sh: generic push-switch framework.

This adds support for a generic push switch framework. Adaptable for
various switches, including GPIO switches and the push switches commonly
found on Renesas debug boards.

This allows switch states to be trivially reported through sysfs.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -473,6 +473,8 @@ config HEARTBEAT
 	  behavior is platform-dependent, but normally the flash frequency is
 	  a hyperbolic function of the 5-minute load average.
 
+source "arch/sh/drivers/Kconfig"
+
 endmenu
 
 config ISA_DMA_API

arch/sh/drivers/Kconfig

@@ -0,0 +1,9 @@
+menu "Additional SuperH Device Drivers"
+
+config PUSH_SWITCH
+	tristate "Push switch support"
+	help
+	  This enables support for the push switch framework, a simple
+	  framework that allows for sysfs driven switch status reporting.
+
+endmenu

arch/sh/drivers/Makefile

@@ -5,4 +5,4 @@
 obj-$(CONFIG_PCI)		+= pci/
 obj-$(CONFIG_SH_DMA)		+= dma/
 obj-$(CONFIG_SUPERHYWAY)	+= superhyway/
-
+obj-$(CONFIG_PUSH_SWITCH)	+= push-switch.o

arch/sh/drivers/push-switch.c

@@ -0,0 +1,138 @@
+/*
+ * Generic push-switch framework
+ *
+ * Copyright (C) 2006  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <asm/push-switch.h>
+
+#define DRV_NAME "push-switch"
+#define DRV_VERSION "0.1.0"
+
+static ssize_t switch_show(struct device *dev,
+			   struct device_attribute *attr,
+			   char *buf)
+{
+	struct push_switch_platform_info *psw_info = dev->platform_data;
+	return sprintf(buf, "%s\n", psw_info->name);
+}
+static DEVICE_ATTR(switch, S_IRUGO, switch_show, NULL);
+
+static void switch_timer(unsigned long data)
+{
+	struct push_switch *psw = (struct push_switch *)data;
+
+	schedule_work(&psw->work);
+}
+
+static void switch_work_handler(void *data)
+{
+	struct platform_device *pdev = data;
+	struct push_switch *psw = platform_get_drvdata(pdev);
+
+	psw->state = 0;
+
+	kobject_uevent(&pdev->dev.kobj, KOBJ_CHANGE);
+}
+
+static int switch_drv_probe(struct platform_device *pdev)
+{
+	struct push_switch_platform_info *psw_info;
+	struct push_switch *psw;
+	int ret, irq;
+
+	psw = kzalloc(sizeof(struct push_switch), GFP_KERNEL);
+	if (unlikely(!psw))
+		return -ENOMEM;
+
+	irq = platform_get_irq(pdev, 0);
+	if (unlikely(irq < 0)) {
+		ret = -ENODEV;
+		goto err;
+	}
+
+	psw_info = pdev->dev.platform_data;
+	BUG_ON(!psw_info);
+
+	ret = request_irq(irq, psw_info->irq_handler,
+			  IRQF_DISABLED | psw_info->irq_flags,
+			  psw_info->name ? psw_info->name : DRV_NAME, pdev);
+	if (unlikely(ret < 0))
+		goto err;
+
+	if (psw_info->name) {
+		ret = device_create_file(&pdev->dev, &dev_attr_switch);
+		if (unlikely(ret)) {
+			dev_err(&pdev->dev, "Failed creating device attrs\n");
+			ret = -EINVAL;
+			goto err_irq;
+		}
+	}
+
+	INIT_WORK(&psw->work, switch_work_handler, pdev);
+	init_timer(&psw->debounce);
+
+	psw->debounce.function = switch_timer;
+	psw->debounce.data = (unsigned long)psw;
+
+	platform_set_drvdata(pdev, psw);
+
+	return 0;
+
+err_irq:
+	free_irq(irq, pdev);
+err:
+	kfree(psw);
+	return ret;
+}
+
+static int switch_drv_remove(struct platform_device *pdev)
+{
+	struct push_switch *psw = platform_get_drvdata(pdev);
+	struct push_switch_platform_info *psw_info = pdev->dev.platform_data;
+	int irq = platform_get_irq(pdev, 0);
+
+	if (psw_info->name)
+		device_remove_file(&pdev->dev, &dev_attr_switch);
+
+	platform_set_drvdata(pdev, NULL);
+	flush_scheduled_work();
+	del_timer_sync(&psw->debounce);
+	free_irq(irq, pdev);
+
+	kfree(psw);
+
+	return 0;
+}
+
+static struct platform_driver switch_driver = {
+	.probe		= switch_drv_probe,
+	.remove		= switch_drv_remove,
+	.driver		= {
+		.name	= DRV_NAME,
+	},
+};
+
+static int __init switch_init(void)
+{
+	printk(KERN_NOTICE DRV_NAME ": version %s loaded\n", DRV_VERSION);
+	return platform_driver_register(&switch_driver);
+}
+
+static void __exit switch_exit(void)
+{
+	platform_driver_unregister(&switch_driver);
+}
+module_init(switch_init);
+module_exit(switch_exit);
+
+MODULE_VERSION(DRV_VERSION);
+MODULE_AUTHOR("Paul Mundt");
+MODULE_LICENSE("GPLv2");

include/asm-sh/push-switch.h

@@ -0,0 +1,28 @@
+#ifndef __ASM_SH_PUSH_SWITCH_H
+#define __ASM_SH_PUSH_SWITCH_H
+
+#include <linux/timer.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+
+struct push_switch {
+	/* switch state */
+	unsigned int		state:1;
+	/* debounce timer */
+	struct timer_list	debounce;
+	/* workqueue */
+	struct work_struct	work;
+};
+
+struct push_switch_platform_info {
+	/* IRQ handler */
+	irqreturn_t		(*irq_handler)(int irq, void *data);
+	/* Special IRQ flags */
+	unsigned int		irq_flags;
+	/* Bit location of switch */
+	unsigned int		bit;
+	/* Symbolic switch name */
+	const char		*name;
+};
+
+#endif /* __ASM_SH_PUSH_SWITCH_H */