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/miscdevice.h>
  21 #include <linux/watchdog.h>
  22 #include <linux/init.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/io.h>
  25 #include <linux/device.h>
  26 #include <linux/clk.h>
  27 #include <linux/slab.h>
  28 #include <linux/err.h>
  29
  30 #include <asm/mach-jz4740/timer.h>
  31
  32 #define JZ_REG_WDT_TIMER_DATA     0x0
  33 #define JZ_REG_WDT_COUNTER_ENABLE 0x4
  34 #define JZ_REG_WDT_TIMER_COUNTER  0x8
  35 #define JZ_REG_WDT_TIMER_CONTROL  0xC
  36
  37 #define JZ_WDT_CLOCK_PCLK 0x1
  38 #define JZ_WDT_CLOCK_RTC  0x2
  39 #define JZ_WDT_CLOCK_EXT  0x4
  40
  41 #define JZ_WDT_CLOCK_DIV_SHIFT   3
  42
  43 #define JZ_WDT_CLOCK_DIV_1    (0 << JZ_WDT_CLOCK_DIV_SHIFT)
  44 #define JZ_WDT_CLOCK_DIV_4    (1 << JZ_WDT_CLOCK_DIV_SHIFT)
  45 #define JZ_WDT_CLOCK_DIV_16   (2 << JZ_WDT_CLOCK_DIV_SHIFT)
  46 #define JZ_WDT_CLOCK_DIV_64   (3 << JZ_WDT_CLOCK_DIV_SHIFT)
  47 #define JZ_WDT_CLOCK_DIV_256  (4 << JZ_WDT_CLOCK_DIV_SHIFT)
  48 #define JZ_WDT_CLOCK_DIV_1024 (5 << JZ_WDT_CLOCK_DIV_SHIFT)
  49
  50 #define DEFAULT_HEARTBEAT 5
  51 #define MAX_HEARTBEAT     2048
  52
  53 static bool nowayout = WATCHDOG_NOWAYOUT;
  54 module_param(nowayout, bool, 0);
  55 MODULE_PARM_DESC(nowayout,
  56                  "Watchdog cannot be stopped once started (default="
  57                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  58
  59 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  60 module_param(heartbeat, uint, 0);
  61 MODULE_PARM_DESC(heartbeat,
  62                 "Watchdog heartbeat period in seconds from 1 to "
  63                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
  64                 __MODULE_STRING(DEFAULT_HEARTBEAT));
  65
  66 struct jz4740_wdt_drvdata {
  67         struct watchdog_device wdt;
  68         void __iomem *base;
  69         struct clk *rtc_clk;
  70 };
  71
  72 static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)
  73 {
  74         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  75
  76         writew(0x0, drvdata->base + JZ_REG_WDT_TIMER_COUNTER);
  77         return 0;
  78 }
  79
  80 static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
  81                                     unsigned int new_timeout)
  82 {
  83         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
  84         unsigned int rtc_clk_rate;
  85         unsigned int timeout_value;
  86         unsigned short clock_div = JZ_WDT_CLOCK_DIV_1;
  87
  88         rtc_clk_rate = clk_get_rate(drvdata->rtc_clk);
  89
  90         timeout_value = rtc_clk_rate * new_timeout;
  91         while (timeout_value > 0xffff) {
  92                 if (clock_div == JZ_WDT_CLOCK_DIV_1024) {
  93                         /* Requested timeout too high;
  94                         * use highest possible value. */
  95                         timeout_value = 0xffff;
  96                         break;
  97                 }
  98                 timeout_value >>= 2;
  99                 clock_div += (1 << JZ_WDT_CLOCK_DIV_SHIFT);
 100         }
 101
 102         writeb(0x0, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
 103         writew(clock_div, drvdata->base + JZ_REG_WDT_TIMER_CONTROL);
 104
 105         writew((u16)timeout_value, drvdata->base + JZ_REG_WDT_TIMER_DATA);
 106         writew(0x0, drvdata->base + JZ_REG_WDT_TIMER_COUNTER);
 107         writew(clock_div | JZ_WDT_CLOCK_RTC,
 108                 drvdata->base + JZ_REG_WDT_TIMER_CONTROL);
 109
 110         writeb(0x1, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
 111
 112         wdt_dev->timeout = new_timeout;
 113         return 0;
 114 }
 115
 116 static int jz4740_wdt_start(struct watchdog_device *wdt_dev)
 117 {
