drivers/watchdog/max63xx_wdt.c

   1 /*
   2  * drivers/char/watchdog/max63xx_wdt.c
   3  *
   4  * Driver for max63{69,70,71,72,73,74} watchdog timers
   5  *
   6  * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2. This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  *
  12  * This driver assumes the watchdog pins are memory mapped (as it is
  13  * the case for the Arcom Zeus). Should it be connected over GPIOs or
  14  * another interface, some abstraction will have to be introduced.
  15  */
  16
  17 #include <linux/err.h>
  18 #include <linux/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/watchdog.h>
  23 #include <linux/bitops.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/io.h>
  27 #include <linux/slab.h>
  28
  29 #define DEFAULT_HEARTBEAT 60
  30 #define MAX_HEARTBEAT     60
  31
  32 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  33 static bool nowayout  = WATCHDOG_NOWAYOUT;
  34
  35 /*
  36  * Memory mapping: a single byte, 3 first lower bits to select bit 3
  37  * to ping the watchdog.
  38  */
  39 #define MAX6369_WDSET   (7 << 0)
  40 #define MAX6369_WDI     (1 << 3)
  41
  42 #define MAX6369_WDSET_DISABLED  3
  43
  44 static int nodelay;
  45
  46 struct max63xx_wdt {
  47         struct watchdog_device wdd;
  48         const struct max63xx_timeout *timeout;
  49
  50         /* memory mapping */
  51         void __iomem *base;
  52         spinlock_t lock;
  53
  54         /* WDI and WSET bits write access routines */
  55         void (*ping)(struct max63xx_wdt *wdt);
  56         void (*set)(struct max63xx_wdt *wdt, u8 set);
  57 };
  58
  59 /*
  60  * The timeout values used are actually the absolute minimum the chip
  61  * offers. Typical values on my board are slightly over twice as long
  62  * (10s setting ends up with a 25s timeout), and can be up to 3 times
  63  * the nominal setting (according to the datasheet). So please take
  64  * these values with a grain of salt. Same goes for the initial delay
  65  * "feature". Only max6373/74 have a few settings without this initial
  66  * delay (selected with the "nodelay" parameter).
  67  *
  68  * I also decided to remove from the tables any timeout smaller than a
  69  * second, as it looked completly overkill...
  70  */
  71
  72 /* Timeouts in second */
  73 struct max63xx_timeout {
  74         const u8 wdset;
  75         const u8 tdelay;
  76         const u8 twd;
  77 };
  78
  79 static const struct max63xx_timeout max6369_table[] = {
  80         { 5,  1,  1 },
  81         { 6, 10, 10 },
  82         { 7, 60, 60 },
  83         { },
  84 };
  85
  86 static const struct max63xx_timeout max6371_table[] = {
  87         { 6, 60,  3 },
  88         { 7, 60, 60 },
  89         { },
  90 };
  91
  92 static const struct max63xx_timeout max6373_table[] = {
  93         { 2, 60,  1 },
  94         { 5,  0,  1 },
  95         { 1,  3,  3 },
  96         { 7, 60, 10 },
  97         { 6,  0, 10 },
  98         { },
  99 };
 100
 101 static struct max63xx_timeout *
 102 max63xx_select_timeout(struct max63xx_timeout *table, int value)
 103 {
 104         while (table->twd) {
 105                 if (value <= table->twd) {
 106                         if (nodelay && table->tdelay == 0)
 107                                 return table;
 108
 109                         if (!nodelay)
 110                                 return table;
 111                 }
 112
 113                 table++;
 114         }
 115
 116         return NULL;
 117 }
 118
 119 static int max63xx_wdt_ping(struct watchdog_device *wdd)
 120 {
 121         struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 122
 123         wdt->ping(wdt);
 124         return 0;
 125 }
 126
 127 static int max63xx_wdt_start(struct watchdog_device *wdd)
 128 {
 129         struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 130
 131         wdt->set(wdt, wdt->timeout->wdset);
 132
 133         /* check for a edge triggered startup */
 134         if (wdt->timeout->tdelay == 0)
 135                 wdt->ping(wdt);
 136         return 0;
 137 }
 138
 139 static int max63xx_wdt_stop(struct watchdog_device *wdd)
 140 {
 141         struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 142
 143         wdt->set(wdt, MAX6369_WDSET_DISABLED);
 144         return 0;
 145 }
 146
 147 static const struct watchdog_ops max63xx_wdt_ops = {
 148         .owner = THIS_MODULE,
 149         .start = max63xx_wdt_start,
 150         .stop = max63xx_wdt_stop,
 151         .ping = max63xx_wdt_ping,
 152 };
 153
 154 static const struct watchdog_info max63xx_wdt_info = {
 155         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 156         .identity = "max63xx Watchdog",
