1 files changed, 616 insertions, 0 deletions

diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
new file mode 100644
index 000000000..ef9ecd1f5
--- /dev/null
+++ b/drivers/mailbox/pcc.c
@@ -0,0 +1,616 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	Copyright (C) 2014 Linaro Ltd.
+ *	Author:	Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ *  PCC (Platform Communication Channel) is defined in the ACPI 5.0+
+ *  specification. It is a mailbox like mechanism to allow clients
+ *  such as CPPC (Collaborative Processor Performance Control), RAS
+ *  (Reliability, Availability and Serviceability) and MPST (Memory
+ *  Node Power State Table) to talk to the platform (e.g. BMC) through
+ *  shared memory regions as defined in the PCC table entries. The PCC
+ *  specification supports a Doorbell mechanism for the PCC clients
+ *  to notify the platform about new data. This Doorbell information
+ *  is also specified in each PCC table entry.
+ *
+ *  Typical high level flow of operation is:
+ *
+ *  PCC Reads:
+ *  * Client tries to acquire a channel lock.
+ *  * After it is acquired it writes READ cmd in communication region cmd
+ *		address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then client has control over channel and
+ *		it can proceed with its reads.
+ *  * Client releases lock.
+ *
+ *  PCC Writes:
+ *  * Client tries to acquire channel lock.
+ *  * Client writes to its communication region after it acquires a
+ *		channel lock.
+ *  * Client writes WRITE cmd in communication region cmd address.
+ *  * Client issues mbox_send_message() which rings the PCC doorbell
+ *		for its PCC channel.
+ *  * If command completes, then writes have succeded and it can release
+ *		the channel lock.
+ *
+ *  There is a Nominal latency defined for each channel which indicates
+ *  how long to wait until a command completes. If command is not complete
+ *  the client needs to retry or assume failure.
+ *
+ *	For more details about PCC, please see the ACPI specification from
+ *  http://www.uefi.org/ACPIv5.1 Section 14.
+ *
+ *  This file implements PCC as a Mailbox controller and allows for PCC
+ *  clients to be implemented as its Mailbox Client Channels.
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/platform_device.h>
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <acpi/pcc.h>
+
+#include "mailbox.h"
+
+#define MBOX_IRQ_NAME		"pcc-mbox"
+
+static struct mbox_chan *pcc_mbox_channels;
+
+/* Array of cached virtual address for doorbell registers */
+static void __iomem **pcc_doorbell_vaddr;
+/* Array of cached virtual address for doorbell ack registers */
+static void __iomem **pcc_doorbell_ack_vaddr;
+/* Array of doorbell interrupts */
+static int *pcc_doorbell_irq;
+
+static struct mbox_controller pcc_mbox_ctrl = {};
+/**
+ * get_pcc_channel - Given a PCC subspace idx, get
+ *	the respective mbox_channel.
+ * @id: PCC subspace index.
+ *
+ * Return: ERR_PTR(errno) if error, else pointer
+ *	to mbox channel.
+ */
+static struct mbox_chan *get_pcc_channel(int id)
+{
+	if (id < 0 || id >= pcc_mbox_ctrl.num_chans)
+		return ERR_PTR(-ENOENT);
+
+	return &pcc_mbox_channels[id];
+}
+
+/*
+ * PCC can be used with perf critical drivers such as CPPC
+ * So it makes sense to locally cache the virtual address and
+ * use it to read/write to PCC registers such as doorbell register
+ *
+ * The below read_register and write_registers are used to read and
+ * write from perf critical registers such as PCC doorbell register
+ */
+static int read_register(void __iomem *vaddr, u64 *val, unsigned int bit_width)
+{
+	int ret_val = 0;
+
+	switch (bit_width) {
+	case 8:
+		*val = readb(vaddr);
+		break;
+	case 16:
+		*val = readw(vaddr);
+		break;
+	case 32:
+		*val = readl(vaddr);
+		break;
+	case 64:
+		*val = readq(vaddr);
+		break;
+	default:
+		pr_debug("Error: Cannot read register of %u bit width",
+			bit_width);
+		ret_val = -EFAULT;
+		break;
+	}
+	return ret_val;
+}
+
+static int write_register(void __iomem *vaddr, u64 val, unsigned int bit_width)
+{
+	int ret_val = 0;
+
+	switch (bit_width) {
+	case 8:
+		writeb(val, vaddr);
+		break;
+	case 16:
+		writew(val, vaddr);
+		break;
+	case 32:
+		writel(val, vaddr);
+		break;
+	case 64:
+		writeq(val, vaddr);
+		break;
+	default:
+		pr_debug("Error: Cannot write register of %u bit width",
+			bit_width);
+		ret_val = -EFAULT;
+		break;
+	}
+	return ret_val;
+}
+
+/**
+ * pcc_map_interrupt - Map a PCC subspace GSI to a linux IRQ number
+ * @interrupt: GSI number.
