drivers/watchdog/jz4740_wdt.c

   1 /*
   2  *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
   3  *  JZ4740 Watchdog driver
   4  *
   5  *  This program is free software; you can redistribute it and/or modify it
   6  *  under  the terms of the GNU General  Public License as published by the
   7  *  Free Software Foundation;  either version 2 of the License, or (at your
   8  *  option) any later version.
   9  *
  10  *  You should have received a copy of the GNU General Public License along
  11  *  with this program; if not, write to the Free Software Foundation, Inc.,
  12  *  675 Mass Ave, Cambridge, MA 02139, USA.
  13  *
  14  */
  15
  16 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/fs.h>
  21 #include <linux/miscdevice.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/init.h>
  24 #include <linux/bitops.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/io.h>
  29 #include <linux/device.h>
  30 #include <linux/clk.h>
  31 #include <linux/slab.h>
  32
  33 #include <asm/mach-jz4740/timer.h>
  34
  35 #define JZ_REG_WDT_TIMER_DATA     0x0
  36 #define JZ_REG_WDT_COUNTER_ENABLE 0x4
  37 #define JZ_REG_WDT_TIMER_COUNTER  0x8
  38 #define JZ_REG_WDT_TIMER_CONTROL  0xC
  39
  40 #define JZ_WDT_CLOCK_PCLK 0x1
  41 #define JZ_WDT_CLOCK_RTC  0x2
  42 #define JZ_WDT_CLOCK_EXT  0x4
  43
  44 #define WDT_IN_USE        0
  45 #define WDT_OK_TO_CLOSE   1
  46
  47 #define JZ_WDT_CLOCK_DIV_SHIFT   3
  48
  49 #define JZ_WDT_CLOCK_DIV_1    (0 << JZ_WDT_CLOCK_DIV_SHIFT)
  50 #define JZ_WDT_CLOCK_DIV_4    (1 << JZ_WDT_CLOCK_DIV_SHIFT)
  51 #define JZ_WDT_CLOCK_DIV_16   (2 << JZ_WDT_CLOCK_DIV_SHIFT)
  52 #define JZ_WDT_CLOCK_DIV_64   (3 << JZ_WDT_CLOCK_DIV_SHIFT)
  53 #define JZ_WDT_CLOCK_DIV_256  (4 << JZ_WDT_CLOCK_DIV_SHIFT)
  54 #define JZ_WDT_CLOCK_DIV_1024 (5 << JZ_WDT_CLOCK_DIV_SHIFT)
  55
  56 #define DEFAULT_HEARTBEAT 5
  57 #define MAX_HEARTBEAT     2048
  58
  59 static struct {
  60         void __iomem *base;
  61         struct resource *mem;
  62         struct clk *rtc_clk;
  63         unsigned long status;
  64 } jz4740_wdt;
  65
  66 static int heartbeat = DEFAULT_HEARTBEAT;
  67
  68
  69 static void jz4740_wdt_service(void)
  70 {
  71         writew(0x0, jz4740_wdt.base + JZ_REG_WDT_TIMER_COUNTER);
  72 }
  73
  74 static void jz4740_wdt_set_heartbeat(int new_heartbeat)
  75 {
  76         unsigned int rtc_clk_rate;
  77         unsigned int timeout_value;
  78         unsigned short clock_div = JZ_WDT_CLOCK_DIV_1;
  79
  80         heartbeat = new_heartbeat;
  81
  82         rtc_clk_rate = clk_get_rate(jz4740_wdt.rtc_clk);
  83
  84         timeout_value = rtc_clk_rate * heartbeat;
  85         while (timeout_value > 0xffff) {
  86                 if (clock_div == JZ_WDT_CLOCK_DIV_1024) {
  87                         /* Requested timeout too high;
  88                         * use highest possible value. */
  89                         timeout_value = 0xffff;
  90                         break;
  91                 }
  92                 timeout_value >>= 2;
  93                 clock_div += (1 << JZ_WDT_CLOCK_DIV_SHIFT);
  94         }
  95
  96         writeb(0x0, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
  97         writew(clock_div, jz4740_wdt.base + JZ_REG_WDT_TIMER_CONTROL);
  98
  99         writew((u16)timeout_value, jz4740_wdt.base + JZ_REG_WDT_TIMER_DATA);
 100         writew(0x0, jz4740_wdt.base + JZ_REG_WDT_TIMER_COUNTER);
