linux/drivers/watchdog/max63xx_wdt.c
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   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/mod_devicetable.h>
  21#include <linux/types.h>
  22#include <linux/kernel.h>
  23#include <linux/watchdog.h>
  24#include <linux/bitops.h>
  25#include <linux/platform_device.h>
  26#include <linux/spinlock.h>
  27#include <linux/io.h>
  28#include <linux/slab.h>
  29
  30#define DEFAULT_HEARTBEAT 60
  31#define MAX_HEARTBEAT     60
  32
  33static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  34static bool nowayout  = WATCHDOG_NOWAYOUT;
  35
  36/*
  37 * Memory mapping: a single byte, 3 first lower bits to select bit 3
  38 * to ping the watchdog.
  39 */
  40#define MAX6369_WDSET   (7 << 0)
  41#define MAX6369_WDI     (1 << 3)
  42
  43#define MAX6369_WDSET_DISABLED  3
  44
  45static int nodelay;
  46
  47struct max63xx_wdt {
  48        struct watchdog_device wdd;
  49        const struct max63xx_timeout *timeout;
  50
  51        /* memory mapping */
  52        void __iomem *base;
  53        spinlock_t lock;
  54
  55        /* WDI and WSET bits write access routines */
  56        void (*ping)(struct max63xx_wdt *wdt);
  57        void (*set)(struct max63xx_wdt *wdt, u8 set);
  58};
  59
  60/*
  61 * The timeout values used are actually the absolute minimum the chip
  62 * offers. Typical values on my board are slightly over twice as long
  63 * (10s setting ends up with a 25s timeout), and can be up to 3 times
  64 * the nominal setting (according to the datasheet). So please take
  65 * these values with a grain of salt. Same goes for the initial delay
  66 * "feature". Only max6373/74 have a few settings without this initial
  67 * delay (selected with the "nodelay" parameter).
  68 *
  69 * I also decided to remove from the tables any timeout smaller than a
  70 * second, as it looked completly overkill...
  71 */
  72
  73/* Timeouts in second */
  74struct max63xx_timeout {
  75        const u8 wdset;
  76        const u8 tdelay;
  77        const u8 twd;
  78};
  79
  80static const struct max63xx_timeout max6369_table[] = {
  81        { 5,  1,  1 },
  82        { 6, 10, 10 },
  83        { 7, 60, 60 },
  84        { },
  85};
  86
  87static const struct max63xx_timeout max6371_table[] = {
  88        { 6, 60,  3 },
  89        { 7, 60, 60 },
  90        { },
  91};
  92
  93static const struct max63xx_timeout max6373_table[] = {
  94        { 2, 60,  1 },
  95        { 5,  0,  1 },
  96        { 1,  3,  3 },
  97        { 7, 60, 10 },
  98        { 6,  0, 10 },
  99        { },
 100};
 101
 102static struct max63xx_timeout *
 103max63xx_select_timeout(struct max63xx_timeout *table, int value)
 104{
 105        while (table->twd) {
 106                if (value <= table->twd) {
 107                        if (nodelay && table->tdelay == 0)
 108                                return table;
 109
 110                        if (!nodelay)
 111                                return table;
 112                }
 113
 114                table++;
 115        }
 116
 117        return NULL;
 118}
 119
 120static int max63xx_wdt_ping(struct watchdog_device *wdd)
 121{
 122        struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 123
 124        wdt->ping(wdt);
 125        return 0;
 126}
 127
 128static int max63xx_wdt_start(struct watchdog_device *wdd)
 129{
 130        struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 131
 132        wdt->set(wdt, wdt->timeout->wdset);
 133
 134        /* check for a edge triggered startup */
 135        if (wdt->timeout->tdelay == 0)
 136                wdt->ping(wdt);
 137        return 0;
 138}
 139
 140static int max63xx_wdt_stop(struct watchdog_device *wdd)
 141{
 142        struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
 143
 144        wdt->set(wdt, MAX6369_WDSET_DISABLED);
