drivers/watchdog/m54xx_wdt.c

   1 /*
   2  * drivers/watchdog/m54xx_wdt.c
   3  *
   4  * Watchdog driver for ColdFire MCF547x & MCF548x processors
   5  * Copyright 2010 (c) Philippe De Muyter <phdm@macqel.be>
   6  *
   7  * Adapted from the IXP4xx watchdog driver, which carries these notices:
   8  *
   9  *  Author: Deepak Saxena <dsaxena@plexity.net>
  10  *
  11  *  Copyright 2004 (c) MontaVista, Software, Inc.
  12  *  Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <green@crimea.edu>
  13  *
  14  * This file is licensed under  the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/types.h>
  24 #include <linux/kernel.h>
  25 #include <linux/fs.h>
  26 #include <linux/miscdevice.h>
  27 #include <linux/watchdog.h>
  28 #include <linux/init.h>
  29 #include <linux/bitops.h>
  30 #include <linux/ioport.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/io.h>
  33
  34 #include <asm/coldfire.h>
  35 #include <asm/m54xxsim.h>
  36 #include <asm/m54xxgpt.h>
  37
  38 static bool nowayout = WATCHDOG_NOWAYOUT;
  39 static unsigned int heartbeat = 30;     /* (secs) Default is 0.5 minute */
  40 static unsigned long wdt_status;
  41
  42 #define WDT_IN_USE              0
  43 #define WDT_OK_TO_CLOSE         1
  44
  45 static void wdt_enable(void)
  46 {
  47         unsigned int gms0;
  48
  49         /* preserve GPIO usage, if any */
  50         gms0 = __raw_readl(MCF_GPT_GMS0);
  51         if (gms0 & MCF_GPT_GMS_TMS_GPIO)
  52                 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
  53                                                         | MCF_GPT_GMS_OD);
  54         else
  55                 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
  56         __raw_writel(gms0, MCF_GPT_GMS0);
  57         __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
  58                         MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
  59         gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
  60         __raw_writel(gms0, MCF_GPT_GMS0);
  61 }
  62
  63 static void wdt_disable(void)
  64 {
  65         unsigned int gms0;
  66
  67         /* disable watchdog */
  68         gms0 = __raw_readl(MCF_GPT_GMS0);
  69         gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
  70         __raw_writel(gms0, MCF_GPT_GMS0);
  71 }
  72
  73 static void wdt_keepalive(void)
  74 {
  75         unsigned int gms0;
  76
  77         gms0 = __raw_readl(MCF_GPT_GMS0);
  78         gms0 |= MCF_GPT_GMS_OCPW(0xA5);
  79         __raw_writel(gms0, MCF_GPT_GMS0);
  80 }
  81
  82 static int m54xx_wdt_open(struct inode *inode, struct file *file)
  83 {
  84         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  85                 return -EBUSY;
  86
  87         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  88         wdt_enable();
  89         return stream_open(inode, file);
  90 }
  91
  92 static ssize_t m54xx_wdt_write(struct file *file, const char *data,
  93                                                 size_t len, loff_t *ppos)
  94 {
  95         if (len) {
  96                 if (!nowayout) {
  97                         size_t i;
  98
  99                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 100
 101                         for (i = 0; i != len; i++) {
 102                                 char c;
 103
 104                                 if (get_user(c, data + i))
 105                                         return -EFAULT;
 106                                 if (c == 'V')
 107                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 108                         }
 109                 }
 110                 wdt_keepalive();
 111         }
 112         return len;
 113 }
 114
 115 static const struct watchdog_info ident = {
 116         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 117                                 WDIOF_KEEPALIVEPING,
 118         .identity       = "Coldfire M54xx Watchdog",
 119 };
 120
 121 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
 122                                                          unsigned long arg)
 123 {
 124         int ret = -ENOTTY;
 125         int time;
 126
 127         switch (cmd) {
 128         case WDIOC_GETSUPPORT:
 129                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 130                                    sizeof(ident)) ? -EFAULT : 0;
 131                 break;
 132
 133         case WDIOC_GETSTATUS:
 134                 ret = put_user(0, (int *)arg);
 135                 break;
 136
 137         case WDIOC_GETBOOTSTATUS:
 138                 ret = put_user(0, (int *)arg);
 139                 break;
 140
 141         case WDIOC_KEEPALIVE:
 142                 wdt_keepalive();
 143                 ret = 0;
 144                 break;
 145
 146         case WDIOC_SETTIMEOUT:
 147                 ret = get_user(time, (int *)arg);
 148                 if (ret)
 149                         break;
 150
 151                 if (time <= 0 || time > 30) {
 152                         ret = -EINVAL;
 153                         break;
 154                 }
 155
 156                 heartbeat = time;
 157                 wdt_enable();
 158                 fallthrough;
 159
 160         case WDIOC_GETTIMEOUT:
 161                 ret = put_user(heartbeat, (int *)arg);
 162                 break;
 163         }
 164         return ret;
 165 }
 166
 167 static int m54xx_wdt_release(struct inode *inode, struct file *file)
 168 {
 169         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 170                 wdt_disable();
 171         else {
 172                 pr_crit("Device closed unexpectedly - timer will not stop\n");
 173                 wdt_keepalive();
 174         }
 175         clear_bit(WDT_IN_USE, &wdt_status);
 176         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 177
 178         return 0;
 179 }
 180
 181
 182 static const struct file_operations m54xx_wdt_fops = {
 183         .owner          = THIS_MODULE,
 184         .llseek         = no_llseek,
 185         .write          = m54xx_wdt_write,
 186         .unlocked_ioctl = m54xx_wdt_ioctl,
 187         .compat_ioctl   = compat_ptr_ioctl,
 188         .open           = m54xx_wdt_open,
 189         .release        = m54xx_wdt_release,
 190 };
 191
 192 static struct miscdevice m54xx_wdt_miscdev = {
 193         .minor          = WATCHDOG_MINOR,
 194         .name           = "watchdog",
 195         .fops           = &m54xx_wdt_fops,
 196 };
 197
 198 static int __init m54xx_wdt_init(void)
 199 {
 200         if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) {
 201                 pr_warn("I/O region busy\n");
 202                 return -EBUSY;
 203         }
 204         pr_info("driver is loaded\n");
 205
 206         return misc_register(&m54xx_wdt_miscdev);
 207 }
 208
 209 static void __exit m54xx_wdt_exit(void)
 210 {
 211         misc_deregister(&m54xx_wdt_miscdev);
 212         release_mem_region(MCF_GPT_GCIR0, 4);
 213 }
 214
 215 module_init(m54xx_wdt_init);
 216 module_exit(m54xx_wdt_exit);
 217
 218 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 219 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
 220
 221 module_param(heartbeat, int, 0);
 222 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
 223
 224 module_param(nowayout, bool, 0);
 225 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 226
 227 MODULE_LICENSE("GPL");