summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/arm_scmi/smc.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/firmware/arm_scmi/smc.c')
-rw-r--r--drivers/firmware/arm_scmi/smc.c277
1 files changed, 277 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
new file mode 100644
index 0000000000..c193516a25
--- /dev/null
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Message SMC/HVC
+ * Transport driver
+ *
+ * Copyright 2020 NXP
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/atomic.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/processor.h>
+#include <linux/slab.h>
+
+#include "common.h"
+
+/*
+ * The shmem address is split into 4K page and offset.
+ * This is to make sure the parameters fit in 32bit arguments of the
+ * smc/hvc call to keep it uniform across smc32/smc64 conventions.
+ * This however limits the shmem address to 44 bit.
+ *
+ * These optional parameters can be used to distinguish among multiple
+ * scmi instances that are using the same smc-id.
+ * The page parameter is passed in r1/x1/w1 register and the offset parameter
+ * is passed in r2/x2/w2 register.
+ */
+
+#define SHMEM_SIZE (SZ_4K)
+#define SHMEM_SHIFT 12
+#define SHMEM_PAGE(x) (_UL((x) >> SHMEM_SHIFT))
+#define SHMEM_OFFSET(x) ((x) & (SHMEM_SIZE - 1))
+
+/**
+ * struct scmi_smc - Structure representing a SCMI smc transport
+ *
+ * @irq: An optional IRQ for completion
+ * @cinfo: SCMI channel info
+ * @shmem: Transmit/Receive shared memory area
+ * @shmem_lock: Lock to protect access to Tx/Rx shared memory area.
+ * Used when NOT operating in atomic mode.
+ * @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
+ * Used when operating in atomic mode.
+ * @func_id: smc/hvc call function id
+ * @param_page: 4K page number of the shmem channel
+ * @param_offset: Offset within the 4K page of the shmem channel
+ */
+
+struct scmi_smc {
+ int irq;
+ struct scmi_chan_info *cinfo;
+ struct scmi_shared_mem __iomem *shmem;
+ /* Protect access to shmem area */
+ struct mutex shmem_lock;
+#define INFLIGHT_NONE MSG_TOKEN_MAX
+ atomic_t inflight;
+ u32 func_id;
+ u32 param_page;
+ u32 param_offset;
+};
+
+static irqreturn_t smc_msg_done_isr(int irq, void *data)
+{
+ struct scmi_smc *scmi_info = data;
+
+ scmi_rx_callback(scmi_info->cinfo,
+ shmem_read_header(scmi_info->shmem), NULL);
+
+ return IRQ_HANDLED;
+}
+
+static bool smc_chan_available(struct device_node *of_node, int idx)
+{
+ struct device_node *np = of_parse_phandle(of_node, "shmem", 0);
+ if (!np)
+ return false;
+
+ of_node_put(np);
+ return true;
+}
+
+static inline void smc_channel_lock_init(struct scmi_smc *scmi_info)
+{
+ if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
+ atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
+ else
+ mutex_init(&scmi_info->shmem_lock);
+}
+
+static bool smc_xfer_inflight(struct scmi_xfer *xfer, atomic_t *inflight)
+{
+ int ret;
+
+ ret = atomic_cmpxchg(inflight, INFLIGHT_NONE, xfer->hdr.seq);
+
+ return ret == INFLIGHT_NONE;
+}
+
+static inline void
+smc_channel_lock_acquire(struct scmi_smc *scmi_info,
+ struct scmi_xfer *xfer __maybe_unused)
+{
+ if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
+ spin_until_cond(smc_xfer_inflight(xfer, &scmi_info->inflight));
+ else
+ mutex_lock(&scmi_info->shmem_lock);
+}
+
+static inline void smc_channel_lock_release(struct scmi_smc *scmi_info)
+{
+ if (IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE))
+ atomic_set(&scmi_info->inflight, INFLIGHT_NONE);
+ else
+ mutex_unlock(&scmi_info->shmem_lock);
+}
+
+static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
+ bool tx)
+{
+ struct device *cdev = cinfo->dev;
+ struct scmi_smc *scmi_info;
+ resource_size_t size;
+ struct resource res;
+ struct device_node *np;
+ u32 func_id;
+ int ret;
+
+ if (!tx)
+ return -ENODEV;
+
+ scmi_info = devm_kzalloc(dev, sizeof(*scmi_info), GFP_KERNEL);
+ if (!scmi_info)
+ return -ENOMEM;
+
+ np = of_parse_phandle(cdev->of_node, "shmem", 0);
+ if (!of_device_is_compatible(np, "arm,scmi-shmem")) {
+ of_node_put(np);
+ return -ENXIO;
+ }
+
+ ret = of_address_to_resource(np, 0, &res);
+ of_node_put(np);
+ if (ret) {
+ dev_err(cdev, "failed to get SCMI Tx shared memory\n");
+ return ret;
+ }
+
+ size = resource_size(&res);
+ scmi_info->shmem = devm_ioremap(dev, res.start, size);
+ if (!scmi_info->shmem) {
+ dev_err(dev, "failed to ioremap SCMI Tx shared memory\n");
+ return -EADDRNOTAVAIL;
+ }
+
+ ret = of_property_read_u32(dev->of_node, "arm,smc-id", &func_id);
+ if (ret < 0)
+ return ret;
+
+ if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
+ scmi_info->param_page = SHMEM_PAGE(res.start);
+ scmi_info->param_offset = SHMEM_OFFSET(res.start);
+ }
+ /*
+ * If there is an interrupt named "a2p", then the service and
+ * completion of a message is signaled by an interrupt rather than by
+ * the return of the SMC call.
