[PATCH] gpio: add gpio_of_helper

[Jiri Prchal <jiri.prchal@xxxxxxxxxxx>]

This patch adds new driver "gpio-of-helper", witch has possibility to export
gpios defined in dt. It exports them in defined name under
/sysfs/class/gpio/name.
It's rebased from Pantelis Antoniou patch to new kernel.
Usage example:
	gpio {
		compatible = "gpio-of-helper";
		status = "okay";
		pinctrl-names = "default";
		pinctrl-0 = <&pinctrl_gpio>;

		gsm_on {
			gpio-name = "gsm_on";
			gpio = <&pioB 13 GPIO_ACTIVE_HIGH>;
			output;
			init-low;
		};
	};

This patch needs Alexey Ignatov [PATCH] gpiolib: allow exporting gpios with
custom names.

Signed-off-by: Jiri Prchal <jiri.prchal@xxxxxxxxxxx>
---
 drivers/gpio/Kconfig          |  14 ++
 drivers/gpio/Makefile         |   1 +
 drivers/gpio/gpio-of-helper.c | 423 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 438 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 9de1515..3ec127f 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -85,6 +85,20 @@ config GPIO_SYSFS
 	  Kernel drivers may also request that a particular GPIO be
 	  exported to userspace; this can be useful when debugging.
 
+config GPIO_OF_HELPER
+	bool "GPIO OF helper device"
+	depends on OF_GPIO
+	help
+	  Say Y here to add an GPIO OF helper driver
+
+	  Allows you specify a GPIO helper based on OF
+	  which allows simple export of GPIO functionality
+	  in user-space.
+
+	  Features include, value set/get, direction control,
+	  interrupt/value change poll support, event counting
+	  and others.
+
 config GPIO_GENERIC
 	tristate
 
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 5d024e3..6708880 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib-legacy.o
 obj-$(CONFIG_OF_GPIO)		+= gpiolib-of.o
 obj-$(CONFIG_GPIO_SYSFS)	+= gpiolib-sysfs.o
 obj-$(CONFIG_GPIO_ACPI)		+= gpiolib-acpi.o
+obj-$(CONFIG_GPIO_OF_HELPER)	+= gpio-of-helper.o
 
