[PATCH 4/4] gpio: qcom-smp2p: Qualcomm Shared Memory Point to Point

[Bjorn Andersson]

Introduce the Qualcomm Shard Memory Point to Point driver, exposing bits
from the SMP2P protocol as gpio and interrupt controllers.

Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
---
 drivers/gpio/Kconfig           |   7 +
 drivers/gpio/Makefile          |   1 +
 drivers/gpio/gpio-qcom-smp2p.c | 601 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 609 insertions(+)
 create mode 100644 drivers/gpio/gpio-qcom-smp2p.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 0e57b60faae8..82c61ce5af8f 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -354,6 +354,13 @@ config GPIO_PXA
 	help
 	  Say yes here to support the PXA GPIO device
 
+config GPIO_QCOM_SMP2P
+	bool "Qualcomm Shared Memory Point to Point support"
+	depends on QCOM_SMEM
+	help
+	  Say yes here to support the Qualcomm Shared Memory Point to Point
+	  protocol, exposed to the system as GPIOs.
+
 config GPIO_QCOM_SMSM
 	bool "Qualcomm Shared Memory State Machine"
 	depends on QCOM_SMEM
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 0fd213892403..fdab869a7212 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -75,6 +75,7 @@ obj-$(CONFIG_GPIO_PCF857X)	+= gpio-pcf857x.o
 obj-$(CONFIG_GPIO_PCH)		+= gpio-pch.o
 obj-$(CONFIG_GPIO_PL061)	+= gpio-pl061.o
 obj-$(CONFIG_GPIO_PXA)		+= gpio-pxa.o
+obj-$(CONFIG_GPIO_QCOM_SMP2P)	+= gpio-qcom-smp2p.o
 obj-$(CONFIG_GPIO_QCOM_SMSM)	+= gpio-qcom-smsm.o
 obj-$(CONFIG_GPIO_RC5T583)	+= gpio-rc5t583.o
 obj-$(CONFIG_GPIO_RDC321X)	+= gpio-rdc321x.o
diff --git a/drivers/gpio/gpio-qcom-smp2p.c b/drivers/gpio/gpio-qcom-smp2p.c
new file mode 100644
index 000000000000..f2eb2f095cc0
--- /dev/null
+++ b/drivers/gpio/gpio-qcom-smp2p.c
@@ -0,0 +1,601 @@
+/*
+ * Copyright (c) 2015, Sony Mobile Communications AB.
+ * Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/soc/qcom/smem.h>
+#include <linux/spinlock.h>
+
+/*
+ * The Shared Memory Point to Point (SMP2P) protocol facilitates communication
+ * of a single 32-bit value between two processors.  Each value has a single
+ * writer (the local side) and a single reader (the remote side). Values are
+ * uniquely identified in the system by the directed edge (local processor ID
+ * to remote processor ID) and a string identifier.
+ *
+ * Each processor is responsible for creating the outgoing SMEM items and each
+ * item is writable by the local processor and readable by the remote
+ * processor.  By using two separate SMEM items that are single-reader and
+ * single-writer, SMP2P does not require any remote locking mechanisms.
+ *
+ * The driver uses the Linux GPIO and interrupt framework to expose a virtual
+ * GPIO for each outbound entry and a virtual interrupt controller for each
+ * inbound entry.
