[linux.git] / drivers / watchdog / gef_wdt.c

/*
 * GE watchdog userspace interface
 *
 * Author:  Martyn Welch <[email protected]>
 *
 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
 *
 * 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.
 *
 * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
 *   Author: James Chapman <[email protected]>
 */

/* TODO:
 * This driver does not provide support for the hardwares capability of sending
 * an interrupt at a programmable threshold.
 *
 * This driver currently can only support 1 watchdog - there are 2 in the
 * hardware that this driver supports. Thus one could be configured as a
 * process-based watchdog (via /dev/watchdog), the second (using the interrupt
 * capabilities) a kernel-based watchdog.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/compiler.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#include <sysdev/fsl_soc.h>

/*
 * The watchdog configuration register contains a pair of 2-bit fields,
 *   1.  a reload field, bits 27-26, which triggers a reload of
 *       the countdown register, and
 *   2.  an enable field, bits 25-24, which toggles between
 *       enabling and disabling the watchdog timer.
 * Bit 31 is a read-only field which indicates whether the
 * watchdog timer is currently enabled.
 *
 * The low 24 bits contain the timer reload value.
 */
#define GEF_WDC_ENABLE_SHIFT	24
#define GEF_WDC_SERVICE_SHIFT	26
#define GEF_WDC_ENABLED_SHIFT	31

#define GEF_WDC_ENABLED_TRUE	1
#define GEF_WDC_ENABLED_FALSE	0

/* Flags bits */
#define GEF_WDOG_FLAG_OPENED	0

static unsigned long wdt_flags;
static int wdt_status;
static void __iomem *gef_wdt_regs;
static int gef_wdt_timeout;
static int gef_wdt_count;
static unsigned int bus_clk;
static char expect_close;
static DEFINE_SPINLOCK(gef_wdt_spinlock);

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");


static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
{
	u32 data;
	u32 enabled;
	int ret = 0;

	spin_lock(&gef_wdt_spinlock);
	data = ioread32be(gef_wdt_regs);
	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;

	/* only toggle the requested field if enabled state matches predicate */
	if ((enabled ^ enabled_predicate) == 0) {
		/* We write a 1, then a 2 -- to the appropriate field */
		data = (1 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);

		data = (2 << field_shift) | gef_wdt_count;
		iowrite32be(data, gef_wdt_regs);
		ret = 1;
	}
	spin_unlock(&gef_wdt_spinlock);

	return ret;
}

static void gef_wdt_service(void)
{
	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
		GEF_WDC_SERVICE_SHIFT);
}

static void gef_wdt_handler_enable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
				   GEF_WDC_ENABLE_SHIFT)) {
		gef_wdt_service();
		pr_notice("watchdog activated\n");
	}
}

static void gef_wdt_handler_disable(void)
{
	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
				   GEF_WDC_ENABLE_SHIFT))
		pr_notice("watchdog deactivated\n");
}

static void gef_wdt_set_timeout(unsigned int timeout)
{
	/* maximum bus cycle count is 0xFFFFFFFF */
	if (timeout > 0xFFFFFFFF / bus_clk)
		timeout = 0xFFFFFFFF / bus_clk;

	/* Register only holds upper 24 bits, bit shifted into lower 24 */
	gef_wdt_count = (timeout * bus_clk) >> 8;
	gef_wdt_timeout = timeout;
}


static ssize_t gef_wdt_write(struct file *file, const char __user *data,
				 size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			expect_close = 0;

			for (i = 0; i != len; i++) {
				char c;
				if (get_user(c, data + i))
					return -EFAULT;
				if (c == 'V')
					expect_close = 42;
			}
		}
		gef_wdt_service();
	}

	return len;
}

static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	int timeout;
	int options;
	void __user *argp = (void __user *)arg;
	static const struct watchdog_info info = {
		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
				WDIOF_KEEPALIVEPING,
		.firmware_version = 0,
		.identity = "GE watchdog",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &info, sizeof(info)))
			return -EFAULT;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(wdt_status, (int __user *)argp))
			return -EFAULT;
		wdt_status &= ~WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETOPTIONS:
		if (get_user(options, (int __user *)argp))
			return -EFAULT;

		if (options & WDIOS_DISABLECARD)
			gef_wdt_handler_disable();

		if (options & WDIOS_ENABLECARD)
			gef_wdt_handler_enable();
		break;

	case WDIOC_KEEPALIVE:
		gef_wdt_service();
		wdt_status |= WDIOF_KEEPALIVEPING;
		break;

	case WDIOC_SETTIMEOUT:
		if (get_user(timeout, (int __user *)argp))
			return -EFAULT;
		gef_wdt_set_timeout(timeout);
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		if (put_user(gef_wdt_timeout, (int __user *)argp))
			return -EFAULT;
		break;

	default:
		return -ENOTTY;
	}

	return 0;
}

static int gef_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
		return -EBUSY;

	if (nowayout)
		__module_get(THIS_MODULE);

	gef_wdt_handler_enable();

	return nonseekable_open(inode, file);
}

static int gef_wdt_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42)
		gef_wdt_handler_disable();
	else {
		pr_crit("unexpected close, not stopping timer!\n");
		gef_wdt_service();
	}
	expect_close = 0;

