context base pointer from host */
+	mhi_ep_mmio_get_crc_base(mhi_cntrl);
+
+	/* Allocate and map memory for caching host command context */
+	ret = mhi_cntrl->alloc_map(mhi_cntrl, mhi_cntrl->cmd_ctx_host_pa,
+				   &mhi_cntrl->cmd_ctx_cache_phys,
+				   (void __iomem **) &mhi_cntrl->cmd_ctx_cache,
+				   cmd_ctx_host_size);
+	if (ret) {
+		dev_err(dev, "Failed to allocate and map cmd_ctx_cache\n");
+		goto err_ev_ctx;
+	}
+
+	/* Initialize command ring */
+	ret = mhi_ep_ring_start(mhi_cntrl, &mhi_cntrl->mhi_cmd->ring,
+				(union mhi_ep_ring_ctx *)mhi_cntrl->cmd_ctx_cache);
+	if (ret) {
+		dev_err(dev, "Failed to start the command ring\n");
+		goto err_cmd_ctx;
+	}
+
+	return ret;
+
+err_cmd_ctx:
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->cmd_ctx_host_pa, mhi_cntrl->cmd_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->cmd_ctx_cache, cmd_ctx_host_size);
+
+err_ev_ctx:
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->ev_ctx_host_pa, mhi_cntrl->ev_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->ev_ctx_cache, ev_ctx_host_size);
+
+err_ch_ctx:
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->ch_ctx_host_pa, mhi_cntrl->ch_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->ch_ctx_cache, ch_ctx_host_size);
+
+	return ret;
+}
+
+static void mhi_ep_free_host_cfg(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	size_t cmd_ctx_host_size, ch_ctx_host_size, ev_ctx_host_size;
+
+	ch_ctx_host_size = sizeof(struct mhi_chan_ctxt) * mhi_cntrl->max_chan;
+	ev_ctx_host_size = sizeof(struct mhi_event_ctxt) * mhi_cntrl->event_rings;
+	cmd_ctx_host_size = sizeof(struct mhi_cmd_ctxt) * NR_OF_CMD_RINGS;
+
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->cmd_ctx_host_pa, mhi_cntrl->cmd_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->cmd_ctx_cache, cmd_ctx_host_size);
+
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->ev_ctx_host_pa, mhi_cntrl->ev_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->ev_ctx_cache, ev_ctx_host_size);
+
+	mhi_cntrl->unmap_free(mhi_cntrl, mhi_cntrl->ch_ctx_host_pa, mhi_cntrl->ch_ctx_cache_phys,
+			      (void __iomem *) mhi_cntrl->ch_ctx_cache, ch_ctx_host_size);
+}
+
+static void mhi_ep_enable_int(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	/*
+	 * Doorbell interrupts are enabled when the corresponding channel gets started.
+	 * Enabling all interrupts here triggers spurious irqs as some of the interrupts
+	 * associated with hw channels always get triggered.
+	 */
+	mhi_ep_mmio_enable_ctrl_interrupt(mhi_cntrl);
+	mhi_ep_mmio_enable_cmdb_interrupt(mhi_cntrl);
+}
+
+static int mhi_ep_enable(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_state state;
+	bool mhi_reset;
+	u32 count = 0;
+	int ret;
+
+	/* Wait for Host to set the M0 state */
+	do {
+		msleep(M0_WAIT_DELAY_MS);
+		mhi_ep_mmio_get_mhi_state(mhi_cntrl, &state, &mhi_reset);
+		if (mhi_reset) {
+			/* Clear the MHI reset if host is in reset state */
+			mhi_ep_mmio_clear_reset(mhi_cntrl);
+			dev_info(dev, "Detected Host reset while waiting for M0\n");
+		}
+		count++;
+	} while (state != MHI_STATE_M0 && count < M0_WAIT_COUNT);
+
+	if (state != MHI_STATE_M0) {
+		dev_err(dev, "Host failed to enter M0\n");
+		return -ETIMEDOUT;
+	}
+
+	ret = mhi_ep_cache_host_cfg(mhi_cntrl);
+	if (ret) {
+		dev_err(dev, "Failed to cache host config\n");
+		return ret;
+	}
+
+	mhi_ep_mmio_set_env(mhi_cntrl, MHI_EE_AMSS);
+
+	/* Enable all interrupts now */
+	mhi_ep_enable_int(mhi_cntrl);
+
+	return 0;
+}
+
+static void mhi_ep_cmd_ring_worker(struct work_struct *work)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = container_of(work, struct mhi_ep_cntrl, cmd_ring_work);
+	struct mhi_ep_ring *ring = &mhi_cntrl->mhi_cmd->ring;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_ring_element *el;
+	int ret;
+
+	/* Update the write offset for the ring */
+	ret = mhi_ep_update_wr_offset(ring);
+	if (ret) {
+		dev_err(dev, "Error updating write offset for ring\n");
+		return;
+	}
+
+	/* Sanity check to make sure there are elements in the ring */
+	if (ring->rd_offset == ring->wr_offset)
+		return;
+
+	/*
+	 * Process command ring element till write offset. In case of an error, just try to
+	 * process next element.
+	 */
+	while (ring->rd_offset != ring->wr_offset) {
+		el = &ring->ring_cache[ring->rd_offset];
+
+		ret = mhi_ep_process_cmd_ring(ring, el);
+		if (ret && ret != -ENODEV)
+			dev_err(dev, "Error processing cmd ring element: %zu\n", ring->rd_offset);
+
+		mhi_ep_ring_inc_index(ring);
+	}
+}
+
+static void mhi_ep_ch_ring_worker(struct work_struct *work)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = container_of(work, struct mhi_ep_cntrl, ch_ring_work);
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_ep_ring_item *itr, *tmp;
+	struct mhi_ring_element *el;
+	struct mhi_ep_ring *ring;
+	struct mhi_ep_chan *chan;
+	unsigned long flags;
+	LIST_HEAD(head);
+	int ret;
+
+	spin_lock_irqsave(&mhi_cntrl->list_lock, flags);
+	list_splice_tail_init(&mhi_cntrl->ch_db_list, &head);
+	spin_unlock_irqrestore(&mhi_cntrl->list_lock, flags);
+
+	/* Process each queued channel ring. In case of an error, just process next element. */
+	list_for_each_entry_safe(itr, tmp, &head, node) {
+		list_del(&itr->node);
+		ring = itr->ring;
+
+		chan = &mhi_cntrl->mhi_chan[ring->ch_id];
+		mutex_lock(&chan->lock);
+
+		/*
+		 * The ring could've stopped while we waited to grab the (chan->lock), so do
+		 * a sanity check before going further.