 # Device drivers. Generally keep list sorted alphabetically
 obj-$(CONFIG_GPIO_GENERIC)	+= gpio-generic.o
diff --git a/drivers/gpio/gpio-of-helper.c b/drivers/gpio/gpio-of-helper.c
new file mode 100644
index 0000000..4e6f2e2
--- /dev/null
+++ b/drivers/gpio/gpio-of-helper.c
@@ -0,0 +1,423 @@
+/*
+ * GPIO OF based helper
+ *
+ * A simple DT based driver to provide access to GPIO functionality
+ * to user-space via sysfs.
+ *
+ * Copyright (C) 2013 Pantelis Antoniou <panto@xxxxxxxxxxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/timer.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
+#include <linux/pinctrl/pinctrl.h>
+#include <linux/pinctrl/pinmux.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/math64.h>
+#include <linux/atomic.h>
+#include <linux/idr.h>
+
+/* fwd decl. */
+struct gpio_of_helper_info;
+
+enum gpio_type {
+	GPIO_TYPE_INPUT = 0,
+	GPIO_TYPE_OUTPUT = 1,
+};
+
+struct gpio_of_entry {
+	int id;
+	struct gpio_of_helper_info *info;
+	struct device_node *node;
+	enum gpio_type type;
+	int gpio;
+	enum of_gpio_flags gpio_flags;
+	int irq;
+	const char *name;
+	atomic64_t counter;
+	unsigned int count_flags;
+#define COUNT_RISING_EDGE	(1 << 0)
+#define COUNT_FALLING_EDGE	(1 << 1)
+};
+
+struct gpio_of_helper_info {
+	struct platform_device *pdev;
+	struct idr idr;
+};
+
+static DEFINE_IDR(gpio_of_helper_idr);
+static DEFINE_SPINLOCK(gpio_of_helper_lock);
+
+static const struct of_device_id gpio_of_helper_of_match[] = {
+	{ .compatible = "gpio-of-helper", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, gpio_of_helper_of_match);
+
+static ssize_t gpio_of_helper_show_status(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct gpio_of_helper_info *info = platform_get_drvdata(pdev);
+	struct gpio_of_entry *entry;
+	char *p, *e;
+	int id, n;
+
+	p = buf;
+	e = p + PAGE_SIZE;
+	n = 0;
+	idr_for_each_entry(&info->idr, entry, id) {
+		switch (entry->type) {
+		case GPIO_TYPE_INPUT:
+			n = snprintf(p, e - p, "%2d %-24s %3d %-3s %llu\n",
+				entry->id, entry->name, entry->gpio, "IN",
+				(unsigned long long)
+					atomic64_read(&entry->counter));
+			break;
+		case GPIO_TYPE_OUTPUT:
+			n = snprintf(p, e - p, "%2d %-24s %3d %-3s\n",
+				entry->id, entry->name, entry->gpio, "OUT");
+			break;
+		}
+		p += n;
+	}
+
+	return p - buf;
+}
+
+static DEVICE_ATTR(status, S_IRUGO,
+		gpio_of_helper_show_status, NULL);
+
+static irqreturn_t gpio_of_helper_handler(int irq, void *ptr)
+{
+	struct gpio_of_entry *entry = ptr;
+
+	/* caution - low speed interfaces only! */
+	atomic64_inc(&entry->counter);
+
+	return IRQ_HANDLED;
+}
+
+static struct gpio_of_entry *
+gpio_of_entry_create(struct gpio_of_helper_info *info, struct device_node *node)
+{
+	struct platform_device *pdev = info->pdev;
+	struct device *dev = &pdev->dev;
+	struct gpio_of_entry *entry;
+	int err, gpio, irq;
+	unsigned int req_flags, count_flags, irq_flags;
+	enum gpio_type type;
+	enum of_gpio_flags gpio_flags;
+	const char *name;
+
+	/* get the type of the node first */
+	if (of_property_read_bool(node, "input"))
+		type = GPIO_TYPE_INPUT;
+	else if (of_property_read_bool(node, "output"))
+		type = GPIO_TYPE_OUTPUT;
+	else {
+		dev_err(dev, "Not valid gpio node type\n");
+		err = -EINVAL;
+		goto err_bad_node;
+	}
+
+	/* get the name */
+	err = of_property_read_string(node, "gpio-name", &name);
+	if (err != 0) {
+		dev_err(dev, "Failed to get name property\n");
+		goto err_bad_node;
+	}
+
+	err = of_get_named_gpio_flags(node, "gpio", 0, &gpio_flags);
+	if (IS_ERR_VALUE(err)) {
+		dev_err(dev, "Failed to get gpio property of '%s'\n", name);
+		goto err_bad_node;
+	}
+	gpio = err;
+
+	if (!gpio_is_valid(gpio)) {
+		dev_err(dev, "Skipping unavailable gpio %d (%s)\n",
+		         gpio, name);
+		goto err_bad_node;
+	}
+
+	req_flags = 0;
+	count_flags = 0;
+
+	/* set the request flags */
+	switch (type) {
+		case GPIO_TYPE_INPUT:
+			req_flags = GPIOF_DIR_IN;
+			if (of_property_read_bool(node, "count-falling-edge"))
+				count_flags |= COUNT_FALLING_EDGE;
+			if (of_property_read_bool(node, "count-rising-edge"))
+				count_flags |= COUNT_RISING_EDGE;
+			break;
+		case GPIO_TYPE_OUTPUT:
+			req_flags = GPIOF_DIR_OUT;
+			if (of_property_read_bool(node, "init-high"))
+				req_flags |= GPIOF_OUT_INIT_HIGH;
+			else if (of_property_read_bool(node, "init-low"))
+				req_flags |= GPIOF_OUT_INIT_LOW;
+			break;
+	}
+	if (gpio_flags)
+		req_flags |= GPIOF_ACTIVE_LOW;
+
+	/* request the gpio */
+	err = devm_gpio_request_one(dev, gpio, req_flags, name);
+	if (err != 0) {
+		dev_err(dev, "Failed to request gpio '%s'\n", name);
+		goto err_bad_node;
+	}
+
+	gpio_export_name(gpio, 0, name);
+
+	irq = -1;
+	irq_flags = 0;
+
+	/* counter mode requested - need an interrupt */
+	if (count_flags != 0) {
+		irq = gpio_to_irq(gpio);
+		if (IS_ERR_VALUE(irq)) {
+			dev_err(dev, "Failed to request gpio '%s'\n", name);
+			goto err_bad_node;
+		}
+
+		if (count_flags & COUNT_RISING_EDGE)
+			irq_flags |= IRQF_TRIGGER_RISING;
+		if (count_flags & COUNT_FALLING_EDGE)