	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);

	return 0;
}

static const struct file_operations gef_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = gef_wdt_write,
	.unlocked_ioctl = gef_wdt_ioctl,
	.open = gef_wdt_open,
	.release = gef_wdt_release,
};

static struct miscdevice gef_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &gef_wdt_fops,
};


static int gef_wdt_probe(struct platform_device *dev)
{
	int timeout = 10;
	u32 freq;

	bus_clk = 133; /* in MHz */

	freq = fsl_get_sys_freq();
	if (freq != -1)
		bus_clk = freq;

	/* Map devices registers into memory */
	gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
	if (gef_wdt_regs == NULL)
		return -ENOMEM;

	gef_wdt_set_timeout(timeout);

	gef_wdt_handler_disable();	/* in case timer was already running */

	return misc_register(&gef_wdt_miscdev);
}

static int gef_wdt_remove(struct platform_device *dev)
{
	misc_deregister(&gef_wdt_miscdev);

	gef_wdt_handler_disable();

	iounmap(gef_wdt_regs);

	return 0;
}

static const struct of_device_id gef_wdt_ids[] = {
	{
		.compatible = "gef,fpga-wdt",
	},
	{},
};
MODULE_DEVICE_TABLE(of, gef_wdt_ids);

static struct platform_driver gef_wdt_driver = {
	.driver = {
		.name = "gef_wdt",
		.of_match_table = gef_wdt_ids,
	},
	.probe		= gef_wdt_probe,
	.remove		= gef_wdt_remove,
};

static int __init gef_wdt_init(void)
{
	pr_info("GE watchdog driver\n");
	return platform_driver_register(&gef_wdt_driver);
}

static void __exit gef_wdt_exit(void)
{
	platform_driver_unregister(&gef_wdt_driver);
}

module_init(gef_wdt_init);
module_exit(gef_wdt_exit);