+ */
+
+#define SMP2P_MAX_ENTRY 16
+#define SMP2P_MAX_ENTRY_NAME 16
+
+#define SMP2P_FEATURE_SSR_ACK 0x1
+
+#define SMP2P_MAGIC 0x504d5324
+
+/**
+ * struct smp2p_smem_item - in memory communication structure
+ * @magic:		magic number
+ * @version:		version - must be 1
+ * @features:		features flag - currently unused
+ * @local_pid:		processor id of sending end
+ * @remote_pid:		processor id of receiving end
+ * @total_entries:	number of entries - always SMP2P_MAX_ENTRY
+ * @valid_entries:	number of allocated entries
+ * @flags:
+ * @entries:		individual communication entries
+ *     @name:		name of the entry
+ *     @value:		content of the entry
+ */
+struct smp2p_smem_item {
+	u32 magic;
+	u8 version;
+	unsigned features:24;
+	u16 local_pid;
+	u16 remote_pid;
+	u16 total_entries;
+	u16 valid_entries;
+	u32 flags;
+
+	struct {
+		u8 name[SMP2P_MAX_ENTRY_NAME];
+		u32 value;
+	} entries[SMP2P_MAX_ENTRY];
+} __packed;
+
+/**
+ * struct smp2p_entry - driver context matching one entry
+ * @node:	list entry to keep track of allocated entries
+ * @smp2p:	reference to the device driver context
+ * @name:	name of the entry, to match against smp2p_smem_item
+ * @value:	pointer to smp2p_smem_item entry value
+ * @last_value:	last handled value
+ * @domain:	irq_domain for inbound entries
+ * @irq_enabled:bitmap to track enabled irq bits
+ * @irq_rising:	bitmap to mark irq bits for rising detection
+ * @irq_falling:bitmap to mark irq bits for falling detection
+ * @chip:	gpio_chip for outbound entries
+ * @lock:	spinlock to protect read-modify-write of the value
+ */
+struct smp2p_entry {
+	struct list_head node;
+	struct qcom_smp2p *smp2p;
+
+	const char *name;
+	u32 *value;
+	u32 last_value;
+
+	struct irq_domain *domain;
+	DECLARE_BITMAP(irq_enabled, 32);
+	DECLARE_BITMAP(irq_rising, 32);
+	DECLARE_BITMAP(irq_falling, 32);
+
+	struct gpio_chip chip;
+
+	spinlock_t lock;
+};
+
+#define SMP2P_INBOUND	0
+#define SMP2P_OUTBOUND	1
+
+/**
+ * struct qcom_smp2p - device driver context
+ * @dev:	device driver handle
+ * @in:		pointer to the inbound smem item
+ * @smem_items:	ids of the two smem items
+ * @valid_entries: already scanned inbound entries
+ * @local_pid:	processor id of the inbound edge
+ * @remote_pid:	processor id of the outbound edge
+ * @ipc_regmap:	regmap for the outbound ipc
+ * @ipc_offset:	offset within the regmap
+ * @ipc_bit:	bit in regmap@offset to kick to signal remote processor
+ * @inbound:	list of inbound entries
+ * @outbound:	list of outbound entries
+ */
+struct qcom_smp2p {
+	struct device *dev;
+
+	struct smp2p_smem_item *in;
+	struct smp2p_smem_item *out;
+
+	unsigned smem_items[SMP2P_OUTBOUND + 1];
+
+	unsigned valid_entries;
+
+	unsigned local_pid;
+	unsigned remote_pid;
+
+	struct regmap *ipc_regmap;
+	int ipc_offset;
+	int ipc_bit;
+
+	struct list_head inbound;
+	struct list_head outbound;
+};
+
+static void qcom_smp2p_kick(struct qcom_smp2p *smp2p)
+{
+	/* Make sure any updated data is written before the kick */
+	wmb();
+	regmap_write(smp2p->ipc_regmap, smp2p->ipc_offset, BIT(smp2p->ipc_bit));
+}
+
+/**
+ * qcom_smp2p_intr() - interrupt handler for incoming notifications
+ * @irq:	unused
+ * @data:	smp2p driver context
+ *
+ * Handle notifications from the remote side to handle newly allocated entries
+ * or any changes to the state bits of existing entries.
