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
  33 #include <asm/coldfire.h>
  34 #include <asm/m54xxsim.h>
  35 #include <asm/m54xxgpt.h>
  36
  37 static bool nowayout = WATCHDOG_NOWAYOUT;
  38 static unsigned int heartbeat = 30;     /* (secs) Default is 0.5 minute */
  39 static unsigned long wdt_status;
  40
  41 #define WDT_IN_USE              0
  42 #define WDT_OK_TO_CLOSE         1
  43
  44 static void wdt_enable(void)
  45 {
  46         unsigned int gms0;
  47
  48         /* preserve GPIO usage, if any */
  49         gms0 = __raw_readl(MCF_GPT_GMS0);
  50         if (gms0 & MCF_GPT_GMS_TMS_GPIO)
  51                 gms0 &= (MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_GPIO_MASK
  52                                                         | MCF_GPT_GMS_OD);
  53         else
  54                 gms0 = MCF_GPT_GMS_TMS_GPIO | MCF_GPT_GMS_OD;
  55         __raw_writel(gms0, MCF_GPT_GMS0);
  56         __raw_writel(MCF_GPT_GCIR_PRE(heartbeat*(MCF_BUSCLK/0xffff)) |
  57                         MCF_GPT_GCIR_CNT(0xffff), MCF_GPT_GCIR0);
  58         gms0 |= MCF_GPT_GMS_OCPW(0xA5) | MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE;
  59         __raw_writel(gms0, MCF_GPT_GMS0);
  60 }
  61
  62 static void wdt_disable(void)
  63 {
  64         unsigned int gms0;
  65
  66         /* disable watchdog */
  67         gms0 = __raw_readl(MCF_GPT_GMS0);
  68         gms0 &= ~(MCF_GPT_GMS_WDEN | MCF_GPT_GMS_CE);
  69         __raw_writel(gms0, MCF_GPT_GMS0);
  70 }
  71
  72 static void wdt_keepalive(void)
  73 {
  74         unsigned int gms0;
  75
  76         gms0 = __raw_readl(MCF_GPT_GMS0);
  77         gms0 |= MCF_GPT_GMS_OCPW(0xA5);
  78         __raw_writel(gms0, MCF_GPT_GMS0);
  79 }
  80
  81 static int m54xx_wdt_open(struct inode *inode, struct file *file)
  82 {
  83         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
  84                 return -EBUSY;
  85
  86         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  87         wdt_enable();
  88         return nonseekable_open(inode, file);
  89 }
  90
  91 static ssize_t m54xx_wdt_write(struct file *file, const char *data,
  92                                                 size_t len, loff_t *ppos)
  93 {
  94         if (len) {
  95                 if (!nowayout) {
  96                         size_t i;
  97
  98                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
  99
 100                         for (i = 0; i != len; i++) {
 101                                 char c;
 102
 103                                 if (get_user(c, data + i))
 104                                         return -EFAULT;
 105                                 if (c == 'V')
 106                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
 107                         }
 108                 }
 109                 wdt_keepalive();
 110         }
 111         return len;
 112 }
 113
 114 static const struct watchdog_info ident = {
 115         .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 116                                 WDIOF_KEEPALIVEPING,
 117         .identity       = "Coldfire M54xx Watchdog",
 118 };
 119
 120 static long m54xx_wdt_ioctl(struct file *file, unsigned int cmd,
 121                                                          unsigned long arg)
 122 {
 123         int ret = -ENOTTY;
 124         int time;
 125
 126         switch (cmd) {
 127         case WDIOC_GETSUPPORT:
 128                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 129                                    sizeof(ident)) ? -EFAULT : 0;
 130                 break;
 131
 132         case WDIOC_GETSTATUS:
 133                 ret = put_user(0, (int *)arg);
 134                 break;
 135
 136         case WDIOC_GETBOOTSTATUS:
 137                 ret = put_user(0, (int *)arg);
 138                 break;
 139
 140         case WDIOC_KEEPALIVE:
 141                 wdt_keepalive();
 142                 ret = 0;
 143                 break;
 144
 145         case WDIOC_SETTIMEOUT:
 146                 ret = get_user(time, (int *)arg);
 147                 if (ret)
 148                         break;
 149
 150                 if (time <= 0 || time > 30) {
 151                         ret = -EINVAL;
 152                         break;
 153                 }
 154
 155                 heartbeat = time;
 156                 wdt_enable();
 157                 /* Fall through */
 158
 159         case WDIOC_GETTIMEOUT:
 160                 ret = put_user(heartbeat, (int *)arg);
 161                 break;
 162         }
 163         return ret;
 164 }
 165
 166 static int m54xx_wdt_release(struct inode *inode, struct file *file)
 167 {
 168         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
 169                 wdt_disable();
 170         else {
 171                 pr_crit("Device closed unexpectedly - timer will not stop\n");
 172                 wdt_keepalive();
 173         }
 174         clear_bit(WDT_IN_USE, &wdt_status);
 175         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
 176
 177         return 0;
 178 }
 179
 180
 181 static const struct file_operations m54xx_wdt_fops = {
 182         .owner          = THIS_MODULE,
 183         .llseek         = no_llseek,
 184         .write          = m54xx_wdt_write,
 185         .unlocked_ioctl = m54xx_wdt_ioctl,
 186         .open           = m54xx_wdt_open,
 187         .release        = m54xx_wdt_release,
 188 };
 189
 190 static struct miscdevice m54xx_wdt_miscdev = {
 191         .minor          = WATCHDOG_MINOR,
 192         .name           = "watchdog",
 193         .fops           = &m54xx_wdt_fops,
 194 };
 195
 196 static int __init m54xx_wdt_init(void)
 197 {
 198         if (!request_mem_region(MCF_GPT_GCIR0, 4, "Coldfire M54xx Watchdog")) {
 199                 pr_warn("I/O region busy\n");
 200                 return -EBUSY;
 201         }
 202         pr_info("driver is loaded\n");
 203
 204         return misc_register(&m54xx_wdt_miscdev);
 205 }
 206
 207 static void __exit m54xx_wdt_exit(void)
 208 {
 209         misc_deregister(&m54xx_wdt_miscdev);
 210         release_mem_region(MCF_GPT_GCIR0, 4);
 211 }
 212
 213 module_init(m54xx_wdt_init);
 214 module_exit(m54xx_wdt_exit);
 215
 216 MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 217 MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
 218
 219 module_param(heartbeat, int, 0);
 220 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
 221
 222 module_param(nowayout, bool, 0);
 223 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 224
 225 MODULE_LICENSE("GPL");
 226 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);