linux/drivers/watchdog/m54xx_wdt.c
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   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
  38static bool nowayout = WATCHDOG_NOWAYOUT;
  39static unsigned int heartbeat = 30;     /* (secs) Default is 0.5 minute */
  40static unsigned long wdt_status;
  41
  42#define WDT_IN_USE              0
  43#define WDT_OK_TO_CLOSE         1
  44
  45static 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
  63static 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
  73static 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
  82static 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
  92static 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
 115static const struct watchdog_info ident = {
 116        .options        = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT |
 117                                WDIOF_KEEPALIVEPING,
 118        .identity       = "Coldfire M54xx Watchdog",
 119};
 120
 121static 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
 167static 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
 182static 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
 192static struct miscdevice m54xx_wdt_miscdev = {
 193        .minor          = WATCHDOG_MINOR,
 194        .name           = "watchdog",
 195        .fops           = &m54xx_wdt_fops,
 196};
 197
 198static 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
 209static void __exit m54xx_wdt_exit(void)
 210{
 211        misc_deregister(&m54xx_wdt_miscdev);
 212        release_mem_region(MCF_GPT_GCIR0, 4);
 213}
 214
 215module_init(m54xx_wdt_init);
 216module_exit(m54xx_wdt_exit);
 217
 218MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
 219MODULE_DESCRIPTION("Coldfire M54xx Watchdog");
 220
 221module_param(heartbeat, int, 0);
 222MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 30s)");
 223
 224module_param(nowayout, bool, 0);
 225MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
 226
 227MODULE_LICENSE("GPL");
 228