+ * @flags: interrupt flags
+ *
+ * Returns: a valid linux IRQ number on success
+ *		0 or -EINVAL on failure
+ */
+static int pcc_map_interrupt(u32 interrupt, u32 flags)
+{
+	int trigger, polarity;
+
+	if (!interrupt)
+		return 0;
+
+	trigger = (flags & ACPI_PCCT_INTERRUPT_MODE) ? ACPI_EDGE_SENSITIVE
+			: ACPI_LEVEL_SENSITIVE;
+
+	polarity = (flags & ACPI_PCCT_INTERRUPT_POLARITY) ? ACPI_ACTIVE_LOW
+			: ACPI_ACTIVE_HIGH;
+
+	return acpi_register_gsi(NULL, interrupt, trigger, polarity);
+}
+
+/**
+ * pcc_mbox_irq - PCC mailbox interrupt handler
+ */
+static irqreturn_t pcc_mbox_irq(int irq, void *p)
+{
+	struct acpi_generic_address *doorbell_ack;
+	struct acpi_pcct_hw_reduced *pcct_ss;
+	struct mbox_chan *chan = p;
+	u64 doorbell_ack_preserve;
+	u64 doorbell_ack_write;
+	u64 doorbell_ack_val;
+	int ret;
+
+	pcct_ss = chan->con_priv;
+
+	mbox_chan_received_data(chan, NULL);
+
+	if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
+		struct acpi_pcct_hw_reduced_type2 *pcct2_ss = chan->con_priv;
+		u32 id = chan - pcc_mbox_channels;
+
+		doorbell_ack = &pcct2_ss->platform_ack_register;
+		doorbell_ack_preserve = pcct2_ss->ack_preserve_mask;
+		doorbell_ack_write = pcct2_ss->ack_write_mask;
+
+		ret = read_register(pcc_doorbell_ack_vaddr[id],
+				    &doorbell_ack_val,
+				    doorbell_ack->bit_width);
+		if (ret)
+			return IRQ_NONE;
+
+		ret = write_register(pcc_doorbell_ack_vaddr[id],
+				     (doorbell_ack_val & doorbell_ack_preserve)
+					| doorbell_ack_write,
+				     doorbell_ack->bit_width);
+		if (ret)
+			return IRQ_NONE;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * pcc_mbox_request_channel - PCC clients call this function to
+ *		request a pointer to their PCC subspace, from which they
+ *		can get the details of communicating with the remote.
+ * @cl: Pointer to Mailbox client, so we know where to bind the
+ *		Channel.
+ * @subspace_id: The PCC Subspace index as parsed in the PCC client
+ *		ACPI package. This is used to lookup the array of PCC
+ *		subspaces as parsed by the PCC Mailbox controller.
+ *
+ * Return: Pointer to the Mailbox Channel if successful or
+ *		ERR_PTR.
+ */
+struct mbox_chan *pcc_mbox_request_channel(struct mbox_client *cl,
+		int subspace_id)
+{
+	struct device *dev = pcc_mbox_ctrl.dev;
+	struct mbox_chan *chan;
+	unsigned long flags;
+
+	/*
+	 * Each PCC Subspace is a Mailbox Channel.
+	 * The PCC Clients get their PCC Subspace ID
+	 * from their own tables and pass it here.
+	 * This returns a pointer to the PCC subspace
+	 * for the Client to operate on.
