[linux.git] / drivers / watchdog / ar7_wdt.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * drivers/watchdog/ar7_wdt.c
 *
 * Copyright (C) 2007 Nicolas Thill <[email protected]>
 * Copyright (c) 2005 Enrik Berkhan <[email protected]>
 *
 * Some code taken from:
 * National Semiconductor SCx200 Watchdog support
 * Copyright (c) 2001,2002 Christer Weinigel <[email protected]>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/clk.h>

#include <asm/addrspace.h>
#include <asm/mach-ar7/ar7.h>

#define LONGNAME "TI AR7 Watchdog Timer"

MODULE_AUTHOR("Nicolas Thill <[email protected]>");
MODULE_DESCRIPTION(LONGNAME);
MODULE_LICENSE("GPL");

static int margin = 60;
module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

#define READ_REG(x) readl((void __iomem *)&(x))
#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))

struct ar7_wdt {
	u32 kick_lock;
	u32 kick;
	u32 change_lock;
	u32 change;
	u32 disable_lock;
	u32 disable;
	u32 prescale_lock;
	u32 prescale;
};

static unsigned long wdt_is_open;
static unsigned expect_close;
static DEFINE_SPINLOCK(wdt_lock);

/* XXX currently fixed, allows max margin ~68.72 secs */
#define prescale_value 0xffff

/* Pointer to the remapped WDT IO space */
static struct ar7_wdt *ar7_wdt;

static struct clk *vbus_clk;

static void ar7_wdt_kick(u32 value)
{
	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
		WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
		if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
			WRITE_REG(ar7_wdt->kick, value);
			return;
		}
	}
	pr_err("failed to unlock WDT kick reg\n");
}

static void ar7_wdt_prescale(u32 value)
{
	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
		WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
		if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
			WRITE_REG(ar7_wdt->prescale, value);
			return;
		}
	}
	pr_err("failed to unlock WDT prescale reg\n");
}

static void ar7_wdt_change(u32 value)
{
	WRITE_REG(ar7_wdt->change_lock, 0x6666);
	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
		WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
		if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
			WRITE_REG(ar7_wdt->change, value);
			return;
		}
	}
	pr_err("failed to unlock WDT change reg\n");
}

static void ar7_wdt_disable(u32 value)
{
	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
		WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
		if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
			WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
			if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
				WRITE_REG(ar7_wdt->disable, value);
				return;
			}
		}
	}
	pr_err("failed to unlock WDT disable reg\n");
}

static void ar7_wdt_update_margin(int new_margin)
{
	u32 change;
	u32 vbus_rate;

	vbus_rate = clk_get_rate(vbus_clk);
	change = new_margin * (vbus_rate / prescale_value);
	if (change < 1)
		change = 1;
	if (change > 0xffff)
		change = 0xffff;
	ar7_wdt_change(change);
	margin = change * prescale_value / vbus_rate;
	pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
		margin, prescale_value, change, vbus_rate);
}

static void ar7_wdt_enable_wdt(void)
{
	pr_debug("enabling watchdog timer\n");
	ar7_wdt_disable(1);
	ar7_wdt_kick(1);
}

static void ar7_wdt_disable_wdt(void)
{
	pr_debug("disabling watchdog timer\n");
	ar7_wdt_disable(0);
}

static int ar7_wdt_open(struct inode *inode, struct file *file)
{
	/* only allow one at a time */
	if (test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;
	ar7_wdt_enable_wdt();
	expect_close = 0;

	return stream_open(inode, file);
}

static int ar7_wdt_release(struct inode *inode, struct file *file)
{
	if (!expect_close)
		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
	else if (!nowayout)
		ar7_wdt_disable_wdt();
	clear_bit(0, &wdt_is_open);
	return 0;
}

static ssize_t ar7_wdt_write(struct file *file, const char *data,
			     size_t len, loff_t *ppos)
{
	/* check for a magic close character */
	if (len) {
		size_t i;

		spin_lock(&wdt_lock);
		ar7_wdt_kick(1);
		spin_unlock(&wdt_lock);

		expect_close = 0;
		for (i = 0; i < len; ++i) {
			char c;
			if (get_user(c, data + i))
				return -EFAULT;
			if (c == 'V')
				expect_close = 1;
		}

