drivers/watchdog/sa1100_wdt.c

   1 /*
   2  *      Watchdog driver for the SA11x0/PXA2xx
   3  *
   4  *      (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
   5  *          Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  *
  12  *      Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
  13  *      warranty for any of this software. This material is provided
  14  *      "AS-IS" and at no charge.
  15  *
  16  *      (c) Copyright 2000           Oleg Drokin <green@crimea.edu>
  17  *
  18  *      27/11/2000 Initial release
  19  */
  20
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/module.h>
  24 #include <linux/moduleparam.h>
  25 #include <linux/clk.h>
  26 #include <linux/types.h>
  27 #include <linux/kernel.h>
  28 #include <linux/fs.h>
  29 #include <linux/miscdevice.h>
  30 #include <linux/watchdog.h>
  31 #include <linux/init.h>
  32 #include <linux/io.h>
  33 #include <linux/bitops.h>
  34 #include <linux/uaccess.h>
  35 #include <linux/timex.h>
  36
  37 #ifdef CONFIG_ARCH_PXA
  38 #include <mach/regs-ost.h>
  39 #endif
  40
  41 #include <mach/reset.h>
  42 #include <mach/hardware.h>
  43
  44 static unsigned long oscr_freq;
  45 static unsigned long sa1100wdt_users;
  46 static unsigned int pre_margin;
  47 static int boot_status;
  48
  49 /*
  50  *      Allow only one person to hold it open
  51  */
  52 static int sa1100dog_open(struct inode *inode, struct file *file)
  53 {
  54         if (test_and_set_bit(1, &sa1100wdt_users))
  55                 return -EBUSY;
  56
  57         /* Activate SA1100 Watchdog timer */
  58         writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  59         writel_relaxed(OSSR_M3, OSSR);
  60         writel_relaxed(OWER_WME, OWER);
  61         writel_relaxed(readl_relaxed(OIER) | OIER_E3, OIER);
  62         return stream_open(inode, file);
  63 }
  64
  65 /*
  66  * The watchdog cannot be disabled.
  67  *
  68  * Previous comments suggested that turning off the interrupt by
  69  * clearing OIER[E3] would prevent the watchdog timing out but this
  70  * does not appear to be true (at least on the PXA255).
  71  */
  72 static int sa1100dog_release(struct inode *inode, struct file *file)
  73 {
  74         pr_crit("Device closed - timer will not stop\n");
  75         clear_bit(1, &sa1100wdt_users);
  76         return 0;
  77 }
  78
  79 static ssize_t sa1100dog_write(struct file *file, const char __user *data,
  80                                                 size_t len, loff_t *ppos)
  81 {
  82         if (len)
  83                 /* Refresh OSMR3 timer. */
  84                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
  85         return len;
  86 }
  87
  88 static const struct watchdog_info ident = {
  89         .options        = WDIOF_CARDRESET | WDIOF_SETTIMEOUT
  90                                 | WDIOF_KEEPALIVEPING,
  91         .identity       = "SA1100/PXA255 Watchdog",
  92         .firmware_version       = 1,
  93 };
  94
  95 static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
  96                                                         unsigned long arg)
  97 {
  98         int ret = -ENOTTY;
  99         int time;
 100         void __user *argp = (void __user *)arg;
 101         int __user *p = argp;
 102
 103         switch (cmd) {
 104         case WDIOC_GETSUPPORT:
 105                 ret = copy_to_user(argp, &ident,
 106                                    sizeof(ident)) ? -EFAULT : 0;
 107                 break;
 108
 109         case WDIOC_GETSTATUS:
 110                 ret = put_user(0, p);
 111                 break;
 112
 113         case WDIOC_GETBOOTSTATUS:
 114                 ret = put_user(boot_status, p);
 115                 break;
 116
 117         case WDIOC_KEEPALIVE:
 118                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 119                 ret = 0;
 120                 break;
 121
 122         case WDIOC_SETTIMEOUT:
 123                 ret = get_user(time, p);
 124                 if (ret)
 125                         break;
 126
 127                 if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
 128                         ret = -EINVAL;
 129                         break;
 130                 }
 131
 132                 pre_margin = oscr_freq * time;
 133                 writel_relaxed(readl_relaxed(OSCR) + pre_margin, OSMR3);
 134                 /*fall through*/
 135
 136         case WDIOC_GETTIMEOUT:
 137                 ret = put_user(pre_margin / oscr_freq, p);
 138                 break;
 139         }
 140         return ret;
 141 }
 142
 143 static const struct file_operations sa1100dog_fops = {
 144         .owner          = THIS_MODULE,
 145         .llseek         = no_llseek,
 146         .write          = sa1100dog_write,
 147         .unlocked_ioctl = sa1100dog_ioctl,
 148         .open           = sa1100dog_open,
 149         .release        = sa1100dog_release,
 150 };
 151
 152 static struct miscdevice sa1100dog_miscdev = {
 153         .minor          = WATCHDOG_MINOR,
 154         .name           = "watchdog",
 155         .fops           = &sa1100dog_fops,
 156 };
 157
 158 static int margin __initdata = 60;              /* (secs) Default is 1 minute */
 159 static struct clk *clk;
 160
 161 static int __init sa1100dog_init(void)
 162 {
 163         int ret;
 164
 165         clk = clk_get(NULL, "OSTIMER0");
 166         if (IS_ERR(clk)) {
 167                 pr_err("SA1100/PXA2xx Watchdog Timer: clock not found: %d\n",
 168                        (int) PTR_ERR(clk));
 169                 return PTR_ERR(clk);
 170         }
 171
 172         ret = clk_prepare_enable(clk);
 173         if (ret) {
 174                 pr_err("SA1100/PXA2xx Watchdog Timer: clock failed to prepare+enable: %d\n",
 175                        ret);
 176                 goto err;
 177         }
 178
 179         oscr_freq = clk_get_rate(clk);
 180
 181         /*
 182          * Read the reset status, and save it for later.  If
 183          * we suspend, RCSR will be cleared, and the watchdog
 184          * reset reason will be lost.
 185          */
 186         boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
 187                                 WDIOF_CARDRESET : 0;
 188         pre_margin = oscr_freq * margin;
 189
 190         ret = misc_register(&sa1100dog_miscdev);
 191         if (ret == 0) {
 192                 pr_info("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
 193                         margin);
 194                 return 0;
 195         }
 196
 197         clk_disable_unprepare(clk);
 198 err:
 199         clk_put(clk);
 200         return ret;
 201 }
 202
 203 static void __exit sa1100dog_exit(void)
 204 {
 205         misc_deregister(&sa1100dog_miscdev);
 206         clk_disable_unprepare(clk);
 207         clk_put(clk);
 208 }
 209
 210 module_init(sa1100dog_init);
 211 module_exit(sa1100dog_exit);
 212
 213 MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
 214 MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
 215
 216 module_param(margin, int, 0);
 217 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
 218
 219 MODULE_LICENSE("GPL");