+		 */
+		if (!ring->started) {
+			mutex_unlock(&chan->lock);
+			kfree(itr);
+			continue;
+		}
+
+		/* Update the write offset for the ring */
+		ret = mhi_ep_update_wr_offset(ring);
+		if (ret) {
+			dev_err(dev, "Error updating write offset for ring\n");
+			mutex_unlock(&chan->lock);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
+			continue;
+		}
+
+		/* Sanity check to make sure there are elements in the ring */
+		if (ring->rd_offset == ring->wr_offset) {
+			mutex_unlock(&chan->lock);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
+			continue;
+		}
+
+		el = &ring->ring_cache[ring->rd_offset];
+
+		dev_dbg(dev, "Processing the ring for channel (%u)\n", ring->ch_id);
+		ret = mhi_ep_process_ch_ring(ring, el);
+		if (ret) {
+			dev_err(dev, "Error processing ring for channel (%u): %d\n",
+				ring->ch_id, ret);
+			mutex_unlock(&chan->lock);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
+			continue;
+		}
+
+		mutex_unlock(&chan->lock);
+		kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
+	}
+}
+
+static void mhi_ep_state_worker(struct work_struct *work)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = container_of(work, struct mhi_ep_cntrl, state_work);
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_ep_state_transition *itr, *tmp;
+	unsigned long flags;
+	LIST_HEAD(head);
+	int ret;
+
+	spin_lock_irqsave(&mhi_cntrl->list_lock, flags);
+	list_splice_tail_init(&mhi_cntrl->st_transition_list, &head);
+	spin_unlock_irqrestore(&mhi_cntrl->list_lock, flags);
+
+	list_for_each_entry_safe(itr, tmp, &head, node) {
+		list_del(&itr->node);
+		dev_dbg(dev, "Handling MHI state transition to %s\n",
+			 mhi_state_str(itr->state));
+
+		switch (itr->state) {
+		case MHI_STATE_M0:
+			ret = mhi_ep_set_m0_state(mhi_cntrl);
+			if (ret)
+				dev_err(dev, "Failed to transition to M0 state\n");
+			break;
+		case MHI_STATE_M3:
+			ret = mhi_ep_set_m3_state(mhi_cntrl);
+			if (ret)
+				dev_err(dev, "Failed to transition to M3 state\n");
+			break;
+		default:
+			dev_err(dev, "Invalid MHI state transition: %d\n", itr->state);
+			break;
+		}
+		kfree(itr);
+	}
+}
+
+static void mhi_ep_queue_channel_db(struct mhi_ep_cntrl *mhi_cntrl, unsigned long ch_int,
+				    u32 ch_idx)
+{
+	struct mhi_ep_ring_item *item;
+	struct mhi_ep_ring *ring;
+	bool work = !!ch_int;
+	LIST_HEAD(head);
+	u32 i;
+
+	/* First add the ring items to a local list */
+	for_each_set_bit(i, &ch_int, 32) {
+		/* Channel index varies for each register: 0, 32, 64, 96 */
+		u32 ch_id = ch_idx + i;
+
+		ring = &mhi_cntrl->mhi_chan[ch_id].ring;
+		item = kmem_cache_zalloc(mhi_cntrl->ring_item_cache, GFP_ATOMIC);
+		if (!item)
+			return;
+
+		item->ring = ring;
+		list_add_tail(&item->node, &head);
+	}
+
+	/* Now, splice the local list into ch_db_list and queue the work item */
+	if (work) {
+		spin_lock(&mhi_cntrl->list_lock);
+		list_splice_tail_init(&head, &mhi_cntrl->ch_db_list);
+		spin_unlock(&mhi_cntrl->list_lock);
+
+		queue_work(mhi_cntrl->wq, &mhi_cntrl->ch_ring_work);
+	}
+}
+
+/*
+ * Channel interrupt statuses are contained in 4 registers each of 32bit length.
+ * For checking all interrupts, we need to loop through each registers and then
+ * check for bits set.
+ */
+static void mhi_ep_check_channel_interrupt(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 ch_int, ch_idx, i;
+
+	/* Bail out if there is no channel doorbell interrupt */
+	if (!mhi_ep_mmio_read_chdb_status_interrupts(mhi_cntrl))
+		return;
+
+	for (i = 0; i < MHI_MASK_ROWS_CH_DB; i++) {
+		ch_idx = i * MHI_MASK_CH_LEN;
+
+		/* Only process channel interrupt if the mask is enabled */
+		ch_int = mhi_cntrl->chdb[i].status & mhi_cntrl->chdb[i].mask;
+		if (ch_int) {
+			mhi_ep_queue_channel_db(mhi_cntrl, ch_int, ch_idx);
+			mhi_ep_mmio_write(mhi_cntrl, MHI_CHDB_INT_CLEAR_n(i),
+							mhi_cntrl->chdb[i].status);
+		}
+	}
+}
+
+static void mhi_ep_process_ctrl_interrupt(struct mhi_ep_cntrl *mhi_cntrl,
+					 enum mhi_state state)
+{
+	struct mhi_ep_state_transition *item;
+
+	item = kzalloc(sizeof(*item), GFP_ATOMIC);
+	if (!item)
+		return;
+
+	item->state = state;
+	spin_lock(&mhi_cntrl->list_lock);
+	list_add_tail(&item->node, &mhi_cntrl->st_transition_list);
+	spin_unlock(&mhi_cntrl->list_lock);
+
+	queue_work(mhi_cntrl->wq, &mhi_cntrl->state_work);
+}
+
+/*
+ * Interrupt handler that services interrupts raised by the host writing to
+ * MHICTRL and Command ring doorbell (CRDB) registers for state change and
+ * channel interrupts.
+ */
+static irqreturn_t mhi_ep_irq(int irq, void *data)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = data;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_state state;
+	u32 int_value;
+	bool mhi_reset;
+
+	/* Acknowledge the ctrl interrupt */
+	int_value = mhi_ep_mmio_read(mhi_cntrl, MHI_CTRL_INT_STATUS);
+	mhi_ep_mmio_write(mhi_cntrl, MHI_CTRL_INT_CLEAR, int_value);
+
+	/* Check for ctrl interrupt */
+	if (FIELD_GET(MHI_CTRL_INT_STATUS_MSK, int_value)) {
+		dev_dbg(dev, "Processing ctrl interrupt\n");
+		mhi_ep_mmio_get_mhi_state(mhi_cntrl, &state, &mhi_reset);
+		if (mhi_reset) {
+			dev_info(dev, "Host triggered MHI reset!\n");
+			disable_irq_nosync(mhi_cntrl->irq);
+			schedule_work(&mhi_cntrl->reset_work);
+			return IRQ_HANDLED;
+		}
+
+		mhi_ep_process_ctrl_interrupt(mhi_cntrl, state);
+	}
+
+	/* Check for command doorbell interrupt */
+	if (FIELD_GET(MHI_CTRL_INT_STATUS_CRDB_MSK, int_value)) {
+		dev_dbg(dev, "Processing command doorbell interrupt\n");
+		queue_work(mhi_cntrl->wq, &mhi_cntrl->cmd_ring_work);
+	}
+
+	/* Check for channel interrupts */
+	mhi_ep_check_channel_interrupt(mhi_cntrl);
+
+	return IRQ_HANDLED;
+}
+
+static void mhi_ep_abort_transfer(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_ring *ch_ring, *ev_ring;
+	struct mhi_result result = {};
+	struct mhi_ep_chan *mhi_chan;
+	int i;
+
+	/* Stop all the channels */
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+		if (!mhi_chan->ring.started)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Send channel disconnect status to client drivers */
+		if (mhi_chan->xfer_cb) {
+			result.transaction_status = -ENOTCONN;
+			result.bytes_xferd = 0;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+		}
+
+		mhi_chan->state = MHI_CH_STATE_DISABLED;
+		mutex_unlock(&mhi_chan->lock);
+	}
+
+	flush_workqueue(mhi_cntrl->wq);
+
+	/* Destroy devices associated with all channels */
+	device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_ep_destroy_device);
+
+	/* Stop and reset the transfer rings */
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+		if (!mhi_chan->ring.started)
+			continue;
+
+		ch_ring = &mhi_cntrl->mhi_chan[i].ring;
+		mutex_lock(&mhi_chan->lock);
+		mhi_ep_ring_reset(mhi_cntrl, ch_ring);
+		mutex_unlock(&mhi_chan->lock);
+	}
+
+	/* Stop and reset the event rings */
+	for (i = 0; i < mhi_cntrl->event_rings; i++) {
+		ev_ring = &mhi_cntrl->mhi_event[i].ring;
+		if (!ev_ring->started)
+			continue;
+
+		mutex_lock(&mhi_cntrl->event_lock);
+		mhi_ep_ring_reset(mhi_cntrl, ev_ring);
+		mutex_unlock(&mhi_cntrl->event_lock);
+	}
+
+	/* Stop and reset the command ring */
+	mhi_ep_ring_reset(mhi_cntrl, &mhi_cntrl->mhi_cmd->ring);
+
+	mhi_ep_free_host_cfg(mhi_cntrl);
+	mhi_ep_mmio_mask_interrupts(mhi_cntrl);
+
+	mhi_cntrl->enabled = false;
+}
+
+static void mhi_ep_reset_worker(struct work_struct *work)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = container_of(work, struct mhi_ep_cntrl, reset_work);
+	enum mhi_state cur_state;
+
+	mhi_ep_power_down(mhi_cntrl);
+
+	mutex_lock(&mhi_cntrl->state_lock);
+
+	/* Reset MMIO to signal host that the MHI_RESET is completed in endpoint */
+	mhi_ep_mmio_reset(mhi_cntrl);
+	cur_state = mhi_cntrl->mhi_state;
+
+	/*
+	 * Only proceed further if the reset is due to SYS_ERR. The host will
+	 * issue reset during shutdown also and we don't need to do re-init in
+	 * that case.