	}
	return len;
}

static long ar7_wdt_ioctl(struct file *file,
					unsigned int cmd, unsigned long arg)
{
	static const struct watchdog_info ident = {
		.identity = LONGNAME,
		.firmware_version = 1,
		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
						WDIOF_MAGICCLOSE),
	};
	int new_margin;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user((struct watchdog_info *)arg, &ident,
				sizeof(ident)))
			return -EFAULT;
		return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(0, (int *)arg))
			return -EFAULT;
		return 0;
	case WDIOC_KEEPALIVE:
		ar7_wdt_kick(1);
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, (int *)arg))
			return -EFAULT;
		if (new_margin < 1)
			return -EINVAL;

		spin_lock(&wdt_lock);
		ar7_wdt_update_margin(new_margin);
		ar7_wdt_kick(1);
		spin_unlock(&wdt_lock);
		fallthrough;
	case WDIOC_GETTIMEOUT:
		if (put_user(margin, (int *)arg))
			return -EFAULT;
		return 0;
	default:
		return -ENOTTY;
	}
}

static const struct file_operations ar7_wdt_fops = {
	.owner		= THIS_MODULE,
	.write		= ar7_wdt_write,
	.unlocked_ioctl	= ar7_wdt_ioctl,
	.compat_ioctl	= compat_ptr_ioctl,
	.open		= ar7_wdt_open,
	.release	= ar7_wdt_release,
	.llseek		= no_llseek,
};

static struct miscdevice ar7_wdt_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &ar7_wdt_fops,
};

static int ar7_wdt_probe(struct platform_device *pdev)
{
	int rc;

	ar7_wdt = devm_platform_ioremap_resource_byname(pdev, "regs");
	if (IS_ERR(ar7_wdt))
		return PTR_ERR(ar7_wdt);

	vbus_clk = clk_get(NULL, "vbus");
	if (IS_ERR(vbus_clk)) {
		pr_err("could not get vbus clock\n");
		return PTR_ERR(vbus_clk);
	}

	ar7_wdt_disable_wdt();
	ar7_wdt_prescale(prescale_value);
	ar7_wdt_update_margin(margin);

	rc = misc_register(&ar7_wdt_miscdev);
	if (rc) {
		pr_err("unable to register misc device\n");
		goto out;
	}
	return 0;

out:
	clk_put(vbus_clk);
	vbus_clk = NULL;
	return rc;
}

static int ar7_wdt_remove(struct platform_device *pdev)
{
	misc_deregister(&ar7_wdt_miscdev);
	clk_put(vbus_clk);
	vbus_clk = NULL;
	return 0;
}

static void ar7_wdt_shutdown(struct platform_device *pdev)
{
	if (!nowayout)
		ar7_wdt_disable_wdt();
}

static struct platform_driver ar7_wdt_driver = {
	.probe = ar7_wdt_probe,
	.remove = ar7_wdt_remove,
	.shutdown = ar7_wdt_shutdown,
	.driver = {
		.name = "ar7_wdt",
	},
};

