ARM: vexpress: Reset driver

This is a simple driver providing platform restart and power off
functions using VE config infrastructure.

By writing to the "active" attribute of the reboot or reset device,
user can decide what if the platform is supposed to execute full power
cycle (reboot, default) or simply assert system level reset signal.
Signed-off-by: Pawel Moll <pawel.moll@arm.com>

Conflicts:

	include/linux/vexpress.h

arch/arm/mach-vexpress/reset.c

+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 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.
+ *
+ * Copyright (C) 2012 ARM Limited
+ */
+
+#include <linux/jiffies.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/stat.h>
+#include <linux/vexpress.h>
+
+static void vexpress_reset_do(struct device *dev, const char *what)
+{
+	int err = -ENOENT;
+	struct vexpress_config_func *func =
+			vexpress_config_func_get_by_dev(dev);
+
+	if (func) {
+		unsigned long timeout;
+
+		err = vexpress_config_write(func, 0, 0);
+
+		timeout = jiffies + HZ;
+		while (time_before(jiffies, timeout))
+			cpu_relax();
+	}
+
+	dev_emerg(dev, "Unable to %s (%d)\n", what, err);
+}
+
+static struct device *vexpress_power_off_device;
+
+void vexpress_power_off(void)
+{
+	vexpress_reset_do(vexpress_power_off_device, "power off");
+}
+
+static struct device *vexpress_restart_device;
+
+void vexpress_restart(char str, const char *cmd)
+{
+	vexpress_reset_do(vexpress_restart_device, "restart");
+}
+
+static ssize_t vexpress_reset_active_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", vexpress_restart_device == dev);
+}
+
+static ssize_t vexpress_reset_active_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	long value;
+	int err = kstrtol(buf, 0, &value);
+
+	if (!err && value)
+		vexpress_restart_device = dev;
+
+	return err ? err : count;
+}
+
+DEVICE_ATTR(active, S_IRUGO | S_IWUSR, vexpress_reset_active_show,
+		vexpress_reset_active_store);
+
+
+enum vexpress_reset_func { FUNC_RESET, FUNC_SHUTDOWN, FUNC_REBOOT };
+
+static struct of_device_id vexpress_reset_of_match[] = {
+	{
+		.compatible = "arm,vexpress-reset",
+		.data = (void *)FUNC_RESET,
+	}, {
+		.compatible = "arm,vexpress-shutdown",
+		.data = (void *)FUNC_SHUTDOWN
+	}, {
+		.compatible = "arm,vexpress-reboot",
+		.data = (void *)FUNC_REBOOT
+	},
+	{}
+};
+
+static int vexpress_reset_probe(struct platform_device *pdev)
+{
+	enum vexpress_reset_func func;
+	const struct of_device_id *match =
+			of_match_device(vexpress_reset_of_match, &pdev->dev);
+
+	if (match)
+		func = (enum vexpress_reset_func)match->data;
+	else
+		func = pdev->id_entry->driver_data;
+
+	switch (func) {
+	case FUNC_SHUTDOWN:
+		vexpress_power_off_device = &pdev->dev;
+		break;
+	case FUNC_RESET:
+		if (!vexpress_restart_device)
+			vexpress_restart_device = &pdev->dev;
+		device_create_file(&pdev->dev, &dev_attr_active);
+		break;
+	case FUNC_REBOOT:
+		vexpress_restart_device = &pdev->dev;
+		device_create_file(&pdev->dev, &dev_attr_active);
+		break;
+	};
+
+	return 0;
+}
+
+static const struct platform_device_id vexpress_reset_id_table[] = {
+	{ .name = "vexpress-reset", .driver_data = FUNC_RESET, },
+	{ .name = "vexpress-shutdown", .driver_data = FUNC_SHUTDOWN, },
+	{ .name = "vexpress-reboot", .driver_data = FUNC_REBOOT, },
+	{}
+};
+
+static struct platform_driver vexpress_reset_driver = {
+	.probe = vexpress_reset_probe,
+	.driver = {
+		.name = "vexpress-reset",
+		.of_match_table = vexpress_reset_of_match,
+	},
+	.id_table = vexpress_reset_id_table,
+};
+
+static int __init vexpress_reset_init(void)
+{
+	return platform_driver_register(&vexpress_reset_driver);
+}
+device_initcall(vexpress_reset_init);