+	 */
+	if (cur_state == MHI_STATE_SYS_ERR)
+		mhi_ep_power_up(mhi_cntrl);
+
+	mutex_unlock(&mhi_cntrl->state_lock);
+}
+
+/*
+ * We don't need to do anything special other than setting the MHI SYS_ERR
+ * state. The host will reset all contexts and issue MHI RESET so that we
+ * could also recover from error state.
+ */
+void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int ret;
+
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_SYS_ERR);
+	if (ret)
+		return;
+
+	/* Signal host that the device went to SYS_ERR state */
+	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_SYS_ERR);
+	if (ret)
+		dev_err(dev, "Failed sending SYS_ERR state change event: %d\n", ret);
+}
+
+int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int ret, i;
+
+	/*
+	 * Mask all interrupts until the state machine is ready. Interrupts will
+	 * be enabled later with mhi_ep_enable().
+	 */
+	mhi_ep_mmio_mask_interrupts(mhi_cntrl);
+	mhi_ep_mmio_init(mhi_cntrl);
+
+	mhi_cntrl->mhi_event = kzalloc(mhi_cntrl->event_rings * (sizeof(*mhi_cntrl->mhi_event)),
+					GFP_KERNEL);
+	if (!mhi_cntrl->mhi_event)
+		return -ENOMEM;
+
+	/* Initialize command, channel and event rings */
+	mhi_ep_ring_init(&mhi_cntrl->mhi_cmd->ring, RING_TYPE_CMD, 0);
+	for (i = 0; i < mhi_cntrl->max_chan; i++)
+		mhi_ep_ring_init(&mhi_cntrl->mhi_chan[i].ring, RING_TYPE_CH, i);
+	for (i = 0; i < mhi_cntrl->event_rings; i++)
+		mhi_ep_ring_init(&mhi_cntrl->mhi_event[i].ring, RING_TYPE_ER, i);
+
+	mhi_cntrl->mhi_state = MHI_STATE_RESET;
+
+	/* Set AMSS EE before signaling ready state */
+	mhi_ep_mmio_set_env(mhi_cntrl, MHI_EE_AMSS);
+
+	/* All set, notify the host that we are ready */
+	ret = mhi_ep_set_ready_state(mhi_cntrl);
+	if (ret)
+		goto err_free_event;
+
+	dev_dbg(dev, "READY state notification sent to the host\n");
+
+	ret = mhi_ep_enable(mhi_cntrl);
+	if (ret) {
+		dev_err(dev, "Failed to enable MHI endpoint\n");
+		goto err_free_event;
+	}
+
+	enable_irq(mhi_cntrl->irq);
+	mhi_cntrl->enabled = true;
+
+	return 0;
+
+err_free_event:
+	kfree(mhi_cntrl->mhi_event);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mhi_ep_power_up);
+
+void mhi_ep_power_down(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	if (mhi_cntrl->enabled) {
+		mhi_ep_abort_transfer(mhi_cntrl);
+		kfree(mhi_cntrl->mhi_event);
+		disable_irq(mhi_cntrl->irq);
+	}
+}
+EXPORT_SYMBOL_GPL(mhi_ep_power_down);
+
+void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_chan *mhi_chan;
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+
+		if (!mhi_chan->mhi_dev)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Skip if the channel is not currently running */
+		tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[i].chcfg);
+		if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_RUNNING) {
+			mutex_unlock(&mhi_chan->lock);
+			continue;
+		}
+
+		dev_dbg(&mhi_chan->mhi_dev->dev, "Suspending channel\n");
+		/* Set channel state to SUSPENDED */
+		mhi_chan->state = MHI_CH_STATE_SUSPENDED;
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_SUSPENDED);
+		mhi_cntrl->ch_ctx_cache[i].chcfg = cpu_to_le32(tmp);
+		mutex_unlock(&mhi_chan->lock);
+	}
+}
+
+void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_chan *mhi_chan;
+	u32 tmp;
+	int i;
+
+	for (i = 0; i < mhi_cntrl->max_chan; i++) {
+		mhi_chan = &mhi_cntrl->mhi_chan[i];
+
+		if (!mhi_chan->mhi_dev)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Skip if the channel is not currently suspended */
+		tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[i].chcfg);
+		if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_SUSPENDED) {
+			mutex_unlock(&mhi_chan->lock);
+			continue;
+		}
+
+		dev_dbg(&mhi_chan->mhi_dev->dev, "Resuming channel\n");
+		/* Set channel state to RUNNING */
+		mhi_chan->state = MHI_CH_STATE_RUNNING;
+		tmp &= ~CHAN_CTX_CHSTATE_MASK;
+		tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_RUNNING);
+		mhi_cntrl->ch_ctx_cache[i].chcfg = cpu_to_le32(tmp);
+		mutex_unlock(&mhi_chan->lock);
+	}
+}
+
+static void mhi_ep_release_device(struct device *dev)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		mhi_dev->mhi_cntrl->mhi_dev = NULL;
+
+	/*
+	 * We need to set the mhi_chan->mhi_dev to NULL here since the MHI
+	 * devices for the channels will only get created in mhi_ep_create_device()
+	 * if the mhi_dev associated with it is NULL.
+	 */
+	if (mhi_dev->ul_chan)
+		mhi_dev->ul_chan->mhi_dev = NULL;
+
+	if (mhi_dev->dl_chan)
+		mhi_dev->dl_chan->mhi_dev = NULL;
+
+	kfree(mhi_dev);
+}
+
+static struct mhi_ep_device *mhi_ep_alloc_device(struct mhi_ep_cntrl *mhi_cntrl,
+						 enum mhi_device_type dev_type)
+{
+	struct mhi_ep_device *mhi_dev;
+	struct device *dev;
+
+	mhi_dev = kzalloc(sizeof(*mhi_dev), GFP_KERNEL);
+	if (!mhi_dev)
+		return ERR_PTR(-ENOMEM);
+
+	dev = &mhi_dev->dev;
+	device_initialize(dev);
+	dev->bus = &mhi_ep_bus_type;
+	dev->release = mhi_ep_release_device;
+
+	/* Controller device is always allocated first */
+	if (dev_type == MHI_DEVICE_CONTROLLER)
+		/* for MHI controller device, parent is the bus device (e.g. PCI EPF) */
+		dev->parent = mhi_cntrl->cntrl_dev;
+	else
+		/* for MHI client devices, parent is the MHI controller device */
+		dev->parent = &mhi_cntrl->mhi_dev->dev;
+
+	mhi_dev->mhi_cntrl = mhi_cntrl;
+	mhi_dev->dev_type = dev_type;
+
+	return mhi_dev;
+}
+
+/*
+ * MHI channels are always defined in pairs with UL as the even numbered
+ * channel and DL as odd numbered one. This function gets UL channel (primary)
+ * as the ch_id and always looks after the next entry in channel list for
+ * the corresponding DL channel (secondary).