module_platform_driver(ar7_wdt_driver);
Commit	Line	Data
2e62c498	1	// SPDX-License-Identifier: GPL-2.0+
c283cf2c MC	2	/*
	3	* drivers/watchdog/ar7_wdt.c
	4	*
	5	* Copyright (C) 2007 Nicolas Thill <[email protected]>
	6	* Copyright (c) 2005 Enrik Berkhan <[email protected]>
	7	*
	8	* Some code taken from:
	9	* National Semiconductor SCx200 Watchdog support
	10	* Copyright (c) 2001,2002 Christer Weinigel <[email protected]>
	11	*
c283cf2c MC	12	*/
c283cf2c MC	13
27c766aa JP	14	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	15
c283cf2c MC	16	#include <linux/module.h>
	17	#include <linux/moduleparam.h>
	18	#include <linux/errno.h>
c283cf2c	19	#include <linux/miscdevice.h>
64d4062a	20	#include <linux/platform_device.h>
c283cf2c	21	#include <linux/watchdog.h>
c283cf2c MC	22	#include <linux/fs.h>
	23	#include <linux/ioport.h>
	24	#include <linux/io.h>
	25	#include <linux/uaccess.h>
780019dd	26	#include <linux/clk.h>
c283cf2c MC	27
c283cf2c MC	28	#include <asm/addrspace.h>
c5e7f5a3	29	#include <asm/mach-ar7/ar7.h>
c283cf2c	30
c283cf2c MC	31	#define LONGNAME "TI AR7 Watchdog Timer"
	32
	33	MODULE_AUTHOR("Nicolas Thill <[email protected]>");
	34	MODULE_DESCRIPTION(LONGNAME);
	35	MODULE_LICENSE("GPL");
c283cf2c MC	36
	37	static int margin = 60;
	38	module_param(margin, int, 0);
	39	MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
	40
86a1e189 WVS	41	static bool nowayout = WATCHDOG_NOWAYOUT;
86a1e189 WVS	42	module_param(nowayout, bool, 0);
c283cf2c MC	43	MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
	44
	45	#define READ_REG(x) readl((void __iomem *)&(x))
	46	#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
	47
	48	struct ar7_wdt {
	49	u32 kick_lock;
	50	u32 kick;
	51	u32 change_lock;
	52	u32 change;
	53	u32 disable_lock;
	54	u32 disable;
	55	u32 prescale_lock;
	56	u32 prescale;
	57	};
	58
670d59c0	59	static unsigned long wdt_is_open;
c283cf2c	60	static unsigned expect_close;
1334f329	61	static DEFINE_SPINLOCK(wdt_lock);
c283cf2c MC	62
	63	/* XXX currently fixed, allows max margin ~68.72 secs */
	64	#define prescale_value 0xffff
	65
c283cf2c MC	66	/* Pointer to the remapped WDT IO space */
c283cf2c MC	67	static struct ar7_wdt *ar7_wdt;
c283cf2c	68
780019dd FF	69	static struct clk *vbus_clk;
780019dd FF	70
c283cf2c MC	71	static void ar7_wdt_kick(u32 value)
	72	{
	73	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
	74	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
	75	WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
	76	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
	77	WRITE_REG(ar7_wdt->kick, value);
	78	return;
	79	}
	80	}
27c766aa	81	pr_err("failed to unlock WDT kick reg\n");
c283cf2c MC	82	}
	83
	84	static void ar7_wdt_prescale(u32 value)
	85	{
	86	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
	87	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
	88	WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
	89	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
	90	WRITE_REG(ar7_wdt->prescale, value);
	91	return;
	92	}
	93	}
27c766aa	94	pr_err("failed to unlock WDT prescale reg\n");
c283cf2c MC	95	}
	96
	97	static void ar7_wdt_change(u32 value)
	98	{
	99	WRITE_REG(ar7_wdt->change_lock, 0x6666);
