net: rfkill: add generic gpio rfkill driver

This adds a new generic gpio rfkill driver to support rfkill switches
which are controlled by gpios. The driver also supports passing in
data about the clock for the radio, so that when rfkill is blocking,
it can disable the clock.

This driver assumes platform data is passed from the board files to
configure it for specific devices.
Original-patch-by: Anantha Idapalapati <aidapalapati@nvidia.com>
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/rfkill-gpio.h

+/*
+ * Copyright (c) 2011, NVIDIA Corporation.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+
+#ifndef __RFKILL_GPIO_H
+#define __RFKILL_GPIO_H
+
+#include <linux/types.h>
+#include <linux/rfkill.h>
+
+/**
+ * struct rfkill_gpio_platform_data - platform data for rfkill gpio device.
+ * for unused gpio's, the expected value is -1.
+ * @name:		name for the gpio rf kill instance
+ * @reset_gpio:		GPIO which is used for reseting rfkill switch
+ * @shutdown_gpio:	GPIO which is used for shutdown of rfkill switch
+ * @power_clk_name:	[optional] name of clk to turn off while blocked
+ */
+
+struct rfkill_gpio_platform_data {
+	char			*name;
+	int			reset_gpio;
+	int			shutdown_gpio;
+	const char		*power_clk_name;
+	enum rfkill_type	type;
+};
+
+#endif /* __RFKILL_GPIO_H */

net/rfkill/Kconfig

@@ -33,3 +33,12 @@ config RFKILL_REGULATOR
 
           To compile this driver as a module, choose M here: the module will
           be called rfkill-regulator.
+
+config RFKILL_GPIO
+	tristate "GPIO RFKILL driver"
+	depends on RFKILL && GPIOLIB && HAVE_CLK
+	default n
+	help
+	  If you say yes here you get support of a generic gpio RFKILL
+	  driver. The platform should fill in the appropriate fields in the
+	  rfkill_gpio_platform_data structure and pass that to the driver.

net/rfkill/Makefile

@@ -6,3 +6,4 @@ rfkill-y			+= core.o
 rfkill-$(CONFIG_RFKILL_INPUT)	+= input.o
 obj-$(CONFIG_RFKILL)		+= rfkill.o
 obj-$(CONFIG_RFKILL_REGULATOR)	+= rfkill-regulator.o
+obj-$(CONFIG_RFKILL_GPIO)	+= rfkill-gpio.o