+ */
+static int mhi_ep_create_device(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id)
+{
+	struct mhi_ep_chan *mhi_chan = &mhi_cntrl->mhi_chan[ch_id];
+	struct device *dev = mhi_cntrl->cntrl_dev;
+	struct mhi_ep_device *mhi_dev;
+	int ret;
+
+	/* Check if the channel name is same for both UL and DL */
+	if (strcmp(mhi_chan->name, mhi_chan[1].name)) {
+		dev_err(dev, "UL and DL channel names are not same: (%s) != (%s)\n",
+			mhi_chan->name, mhi_chan[1].name);
+		return -EINVAL;
+	}
+
+	mhi_dev = mhi_ep_alloc_device(mhi_cntrl, MHI_DEVICE_XFER);
+	if (IS_ERR(mhi_dev))
+		return PTR_ERR(mhi_dev);
+
+	/* Configure primary channel */
+	mhi_dev->ul_chan = mhi_chan;
+	get_device(&mhi_dev->dev);
+	mhi_chan->mhi_dev = mhi_dev;
+
+	/* Configure secondary channel as well */
+	mhi_chan++;
+	mhi_dev->dl_chan = mhi_chan;
+	get_device(&mhi_dev->dev);
+	mhi_chan->mhi_dev = mhi_dev;
+
+	/* Channel name is same for both UL and DL */
+	mhi_dev->name = mhi_chan->name;
+	ret = dev_set_name(&mhi_dev->dev, "%s_%s",
+		     dev_name(&mhi_cntrl->mhi_dev->dev),
+		     mhi_dev->name);
+	if (ret) {
+		put_device(&mhi_dev->dev);
+		return ret;
+	}
+
+	ret = device_add(&mhi_dev->dev);
+	if (ret)
+		put_device(&mhi_dev->dev);
+
+	return ret;
+}
+
+static int mhi_ep_destroy_device(struct device *dev, void *data)
+{
+	struct mhi_ep_device *mhi_dev;
+	struct mhi_ep_cntrl *mhi_cntrl;
+	struct mhi_ep_chan *ul_chan, *dl_chan;
+
+	if (dev->bus != &mhi_ep_bus_type)
+		return 0;
+
+	mhi_dev = to_mhi_ep_device(dev);
+	mhi_cntrl = mhi_dev->mhi_cntrl;
+
+	/* Only destroy devices created for channels */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	ul_chan = mhi_dev->ul_chan;
+	dl_chan = mhi_dev->dl_chan;
+
+	if (ul_chan)
+		put_device(&ul_chan->mhi_dev->dev);
+
+	if (dl_chan)
+		put_device(&dl_chan->mhi_dev->dev);
+
+	dev_dbg(&mhi_cntrl->mhi_dev->dev, "Destroying device for chan:%s\n",
+		 mhi_dev->name);
+
+	/* Notify the client and remove the device from MHI bus */
+	device_del(dev);
+	put_device(dev);
+
+	return 0;
+}
+
+static int mhi_ep_chan_init(struct mhi_ep_cntrl *mhi_cntrl,
+			    const struct mhi_ep_cntrl_config *config)
+{
+	const struct mhi_ep_channel_config *ch_cfg;
+	struct device *dev = mhi_cntrl->cntrl_dev;
+	u32 chan, i;
+	int ret = -EINVAL;
+
+	mhi_cntrl->max_chan = config->max_channels;
+
+	/*
+	 * Allocate max_channels supported by the MHI endpoint and populate
+	 * only the defined channels
+	 */
+	mhi_cntrl->mhi_chan = kcalloc(mhi_cntrl->max_chan, sizeof(*mhi_cntrl->mhi_chan),
+				      GFP_KERNEL);
+	if (!mhi_cntrl->mhi_chan)
+		return -ENOMEM;
+
+	for (i = 0; i < config->num_channels; i++) {
+		struct mhi_ep_chan *mhi_chan;
+
+		ch_cfg = &config->ch_cfg[i];
+
+		chan = ch_cfg->num;
+		if (chan >= mhi_cntrl->max_chan) {
+			dev_err(dev, "Channel (%u) exceeds maximum available channels (%u)\n",
+				chan, mhi_cntrl->max_chan);
+			goto error_chan_cfg;
+		}
+
+		/* Bi-directional and direction less channels are not supported */
+		if (ch_cfg->dir == DMA_BIDIRECTIONAL || ch_cfg->dir == DMA_NONE) {
+			dev_err(dev, "Invalid direction (%u) for channel (%u)\n",
+				ch_cfg->dir, chan);
+			goto error_chan_cfg;
+		}
+
+		mhi_chan = &mhi_cntrl->mhi_chan[chan];
+		mhi_chan->name = ch_cfg->name;
+		mhi_chan->chan = chan;
+		mhi_chan->dir = ch_cfg->dir;
+		mutex_init(&mhi_chan->lock);
+	}
+
+	return 0;
+
+error_chan_cfg:
+	kfree(mhi_cntrl->mhi_chan);
+
+	return ret;
+}
+
+/*
+ * Allocate channel and command rings here. Event rings will be allocated
+ * in mhi_ep_power_up() as the config comes from the host.
+ */
+int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
+				const struct mhi_ep_cntrl_config *config)
+{
+	struct mhi_ep_device *mhi_dev;
+	int ret;
+
+	if (!mhi_cntrl || !mhi_cntrl->cntrl_dev || !mhi_cntrl->mmio || !mhi_cntrl->irq)
+		return -EINVAL;
+
+	ret = mhi_ep_chan_init(mhi_cntrl, config);
+	if (ret)
+		return ret;
+
+	mhi_cntrl->mhi_cmd = kcalloc(NR_OF_CMD_RINGS, sizeof(*mhi_cntrl->mhi_cmd), GFP_KERNEL);
+	if (!mhi_cntrl->mhi_cmd) {
+		ret = -ENOMEM;
+		goto err_free_ch;
+	}
+
+	mhi_cntrl->ev_ring_el_cache = kmem_cache_create("mhi_ep_event_ring_el",
+							sizeof(struct mhi_ring_element), 0,
+							SLAB_CACHE_DMA, NULL);
+	if (!mhi_cntrl->ev_ring_el_cache) {
+		ret = -ENOMEM;
+		goto err_free_cmd;
+	}
+
+	mhi_cntrl->tre_buf_cache = kmem_cache_create("mhi_ep_tre_buf", MHI_EP_DEFAULT_MTU, 0,
+						      SLAB_CACHE_DMA, NULL);
+	if (!mhi_cntrl->tre_buf_cache) {
+		ret = -ENOMEM;
+		goto err_destroy_ev_ring_el_cache;
+	}
+
+	mhi_cntrl->ring_item_cache = kmem_cache_create("mhi_ep_ring_item",
+							sizeof(struct mhi_ep_ring_item), 0,
+							0, NULL);
+	if (!mhi_cntrl->ev_ring_el_cache) {
+		ret = -ENOMEM;
+		goto err_destroy_tre_buf_cache;
+	}
+	INIT_WORK(&mhi_cntrl->state_work, mhi_ep_state_worker);
+	INIT_WORK(&mhi_cntrl->reset_work, mhi_ep_reset_worker);
+	INIT_WORK(&mhi_cntrl->cmd_ring_work, mhi_ep_cmd_ring_worker);
+	INIT_WORK(&mhi_cntrl->ch_ring_work, mhi_ep_ch_ring_worker);
+
+	mhi_cntrl->wq = alloc_workqueue("mhi_ep_wq", 0, 0);
+	if (!mhi_cntrl->wq) {
+		ret = -ENOMEM;
+		goto err_destroy_ring_item_cache;
+	}
+
+	INIT_LIST_HEAD(&mhi_cntrl->st_transition_list);
+	INIT_LIST_HEAD(&mhi_cntrl->ch_db_list);
+	spin_lock_init(&mhi_cntrl->list_lock);
+	mutex_init(&mhi_cntrl->state_lock);
+	mutex_init(&mhi_cntrl->event_lock);
+
+	/* Set MHI version and AMSS EE before enumeration */
+	mhi_ep_mmio_write(mhi_cntrl, EP_MHIVER, config->mhi_version);
+	mhi_ep_mmio_set_env(mhi_cntrl, MHI_EE_AMSS);
+
+	/* Set controller index */
+	ret = ida_alloc(&mhi_ep_cntrl_ida, GFP_KERNEL);
+	if (ret < 0)
+		goto err_destroy_wq;
+
+	mhi_cntrl->index = ret;
+
+	irq_set_status_flags(mhi_cntrl->irq, IRQ_NOAUTOEN);
+	ret = request_irq(mhi_cntrl->irq, mhi_ep_irq, IRQF_TRIGGER_HIGH,
