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
40 static unsigned long oscr_freq;
41 static unsigned long sa1100wdt_users;
42 static unsigned int pre_margin;
43 static int boot_status;
44
45 /*
46 * Allow only one person to hold it open
47 */
sa1100dog_open(struct inode * inode,struct file * file)48 static 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 */
sa1100dog_release(struct inode * inode,struct file * file)68 static 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
sa1100dog_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)75 static 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
84 static 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
sa1100dog_ioctl(struct file * file,unsigned int cmd,unsigned long arg)91 static 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
139 static 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
149 static struct miscdevice sa1100dog_miscdev = {
150 .minor = WATCHDOG_MINOR,
151 .name = "watchdog",
152 .fops = &sa1100dog_fops,
153 };
154
155 static int margin __initdata = 60; /* (secs) Default is 1 minute */
156 static struct clk *clk;
157
sa1100dog_init(void)158 static 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);
195 err:
196 clk_put(clk);
197 return ret;
198 }
199
sa1100dog_exit(void)200 static void __exit sa1100dog_exit(void)
201 {
202 misc_deregister(&sa1100dog_miscdev);
203 clk_disable_unprepare(clk);
204 clk_put(clk);
205 }
206
207 module_init(sa1100dog_init);
208 module_exit(sa1100dog_exit);
209
210 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
211 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
212
213 module_param(margin, int, 0);
214 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
215
216 MODULE_LICENSE("GPL");
217