 118         jz4740_timer_enable_watchdog();
 119         jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
 120
 121         return 0;
 122 }
 123
 124 static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
 125 {
 126         struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);
 127
 128         jz4740_timer_disable_watchdog();
 129         writeb(0x0, drvdata->base + JZ_REG_WDT_COUNTER_ENABLE);
 130
 131         return 0;
 132 }
 133
 134 static const struct watchdog_info jz4740_wdt_info = {
 135         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 136         .identity = "jz4740 Watchdog",
 137 };
 138
 139 static const struct watchdog_ops jz4740_wdt_ops = {
 140         .owner = THIS_MODULE,
 141         .start = jz4740_wdt_start,
 142         .stop = jz4740_wdt_stop,
 143         .ping = jz4740_wdt_ping,
 144         .set_timeout = jz4740_wdt_set_timeout,
 145 };
 146
 147 static int jz4740_wdt_probe(struct platform_device *pdev)
 148 {
 149         struct jz4740_wdt_drvdata *drvdata;
 150         struct watchdog_device *jz4740_wdt;
 151         struct resource *res;
 152         int ret;
 153
 154         drvdata = devm_kzalloc(&pdev->dev, sizeof(struct jz4740_wdt_drvdata),
 155                                GFP_KERNEL);
 156         if (!drvdata) {
 157                 dev_err(&pdev->dev, "Unable to alloacate watchdog device\n");
 158                 return -ENOMEM;
 159         }
 160
 161         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
 162                 heartbeat = DEFAULT_HEARTBEAT;
 163
 164         jz4740_wdt = &drvdata->wdt;
 165         jz4740_wdt->info = &jz4740_wdt_info;
 166         jz4740_wdt->ops = &jz4740_wdt_ops;
 167         jz4740_wdt->timeout = heartbeat;
 168         jz4740_wdt->min_timeout = 1;
 169         jz4740_wdt->max_timeout = MAX_HEARTBEAT;
 170         watchdog_set_nowayout(jz4740_wdt, nowayout);
 171         watchdog_set_drvdata(jz4740_wdt, drvdata);
 172
 173         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 174         drvdata->base = devm_ioremap_resource(&pdev->dev, res);
 175         if (IS_ERR(drvdata->base)) {
 176                 ret = PTR_ERR(drvdata->base);
 177                 goto err_out;
 178         }
 179
 180         drvdata->rtc_clk = clk_get(&pdev->dev, "rtc");
 181         if (IS_ERR(drvdata->rtc_clk)) {
 182                 dev_err(&pdev->dev, "cannot find RTC clock\n");
 183                 ret = PTR_ERR(drvdata->rtc_clk);
 184                 goto err_out;
 185         }
 186
 187         ret = watchdog_register_device(&drvdata->wdt);
 188         if (ret < 0)
 189                 goto err_disable_clk;
 190
 191         platform_set_drvdata(pdev, drvdata);
 192         return 0;
 193
 194 err_disable_clk:
 195         clk_put(drvdata->rtc_clk);
 196 err_out:
 197         return ret;
 198 }
 199
 200 static int jz4740_wdt_remove(struct platform_device *pdev)
 201 {
 202         struct jz4740_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
 203
 204         jz4740_wdt_stop(&drvdata->wdt);
 205         watchdog_unregister_device(&drvdata->wdt);
 206         clk_put(drvdata->rtc_clk);
 207
 208         return 0;
 209 }
 210
 211 static struct platform_driver jz4740_wdt_driver = {
 212         .probe = jz4740_wdt_probe,
 213         .remove = jz4740_wdt_remove,
 214         .driver = {
 215                 .name = "jz4740-wdt",
 216                 .owner  = THIS_MODULE,
 217         },
 218 };
 219
 220 module_platform_driver(jz4740_wdt_driver);
 221
 222 MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
 223 MODULE_DESCRIPTION("jz4740 Watchdog Driver");
 224 MODULE_LICENSE("GPL");
 225 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 226 MODULE_ALIAS("platform:jz4740-wdt");