+			  "doorbell_irq", mhi_cntrl);
+	if (ret) {
+		dev_err(mhi_cntrl->cntrl_dev, "Failed to request Doorbell IRQ\n");
+		goto err_ida_free;
+	}
+
+	/* Allocate the controller device */
+	mhi_dev = mhi_ep_alloc_device(mhi_cntrl, MHI_DEVICE_CONTROLLER);
+	if (IS_ERR(mhi_dev)) {
+		dev_err(mhi_cntrl->cntrl_dev, "Failed to allocate controller device\n");
+		ret = PTR_ERR(mhi_dev);
+		goto err_free_irq;
+	}
+
+	ret = dev_set_name(&mhi_dev->dev, "mhi_ep%u", mhi_cntrl->index);
+	if (ret)
+		goto err_put_dev;
+
+	mhi_dev->name = dev_name(&mhi_dev->dev);
+	mhi_cntrl->mhi_dev = mhi_dev;
+
+	ret = device_add(&mhi_dev->dev);
+	if (ret)
+		goto err_put_dev;
+
+	dev_dbg(&mhi_dev->dev, "MHI EP Controller registered\n");
+
+	return 0;
+
+err_put_dev:
+	put_device(&mhi_dev->dev);
+err_free_irq:
+	free_irq(mhi_cntrl->irq, mhi_cntrl);
+err_ida_free:
+	ida_free(&mhi_ep_cntrl_ida, mhi_cntrl->index);
+err_destroy_wq:
+	destroy_workqueue(mhi_cntrl->wq);
+err_destroy_ring_item_cache:
+	kmem_cache_destroy(mhi_cntrl->ring_item_cache);
+err_destroy_ev_ring_el_cache:
+	kmem_cache_destroy(mhi_cntrl->ev_ring_el_cache);
+err_destroy_tre_buf_cache:
+	kmem_cache_destroy(mhi_cntrl->tre_buf_cache);
+err_free_cmd:
+	kfree(mhi_cntrl->mhi_cmd);
+err_free_ch:
+	kfree(mhi_cntrl->mhi_chan);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mhi_ep_register_controller);
+
+/*
+ * It is expected that the controller drivers will power down the MHI EP stack
+ * using "mhi_ep_power_down()" before calling this function to unregister themselves.
+ */
+void mhi_ep_unregister_controller(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct mhi_ep_device *mhi_dev = mhi_cntrl->mhi_dev;
+
+	destroy_workqueue(mhi_cntrl->wq);
+
+	free_irq(mhi_cntrl->irq, mhi_cntrl);
+
+	kmem_cache_destroy(mhi_cntrl->tre_buf_cache);
+	kmem_cache_destroy(mhi_cntrl->ev_ring_el_cache);
+	kmem_cache_destroy(mhi_cntrl->ring_item_cache);
+	kfree(mhi_cntrl->mhi_cmd);
+	kfree(mhi_cntrl->mhi_chan);
+
+	device_del(&mhi_dev->dev);
+	put_device(&mhi_dev->dev);
+
+	ida_free(&mhi_ep_cntrl_ida, mhi_cntrl->index);
+}
+EXPORT_SYMBOL_GPL(mhi_ep_unregister_controller);
+
+static int mhi_ep_driver_probe(struct device *dev)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(dev->driver);
+	struct mhi_ep_chan *ul_chan = mhi_dev->ul_chan;
+	struct mhi_ep_chan *dl_chan = mhi_dev->dl_chan;
+
+	ul_chan->xfer_cb = mhi_drv->ul_xfer_cb;
+	dl_chan->xfer_cb = mhi_drv->dl_xfer_cb;
+
+	return mhi_drv->probe(mhi_dev, mhi_dev->id);
+}
+
+static int mhi_ep_driver_remove(struct device *dev)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(dev->driver);
+	struct mhi_result result = {};
+	struct mhi_ep_chan *mhi_chan;
+	int dir;
+
+	/* Skip if it is a controller device */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	/* Disconnect the channels associated with the driver */
+	for (dir = 0; dir < 2; dir++) {
+		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;
+
+		if (!mhi_chan)
+			continue;
+
+		mutex_lock(&mhi_chan->lock);
+		/* Send channel disconnect status to the client driver */
+		if (mhi_chan->xfer_cb) {
+			result.transaction_status = -ENOTCONN;
+			result.bytes_xferd = 0;
+			mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
+		}
+
+		mhi_chan->state = MHI_CH_STATE_DISABLED;
+		mhi_chan->xfer_cb = NULL;
+		mutex_unlock(&mhi_chan->lock);
+	}
+
+	/* Remove the client driver now */
+	mhi_drv->remove(mhi_dev);
+
+	return 0;
+}
+
+int __mhi_ep_driver_register(struct mhi_ep_driver *mhi_drv, struct module *owner)
+{
+	struct device_driver *driver = &mhi_drv->driver;
+
+	if (!mhi_drv->probe || !mhi_drv->remove)
+		return -EINVAL;
+
+	/* Client drivers should have callbacks defined for both channels */
+	if (!mhi_drv->ul_xfer_cb || !mhi_drv->dl_xfer_cb)
+		return -EINVAL;
+
+	driver->bus = &mhi_ep_bus_type;
+	driver->owner = owner;
+	driver->probe = mhi_ep_driver_probe;
+	driver->remove = mhi_ep_driver_remove;
+
+	return driver_register(driver);
+}
+EXPORT_SYMBOL_GPL(__mhi_ep_driver_register);
+
+void mhi_ep_driver_unregister(struct mhi_ep_driver *mhi_drv)
+{
+	driver_unregister(&mhi_drv->driver);
+}
+EXPORT_SYMBOL_GPL(mhi_ep_driver_unregister);
+
+static int mhi_ep_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	const struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+
+	return add_uevent_var(env, "MODALIAS=" MHI_EP_DEVICE_MODALIAS_FMT,
+					mhi_dev->name);
+}
+
+static int mhi_ep_match(struct device *dev, struct device_driver *drv)
+{
+	struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
+	struct mhi_ep_driver *mhi_drv = to_mhi_ep_driver(drv);
+	const struct mhi_device_id *id;
+
+	/*
+	 * If the device is a controller type then there is no client driver
+	 * associated with it
+	 */
+	if (mhi_dev->dev_type == MHI_DEVICE_CONTROLLER)
+		return 0;
+
+	for (id = mhi_drv->id_table; id->chan[0]; id++)
+		if (!strcmp(mhi_dev->name, id->chan)) {
+			mhi_dev->id = id;
+			return 1;
+		}
+
+	return 0;
+};
+
+struct bus_type mhi_ep_bus_type = {
+	.name = "mhi_ep",
+	.dev_name = "mhi_ep",
+	.match = mhi_ep_match,
+	.uevent = mhi_ep_uevent,
+};
+
+static int __init mhi_ep_init(void)
+{
+	return bus_register(&mhi_ep_bus_type);
+}
+
+static void __exit mhi_ep_exit(void)
+{
+	bus_unregister(&mhi_ep_bus_type);
+}
+
+postcore_initcall(mhi_ep_init);
+module_exit(mhi_ep_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MHI Bus Endpoint stack");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
diff --git a/drivers/bus/mhi/ep/mmio.c b/drivers/bus/mhi/ep/mmio.c
new file mode 100644
index 0000000000..b5bfd22f2c
--- /dev/null
+++ b/drivers/bus/mhi/ep/mmio.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/io.h>
+#include <linux/mhi_ep.h>
+
+#include "internal.h"
+