+	 */
+	chan = get_pcc_channel(subspace_id);
+
+	if (IS_ERR(chan) || chan->cl) {
+		dev_err(dev, "Channel not found for idx: %d\n", subspace_id);
+		return ERR_PTR(-EBUSY);
+	}
+
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->msg_free = 0;
+	chan->msg_count = 0;
+	chan->active_req = NULL;
+	chan->cl = cl;
+	init_completion(&chan->tx_complete);
+
+	if (chan->txdone_method == TXDONE_BY_POLL && cl->knows_txdone)
+		chan->txdone_method = TXDONE_BY_ACK;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	if (pcc_doorbell_irq[subspace_id] > 0) {
+		int rc;
+
+		rc = devm_request_irq(dev, pcc_doorbell_irq[subspace_id],
+				      pcc_mbox_irq, 0, MBOX_IRQ_NAME, chan);
+		if (unlikely(rc)) {
+			dev_err(dev, "failed to register PCC interrupt %d\n",
+				pcc_doorbell_irq[subspace_id]);
+			pcc_mbox_free_channel(chan);
+			chan = ERR_PTR(rc);
+		}
+	}
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_request_channel);
+
+/**
+ * pcc_mbox_free_channel - Clients call this to free their Channel.
+ *
+ * @chan: Pointer to the mailbox channel as returned by
+ *		pcc_mbox_request_channel()
+ */
+void pcc_mbox_free_channel(struct mbox_chan *chan)
+{
+	u32 id = chan - pcc_mbox_channels;
+	unsigned long flags;
+
+	if (!chan || !chan->cl)
+		return;
+
+	if (id >= pcc_mbox_ctrl.num_chans) {
+		pr_debug("pcc_mbox_free_channel: Invalid mbox_chan passed\n");
+		return;
+	}
+
+	if (pcc_doorbell_irq[id] > 0)
+		devm_free_irq(chan->mbox->dev, pcc_doorbell_irq[id], chan);
+
+	spin_lock_irqsave(&chan->lock, flags);
+	chan->cl = NULL;
+	chan->active_req = NULL;
+	if (chan->txdone_method == TXDONE_BY_ACK)
+		chan->txdone_method = TXDONE_BY_POLL;
+
+	spin_unlock_irqrestore(&chan->lock, flags);
+}
+EXPORT_SYMBOL_GPL(pcc_mbox_free_channel);
+
+/**
+ * pcc_send_data - Called from Mailbox Controller code. Used
+ *		here only to ring the channel doorbell. The PCC client
+ *		specific read/write is done in the client driver in
+ *		order to maintain atomicity over PCC channel once
+ *		OS has control over it. See above for flow of operations.
+ * @chan: Pointer to Mailbox channel over which to send data.
+ * @data: Client specific data written over channel. Used here
+ *		only for debug after PCC transaction completes.
+ *
+ * Return: Err if something failed else 0 for success.
+ */
+static int pcc_send_data(struct mbox_chan *chan, void *data)
+{
+	struct acpi_pcct_hw_reduced *pcct_ss = chan->con_priv;
+	struct acpi_generic_address *doorbell;
+	u64 doorbell_preserve;
+	u64 doorbell_val;
+	u64 doorbell_write;
+	u32 id = chan - pcc_mbox_channels;
+	int ret = 0;
+
+	if (id >= pcc_mbox_ctrl.num_chans) {
+		pr_debug("pcc_send_data: Invalid mbox_chan passed\n");
+		return -ENOENT;
+	}
+
+	doorbell = &pcct_ss->doorbell_register;
+	doorbell_preserve = pcct_ss->preserve_mask;
+	doorbell_write = pcct_ss->write_mask;
+
+	/* Sync notification from OS to Platform. */
+	if (pcc_doorbell_vaddr[id]) {
+		ret = read_register(pcc_doorbell_vaddr[id], &doorbell_val,
+			doorbell->bit_width);
+		if (ret)
+			return ret;
+		ret = write_register(pcc_doorbell_vaddr[id],
+			(doorbell_val & doorbell_preserve) | doorbell_write,
+			doorbell->bit_width);
+	} else {
+		ret = acpi_read(&doorbell_val, doorbell);
+		if (ret)
+			return ret;
+		ret = acpi_write((doorbell_val & doorbell_preserve) | doorbell_write,
+			doorbell);
+	}
+	return ret;
+}
+
+static const struct mbox_chan_ops pcc_chan_ops = {
+	.send_data = pcc_send_data,
+};
+
+/**
+ * parse_pcc_subspaces -- Count PCC subspaces defined
+ * @header: Pointer to the ACPI subtable header under the PCCT.
+ * @end: End of subtable entry.