 101         writew(clock_div | JZ_WDT_CLOCK_RTC,
 102                 jz4740_wdt.base + JZ_REG_WDT_TIMER_CONTROL);
 103
 104         writeb(0x1, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
 105 }
 106
 107 static void jz4740_wdt_enable(void)
 108 {
 109         jz4740_timer_enable_watchdog();
 110         jz4740_wdt_set_heartbeat(heartbeat);
 111 }
 112
 113 static void jz4740_wdt_disable(void)
 114 {
 115         jz4740_timer_disable_watchdog();
 116         writeb(0x0, jz4740_wdt.base + JZ_REG_WDT_COUNTER_ENABLE);
 117 }
 118
 119 static int jz4740_wdt_open(struct inode *inode, struct file *file)
 120 {
 121         if (test_and_set_bit(WDT_IN_USE, &jz4740_wdt.status))
 122                 return -EBUSY;
 123
 124         jz4740_wdt_enable();
 125
 126         return nonseekable_open(inode, file);
 127 }
 128
 129 static ssize_t jz4740_wdt_write(struct file *file, const char *data,
 130                 size_t len, loff_t *ppos)
 131 {
 132         if (len) {
 133                 size_t i;
 134
 135                 clear_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status);
 136                 for (i = 0; i != len; i++) {
 137                         char c;
 138
 139                         if (get_user(c, data + i))
 140                                 return -EFAULT;
 141
 142                         if (c == 'V')
 143                                 set_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status);
 144                 }
 145                 jz4740_wdt_service();
 146         }
 147
 148         return len;
 149 }
 150
 151 static const struct watchdog_info ident = {
 152         .options = WDIOF_KEEPALIVEPING,
 153         .identity = "jz4740 Watchdog",
 154 };
 155
 156 static long jz4740_wdt_ioctl(struct file *file,
 157                                         unsigned int cmd, unsigned long arg)
 158 {
 159         int ret = -ENOTTY;
 160         int heartbeat_seconds;
 161
 162         switch (cmd) {
 163         case WDIOC_GETSUPPORT:
 164                 ret = copy_to_user((struct watchdog_info *)arg, &ident,
 165                                 sizeof(ident)) ? -EFAULT : 0;
 166                 break;
 167
 168         case WDIOC_GETSTATUS:
 169         case WDIOC_GETBOOTSTATUS:
 170                 ret = put_user(0, (int *)arg);
 171                 break;
 172
 173         case WDIOC_KEEPALIVE:
 174                 jz4740_wdt_service();
 175                 return 0;
 176
 177         case WDIOC_SETTIMEOUT:
 178                 if (get_user(heartbeat_seconds, (int __user *)arg))
 179                         return -EFAULT;
 180
 181                 jz4740_wdt_set_heartbeat(heartbeat_seconds);
 182                 return 0;
 183
 184         case WDIOC_GETTIMEOUT:
 185                 return put_user(heartbeat, (int *)arg);
 186
 187         default:
 188                 break;
 189         }
 190
 191         return ret;
 192 }
 193
 194 static int jz4740_wdt_release(struct inode *inode, struct file *file)
 195 {
 196         jz4740_wdt_service();
 197
 198         if (test_and_clear_bit(WDT_OK_TO_CLOSE, &jz4740_wdt.status))
 199                 jz4740_wdt_disable();
 200
 201         clear_bit(WDT_IN_USE, &jz4740_wdt.status);
 202         return 0;
 203 }
 204
 205 static const struct file_operations jz4740_wdt_fops = {
 206         .owner = THIS_MODULE,
 207         .llseek = no_llseek,
 208         .write = jz4740_wdt_write,
 209         .unlocked_ioctl = jz4740_wdt_ioctl,