+u32 mhi_ep_mmio_read(struct mhi_ep_cntrl *mhi_cntrl, u32 offset)
+{
+	return readl(mhi_cntrl->mmio + offset);
+}
+
+void mhi_ep_mmio_write(struct mhi_ep_cntrl *mhi_cntrl, u32 offset, u32 val)
+{
+	writel(val, mhi_cntrl->mmio + offset);
+}
+
+void mhi_ep_mmio_masked_write(struct mhi_ep_cntrl *mhi_cntrl, u32 offset, u32 mask, u32 val)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, offset);
+	regval &= ~mask;
+	regval |= (val << __ffs(mask)) & mask;
+	mhi_ep_mmio_write(mhi_cntrl, offset, regval);
+}
+
+u32 mhi_ep_mmio_masked_read(struct mhi_ep_cntrl *dev, u32 offset, u32 mask)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(dev, offset);
+	regval &= mask;
+	regval >>= __ffs(mask);
+
+	return regval;
+}
+
+void mhi_ep_mmio_get_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state *state,
+				bool *mhi_reset)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_MHICTRL);
+	*state = FIELD_GET(MHICTRL_MHISTATE_MASK, regval);
+	*mhi_reset = !!FIELD_GET(MHICTRL_RESET_MASK, regval);
+}
+
+static void mhi_ep_mmio_set_chdb(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id, bool enable)
+{
+	u32 chid_mask, chid_shift, chdb_idx, val;
+
+	chid_shift = ch_id % 32;
+	chid_mask = BIT(chid_shift);
+	chdb_idx = ch_id / 32;
+
+	val = enable ? 1 : 0;
+
+	mhi_ep_mmio_masked_write(mhi_cntrl, MHI_CHDB_INT_MASK_n(chdb_idx), chid_mask, val);
+
+	/* Update the local copy of the channel mask */
+	mhi_cntrl->chdb[chdb_idx].mask &= ~chid_mask;
+	mhi_cntrl->chdb[chdb_idx].mask |= val << chid_shift;
+}
+
+void mhi_ep_mmio_enable_chdb(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id)
+{
+	mhi_ep_mmio_set_chdb(mhi_cntrl, ch_id, true);
+}
+
+void mhi_ep_mmio_disable_chdb(struct mhi_ep_cntrl *mhi_cntrl, u32 ch_id)
+{
+	mhi_ep_mmio_set_chdb(mhi_cntrl, ch_id, false);
+}
+
+static void mhi_ep_mmio_set_chdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl, bool enable)
+{
+	u32 val, i;
+
+	val = enable ? MHI_CHDB_INT_MASK_n_EN_ALL : 0;
+
+	for (i = 0; i < MHI_MASK_ROWS_CH_DB; i++) {
+		mhi_ep_mmio_write(mhi_cntrl, MHI_CHDB_INT_MASK_n(i), val);
+		mhi_cntrl->chdb[i].mask = val;
+	}
+}
+
+void mhi_ep_mmio_enable_chdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_set_chdb_interrupts(mhi_cntrl, true);
+}
+
+static void mhi_ep_mmio_mask_chdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_set_chdb_interrupts(mhi_cntrl, false);
+}
+
+bool mhi_ep_mmio_read_chdb_status_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	bool chdb = false;
+	u32 i;
+
+	for (i = 0; i < MHI_MASK_ROWS_CH_DB; i++) {
+		mhi_cntrl->chdb[i].status = mhi_ep_mmio_read(mhi_cntrl, MHI_CHDB_INT_STATUS_n(i));
+		if (mhi_cntrl->chdb[i].status)
+			chdb = true;
+	}
+
+	/* Return whether a channel doorbell interrupt occurred or not */
+	return chdb;
+}
+
+static void mhi_ep_mmio_set_erdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl, bool enable)
+{
+	u32 val, i;
+
+	val = enable ? MHI_ERDB_INT_MASK_n_EN_ALL : 0;
+
+	for (i = 0; i < MHI_MASK_ROWS_EV_DB; i++)
+		mhi_ep_mmio_write(mhi_cntrl, MHI_ERDB_INT_MASK_n(i), val);
+}
+
+static void mhi_ep_mmio_mask_erdb_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_set_erdb_interrupts(mhi_cntrl, false);
+}
+
+void mhi_ep_mmio_enable_ctrl_interrupt(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_masked_write(mhi_cntrl, MHI_CTRL_INT_MASK,
+				  MHI_CTRL_MHICTRL_MASK, 1);
+}
+
+void mhi_ep_mmio_disable_ctrl_interrupt(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_masked_write(mhi_cntrl, MHI_CTRL_INT_MASK,
+				  MHI_CTRL_MHICTRL_MASK, 0);
+}
+
+void mhi_ep_mmio_enable_cmdb_interrupt(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_masked_write(mhi_cntrl, MHI_CTRL_INT_MASK,
+				  MHI_CTRL_CRDB_MASK, 1);
+}
+
+void mhi_ep_mmio_disable_cmdb_interrupt(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_masked_write(mhi_cntrl, MHI_CTRL_INT_MASK,
+				  MHI_CTRL_CRDB_MASK, 0);
+}
+
+void mhi_ep_mmio_mask_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_disable_ctrl_interrupt(mhi_cntrl);
+	mhi_ep_mmio_disable_cmdb_interrupt(mhi_cntrl);
+	mhi_ep_mmio_mask_chdb_interrupts(mhi_cntrl);
+	mhi_ep_mmio_mask_erdb_interrupts(mhi_cntrl);
+}
+
+static void mhi_ep_mmio_clear_interrupts(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 i;
+
+	for (i = 0; i < MHI_MASK_ROWS_CH_DB; i++)
+		mhi_ep_mmio_write(mhi_cntrl, MHI_CHDB_INT_CLEAR_n(i),
+				   MHI_CHDB_INT_CLEAR_n_CLEAR_ALL);
+
+	for (i = 0; i < MHI_MASK_ROWS_EV_DB; i++)
+		mhi_ep_mmio_write(mhi_cntrl, MHI_ERDB_INT_CLEAR_n(i),
+				   MHI_ERDB_INT_CLEAR_n_CLEAR_ALL);
+
+	mhi_ep_mmio_write(mhi_cntrl, MHI_CTRL_INT_CLEAR,
+			   MHI_CTRL_INT_MMIO_WR_CLEAR |
+			   MHI_CTRL_INT_CRDB_CLEAR |
+			   MHI_CTRL_INT_CRDB_MHICTRL_CLEAR);
+}
+
+void mhi_ep_mmio_get_chc_base(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_CCABAP_HIGHER);
+	mhi_cntrl->ch_ctx_host_pa = regval;
+	mhi_cntrl->ch_ctx_host_pa <<= 32;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_CCABAP_LOWER);
+	mhi_cntrl->ch_ctx_host_pa |= regval;
+}
+
+void mhi_ep_mmio_get_erc_base(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_ECABAP_HIGHER);
+	mhi_cntrl->ev_ctx_host_pa = regval;
+	mhi_cntrl->ev_ctx_host_pa <<= 32;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_ECABAP_LOWER);
+	mhi_cntrl->ev_ctx_host_pa |= regval;
+}
+
+void mhi_ep_mmio_get_crc_base(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_CRCBAP_HIGHER);
+	mhi_cntrl->cmd_ctx_host_pa = regval;
+	mhi_cntrl->cmd_ctx_host_pa <<= 32;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_CRCBAP_LOWER);
+	mhi_cntrl->cmd_ctx_host_pa |= regval;
+}
+
+u64 mhi_ep_mmio_get_db(struct mhi_ep_ring *ring)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
+	u64 db_offset;
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, ring->db_offset_h);
+	db_offset = regval;