+ *
+ * Return: If we find a PCC subspace entry of a valid type, return 0.
+ *	Otherwise, return -EINVAL.
+ *
+ * This gets called for each entry in the PCC table.
+ */
+static int parse_pcc_subspace(union acpi_subtable_headers *header,
+		const unsigned long end)
+{
+	struct acpi_pcct_subspace *ss = (struct acpi_pcct_subspace *) header;
+
+	if (ss->header.type < ACPI_PCCT_TYPE_RESERVED)
+		return 0;
+
+	return -EINVAL;
+}
+
+/**
+ * pcc_parse_subspace_irq - Parse the PCC IRQ and PCC ACK register
+ *		There should be one entry per PCC client.
+ * @id: PCC subspace index.
+ * @pcct_ss: Pointer to the ACPI subtable header under the PCCT.
+ *
+ * Return: 0 for Success, else errno.
+ *
+ * This gets called for each entry in the PCC table.
+ */
+static int pcc_parse_subspace_irq(int id,
+				  struct acpi_pcct_hw_reduced *pcct_ss)
+{
+	pcc_doorbell_irq[id] = pcc_map_interrupt(pcct_ss->platform_interrupt,
+						 (u32)pcct_ss->flags);
+	if (pcc_doorbell_irq[id] <= 0) {
+		pr_err("PCC GSI %d not registered\n",
+		       pcct_ss->platform_interrupt);
+		return -EINVAL;
+	}
+
+	if (pcct_ss->header.type
+		== ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
+		struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
+
+		pcc_doorbell_ack_vaddr[id] = acpi_os_ioremap(
+				pcct2_ss->platform_ack_register.address,
+				pcct2_ss->platform_ack_register.bit_width / 8);
+		if (!pcc_doorbell_ack_vaddr[id]) {
+			pr_err("Failed to ioremap PCC ACK register\n");
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * acpi_pcc_probe - Parse the ACPI tree for the PCCT.
+ *
+ * Return: 0 for Success, else errno.
+ */
+static int __init acpi_pcc_probe(void)
+{
+	struct acpi_table_header *pcct_tbl;
+	struct acpi_subtable_header *pcct_entry;
+	struct acpi_table_pcct *acpi_pcct_tbl;
+	struct acpi_subtable_proc proc[ACPI_PCCT_TYPE_RESERVED];
+	int count, i, rc;
+	acpi_status status = AE_OK;
+
+	/* Search for PCCT */
+	status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
+
+	if (ACPI_FAILURE(status) || !pcct_tbl)
+		return -ENODEV;
+
+	/* Set up the subtable handlers */
+	for (i = ACPI_PCCT_TYPE_GENERIC_SUBSPACE;
+	     i < ACPI_PCCT_TYPE_RESERVED; i++) {
+		proc[i].id = i;
+		proc[i].count = 0;
+		proc[i].handler = parse_pcc_subspace;
+	}
+
+	count = acpi_table_parse_entries_array(ACPI_SIG_PCCT,
+			sizeof(struct acpi_table_pcct), proc,
+			ACPI_PCCT_TYPE_RESERVED, MAX_PCC_SUBSPACES);
+	if (count <= 0 || count > MAX_PCC_SUBSPACES) {
+		if (count < 0)
+			pr_warn("Error parsing PCC subspaces from PCCT\n");
+		else
+			pr_warn("Invalid PCCT: %d PCC subspaces\n", count);
+
+		rc = -EINVAL;
+		goto err_put_pcct;
+	}
+
+	pcc_mbox_channels = kcalloc(count, sizeof(struct mbox_chan),
+				    GFP_KERNEL);
+	if (!pcc_mbox_channels) {
+		pr_err("Could not allocate space for PCC mbox channels\n");
+		rc = -ENOMEM;
+		goto err_put_pcct;
+	}
+
+	pcc_doorbell_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
+	if (!pcc_doorbell_vaddr) {
+		rc = -ENOMEM;
+		goto err_free_mbox;
+	}
+
+	pcc_doorbell_ack_vaddr = kcalloc(count, sizeof(void *), GFP_KERNEL);
+	if (!pcc_doorbell_ack_vaddr) {
+		rc = -ENOMEM;
+		goto err_free_db_vaddr;
+	}
+
+	pcc_doorbell_irq = kcalloc(count, sizeof(int), GFP_KERNEL);
+	if (!pcc_doorbell_irq) {
+		rc = -ENOMEM;