 210         .open = jz4740_wdt_open,
 211         .release = jz4740_wdt_release,
 212 };
 213
 214 static struct miscdevice jz4740_wdt_miscdev = {
 215         .minor = WATCHDOG_MINOR,
 216         .name = "watchdog",
 217         .fops = &jz4740_wdt_fops,
 218 };
 219
 220 static int __devinit jz4740_wdt_probe(struct platform_device *pdev)
 221 {
 222         int ret = 0, size;
 223         struct resource *res;
 224         struct device *dev = &pdev->dev;
 225
 226         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 227         if (res == NULL) {
 228                 dev_err(dev, "failed to get memory region resource\n");
 229                 return -ENXIO;
 230         }
 231
 232         size = resource_size(res);
 233         jz4740_wdt.mem = request_mem_region(res->start, size, pdev->name);
 234         if (jz4740_wdt.mem == NULL) {
 235                 dev_err(dev, "failed to get memory region\n");
 236                 return -EBUSY;
 237         }
 238
 239         jz4740_wdt.base = ioremap_nocache(res->start, size);
 240         if (jz4740_wdt.base == NULL) {
 241                 dev_err(dev, "failed to map memory region\n");
 242                 ret = -EBUSY;
 243                 goto err_release_region;
 244         }
 245
 246         jz4740_wdt.rtc_clk = clk_get(NULL, "rtc");
 247         if (IS_ERR(jz4740_wdt.rtc_clk)) {
 248                 dev_err(dev, "cannot find RTC clock\n");
 249                 ret = PTR_ERR(jz4740_wdt.rtc_clk);
 250                 goto err_iounmap;
 251         }
 252
 253         ret = misc_register(&jz4740_wdt_miscdev);
 254         if (ret < 0) {
 255                 dev_err(dev, "cannot register misc device\n");
 256                 goto err_disable_clk;
 257         }
 258
 259         return 0;
 260
 261 err_disable_clk:
 262         clk_put(jz4740_wdt.rtc_clk);
 263 err_iounmap:
 264         iounmap(jz4740_wdt.base);
 265 err_release_region:
 266         release_mem_region(jz4740_wdt.mem->start,
 267                         resource_size(jz4740_wdt.mem));
 268         return ret;
 269 }
 270
 271
 272 static int __devexit jz4740_wdt_remove(struct platform_device *pdev)
 273 {
 274         jz4740_wdt_disable();
 275         misc_deregister(&jz4740_wdt_miscdev);
 276         clk_put(jz4740_wdt.rtc_clk);
 277
 278         iounmap(jz4740_wdt.base);
 279         jz4740_wdt.base = NULL;
 280
 281         release_mem_region(jz4740_wdt.mem->start,
 282                                 resource_size(jz4740_wdt.mem));
 283         jz4740_wdt.mem = NULL;
 284
 285         return 0;
 286 }
 287
 288
 289 static struct platform_driver jz4740_wdt_driver = {
 290         .probe = jz4740_wdt_probe,
 291         .remove = __devexit_p(jz4740_wdt_remove),
 292         .driver = {
 293                 .name = "jz4740-wdt",
 294                 .owner  = THIS_MODULE,
 295         },
 296 };
 297
 298 module_platform_driver(jz4740_wdt_driver);
 299
 300 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
 301 MODULE_DESCRIPTION("jz4740 Watchdog Driver");
 302
 303 module_param(heartbeat, int, 0);
 304 MODULE_PARM_DESC(heartbeat,
 305                 "Watchdog heartbeat period in seconds from 1 to "
 306                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 307                 __MODULE_STRING(DEFAULT_HEARTBEAT));
 308
 309 MODULE_LICENSE("GPL");
 310 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 311 MODULE_ALIAS("platform:jz4740-wdt");