1// SPDX-License-Identifier: GPL-2.0+
2/*
3 *	Watchdog driver for the SA11x0/PXA2xx
4 *
5 *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
6 *	    Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
7 *
8 *	Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
9 *	warranty for any of this software. This material is provided
10 *	"AS-IS" and at no charge.
11 *
12 *	(c) Copyright 2000           Oleg Drokin <green@crimea.edu>
13 *
14 *	27/11/2000 Initial release
15 */
16
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/clk.h>
22#include <linux/types.h>
23#include <linux/kernel.h>
24#include <linux/fs.h>
25#include <linux/platform_device.h>
26#include <linux/miscdevice.h>
27#include <linux/watchdog.h>
28#include <linux/init.h>
29#include <linux/io.h>
30#include <linux/bitops.h>
31#include <linux/uaccess.h>
32#include <linux/timex.h>
33
34#define REG_OSMR0  	0x0000  /* OS timer Match Reg. 0 */
35#define REG_OSMR1  	0x0004  /* OS timer Match Reg. 1 */
36#define REG_OSMR2  	0x0008  /* OS timer Match Reg. 2 */
37#define REG_OSMR3  	0x000c  /* OS timer Match Reg. 3 */
38#define REG_OSCR   	0x0010  /* OS timer Counter Reg. */
39#define REG_OSSR   	0x0014  /* OS timer Status Reg. */
40#define REG_OWER   	0x0018  /* OS timer Watch-dog Enable Reg. */
41#define REG_OIER  	0x001C  /* OS timer Interrupt Enable Reg. */
42
43#define OSSR_M3		(1 << 3)	/* Match status channel 3 */
44#define OSSR_M2		(1 << 2)	/* Match status channel 2 */
45#define OSSR_M1		(1 << 1)	/* Match status channel 1 */
46#define OSSR_M0		(1 << 0)	/* Match status channel 0 */
47
48#define OWER_WME	(1 << 0)	/* Watchdog Match Enable */
49
50#define OIER_E3		(1 << 3)	/* Interrupt enable channel 3 */
51#define OIER_E2		(1 << 2)	/* Interrupt enable channel 2 */
52#define OIER_E1		(1 << 1)	/* Interrupt enable channel 1 */
53#define OIER_E0		(1 << 0)	/* Interrupt enable channel 0 */
54
55static unsigned long oscr_freq;
56static unsigned long sa1100wdt_users;
57static unsigned int pre_margin;
58static int boot_status;
59static void __iomem *reg_base;
60
61static inline void sa1100_wr(u32 val, u32 offset)
62{
63	writel_relaxed(val, reg_base + offset);
64}
65
66static inline u32 sa1100_rd(u32 offset)
67{
68	return readl_relaxed(reg_base + offset);
69}
70
71/*
72 *	Allow only one person to hold it open
73 */
74static int sa1100dog_open(struct inode *inode, struct file *file)
75{
76	if (test_and_set_bit(1, &sa1100wdt_users))
77		return -EBUSY;
78
79	/* Activate SA1100 Watchdog timer */
80	sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
81	sa1100_wr(OSSR_M3, REG_OSSR);
82	sa1100_wr(OWER_WME, REG_OWER);
83	sa1100_wr(sa1100_rd(REG_OIER) | OIER_E3, REG_OIER);
84	return stream_open(inode, file);
85}
86
87/*
88 * The watchdog cannot be disabled.
89 *
90 * Previous comments suggested that turning off the interrupt by
91 * clearing REG_OIER[E3] would prevent the watchdog timing out but this
92 * does not appear to be true (at least on the PXA255).