 145        return 0;
 146}
 147
 148static const struct watchdog_ops max63xx_wdt_ops = {
 149        .owner = THIS_MODULE,
 150        .start = max63xx_wdt_start,
 151        .stop = max63xx_wdt_stop,
 152        .ping = max63xx_wdt_ping,
 153};
 154
 155static const struct watchdog_info max63xx_wdt_info = {
 156        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 157        .identity = "max63xx Watchdog",
 158};
 159
 160static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
 161{
 162        u8 val;
 163
 164        spin_lock(&wdt->lock);
 165
 166        val = __raw_readb(wdt->base);
 167
 168        __raw_writeb(val | MAX6369_WDI, wdt->base);
 169        __raw_writeb(val & ~MAX6369_WDI, wdt->base);
 170
 171        spin_unlock(&wdt->lock);
 172}
 173
 174static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
 175{
 176        u8 val;
 177
 178        spin_lock(&wdt->lock);
 179
 180        val = __raw_readb(wdt->base);
 181        val &= ~MAX6369_WDSET;
 182        val |= set & MAX6369_WDSET;
 183        __raw_writeb(val, wdt->base);
 184
 185        spin_unlock(&wdt->lock);
 186}
 187
 188static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
 189{
 190        wdt->base = devm_platform_ioremap_resource(p, 0);
 191        if (IS_ERR(wdt->base))
 192                return PTR_ERR(wdt->base);
 193
 194        spin_lock_init(&wdt->lock);
 195
 196        wdt->ping = max63xx_mmap_ping;
 197        wdt->set = max63xx_mmap_set;
 198        return 0;
 199}
 200
 201static int max63xx_wdt_probe(struct platform_device *pdev)
 202{
 203        struct device *dev = &pdev->dev;
 204        struct max63xx_wdt *wdt;
 205        struct max63xx_timeout *table;
 206        int err;
 207
 208        wdt = devm_kzalloc(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(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 = 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 = devm_watchdog_register_device(dev, &wdt->wdd);
 239        if (err)
 240                return err;
 241
 242        dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
 243                 wdt->timeout->twd, wdt->timeout->tdelay);
 244        return 0;
 245}
 246
 247static const struct platform_device_id max63xx_id_table[] = {
 248        { "max6369_wdt", (kernel_ulong_t)max6369_table, },
 249        { "max6370_wdt", (kernel_ulong_t)max6369_table, },
 250        { "max6371_wdt", (kernel_ulong_t)max6371_table, },
 251        { "max6372_wdt", (kernel_ulong_t)max6371_table, },
 252        { "max6373_wdt", (kernel_ulong_t)max6373_table, },
 253        { "max6374_wdt", (kernel_ulong_t)max6373_table, },
 254        { },
 255};
 256MODULE_DEVICE_TABLE(platform, max63xx_id_table);
 257
 258static struct platform_driver max63xx_wdt_driver = {
 259        .probe          = max63xx_wdt_probe,
 260        .id_table       = max63xx_id_table,
 261        .driver         = {
 262                .name   = "max63xx_wdt",
 263        },
 264};
 265
 266module_platform_driver(max63xx_wdt_driver);
 267
 268MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
 269MODULE_DESCRIPTION("max63xx Watchdog Driver");
 270
 271module_param(heartbeat, int, 0);
 272MODULE_PARM_DESC(heartbeat,
 273                 "Watchdog heartbeat period in seconds from 1 to "
 274                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 275                 __MODULE_STRING(DEFAULT_HEARTBEAT));
 276
 277module_param(nowayout, bool, 0);
 278MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 279                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 280
 281module_param(nodelay, int, 0);
 282MODULE_PARM_DESC(nodelay,
 283                 "Force selection of a timeout setting without initial delay "
 284                 "(max6373/74 only, default=0)");
 285
 286MODULE_LICENSE("GPL v2");
 287