+	db_offset <<= 32;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, ring->db_offset_l);
+	db_offset |= regval;
+
+	return db_offset;
+}
+
+void mhi_ep_mmio_set_env(struct mhi_ep_cntrl *mhi_cntrl, u32 value)
+{
+	mhi_ep_mmio_write(mhi_cntrl, EP_BHI_EXECENV, value);
+}
+
+void mhi_ep_mmio_clear_reset(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_masked_write(mhi_cntrl, EP_MHICTRL, MHICTRL_RESET_MASK, 0);
+}
+
+void mhi_ep_mmio_reset(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	mhi_ep_mmio_write(mhi_cntrl, EP_MHICTRL, 0);
+	mhi_ep_mmio_write(mhi_cntrl, EP_MHISTATUS, 0);
+	mhi_ep_mmio_clear_interrupts(mhi_cntrl);
+}
+
+void mhi_ep_mmio_init(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 regval;
+
+	mhi_cntrl->chdb_offset = mhi_ep_mmio_read(mhi_cntrl, EP_CHDBOFF);
+	mhi_cntrl->erdb_offset = mhi_ep_mmio_read(mhi_cntrl, EP_ERDBOFF);
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_MHICFG);
+	mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
+	mhi_cntrl->hw_event_rings = FIELD_GET(MHICFG_NHWER_MASK, regval);
+
+	mhi_ep_mmio_reset(mhi_cntrl);
+}
+
+void mhi_ep_mmio_update_ner(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	u32 regval;
+
+	regval = mhi_ep_mmio_read(mhi_cntrl, EP_MHICFG);
+	mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
+	mhi_cntrl->hw_event_rings = FIELD_GET(MHICFG_NHWER_MASK, regval);
+}
diff --git a/drivers/bus/mhi/ep/ring.c b/drivers/bus/mhi/ep/ring.c
new file mode 100644
index 0000000000..c673d7200b
--- /dev/null
+++ b/drivers/bus/mhi/ep/ring.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ */
+
+#include <linux/mhi_ep.h>
+#include "internal.h"
+
+size_t mhi_ep_ring_addr2offset(struct mhi_ep_ring *ring, u64 ptr)
+{
+	return (ptr - ring->rbase) / sizeof(struct mhi_ring_element);
+}
+
+static u32 mhi_ep_ring_num_elems(struct mhi_ep_ring *ring)
+{
+	__le64 rlen;
+
+	memcpy_fromio(&rlen, (void __iomem *) &ring->ring_ctx->generic.rlen, sizeof(u64));
+
+	return le64_to_cpu(rlen) / sizeof(struct mhi_ring_element);
+}
+
+void mhi_ep_ring_inc_index(struct mhi_ep_ring *ring)
+{
+	ring->rd_offset = (ring->rd_offset + 1) % ring->ring_size;
+}
+
+static int __mhi_ep_cache_ring(struct mhi_ep_ring *ring, size_t end)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_ep_buf_info buf_info = {};
+	size_t start;
+	int ret;
+
+	/* Don't proceed in the case of event ring. This happens during mhi_ep_ring_start(). */
+	if (ring->type == RING_TYPE_ER)
+		return 0;
+
+	/* No need to cache the ring if write pointer is unmodified */
+	if (ring->wr_offset == end)
+		return 0;
+
+	start = ring->wr_offset;
+	if (start < end) {
+		buf_info.size = (end - start) * sizeof(struct mhi_ring_element);
+		buf_info.host_addr = ring->rbase + (start * sizeof(struct mhi_ring_element));
+		buf_info.dev_addr = &ring->ring_cache[start];
+
+		ret = mhi_cntrl->read_from_host(mhi_cntrl, &buf_info);
+		if (ret < 0)
+			return ret;
+	} else {
+		buf_info.size = (ring->ring_size - start) * sizeof(struct mhi_ring_element);
+		buf_info.host_addr = ring->rbase + (start * sizeof(struct mhi_ring_element));
+		buf_info.dev_addr = &ring->ring_cache[start];
+
+		ret = mhi_cntrl->read_from_host(mhi_cntrl, &buf_info);
+		if (ret < 0)
+			return ret;
+
+		if (end) {
+			buf_info.host_addr = ring->rbase;
+			buf_info.dev_addr = &ring->ring_cache[0];
+			buf_info.size = end * sizeof(struct mhi_ring_element);
+
+			ret = mhi_cntrl->read_from_host(mhi_cntrl, &buf_info);
+			if (ret < 0)
+				return ret;
+		}
+	}
+
+	dev_dbg(dev, "Cached ring: start %zu end %zu size %zu\n", start, end, buf_info.size);
+
+	return 0;
+}
+
+static int mhi_ep_cache_ring(struct mhi_ep_ring *ring, u64 wr_ptr)
+{
+	size_t wr_offset;
+	int ret;
+
+	wr_offset = mhi_ep_ring_addr2offset(ring, wr_ptr);
+
+	/* Cache the host ring till write offset */
+	ret = __mhi_ep_cache_ring(ring, wr_offset);
+	if (ret)
+		return ret;
+
+	ring->wr_offset = wr_offset;
+
+	return 0;
+}
+
+int mhi_ep_update_wr_offset(struct mhi_ep_ring *ring)
+{
+	u64 wr_ptr;
+
+	wr_ptr = mhi_ep_mmio_get_db(ring);
+
+	return mhi_ep_cache_ring(ring, wr_ptr);
+}
+
+/* TODO: Support for adding multiple ring elements to the ring */
+int mhi_ep_ring_add_element(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
+{
+	struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	struct mhi_ep_buf_info buf_info = {};
+	size_t old_offset = 0;
+	u32 num_free_elem;
+	__le64 rp;
+	int ret;
+
+	ret = mhi_ep_update_wr_offset(ring);
+	if (ret) {
+		dev_err(dev, "Error updating write pointer\n");
+		return ret;
+	}
+
+	if (ring->rd_offset < ring->wr_offset)
+		num_free_elem = (ring->wr_offset - ring->rd_offset) - 1;
+	else
+		num_free_elem = ((ring->ring_size - ring->rd_offset) + ring->wr_offset) - 1;
+
+	/* Check if there is space in ring for adding at least an element */
+	if (!num_free_elem) {
+		dev_err(dev, "No space left in the ring\n");
+		return -ENOSPC;
+	}
+
+	old_offset = ring->rd_offset;
+	mhi_ep_ring_inc_index(ring);
+
+	dev_dbg(dev, "Adding an element to ring at offset (%zu)\n", ring->rd_offset);
+
+	/* Update rp in ring context */
+	rp = cpu_to_le64(ring->rd_offset * sizeof(*el) + ring->rbase);
+	memcpy_toio((void __iomem *) &ring->ring_ctx->generic.rp, &rp, sizeof(u64));
+
+	buf_info.host_addr = ring->rbase + (old_offset * sizeof(*el));
+	buf_info.dev_addr = el;
+	buf_info.size = sizeof(*el);
+
+	return mhi_cntrl->write_to_host(mhi_cntrl, &buf_info);
+}
+
+void mhi_ep_ring_init(struct mhi_ep_ring *ring, enum mhi_ep_ring_type type, u32 id)
+{
+	ring->type = type;
+	if (ring->type == RING_TYPE_CMD) {
+		ring->db_offset_h = EP_CRDB_HIGHER;
+		ring->db_offset_l = EP_CRDB_LOWER;
+	} else if (ring->type == RING_TYPE_CH) {
+		ring->db_offset_h = CHDB_HIGHER_n(id);
+		ring->db_offset_l = CHDB_LOWER_n(id);