+ */
+ scmi_info->irq = of_irq_get_byname(cdev->of_node, "a2p");
+ if (scmi_info->irq > 0) {
+ ret = request_irq(scmi_info->irq, smc_msg_done_isr,
+ IRQF_NO_SUSPEND, dev_name(dev), scmi_info);
+ if (ret) {
+ dev_err(dev, "failed to setup SCMI smc irq\n");
+ return ret;
+ }
+ } else {
+ cinfo->no_completion_irq = true;
+ }
+
+ scmi_info->func_id = func_id;
+ scmi_info->cinfo = cinfo;
+ smc_channel_lock_init(scmi_info);
+ cinfo->transport_info = scmi_info;
+
+ return 0;
+}
+
+static int smc_chan_free(int id, void *p, void *data)
+{
+ struct scmi_chan_info *cinfo = p;
+ struct scmi_smc *scmi_info = cinfo->transport_info;
+
+ /* Ignore any possible further reception on the IRQ path */
+ if (scmi_info->irq > 0)
+ free_irq(scmi_info->irq, scmi_info);
+
+ cinfo->transport_info = NULL;
+ scmi_info->cinfo = NULL;
+
+ return 0;
+}
+
+static int smc_send_message(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer)
+{
+ struct scmi_smc *scmi_info = cinfo->transport_info;
+ struct arm_smccc_res res;
+ unsigned long page = scmi_info->param_page;
+ unsigned long offset = scmi_info->param_offset;
+
+ /*
+ * Channel will be released only once response has been
+ * surely fully retrieved, so after .mark_txdone()
+ */
+ smc_channel_lock_acquire(scmi_info, xfer);
+
+ shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);
+
+ arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, 0, 0,
+ &res);
+
+ /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
+ if (res.a0) {
+ smc_channel_lock_release(scmi_info);
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static void smc_fetch_response(struct scmi_chan_info *cinfo,
+ struct scmi_xfer *xfer)
+{
+ struct scmi_smc *scmi_info = cinfo->transport_info;
+
+ shmem_fetch_response(scmi_info->shmem, xfer);
+}
+
+static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret,
+ struct scmi_xfer *__unused)
+{
+ struct scmi_smc *scmi_info = cinfo->transport_info;
+
+ smc_channel_lock_release(scmi_info);
+}
+
+static const struct scmi_transport_ops scmi_smc_ops = {
+ .chan_available = smc_chan_available,
+ .chan_setup = smc_chan_setup,
+ .chan_free = smc_chan_free,
+ .send_message = smc_send_message,
+ .mark_txdone = smc_mark_txdone,
+ .fetch_response = smc_fetch_response,
+};
+
+const struct scmi_desc scmi_smc_desc = {
+ .ops = &scmi_smc_ops,
+ .max_rx_timeout_ms = 30,
+ .max_msg = 20,
+ .max_msg_size = 128,
+ /*
+ * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
+ * once the SMC instruction has completed successfully, the issued
+ * SCMI command would have been already fully processed by the SCMI
+ * platform firmware and so any possible response value expected
+ * for the issued command will be immmediately ready to be fetched
+ * from the shared memory area.
+ */
+ .sync_cmds_completed_on_ret = true,
+ .atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
+};