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