+ */
+static irqreturn_t qcom_smp2p_intr(int irq, void *data)
+{
+	struct smp2p_smem_item *in;
+	struct smp2p_entry *entry;
+	struct qcom_smp2p *smp2p = data;
+	unsigned smem_id = smp2p->smem_items[SMP2P_INBOUND];
+	unsigned pid = smp2p->remote_pid;
+	size_t size;
+	int irq_pin;
+	u32 status;
+	char buf[SMP2P_MAX_ENTRY_NAME];
+	u32 val;
+	int ret;
+	int i;
+
+	in = smp2p->in;
+
+	/* Acquire smem item, if not already found */
+	if (!in) {
+		ret = qcom_smem_get(pid, smem_id, (void **)&in, &size);
+		if (ret < 0) {
+			dev_err(smp2p->dev,
+				"Unable to acquire remote smp2p item\n");
+			return IRQ_HANDLED;
+		}
+
+		smp2p->in = in;
+	}
+
+	/* Match newly created entries */
+	for (i = smp2p->valid_entries; i < in->valid_entries; i++) {
+		list_for_each_entry(entry, &smp2p->inbound, node) {
+			memcpy_fromio(buf, in->entries[i].name, sizeof(buf));
+			if (!strcmp(buf, entry->name)) {
+				entry->value = &in->entries[i].value;
+				break;
+			}
+		}
+	}
+	smp2p->valid_entries = i;
+
+	/* Fire interrupts based on any value changes */
+	list_for_each_entry(entry, &smp2p->inbound, node) {
+		/* Ignore entries not yet allocated by the remote side */
+		if (!entry->value)
+			continue;
+
+		val = readl(entry->value);
+
+		status = val ^ entry->last_value;
+		entry->last_value = val;
+
+		/* No changes of this entry? */
+		if (!status)
+			continue;
+
+		for_each_set_bit(i, entry->irq_enabled, 32) {
+			if (!(status & BIT(i)))
+				continue;
+
+			if (val & BIT(i)) {
+				if (test_bit(i, entry->irq_rising)) {
+					irq_pin = irq_find_mapping(entry->domain, i);
+					handle_nested_irq(irq_pin);
+				}
+			} else {
+				if (test_bit(i, entry->irq_falling)) {
+					irq_pin = irq_find_mapping(entry->domain, i);
+					handle_nested_irq(irq_pin);
+				}
+			}
+
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void smp2p_mask_irq(struct irq_data *irqd)
+{
+	struct smp2p_entry *entry = irq_data_get_irq_chip_data(irqd);
+	irq_hw_number_t irq = irqd_to_hwirq(irqd);
+
+	clear_bit(irq, entry->irq_enabled);
+}
+
+static void smp2p_unmask_irq(struct irq_data *irqd)
+{
+	struct smp2p_entry *entry = irq_data_get_irq_chip_data(irqd);
+	irq_hw_number_t irq = irqd_to_hwirq(irqd);
+
+	set_bit(irq, entry->irq_enabled);
+}
+
+static int smp2p_set_irq_type(struct irq_data *irqd, unsigned int type)
+{
+	struct smp2p_entry *entry = irq_data_get_irq_chip_data(irqd);
+	irq_hw_number_t irq = irqd_to_hwirq(irqd);
+
+	if (!(type & IRQ_TYPE_EDGE_BOTH))
+		return -EINVAL;
+
+	if (type & IRQ_TYPE_EDGE_RISING)
+		set_bit(irq, entry->irq_rising);
+	else
+		clear_bit(irq, entry->irq_rising);
+
+	if (type & IRQ_TYPE_EDGE_FALLING)
+		set_bit(irq, entry->irq_falling);
+	else
+		clear_bit(irq, entry->irq_falling);
+
+	return 0;
+}
+
+static struct irq_chip smp2p_irq_chip = {
+	.name           = "smp2p",
+	.irq_mask       = smp2p_mask_irq,
+	.irq_unmask     = smp2p_unmask_irq,
+	.irq_set_type	= smp2p_set_irq_type,
+};
+
+static int smp2p_irq_map(struct irq_domain *d,
+			 unsigned int irq,
+			 irq_hw_number_t hw)
+{
+	struct smp2p_entry *entry = d->host_data;
+
+	irq_set_chip_and_handler(irq, &smp2p_irq_chip, handle_level_irq);
+	irq_set_chip_data(irq, entry);
+	irq_set_nested_thread(irq, 1);
+	irq_set_noprobe(irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops smp2p_irq_ops = {
+	.map = smp2p_irq_map,
+	.xlate = irq_domain_xlate_twocell,
+};
+
+static int smp2p_gpio_direction_output(struct gpio_chip *chip,
+				       unsigned offset,
+				       int value)
+{
+	struct smp2p_entry *entry = container_of(chip, struct smp2p_entry, chip);
+	u32 val;
+
+	spin_lock(&entry->lock);
