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/miscdevice.h>
26#include <linux/watchdog.h>
27#include <linux/init.h>
28#include <linux/io.h>
29#include <linux/bitops.h>
30#include <linux/uaccess.h>
31#include <linux/timex.h>
32
33#ifdef CONFIG_ARCH_PXA
34#include <mach/regs-ost.h>
35#endif
36
37#include <mach/reset.h>
38#include <mach/hardware.h>
39
40static unsigned long oscr_freq;
41static unsigned long sa1100wdt_users;
42static unsigned int pre_margin;
43static int boot_status;
44
45/*
46 *	Allow only one person to hold it open
47 */
48static int sa1100dog_open(struct inode *inode, struct file *file)
49{
50	if (test_and_set_bit(1, &sa1100wdt_users))
51		return -EBUSY;
52
53	/* Activate SA1100 Watchdog timer */
54	writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
55	writel_relaxed(OSSR_M3, OSSR);
56	writel_relaxed(OWER_WME, OWER);
57	writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
58	return stream_open(inode, file);
59}
60
61/*
62 * The watchdog cannot be disabled.
63 *
64 * Previous comments suggested that turning off the interrupt by
65 * clearing OIER[E3] would prevent the watchdog timing out but this
66 * does not appear to be true (at least on the PXA255).
67 */
68static int sa1100dog_release(struct inode *inode, struct file *file)
69{
70	pr_crit("Device closed - timer will not stop\n");
71	clear_bit(1, &sa1100wdt_users);
72	return 0;
73}
74
75static ssize_t sa1100dog_write(struct file *file, const char __user *data,
76						size_t len, loff_t *ppos)
77{
78	if (len)
79		/* Refresh OSMR3 timer. */
80		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
81	return len;
82}
83
84static const struct watchdog_info ident = {
85	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT
86				| WDIOF_KEEPALIVEPING,
87	.identity	= "SA1100/PXA255 Watchdog",
88	.firmware_version	= 1,
89};
90
91static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
92							unsigned long arg)
93{
94	int ret = -ENOTTY;
95	int time;
96	void __user *argp = (void __user *)arg;
97	int __user *p = argp;
98
99	switch (cmd) {
100	case WDIOC_GETSUPPORT:
101		ret = copy_to_user(argp, &ident,
102				   sizeof(ident)) ? -EFAULT : 0;
103		break;
104
105	case WDIOC_GETSTATUS:
106		ret = put_user(0, p);
107		break;
108
109	case WDIOC_GETBOOTSTATUS:
110		ret = put_user(boot_status, p);
111		break;
112
113	case WDIOC_KEEPALIVE:
114		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
115		ret = 0;
116		break;
117
118	case WDIOC_SETTIMEOUT:
119		ret = get_user(time, p);
120		if (ret)
121			break;
122
123		if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
124			ret = -EINVAL;
125			break;
126		}
127
128		pre_margin = oscr_freq * time;
129		writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
130		fallthrough;
131
132	case WDIOC_GETTIMEOUT:
133		ret = put_user(pre_margin / oscr_freq, p);
134		break;
135	}
136	return ret;
137}
138
139static const struct file_operations sa1100dog_fops = {
140	.owner		= THIS_MODULE,
141	.llseek		= no_llseek,
142	.write		= sa1100dog_write,
143	.unlocked_ioctl	= sa1100dog_ioctl,
144	.compat_ioctl	= compat_ptr_ioctl,
145	.open		= sa1100dog_open,
146	.release	= sa1100dog_release,
147};
148
149static struct miscdevice sa1100dog_miscdev = {
150	.minor		= WATCHDOG_MINOR,
151	.name		= "watchdog",
152	.fops		= &sa1100dog_fops,
153};
154
155static int margin __initdata = 60;		/* (secs) Default is 1 minute */
156static struct clk *clk;
157
158static int __init sa1100dog_init(void)
159{
160	int ret;
161
162	clk = clk_get(NULL, "OSTIMER0");
163	if (IS_ERR(clk)) {
164		pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
165		       (int) PTR_ERR(clk));
166		return PTR_ERR(clk);
167	}
168
169	ret = clk_prepare_enable(clk);
170	if (ret) {
171		pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
172		       ret);
173		goto err;
174	}
175
176	oscr_freq = clk_get_rate(clk);
177
178	/*
179	 * Read the reset status, and save it for later.  If
180	 * we suspend, RCSR will be cleared, and the watchdog
181	 * reset reason will be lost.
182	 */
183	boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
184				WDIOF_CARDRESET : 0;
185	pre_margin = oscr_freq * margin;
186
187	ret = misc_register(&sa1100dog_miscdev);
188	if (ret == 0) {
189		pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
190			margin);
191		return 0;
192	}
193
194	clk_disable_unprepare(clk);
195err:
196	clk_put(clk);
197	return ret;
198}
199
200static void __exit sa1100dog_exit(void)
201{
202	misc_deregister(&sa1100dog_miscdev);
203	clk_disable_unprepare(clk);
204	clk_put(clk);
205}
206
207module_init(sa1100dog_init);
208module_exit(sa1100dog_exit);
209
210MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
211MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
212
213module_param(margin, int, 0);
214MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
215
216MODULE_LICENSE("GPL");
217