Merge remote-tracking branch 'stable/linux-5.15.y' into rpi-5.15.y
[platform/kernel/linux-rpi.git] / drivers / watchdog / sa1100_wdt.c
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  */
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  */
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
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
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
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
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");