	100	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
	101	WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
	102	if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
	103	WRITE_REG(ar7_wdt->change, value);
	104	return;
	105	}
	106	}
27c766aa	107	pr_err("failed to unlock WDT change reg\n");
c283cf2c MC	108	}
	109
	110	static void ar7_wdt_disable(u32 value)
	111	{
	112	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
	113	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
	114	WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
	115	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
	116	WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
	117	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
	118	WRITE_REG(ar7_wdt->disable, value);
	119	return;
	120	}
	121	}
	122	}
27c766aa	123	pr_err("failed to unlock WDT disable reg\n");
c283cf2c MC	124	}
	125
	126	static void ar7_wdt_update_margin(int new_margin)
	127	{
	128	u32 change;
780019dd	129	u32 vbus_rate;
c283cf2c	130
780019dd FF	131	vbus_rate = clk_get_rate(vbus_clk);
780019dd FF	132	change = new_margin * (vbus_rate / prescale_value);
670d59c0 AC	133	if (change < 1)
	134	change = 1;
	135	if (change > 0xffff)
	136	change = 0xffff;
c283cf2c	137	ar7_wdt_change(change);
780019dd	138	margin = change * prescale_value / vbus_rate;
27c766aa JP	139	pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
27c766aa JP	140	margin, prescale_value, change, vbus_rate);
c283cf2c MC	141	}
	142
	143	static void ar7_wdt_enable_wdt(void)
	144	{
27c766aa	145	pr_debug("enabling watchdog timer\n");
c283cf2c MC	146	ar7_wdt_disable(1);
	147	ar7_wdt_kick(1);
	148	}
	149
	150	static void ar7_wdt_disable_wdt(void)
	151	{
27c766aa	152	pr_debug("disabling watchdog timer\n");
c283cf2c MC	153	ar7_wdt_disable(0);
	154	}
	155
	156	static int ar7_wdt_open(struct inode inode, struct file file)
	157	{
	158	/* only allow one at a time */
670d59c0	159	if (test_and_set_bit(0, &wdt_is_open))
c283cf2c MC	160	return -EBUSY;
	161	ar7_wdt_enable_wdt();
	162	expect_close = 0;
	163
c5bf68fe	164	return stream_open(inode, file);
c283cf2c MC	165	}
	166
	167	static int ar7_wdt_release(struct inode inode, struct file file)
	168	{
	169	if (!expect_close)
27c766aa	170	pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
c283cf2c MC	171	else if (!nowayout)
c283cf2c MC	172	ar7_wdt_disable_wdt();
670d59c0	173	clear_bit(0, &wdt_is_open);
c283cf2c MC	174	return 0;
	175	}
	176
c283cf2c MC	177	static ssize_t ar7_wdt_write(struct file file, const char data,
	178	size_t len, loff_t *ppos)
	179	{
	180	/* check for a magic close character */
	181	if (len) {
	182	size_t i;
	183
670d59c0	184	spin_lock(&wdt_lock);
c283cf2c	185	ar7_wdt_kick(1);
670d59c0	186	spin_unlock(&wdt_lock);
c283cf2c MC	187
	188	expect_close = 0;
	189	for (i = 0; i < len; ++i) {
	190	char c;
7944d3a5	191	if (get_user(c, data + i))
c283cf2c MC	192	return -EFAULT;
	193	if (c == 'V')
	194	expect_close = 1;
	195	}
	196
	197	}
	198	return len;
	199	}
	200
670d59c0 AC	201	static long ar7_wdt_ioctl(struct file *file,
670d59c0 AC	202	unsigned int cmd, unsigned long arg)
c283cf2c	203	{
42747d71	204	static const struct watchdog_info ident = {
c283cf2c MC	205	.identity = LONGNAME,
c283cf2c MC	206	.firmware_version = 1,