93 */
94static int sa1100dog_release(struct inode *inode, struct file *file)
95{
96	pr_crit("Device closed - timer will not stop\n");
97	clear_bit(1, &sa1100wdt_users);
98	return 0;
99}
100
101static ssize_t sa1100dog_write(struct file *file, const char __user *data,
102						size_t len, loff_t *ppos)
103{
104	if (len)
105		/* Refresh OSMR3 timer. */
106		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
107	return len;
108}
109
110static const struct watchdog_info ident = {
111	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT
112				| WDIOF_KEEPALIVEPING,
113	.identity	= "SA1100/PXA255 Watchdog",
114	.firmware_version	= 1,
115};
116
117static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
118							unsigned long arg)
119{
120	int ret = -ENOTTY;
121	int time;
122	void __user *argp = (void __user *)arg;
123	int __user *p = argp;
124
125	switch (cmd) {
126	case WDIOC_GETSUPPORT:
127		ret = copy_to_user(argp, &ident,
128				   sizeof(ident)) ? -EFAULT : 0;
129		break;
130
131	case WDIOC_GETSTATUS:
132		ret = put_user(0, p);
133		break;
134
135	case WDIOC_GETBOOTSTATUS:
136		ret = put_user(boot_status, p);
137		break;
138
139	case WDIOC_KEEPALIVE:
140		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
141		ret = 0;
142		break;
143
144	case WDIOC_SETTIMEOUT:
145		ret = get_user(time, p);
146		if (ret)
147			break;
148
149		if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
150			ret = -EINVAL;
151			break;
152		}
153
154		pre_margin = oscr_freq * time;
155		sa1100_wr(sa1100_rd(REG_OSCR) + pre_margin, REG_OSMR3);
156		fallthrough;
157
158	case WDIOC_GETTIMEOUT:
159		ret = put_user(pre_margin / oscr_freq, p);
160		break;
161	}
162	return ret;
163}
164
165static const struct file_operations sa1100dog_fops = {
166	.owner		= THIS_MODULE,
167	.llseek		= no_llseek,
168	.write		= sa1100dog_write,
169	.unlocked_ioctl	= sa1100dog_ioctl,
170	.compat_ioctl	= compat_ptr_ioctl,
171	.open		= sa1100dog_open,
172	.release	= sa1100dog_release,
173};
174
175static struct miscdevice sa1100dog_miscdev = {
176	.minor		= WATCHDOG_MINOR,
177	.name		= "watchdog",
178	.fops		= &sa1100dog_fops,
179};
180
181static int margin = 60;		/* (secs) Default is 1 minute */
182static struct clk *clk;
183
184static int sa1100dog_probe(struct platform_device *pdev)
185{
186	int ret;
187	int *platform_data;
188	struct resource *res;
189
190	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191	if (!res)
192		return -ENXIO;
193	reg_base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
194	ret = PTR_ERR_OR_ZERO(reg_base);
195	if (ret)
196		return ret;
197
198	clk = clk_get(NULL, "OSTIMER0");
199	if (IS_ERR(clk)) {
200		pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
201		       (int) PTR_ERR(clk));
202		return PTR_ERR(clk);
203	}
204
205	ret = clk_prepare_enable(clk);
206	if (ret) {
207		pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
208		       ret);
209		goto err;
210	}
211
212	oscr_freq = clk_get_rate(clk);
213
214	platform_data = pdev->dev.platform_data;
215	if (platform_data && *platform_data)
216		boot_status = WDIOF_CARDRESET;
217	pre_margin = oscr_freq * margin;
218
219	ret = misc_register(&sa1100dog_miscdev);
220	if (ret == 0) {
221		pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
222			margin);
223		return 0;
224	}
225
226	clk_disable_unprepare(clk);
227err:
228	clk_put(clk);
229	return ret;
230}
231
232static void sa1100dog_remove(struct platform_device *pdev)
233{
234	misc_deregister(&sa1100dog_miscdev);
235	clk_disable_unprepare(clk);
236	clk_put(clk);
237}
238
239static struct platform_driver sa1100dog_driver = {
240	.driver.name = "sa1100_wdt",
241	.probe	  = sa1100dog_probe,
242	.remove_new	  = sa1100dog_remove,
243};
244module_platform_driver(sa1100dog_driver);
245
246MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
247MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
248
249module_param(margin, int, 0);
250MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
251
252MODULE_LICENSE("GPL");
253