+		ring->ch_id = id;
+	} else {
+		ring->db_offset_h = ERDB_HIGHER_n(id);
+		ring->db_offset_l = ERDB_LOWER_n(id);
+	}
+}
+
+int mhi_ep_ring_start(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
+			union mhi_ep_ring_ctx *ctx)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	__le64 val;
+	int ret;
+
+	ring->mhi_cntrl = mhi_cntrl;
+	ring->ring_ctx = ctx;
+	ring->ring_size = mhi_ep_ring_num_elems(ring);
+	memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rbase, sizeof(u64));
+	ring->rbase = le64_to_cpu(val);
+
+	if (ring->type == RING_TYPE_CH)
+		ring->er_index = le32_to_cpu(ring->ring_ctx->ch.erindex);
+
+	if (ring->type == RING_TYPE_ER)
+		ring->irq_vector = le32_to_cpu(ring->ring_ctx->ev.msivec);
+
+	/* During ring init, both rp and wp are equal */
+	memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rp, sizeof(u64));
+	ring->rd_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));
+	ring->wr_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));
+
+	/* Allocate ring cache memory for holding the copy of host ring */
+	ring->ring_cache = kcalloc(ring->ring_size, sizeof(struct mhi_ring_element), GFP_KERNEL);
+	if (!ring->ring_cache)
+		return -ENOMEM;
+
+	memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.wp, sizeof(u64));
+	ret = mhi_ep_cache_ring(ring, le64_to_cpu(val));
+	if (ret) {
+		dev_err(dev, "Failed to cache ring\n");
+		kfree(ring->ring_cache);
+		return ret;
+	}
+
+	ring->started = true;
+
+	return 0;
+}
+
+void mhi_ep_ring_reset(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring)
+{
+	ring->started = false;
+	kfree(ring->ring_cache);
+	ring->ring_cache = NULL;
+}
diff --git a/drivers/bus/mhi/ep/sm.c b/drivers/bus/mhi/ep/sm.c
new file mode 100644
index 0000000000..fd200b2ac0
--- /dev/null
+++ b/drivers/bus/mhi/ep/sm.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Linaro Ltd.
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/mhi_ep.h>
+#include "internal.h"
+
+bool __must_check mhi_ep_check_mhi_state(struct mhi_ep_cntrl *mhi_cntrl,
+					 enum mhi_state cur_mhi_state,
+					 enum mhi_state mhi_state)
+{
+	if (mhi_state == MHI_STATE_SYS_ERR)
+		return true;    /* Allowed in any state */
+
+	if (mhi_state == MHI_STATE_READY)
+		return cur_mhi_state == MHI_STATE_RESET;
+
+	if (mhi_state == MHI_STATE_M0)
+		return cur_mhi_state == MHI_STATE_M3 || cur_mhi_state == MHI_STATE_READY;
+
+	if (mhi_state == MHI_STATE_M3)
+		return cur_mhi_state == MHI_STATE_M0;
+
+	return false;
+}
+
+int mhi_ep_set_mhi_state(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state mhi_state)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+
+	if (!mhi_ep_check_mhi_state(mhi_cntrl, mhi_cntrl->mhi_state, mhi_state)) {
+		dev_err(dev, "MHI state change to %s from %s is not allowed!\n",
+			mhi_state_str(mhi_state),
+			mhi_state_str(mhi_cntrl->mhi_state));
+		return -EACCES;
+	}
+
+	/* TODO: Add support for M1 and M2 states */
+	if (mhi_state == MHI_STATE_M1 || mhi_state == MHI_STATE_M2) {
+		dev_err(dev, "MHI state (%s) not supported\n", mhi_state_str(mhi_state));
+		return -EOPNOTSUPP;
+	}
+
+	mhi_ep_mmio_masked_write(mhi_cntrl, EP_MHISTATUS, MHISTATUS_MHISTATE_MASK, mhi_state);
+	mhi_cntrl->mhi_state = mhi_state;
+
+	if (mhi_state == MHI_STATE_READY)
+		mhi_ep_mmio_masked_write(mhi_cntrl, EP_MHISTATUS, MHISTATUS_READY_MASK, 1);
+
+	if (mhi_state == MHI_STATE_SYS_ERR)
+		mhi_ep_mmio_masked_write(mhi_cntrl, EP_MHISTATUS, MHISTATUS_SYSERR_MASK, 1);
+
+	return 0;
+}
+
+int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_state old_state;
+	int ret;
+
+	/* If MHI is in M3, resume suspended channels */
+	mutex_lock(&mhi_cntrl->state_lock);
+
+	old_state = mhi_cntrl->mhi_state;
+	if (old_state == MHI_STATE_M3)
+		mhi_ep_resume_channels(mhi_cntrl);
+
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
+	if (ret) {
+		mhi_ep_handle_syserr(mhi_cntrl);
+		goto err_unlock;
+	}
+
+	/* Signal host that the device moved to M0 */
+	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M0);
+	if (ret) {
+		dev_err(dev, "Failed sending M0 state change event\n");
+		goto err_unlock;
+	}
+
+	if (old_state == MHI_STATE_READY) {
+		/* Send AMSS EE event to host */
+		ret = mhi_ep_send_ee_event(mhi_cntrl, MHI_EE_AMSS);
+		if (ret) {
+			dev_err(dev, "Failed sending AMSS EE event\n");
+			goto err_unlock;
+		}
+	}
+
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
+	return ret;
+}
+
+int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	int ret;
+
+	mutex_lock(&mhi_cntrl->state_lock);
+
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M3);
+	if (ret) {
+		mhi_ep_handle_syserr(mhi_cntrl);
+		goto err_unlock;
+	}
+
+	mhi_ep_suspend_channels(mhi_cntrl);
+
+	/* Signal host that the device moved to M3 */
+	ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M3);
+	if (ret) {
+		dev_err(dev, "Failed sending M3 state change event\n");
+		goto err_unlock;
+	}
+
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
+	return ret;
+}
+
+int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl)
+{
+	struct device *dev = &mhi_cntrl->mhi_dev->dev;
+	enum mhi_state mhi_state;
+	int ret, is_ready;
+
+	mutex_lock(&mhi_cntrl->state_lock);
+
+	/* Ensure that the MHISTATUS is set to RESET by host */
+	mhi_state = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_MHISTATE_MASK);
+	is_ready = mhi_ep_mmio_masked_read(mhi_cntrl, EP_MHISTATUS, MHISTATUS_READY_MASK);
+
+	if (mhi_state != MHI_STATE_RESET || is_ready) {
+		dev_err(dev, "READY state transition failed. MHI host not in RESET state\n");
+		ret = -EIO;
+		goto err_unlock;
+	}
+
+	ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_READY);
+	if (ret)
+		mhi_ep_handle_syserr(mhi_cntrl);
+
+err_unlock:
+	mutex_unlock(&mhi_cntrl->state_lock);
+
+	return ret;
+}