e73a7802 WVS	207	.options = (WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \|
e73a7802 WVS	208	WDIOF_MAGICCLOSE),
c283cf2c MC	209	};
	210	int new_margin;
	211
	212	switch (cmd) {
c283cf2c MC	213	case WDIOC_GETSUPPORT:
	214	if (copy_to_user((struct watchdog_info *)arg, &ident,
	215	sizeof(ident)))
	216	return -EFAULT;
	217	return 0;
	218	case WDIOC_GETSTATUS:
	219	case WDIOC_GETBOOTSTATUS:
	220	if (put_user(0, (int *)arg))
	221	return -EFAULT;
	222	return 0;
	223	case WDIOC_KEEPALIVE:
	224	ar7_wdt_kick(1);
	225	return 0;
	226	case WDIOC_SETTIMEOUT:
	227	if (get_user(new_margin, (int *)arg))
	228	return -EFAULT;
	229	if (new_margin < 1)
	230	return -EINVAL;
	231
670d59c0	232	spin_lock(&wdt_lock);
c283cf2c MC	233	ar7_wdt_update_margin(new_margin);
c283cf2c MC	234	ar7_wdt_kick(1);
670d59c0	235	spin_unlock(&wdt_lock);
bd490f82	236	fallthrough;
c283cf2c MC	237	case WDIOC_GETTIMEOUT:
	238	if (put_user(margin, (int *)arg))
	239	return -EFAULT;
	240	return 0;
0c06090c WVS	241	default:
0c06090c WVS	242	return -ENOTTY;
c283cf2c MC	243	}
	244	}
	245
b47a166e	246	static const struct file_operations ar7_wdt_fops = {
c283cf2c MC	247	.owner = THIS_MODULE,
c283cf2c MC	248	.write = ar7_wdt_write,
670d59c0	249	.unlocked_ioctl = ar7_wdt_ioctl,
b6dfb247	250	.compat_ioctl = compat_ptr_ioctl,
c283cf2c MC	251	.open = ar7_wdt_open,
c283cf2c MC	252	.release = ar7_wdt_release,
6038f373	253	.llseek = no_llseek,
c283cf2c MC	254	};
	255
	256	static struct miscdevice ar7_wdt_miscdev = {
	257	.minor = WATCHDOG_MINOR,
	258	.name = "watchdog",
	259	.fops = &ar7_wdt_fops,
	260	};
	261
2d991a16	262	static int ar7_wdt_probe(struct platform_device *pdev)
c283cf2c MC	263	{
	264	int rc;
	265
54ccba2f	266	ar7_wdt = devm_platform_ioremap_resource_byname(pdev, "regs");
4c271bb6 TR	267	if (IS_ERR(ar7_wdt))
4c271bb6 TR	268	return PTR_ERR(ar7_wdt);
c283cf2c	269
780019dd FF	270	vbus_clk = clk_get(NULL, "vbus");
780019dd FF	271	if (IS_ERR(vbus_clk)) {
27c766aa	272	pr_err("could not get vbus clock\n");
ae21cc20	273	return PTR_ERR(vbus_clk);
780019dd FF	274	}
780019dd FF	275
c283cf2c MC	276	ar7_wdt_disable_wdt();
	277	ar7_wdt_prescale(prescale_value);
	278	ar7_wdt_update_margin(margin);
	279
c283cf2c MC	280	rc = misc_register(&ar7_wdt_miscdev);
c283cf2c MC	281	if (rc) {
27c766aa	282	pr_err("unable to register misc device\n");
ae21cc20	283	goto out;
c283cf2c	284	}
ae21cc20	285	return 0;
c283cf2c	286
c283cf2c	287	out:
ae21cc20 JL	288	clk_put(vbus_clk);
ae21cc20 JL	289	vbus_clk = NULL;
c283cf2c MC	290	return rc;
	291	}
	292
4b12b896	293	static int ar7_wdt_remove(struct platform_device *pdev)
c283cf2c MC	294	{
c283cf2c MC	295	misc_deregister(&ar7_wdt_miscdev);
ae21cc20 JL	296	clk_put(vbus_clk);
ae21cc20 JL	297	vbus_clk = NULL;
64d4062a FF	298	return 0;
	299	}
	300
	301	static void ar7_wdt_shutdown(struct platform_device *pdev)
	302	{
	303	if (!nowayout)
	304	ar7_wdt_disable_wdt();
	305	}
	306
	307	static struct platform_driver ar7_wdt_driver = {
	308	.probe = ar7_wdt_probe,
82268714	309	.remove = ar7_wdt_remove,
64d4062a FF	310	.shutdown = ar7_wdt_shutdown,
64d4062a FF	311	.driver = {
64d4062a FF	312	.name = "ar7_wdt",
	313	},
	314	};
	315
b8ec6118	316	module_platform_driver(ar7_wdt_driver);