MODULE_AUTHOR("Martyn Welch <[email protected]>");
MODULE_DESCRIPTION("GE watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gef_wdt");
Commit	Line	Data
3268b561	1	/*
cda61c94	2	* GE watchdog userspace interface
3268b561	3	*
cda61c94	4	* Author: Martyn Welch <[email protected]>
3268b561	5	*
cda61c94	6	* Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
3268b561 MW	7	*
	8	* This program is free software; you can redistribute it and/or modify it
	9	* under the terms of the GNU General Public License as published by the
	10	* Free Software Foundation; either version 2 of the License, or (at your
	11	* option) any later version.
	12	*
	13	* Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
	14	* Author: James Chapman <[email protected]>
	15	*/
	16
	17	/* TODO:
	18	* This driver does not provide support for the hardwares capability of sending
	19	* an interrupt at a programmable threshold.
	20	*
	21	* This driver currently can only support 1 watchdog - there are 2 in the
	22	* hardware that this driver supports. Thus one could be configured as a
	23	* process-based watchdog (via /dev/watchdog), the second (using the interrupt
	24	* capabilities) a kernel-based watchdog.
	25	*/
	26
27c766aa JP	27	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	28
3268b561 MW	29	#include <linux/kernel.h>
	30	#include <linux/compiler.h>
	31	#include <linux/init.h>
	32	#include <linux/module.h>
	33	#include <linux/miscdevice.h>
	34	#include <linux/watchdog.h>
f6e0722f	35	#include <linux/fs.h>
3268b561	36	#include <linux/of.h>
5af50730	37	#include <linux/of_address.h>
3268b561 MW	38	#include <linux/of_platform.h>
	39	#include <linux/io.h>
	40	#include <linux/uaccess.h>
	41
	42	#include <sysdev/fsl_soc.h>
	43
	44	/*
	45	* The watchdog configuration register contains a pair of 2-bit fields,
	46	* 1. a reload field, bits 27-26, which triggers a reload of
	47	* the countdown register, and
	48	* 2. an enable field, bits 25-24, which toggles between
	49	* enabling and disabling the watchdog timer.
	50	* Bit 31 is a read-only field which indicates whether the
	51	* watchdog timer is currently enabled.
	52	*
	53	* The low 24 bits contain the timer reload value.
	54	*/
	55	#define GEF_WDC_ENABLE_SHIFT 24
	56	#define GEF_WDC_SERVICE_SHIFT 26
	57	#define GEF_WDC_ENABLED_SHIFT 31
	58
	59	#define GEF_WDC_ENABLED_TRUE 1
	60	#define GEF_WDC_ENABLED_FALSE 0
	61
	62	/* Flags bits */
	63	#define GEF_WDOG_FLAG_OPENED 0
	64
	65	static unsigned long wdt_flags;
	66	static int wdt_status;
	67	static void __iomem *gef_wdt_regs;
	68	static int gef_wdt_timeout;
	69	static int gef_wdt_count;
	70	static unsigned int bus_clk;
	71	static char expect_close;
	72	static DEFINE_SPINLOCK(gef_wdt_spinlock);
	73
86a1e189 WVS	74	static bool nowayout = WATCHDOG_NOWAYOUT;
86a1e189 WVS	75	module_param(nowayout, bool, 0);
3268b561 MW	76	MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
	77	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
	78
	79
	80	static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
	81	{
	82	u32 data;
	83	u32 enabled;
	84	int ret = 0;
	85
	86	spin_lock(&gef_wdt_spinlock);
	87	data = ioread32be(gef_wdt_regs);
	88	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
	89
	90	/* only toggle the requested field if enabled state matches predicate */
	91	if ((enabled ^ enabled_predicate) == 0) {
	92	/* We write a 1, then a 2 -- to the appropriate field */
	93	data = (1 << field_shift) \| gef_wdt_count;
	94	iowrite32be(data, gef_wdt_regs);
	95
	96	data = (2 << field_shift) \| gef_wdt_count;
	97	iowrite32be(data, gef_wdt_regs);
	98	ret = 1;
	99	}
	100	spin_unlock(&gef_wdt_spinlock);
	101
	102	return ret;
	103	}
	104
	105	static void gef_wdt_service(void)
	106	{
	107	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
	108	GEF_WDC_SERVICE_SHIFT);
	109	}
	110
	111	static void gef_wdt_handler_enable(void)
	112	{
	113	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
	114	GEF_WDC_ENABLE_SHIFT)) {
	115	gef_wdt_service();
27c766aa	116	pr_notice("watchdog activated\n");
3268b561 MW	117	}
	118	}
	119
	120	static void gef_wdt_handler_disable(void)
	121	{
	122	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
	123	GEF_WDC_ENABLE_SHIFT))
27c766aa	124	pr_notice("watchdog deactivated\n");
3268b561 MW	125	}
	126
	127	static void gef_wdt_set_timeout(unsigned int timeout)
	128	{
	129	/* maximum bus cycle count is 0xFFFFFFFF */
	130	if (timeout > 0xFFFFFFFF / bus_clk)
	131	timeout = 0xFFFFFFFF / bus_clk;
	132
	133	/* Register only holds upper 24 bits, bit shifted into lower 24 */
	134	gef_wdt_count = (timeout * bus_clk) >> 8;
	135	gef_wdt_timeout = timeout;
	136	}
	137
	138
	139	static ssize_t gef_wdt_write(struct file file, const char __user data,
	140	size_t len, loff_t *ppos)
	141	{
	142	if (len) {