+	val = readl(entry->value);
+	if (value)
+		val |= BIT(offset);
+	else
+		val &= ~BIT(offset);
+	writel(val, entry->value);
+	spin_unlock(&entry->lock);
+
+	qcom_smp2p_kick(entry->smp2p);
+
+	return 0;
+}
+
+static void smp2p_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	smp2p_gpio_direction_output(chip, offset, value);
+}
+
+static const struct gpio_chip smp2p_gpio_chip = {
+	.set = smp2p_gpio_set,
+	.direction_output = smp2p_gpio_direction_output,
+	.owner = THIS_MODULE,
+};
+
+static int qcom_smp2p_inbound_entry(struct qcom_smp2p *smp2p,
+				    struct smp2p_entry *entry,
+				    struct device_node *node)
+{
+	entry->domain = irq_domain_add_linear(node, 32, &smp2p_irq_ops, entry);
+	if (!entry->domain) {
+		dev_err(smp2p->dev, "failed to add irq_domain\n");
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int qcom_smp2p_outbound_entry(struct qcom_smp2p *smp2p,
+				     struct smp2p_entry *entry,
+				     struct device_node *node)
+{
+	struct smp2p_smem_item *out = smp2p->out;
+	char buf[SMP2P_MAX_ENTRY_NAME] = {};
+	int ret;
+
+	/* Allocate an entry from the smem item */
+	strlcpy(buf, entry->name, SMP2P_MAX_ENTRY_NAME);
+	memcpy_toio(out->entries[out->valid_entries].name, buf, SMP2P_MAX_ENTRY_NAME);
+	out->valid_entries++;
+
+	/* Make the logical entry reference the physical value */
+	entry->value = &out->entries[out->valid_entries].value;
+
+	entry->chip = smp2p_gpio_chip;
+	entry->chip.base = -1;
+	entry->chip.ngpio = 32;
+	entry->chip.label = entry->name;
+	entry->chip.dev = smp2p->dev;
+	entry->chip.of_node = node;
+
+	ret = gpiochip_add(&entry->chip);
+	if (ret)
+		dev_err(smp2p->dev, "failed register gpiochip\n");
+
+	return 0;
+}
+
+static int qcom_smp2p_alloc_outbound_item(struct qcom_smp2p *smp2p)
+{
+	struct smp2p_smem_item *out;
+	unsigned smem_id = smp2p->smem_items[SMP2P_OUTBOUND];
+	unsigned pid = smp2p->remote_pid;
+	int ret;
+
+	ret = qcom_smem_alloc(pid, smem_id, sizeof(*out));
+	if (ret < 0 && ret != -EEXIST) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(smp2p->dev,
+				"unable to allocate local smp2p item\n");
+		return ret;
+	}
+
+	ret = qcom_smem_get(pid, smem_id, (void **)&out, NULL);
+	if (ret < 0) {
+		dev_err(smp2p->dev, "Unable to acquire local smp2p item\n");
+		return ret;
+	}
+
+	memset(out, 0, sizeof(*out));
+	out->magic = SMP2P_MAGIC;
+	out->local_pid = smp2p->local_pid;
+	out->remote_pid = smp2p->remote_pid;
+	out->total_entries = SMP2P_MAX_ENTRY;
+	out->valid_entries = 0;
+
+	/*
+	 * Make sure the rest of the header is written before we validate the
+	 * item by writing a valid version number.
+	 */
+	wmb();
+	out->version = 1;
+
+	qcom_smp2p_kick(smp2p);
+
+	smp2p->out = out;
+
+	return 0;
+}
+
+static int smp2p_parse_ipc(struct qcom_smp2p *smp2p)
+{
+	struct device_node *syscon;
+	struct device *dev = smp2p->dev;
+	const char *key;
+	int ret;
+
+	syscon = of_parse_phandle(dev->of_node, "qcom,ipc", 0);
+	if (!syscon) {
+		dev_err(dev, "no qcom,ipc node\n");
+		return -ENODEV;
+	}
+
+	smp2p->ipc_regmap = syscon_node_to_regmap(syscon);
+	if (IS_ERR(smp2p->ipc_regmap))
+		return PTR_ERR(smp2p->ipc_regmap);
+
+	key = "qcom,ipc";
+	ret = of_property_read_u32_index(dev->of_node, key, 1, &smp2p->ipc_offset);
+	if (ret < 0) {
+		dev_err(dev, "no offset in %s\n", key);
+		return -EINVAL;
+	}
+
+	ret = of_property_read_u32_index(dev->of_node, key, 2, &smp2p->ipc_bit);
+	if (ret < 0) {
+		dev_err(dev, "no bit in %s\n", key);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int qcom_smp2p_probe(struct platform_device *pdev)
+{
+	struct smp2p_entry *entry;