net/rfkill/rfkill-gpio.c

+/*
+ * Copyright (c) 2011, NVIDIA Corporation.
+ *
+ * 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rfkill.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/slab.h>
+
+#include <linux/rfkill-gpio.h>
+
+enum rfkill_gpio_clk_state {
+	UNSPECIFIED = 0,
+	PWR_ENABLED,
+	PWR_DISABLED
+};
+
+#define PWR_CLK_SET(_RF, _EN) \
+	((_RF)->pwr_clk_enabled = (!(_EN) ? PWR_ENABLED : PWR_DISABLED))
+#define PWR_CLK_ENABLED(_RF) ((_RF)->pwr_clk_enabled == PWR_ENABLED)
+#define PWR_CLK_DISABLED(_RF) ((_RF)->pwr_clk_enabled != PWR_ENABLED)
+
+struct rfkill_gpio_data {
+	struct rfkill_gpio_platform_data	*pdata;
+	struct rfkill				*rfkill_dev;
+	char					*reset_name;
+	char					*shutdown_name;
+	enum rfkill_gpio_clk_state		pwr_clk_enabled;
+	struct clk				*pwr_clk;
+};
+
+static int rfkill_gpio_set_power(void *data, bool blocked)
+{
+	struct rfkill_gpio_data *rfkill = data;
+
+	if (blocked) {
+		if (gpio_is_valid(rfkill->pdata->shutdown_gpio))
+			gpio_direction_output(rfkill->pdata->shutdown_gpio, 0);
+		if (gpio_is_valid(rfkill->pdata->reset_gpio))
+			gpio_direction_output(rfkill->pdata->reset_gpio, 0);
+		if (rfkill->pwr_clk && PWR_CLK_ENABLED(rfkill))
+			clk_disable(rfkill->pwr_clk);
+	} else {
+		if (rfkill->pwr_clk && PWR_CLK_DISABLED(rfkill))
+			clk_enable(rfkill->pwr_clk);
+		if (gpio_is_valid(rfkill->pdata->reset_gpio))
+			gpio_direction_output(rfkill->pdata->reset_gpio, 1);
+		if (gpio_is_valid(rfkill->pdata->shutdown_gpio))
+			gpio_direction_output(rfkill->pdata->shutdown_gpio, 1);
+	}
+
+	if (rfkill->pwr_clk)
+		PWR_CLK_SET(rfkill, blocked);
+
+	return 0;
+}
+
+static const struct rfkill_ops rfkill_gpio_ops = {
+	.set_block = rfkill_gpio_set_power,
+};
+
+static int rfkill_gpio_probe(struct platform_device *pdev)
+{
+	struct rfkill_gpio_data *rfkill;
+	struct rfkill_gpio_platform_data *pdata = pdev->dev.platform_data;
+	int ret = 0;
+	int len = 0;
+
+	if (!pdata) {
+		pr_warn("%s: No platform data specified\n", __func__);
+		return -EINVAL;
+	}
+
+	/* make sure at-least one of the GPIO is defined and that
+	 * a name is specified for this instance */
+	if (!pdata->name || (!gpio_is_valid(pdata->reset_gpio) &&
+		!gpio_is_valid(pdata->shutdown_gpio))) {
+		pr_warn("%s: invalid platform data\n", __func__);
+		return -EINVAL;
+	}
+
+	rfkill = kzalloc(sizeof(*rfkill), GFP_KERNEL);
+	if (!rfkill)
+		return -ENOMEM;
+
+	rfkill->pdata = pdata;
+
+	len = strlen(pdata->name);
+	rfkill->reset_name = kzalloc(len + 7, GFP_KERNEL);
+	if (!rfkill->reset_name) {
+		ret = -ENOMEM;
+		goto fail_alloc;
+	}
+
+	rfkill->shutdown_name = kzalloc(len + 10, GFP_KERNEL);
+	if (!rfkill->shutdown_name) {
+		ret = -ENOMEM;
+		goto fail_reset_name;
+	}
+
+	snprintf(rfkill->reset_name, len + 6 , "%s_reset", pdata->name);
+	snprintf(rfkill->shutdown_name, len + 9, "%s_shutdown", pdata->name);
+
+	if (pdata->power_clk_name) {
+		rfkill->pwr_clk = clk_get(&pdev->dev, pdata->power_clk_name);
+		if (IS_ERR(rfkill->pwr_clk)) {
+			pr_warn("%s: can't find pwr_clk.\n", __func__);
+			goto fail_shutdown_name;
+		}
+	}
+
+	if (gpio_is_valid(pdata->reset_gpio)) {
+		ret = gpio_request(pdata->reset_gpio, rfkill->reset_name);
+		if (ret) {
+			pr_warn("%s: failed to get reset gpio.\n", __func__);
+			goto fail_clock;
+		}
+	}
+
+	if (gpio_is_valid(pdata->shutdown_gpio)) {
+		ret = gpio_request(pdata->shutdown_gpio, rfkill->shutdown_name);
+		if (ret) {
+			pr_warn("%s: failed to get shutdown gpio.\n", __func__);
+			goto fail_reset;
+		}
+	}
+
+	rfkill->rfkill_dev = rfkill_alloc(pdata->name, &pdev->dev, pdata->type,
+				&rfkill_gpio_ops, rfkill);
+	if (!rfkill->rfkill_dev)
+		goto fail_shutdown;
+
+	ret = rfkill_register(rfkill->rfkill_dev);
+	if (ret < 0)
+		goto fail_rfkill;
+
+	platform_set_drvdata(pdev, rfkill);
+
+	dev_info(&pdev->dev, "%s device registered.\n", pdata->name);
+
+	return 0;
+
+fail_rfkill:
+	rfkill_destroy(rfkill->rfkill_dev);
+fail_shutdown:
+	if (gpio_is_valid(pdata->shutdown_gpio))
+		gpio_free(pdata->shutdown_gpio);
+fail_reset:
+	if (gpio_is_valid(pdata->reset_gpio))
+		gpio_free(pdata->reset_gpio);
+fail_clock:
+	if (rfkill->pwr_clk)
+		clk_put(rfkill->pwr_clk);
+fail_shutdown_name:
+	kfree(rfkill->shutdown_name);
+fail_reset_name:
+	kfree(rfkill->reset_name);
+fail_alloc:
+	kfree(rfkill);
+
+	return ret;
+}
+
+static int rfkill_gpio_remove(struct platform_device *pdev)
+{
+	struct rfkill_gpio_data *rfkill = platform_get_drvdata(pdev);
+
+	rfkill_unregister(rfkill->rfkill_dev);
+	rfkill_destroy(rfkill->rfkill_dev);
+	if (gpio_is_valid(rfkill->pdata->shutdown_gpio))
+		gpio_free(rfkill->pdata->shutdown_gpio);
+	if (gpio_is_valid(rfkill->pdata->reset_gpio))
+		gpio_free(rfkill->pdata->reset_gpio);
+	if (rfkill->pwr_clk && PWR_CLK_ENABLED(rfkill))
+		clk_disable(rfkill->pwr_clk);
+	if (rfkill->pwr_clk)
+		clk_put(rfkill->pwr_clk);
+	kfree(rfkill->shutdown_name);
+	kfree(rfkill->reset_name);
+	kfree(rfkill);
+
+	return 0;
+}
+
+static struct platform_driver rfkill_gpio_driver = {
+	.probe = rfkill_gpio_probe,
+	.remove = __devexit_p(rfkill_gpio_remove),
+	.driver = {
+		   .name = "rfkill_gpio",
+		   .owner = THIS_MODULE,
+	},
+};
+
+static int __init rfkill_gpio_init(void)
+{
+	return platform_driver_register(&rfkill_gpio_driver);
+}
+
+static void __exit rfkill_gpio_exit(void)
+{
+	platform_driver_unregister(&rfkill_gpio_driver);
+}
+
+module_init(rfkill_gpio_init);
+module_exit(rfkill_gpio_exit);
+
+MODULE_DESCRIPTION("gpio rfkill");
+MODULE_AUTHOR("NVIDIA");
+MODULE_LICENSE("GPL");