	143	if (!nowayout) {
	144	size_t i;
	145
	146	expect_close = 0;
	147
	148	for (i = 0; i != len; i++) {
	149	char c;
	150	if (get_user(c, data + i))
	151	return -EFAULT;
	152	if (c == 'V')
	153	expect_close = 42;
	154	}
	155	}
	156	gef_wdt_service();
	157	}
	158
	159	return len;
	160	}
	161
	162	static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
	163	unsigned long arg)
	164	{
	165	int timeout;
	166	int options;
	167	void __user argp = (void __user )arg;
42747d71	168	static const struct watchdog_info info = {
3268b561 MW	169	.options = WDIOF_SETTIMEOUT \| WDIOF_MAGICCLOSE \|
	170	WDIOF_KEEPALIVEPING,
	171	.firmware_version = 0,
cda61c94	172	.identity = "GE watchdog",
3268b561 MW	173	};
	174
	175	switch (cmd) {
	176	case WDIOC_GETSUPPORT:
	177	if (copy_to_user(argp, &info, sizeof(info)))
	178	return -EFAULT;
	179	break;
	180
	181	case WDIOC_GETSTATUS:
	182	case WDIOC_GETBOOTSTATUS:
	183	if (put_user(wdt_status, (int __user *)argp))
	184	return -EFAULT;
	185	wdt_status &= ~WDIOF_KEEPALIVEPING;
	186	break;
	187
	188	case WDIOC_SETOPTIONS:
	189	if (get_user(options, (int __user *)argp))
	190	return -EFAULT;
	191
	192	if (options & WDIOS_DISABLECARD)
	193	gef_wdt_handler_disable();
	194
	195	if (options & WDIOS_ENABLECARD)
	196	gef_wdt_handler_enable();
	197	break;
	198
	199	case WDIOC_KEEPALIVE:
	200	gef_wdt_service();
	201	wdt_status \|= WDIOF_KEEPALIVEPING;
	202	break;
	203
	204	case WDIOC_SETTIMEOUT:
	205	if (get_user(timeout, (int __user *)argp))
	206	return -EFAULT;
	207	gef_wdt_set_timeout(timeout);
	208	/* Fall through */
	209
	210	case WDIOC_GETTIMEOUT:
	211	if (put_user(gef_wdt_timeout, (int __user *)argp))
	212	return -EFAULT;
	213	break;
	214
	215	default:
	216	return -ENOTTY;
	217	}
	218
	219	return 0;
	220	}
	221
	222	static int gef_wdt_open(struct inode inode, struct file file)
	223	{
	224	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
	225	return -EBUSY;
	226
	227	if (nowayout)
	228	__module_get(THIS_MODULE);
	229
	230	gef_wdt_handler_enable();
	231
	232	return nonseekable_open(inode, file);
	233	}
	234
	235	static int gef_wdt_release(struct inode inode, struct file file)
	236	{
237	if (expect_close == 42)
238	gef_wdt_handler_disable();
239	else {
27c766aa	240	pr_crit("unexpected close, not stopping timer!\n");
3268b561 MW	241	gef_wdt_service();
	242	}
	243	expect_close = 0;
	244
	245	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
	246
	247	return 0;
	248	}
	249
	250	static const struct file_operations gef_wdt_fops = {
	251	.owner = THIS_MODULE,
	252	.llseek = no_llseek,
	253	.write = gef_wdt_write,
	254	.unlocked_ioctl = gef_wdt_ioctl,
	255	.open = gef_wdt_open,
	256	.release = gef_wdt_release,
	257	};
	258
	259	static struct miscdevice gef_wdt_miscdev = {
	260	.minor = WATCHDOG_MINOR,
	261	.name = "watchdog",
	262	.fops = &gef_wdt_fops,
	263	};
	264
	265
2d991a16	266	static int gef_wdt_probe(struct platform_device *dev)
3268b561 MW	267	{
	268	int timeout = 10;
	269	u32 freq;
	270
	271	bus_clk = 133; /* in MHz */
	272
	273	freq = fsl_get_sys_freq();
26952669	274	if (freq != -1)
3268b561 MW	275	bus_clk = freq;
	276
	277	/* Map devices registers into memory */
b74dbf2a	278	gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
3268b561 MW	279	if (gef_wdt_regs == NULL)
	280	return -ENOMEM;
	281
	282	gef_wdt_set_timeout(timeout);
	283
	284	gef_wdt_handler_disable(); /* in case timer was already running */
	285
	286	return misc_register(&gef_wdt_miscdev);
	287	}
	288
4b12b896	289	static int gef_wdt_remove(struct platform_device *dev)
3268b561 MW	290	{
	291	misc_deregister(&gef_wdt_miscdev);
	292
	293	gef_wdt_handler_disable();
	294
	295	iounmap(gef_wdt_regs);
	296
	297	return 0;
	298	}
	299
	300	static const struct of_device_id gef_wdt_ids[] = {
	301	{
	302	.compatible = "gef,fpga-wdt",
	303	},
	304	{},
	305	};
c73318f4	306	MODULE_DEVICE_TABLE(of, gef_wdt_ids);
3268b561	307
1c48a5c9	308	static struct platform_driver gef_wdt_driver = {
4018294b GL	309	.driver = {
4018294b GL	310	.name = "gef_wdt",
4018294b GL	311	.of_match_table = gef_wdt_ids,
4018294b GL	312	},
3268b561	313	.probe = gef_wdt_probe,
67371765	314	.remove = gef_wdt_remove,
3268b561 MW	315	};
	316
	317	static int __init gef_wdt_init(void)
	318	{
27c766aa	319	pr_info("GE watchdog driver\n");
1c48a5c9	320	return platform_driver_register(&gef_wdt_driver);
3268b561 MW	321	}
	322
	323	static void __exit gef_wdt_exit(void)
	324	{
1c48a5c9	325	platform_driver_unregister(&gef_wdt_driver);
3268b561 MW	326	}
	327
	328	module_init(gef_wdt_init);
	329	module_exit(gef_wdt_exit);
	330
cda61c94 MW	331	MODULE_AUTHOR("Martyn Welch <[email protected]>");
cda61c94 MW	332	MODULE_DESCRIPTION("GE watchdog driver");
3268b561	333	MODULE_LICENSE("GPL");
ae2a0060	334	MODULE_ALIAS("platform:gef_wdt");