+			irq_flags |= IRQF_TRIGGER_FALLING;
+	}
+
+	entry = devm_kzalloc(dev, sizeof(*entry), GFP_KERNEL);
+	if (entry == NULL) {
+		dev_err(dev, "Failed to allocate gpio entry of '%s'\n", name);
+		err = -ENOMEM;
+		goto err_no_mem;
+	}
+
+	entry->id = -1;
+	entry->info = info;
+	entry->node = of_node_get(node); /* get node reference */
+	entry->type = type;
+	entry->gpio = gpio;
+	entry->gpio_flags = gpio_flags;
+	entry->irq = irq;
+	entry->name = name;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock(&gpio_of_helper_lock);
+	err = idr_alloc(&gpio_of_helper_idr, entry, 0, 0, GFP_NOWAIT);
+	if (err >= 0)
+		entry->id = err;
+	spin_unlock(&gpio_of_helper_lock);
+	idr_preload_end();
+	if (err < 0) {
+		dev_err(dev, "Failed to idr_get_new  of '%s'\n", name);
+		goto err_fail_idr;
+	}
+
+	/* interrupt enable is last thing done */
+	if (irq >= 0) {
+		atomic64_set(&entry->counter, 0);
+		entry->count_flags = count_flags;
+		err = devm_request_irq(dev, irq, gpio_of_helper_handler,
+				irq_flags, name, entry);
+		if (err != 0) {
+			dev_err(dev, "Failed to request irq of '%s'\n", name);
+			goto err_no_irq;
+		}
+	}
+
+	dev_info(dev, "Allocated GPIO id=%d\n", entry->id);
+
+	return entry;
+
+err_fail_idr:
+	/* nothing to do */
+err_no_irq:
+	/* release node ref */
+	of_node_put(node);
+	/* nothing else needs to be done, devres handles it */
+err_no_mem:
+err_bad_node:
+	return ERR_PTR(err);
+}
+
+static int gpio_of_entry_destroy(struct gpio_of_entry *entry)
+{
+	struct gpio_of_helper_info *info = entry->info;
+	struct platform_device *pdev = info->pdev;
+	struct device *dev = &pdev->dev;
+
+	dev_info(dev, "Destroying GPIO id=%d\n", entry->id);
+
+	/* remove from the IDR */
+	idr_remove(&info->idr, entry->id);
+
+	/* remove node ref */
+	of_node_put(entry->node);
+
+	/* free gpio */
+	devm_gpio_free(dev, entry->gpio);
+
+	/* gree irq */
+	if (entry->irq >= 0)
+		devm_free_irq(dev, entry->irq, entry);
+
+	/* and free */
+	devm_kfree(dev, entry);
+
+	return 0;
+}
+
+static int gpio_of_helper_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_of_helper_info *info;
+	struct gpio_of_entry *entry;
+	struct device_node *pnode = pdev->dev.of_node;
+	struct device_node *cnode;
+	struct pinctrl *pinctrl;
+	int err;
+
+	/* we only support OF */
+	if (pnode == NULL) {
+		dev_err(&pdev->dev, "No platform of_node!\n");
+		return -ENODEV;
+	}
+
+	pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
+	if (IS_ERR(pinctrl)) {
+		/* special handling for probe defer */
+		if (PTR_ERR(pinctrl) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		dev_warn(&pdev->dev,
+			"pins are not configured from the driver\n");
+	}
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (info == NULL) {
+		dev_err(&pdev->dev, "Failed to allocate info\n");
+		err = -ENOMEM;
+		goto err_no_mem;
+	}
+	platform_set_drvdata(pdev, info);
+	info->pdev = pdev;
+
+	idr_init(&info->idr);
+
+	err = device_create_file(dev, &dev_attr_status);
+	if (err != 0) {
+		dev_err(dev, "Failed to create status sysfs attribute\n");
+		goto err_no_sysfs;
+	}
+
+	for_each_child_of_node(pnode, cnode) {
+
+		entry = gpio_of_entry_create(info, cnode);
+		if (IS_ERR_OR_NULL(entry)) {
+			dev_err(dev, "Failed to create gpio entry\n");
+			err = PTR_ERR(entry);
+			goto err_fail_entry;
+		}
+	}
+
+	dev_info(&pdev->dev, "ready\n");
+
+	return 0;
+err_fail_entry:
+	device_remove_file(&pdev->dev, &dev_attr_status);
+err_no_sysfs:
+err_no_mem:
+	return err;
+}
+
+static int gpio_of_helper_remove(struct platform_device *pdev)
+{
+	struct gpio_of_helper_info *info = platform_get_drvdata(pdev);
+	struct gpio_of_entry *entry;
+	int id;
+
+	dev_info(&pdev->dev, "removing\n");
+
+	device_remove_file(&pdev->dev, &dev_attr_status);
+
+	id = 0;
+	idr_for_each_entry(&info->idr, entry, id) {
+		/* destroy each and every one */
+		gpio_of_entry_destroy(entry);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+#ifdef CONFIG_PM_RUNTIME
+static int gpio_of_helper_runtime_suspend(struct device *dev)
+{
+	/* place holder */
+	return 0;
+}
+
+static int gpio_of_helper_runtime_resume(struct device *dev)
+{
+	/* place holder */
+	return 0;
+}
+#endif /* CONFIG_PM_RUNTIME */
+
+static struct dev_pm_ops gpio_of_helper_pm_ops = {
+	SET_RUNTIME_PM_OPS(gpio_of_helper_runtime_suspend,
+			   gpio_of_helper_runtime_resume, NULL)
+};
+#define GPIO_OF_HELPER_PM_OPS (&gpio_of_helper_pm_ops)
+#else
+#define GPIO_OF_HELPER_PM_OPS NULL
+#endif /* CONFIG_PM */
+
+struct platform_driver gpio_of_helper_driver = {
+	.probe		= gpio_of_helper_probe,
+	.remove		= gpio_of_helper_remove,
+	.driver = {
+		.name		= "gpio-of-helper",
+		.owner		= THIS_MODULE,
+		.pm		= GPIO_OF_HELPER_PM_OPS,
+		.of_match_table	= gpio_of_helper_of_match,
+	},
+};
+
+module_platform_driver(gpio_of_helper_driver);
+
+MODULE_AUTHOR("Pantelis Antoniou <panto@xxxxxxxxxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("GPIO OF Helper driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-of-helper");
-- 
1.9.1

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