 157 };
 158
 159 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
 160 {
 161         u8 val;
 162
 163         spin_lock(&wdt->lock);
 164
 165         val = __raw_readb(wdt->base);
 166
 167         __raw_writeb(val | MAX6369_WDI, wdt->base);
 168         __raw_writeb(val & ~MAX6369_WDI, wdt->base);
 169
 170         spin_unlock(&wdt->lock);
 171 }
 172
 173 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
 174 {
 175         u8 val;
 176
 177         spin_lock(&wdt->lock);
 178
 179         val = __raw_readb(wdt->base);
 180         val &= ~MAX6369_WDSET;
 181         val |= set & MAX6369_WDSET;
 182         __raw_writeb(val, wdt->base);
 183
 184         spin_unlock(&wdt->lock);
 185 }
 186
 187 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
 188 {
 189         struct resource *mem = platform_get_resource(p, IORESOURCE_MEM, 0);
 190
 191         wdt->base = devm_ioremap_resource(&p->dev, mem);
 192         if (IS_ERR(wdt->base))
 193                 return PTR_ERR(wdt->base);
 194
 195         spin_lock_init(&wdt->lock);
 196
 197         wdt->ping = max63xx_mmap_ping;
 198         wdt->set = max63xx_mmap_set;
 199         return 0;
 200 }
 201
 202 static int max63xx_wdt_probe(struct platform_device *pdev)
 203 {
 204         struct max63xx_wdt *wdt;
 205         struct max63xx_timeout *table;
 206         int err;
 207
 208         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 209         if (!wdt)
 210                 return -ENOMEM;
 211
 212         table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
 213
 214         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 215                 heartbeat = DEFAULT_HEARTBEAT;
 216
 217         wdt->timeout = max63xx_select_timeout(table, heartbeat);
 218         if (!wdt->timeout) {
 219                 dev_err(&pdev->dev, "unable to satisfy %ds heartbeat request\n",
 220                         heartbeat);
 221                 return -EINVAL;
 222         }
 223
 224         err = max63xx_mmap_init(pdev, wdt);
 225         if (err)
 226                 return err;
 227
 228         platform_set_drvdata(pdev, &wdt->wdd);
 229         watchdog_set_drvdata(&wdt->wdd, wdt);
 230
 231         wdt->wdd.parent = &pdev->dev;
 232         wdt->wdd.timeout = wdt->timeout->twd;
 233         wdt->wdd.info = &max63xx_wdt_info;
 234         wdt->wdd.ops = &max63xx_wdt_ops;
 235
 236         watchdog_set_nowayout(&wdt->wdd, nowayout);
 237
 238         err = watchdog_register_device(&wdt->wdd);
 239         if (err)
 240                 return err;
 241
 242         dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
 243                  wdt->timeout->twd, wdt->timeout->tdelay);
 244         return 0;
 245 }
 246
 247 static int max63xx_wdt_remove(struct platform_device *pdev)
 248 {
 249         struct watchdog_device *wdd = platform_get_drvdata(pdev);
 250
 251         watchdog_unregister_device(wdd);
 252         return 0;
 253 }
 254
 255 static const struct platform_device_id max63xx_id_table[] = {
 256         { "max6369_wdt", (kernel_ulong_t)max6369_table, },
 257         { "max6370_wdt", (kernel_ulong_t)max6369_table, },
 258         { "max6371_wdt", (kernel_ulong_t)max6371_table, },
 259         { "max6372_wdt", (kernel_ulong_t)max6371_table, },
 260         { "max6373_wdt", (kernel_ulong_t)max6373_table, },
 261         { "max6374_wdt", (kernel_ulong_t)max6373_table, },
 262         { },
 263 };
 264 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
 265
 266 static struct platform_driver max63xx_wdt_driver = {
 267         .probe          = max63xx_wdt_probe,
 268         .remove         = max63xx_wdt_remove,
 269         .id_table       = max63xx_id_table,
 270         .driver         = {
 271                 .name   = "max63xx_wdt",
 272         },
 273 };
 274
 275 module_platform_driver(max63xx_wdt_driver);
 276
 277 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
 278 MODULE_DESCRIPTION("max63xx Watchdog Driver");
 279
 280 module_param(heartbeat, int, 0);
 281 MODULE_PARM_DESC(heartbeat,
 282                  "Watchdog heartbeat period in seconds from 1 to "
 283                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 284                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 285
 286 module_param(nowayout, bool, 0);
 287 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 288                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 289
 290 module_param(nodelay, int, 0);
 291 MODULE_PARM_DESC(nodelay,
 292                  "Force selection of a timeout setting without initial delay "
 293                  "(max6373/74 only, default=0)");
 294
 295 MODULE_LICENSE("GPL");