+		goto err_free_db_ack_vaddr;
+	}
+
+	/* Point to the first PCC subspace entry */
+	pcct_entry = (struct acpi_subtable_header *) (
+		(unsigned long) pcct_tbl + sizeof(struct acpi_table_pcct));
+
+	acpi_pcct_tbl = (struct acpi_table_pcct *) pcct_tbl;
+	if (acpi_pcct_tbl->flags & ACPI_PCCT_DOORBELL)
+		pcc_mbox_ctrl.txdone_irq = true;
+
+	for (i = 0; i < count; i++) {
+		struct acpi_generic_address *db_reg;
+		struct acpi_pcct_subspace *pcct_ss;
+		pcc_mbox_channels[i].con_priv = pcct_entry;
+
+		if (pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE ||
+		    pcct_entry->type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
+			struct acpi_pcct_hw_reduced *pcct_hrss;
+
+			pcct_hrss = (struct acpi_pcct_hw_reduced *) pcct_entry;
+
+			if (pcc_mbox_ctrl.txdone_irq) {
+				rc = pcc_parse_subspace_irq(i, pcct_hrss);
+				if (rc < 0)
+					goto err;
+			}
+		}
+		pcct_ss = (struct acpi_pcct_subspace *) pcct_entry;
+
+		/* If doorbell is in system memory cache the virt address */
+		db_reg = &pcct_ss->doorbell_register;
+		if (db_reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
+			pcc_doorbell_vaddr[i] = acpi_os_ioremap(db_reg->address,
+							db_reg->bit_width/8);
+		pcct_entry = (struct acpi_subtable_header *)
+			((unsigned long) pcct_entry + pcct_entry->length);
+	}
+
+	pcc_mbox_ctrl.num_chans = count;
+
+	pr_info("Detected %d PCC Subspaces\n", pcc_mbox_ctrl.num_chans);
+
+	return 0;
+
+err:
+	kfree(pcc_doorbell_irq);
+err_free_db_ack_vaddr:
+	kfree(pcc_doorbell_ack_vaddr);
+err_free_db_vaddr:
+	kfree(pcc_doorbell_vaddr);
+err_free_mbox:
+	kfree(pcc_mbox_channels);
+err_put_pcct:
+	acpi_put_table(pcct_tbl);
+	return rc;
+}
+
+/**
+ * pcc_mbox_probe - Called when we find a match for the
+ *	PCCT platform device. This is purely used to represent
+ *	the PCCT as a virtual device for registering with the
+ *	generic Mailbox framework.
+ *
+ * @pdev: Pointer to platform device returned when a match
+ *	is found.
+ *
+ *	Return: 0 for Success, else errno.
+ */
+static int pcc_mbox_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+
+	pcc_mbox_ctrl.chans = pcc_mbox_channels;
+	pcc_mbox_ctrl.ops = &pcc_chan_ops;
+	pcc_mbox_ctrl.dev = &pdev->dev;
+
+	pr_info("Registering PCC driver as Mailbox controller\n");
+	ret = mbox_controller_register(&pcc_mbox_ctrl);
+
+	if (ret) {
+		pr_err("Err registering PCC as Mailbox controller: %d\n", ret);
+		ret = -ENODEV;
+	}
+
+	return ret;
+}
+
+static struct platform_driver pcc_mbox_driver = {
+	.probe = pcc_mbox_probe,
+	.driver = {
+		.name = "PCCT",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init pcc_init(void)
+{
+	int ret;
+	struct platform_device *pcc_pdev;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	/* Check if PCC support is available. */
+	ret = acpi_pcc_probe();
+
+	if (ret) {
+		pr_debug("ACPI PCC probe failed.\n");
+		return -ENODEV;
+	}
+
+	pcc_pdev = platform_create_bundle(&pcc_mbox_driver,
+			pcc_mbox_probe, NULL, 0, NULL, 0);
+
+	if (IS_ERR(pcc_pdev)) {
+		pr_debug("Err creating PCC platform bundle\n");
+		return PTR_ERR(pcc_pdev);
+	}
+
+	return 0;
+}
+
+/*
+ * Make PCC init postcore so that users of this mailbox
+ * such as the ACPI Processor driver have it available
+ * at their init.
+ */
+postcore_initcall(pcc_init);