+	struct device_node *node;
+	struct qcom_smp2p *smp2p;
+	const char *key;
+	int irq;
+	int ret;
+
+	smp2p = devm_kzalloc(&pdev->dev, sizeof(*smp2p), GFP_KERNEL);
+	if (!smp2p)
+		return -ENOMEM;
+
+	smp2p->dev = &pdev->dev;
+	INIT_LIST_HEAD(&smp2p->inbound);
+	INIT_LIST_HEAD(&smp2p->outbound);
+
+	platform_set_drvdata(pdev, smp2p);
+
+	ret = smp2p_parse_ipc(smp2p);
+	if (ret)
+		return ret;
+
+	key = "qcom,smem";
+	ret = of_property_read_u32_array(pdev->dev.of_node, key,
+					 smp2p->smem_items, 2);
+	if (ret)
+		return ret;
+
+	key = "qcom,local-pid";
+	ret = of_property_read_u32(pdev->dev.of_node, key, &smp2p->local_pid);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to read %s\n", key);
+		return -EINVAL;
+	}
+
+	key = "qcom,remote-pid";
+	ret = of_property_read_u32(pdev->dev.of_node, key, &smp2p->remote_pid);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to read %s\n", key);
+		return -EINVAL;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "unable to acquire smp2p interrupt\n");
+		return irq;
+	}
+
+	ret = qcom_smp2p_alloc_outbound_item(smp2p);
+	if (ret < 0)
+		return ret;
+
+	for_each_available_child_of_node(pdev->dev.of_node, node) {
+		entry = devm_kzalloc(&pdev->dev, sizeof(*entry), GFP_KERNEL);
+		if (!entry) {
+			ret = -ENOMEM;
+			goto unwind_interfaces;
+		}
+
+		entry->smp2p = smp2p;
+		spin_lock_init(&entry->lock);
+
+		ret = of_property_read_string(node, "qcom,entry-name", &entry->name);
+		if (ret < 0)
+			goto unwind_interfaces;
+
+		if (of_property_read_bool(node, "interrupt-controller")) {
+			ret = qcom_smp2p_inbound_entry(smp2p, entry, node);
+			if (ret < 0)
+				goto unwind_interfaces;
+
+			list_add(&entry->node, &smp2p->inbound);
+		} else if (of_property_read_bool(node, "gpio-controller")) {
+			ret = qcom_smp2p_outbound_entry(smp2p, entry, node);
+			if (ret < 0)
+				goto unwind_interfaces;
+
+			list_add(&entry->node, &smp2p->outbound);
+		} else {
+			dev_err(&pdev->dev, "neither inbound nor outbound\n");
+			ret = -EINVAL;
+			goto unwind_interfaces;
+		}
+	}
+
+	/* Kick the outgoing edge after allocating entries */
+	qcom_smp2p_kick(smp2p);
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq,
+					NULL, qcom_smp2p_intr,
+					IRQF_ONESHOT,
+					"smp2p", (void *)smp2p);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request interrupt\n");
+		goto unwind_interfaces;
+	}
+
+
+	return 0;
+
+unwind_interfaces:
+	list_for_each_entry(entry, &smp2p->inbound, node)
+		irq_domain_remove(entry->domain);
+
+	list_for_each_entry(entry, &smp2p->outbound, node)
+		gpiochip_remove(&entry->chip);
+
+	smp2p->out->valid_entries = 0;
+
+	return ret;
+}
+
+static int qcom_smp2p_remove(struct platform_device *pdev)
+{
+	struct qcom_smp2p *smp2p = platform_get_drvdata(pdev);
+	struct smp2p_entry *entry;
+
+	list_for_each_entry(entry, &smp2p->inbound, node)
+		irq_domain_remove(entry->domain);
+
+	list_for_each_entry(entry, &smp2p->outbound, node)
+		gpiochip_remove(&entry->chip);
+
+	smp2p->out->valid_entries = 0;
+
+	return 0;
+}
+
+static const struct of_device_id qcom_smp2p_of_match[] = {
+	{ .compatible = "qcom,smp2p" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_smp2p_of_match);
+
+static struct platform_driver qcom_smp2p_driver = {
+	.probe = qcom_smp2p_probe,
+	.remove = qcom_smp2p_remove,
+	.driver  = {
+		.name  = "qcom_smp2p",
+		.of_match_table = qcom_smp2p_of_match,
+	},
+};
+module_platform_driver(qcom_smp2p_driver);
+
+MODULE_DESCRIPTION("Qualcomm Shared Memory Point to Point driver");
+MODULE_LICENSE("GPL v2");
-- 
1.8.2.2

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