drivers/watchdog/txx9wdt.c

   1 /*
   2  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
   3  *
   4  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/types.h>
  16 #include <linux/watchdog.h>
  17 #include <linux/init.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/clk.h>
  20 #include <linux/err.h>
  21 #include <linux/io.h>
  22 #include <asm/txx9tmr.h>
  23
  24 #define WD_TIMER_CCD    7               /* 1/256 */
  25 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  26 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  27 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  28
  29 static unsigned int timeout = TIMER_MARGIN;     /* in seconds */
  30 module_param(timeout, uint, 0);
  31 MODULE_PARM_DESC(timeout,
  32         "Watchdog timeout in seconds. "
  33         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  34         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
  35
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37 module_param(nowayout, bool, 0);
  38 MODULE_PARM_DESC(nowayout,
  39         "Watchdog cannot be stopped once started "
  40         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  43 static struct clk *txx9_imclk;
  44 static DEFINE_SPINLOCK(txx9_lock);
  45
  46 static int txx9wdt_ping(struct watchdog_device *wdt_dev)
  47 {
  48         spin_lock(&txx9_lock);
  49         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  50         spin_unlock(&txx9_lock);
  51         return 0;
  52 }
  53
  54 static int txx9wdt_start(struct watchdog_device *wdt_dev)
  55 {
  56         spin_lock(&txx9_lock);
  57         __raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
  58         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  59         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  60         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  61                      &txx9wdt_reg->tcr);
  62         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  63         spin_unlock(&txx9_lock);
  64         return 0;
  65 }
  66
  67 static int txx9wdt_stop(struct watchdog_device *wdt_dev)
  68 {
  69         spin_lock(&txx9_lock);
  70         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  71         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  72                      &txx9wdt_reg->tcr);
  73         spin_unlock(&txx9_lock);
  74         return 0;
  75 }
  76
  77 static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
  78                                unsigned int new_timeout)
  79 {
  80         wdt_dev->timeout = new_timeout;
  81         txx9wdt_stop(wdt_dev);
  82         txx9wdt_start(wdt_dev);
  83         return 0;
  84 }
  85
  86 static const struct watchdog_info txx9wdt_info = {
  87         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  88         .identity = "Hardware Watchdog for TXx9",
  89 };
  90
  91 static const struct watchdog_ops txx9wdt_ops = {
  92         .owner = THIS_MODULE,
  93         .start = txx9wdt_start,
  94         .stop = txx9wdt_stop,
  95         .ping = txx9wdt_ping,
  96         .set_timeout = txx9wdt_set_timeout,
  97 };
  98
  99 static struct watchdog_device txx9wdt = {
 100         .info = &txx9wdt_info,
 101         .ops = &txx9wdt_ops,
 102 };
 103
 104 static int __init txx9wdt_probe(struct platform_device *dev)
 105 {
 106         struct resource *res;
 107         int ret;
 108
 109         txx9_imclk = clk_get(NULL, "imbus_clk");
 110         if (IS_ERR(txx9_imclk)) {
 111                 ret = PTR_ERR(txx9_imclk);
 112                 txx9_imclk = NULL;
 113                 goto exit;
 114         }
 115         ret = clk_enable(txx9_imclk);
 116         if (ret) {
 117                 clk_put(txx9_imclk);
 118                 txx9_imclk = NULL;
 119                 goto exit;
 120         }
 121
 122         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
 123         txx9wdt_reg = devm_ioremap_resource(&dev->dev, res);
 124         if (IS_ERR(txx9wdt_reg)) {
 125                 ret = PTR_ERR(txx9wdt_reg);
 126                 goto exit;
 127         }
 128
 129         if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
 130                 timeout = TIMER_MARGIN;
 131         txx9wdt.timeout = timeout;
 132         txx9wdt.min_timeout = 1;
 133         txx9wdt.max_timeout = WD_MAX_TIMEOUT;
 134         watchdog_set_nowayout(&txx9wdt, nowayout);
 135
 136         ret = watchdog_register_device(&txx9wdt);
 137         if (ret)
 138                 goto exit;
 139
 140         pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
 141                 timeout, WD_MAX_TIMEOUT, nowayout);
 142
 143         return 0;
 144 exit:
 145         if (txx9_imclk) {
 146                 clk_disable(txx9_imclk);
 147                 clk_put(txx9_imclk);
 148         }
 149         return ret;
 150 }
 151
 152 static int __exit txx9wdt_remove(struct platform_device *dev)
 153 {
 154         watchdog_unregister_device(&txx9wdt);
 155         clk_disable(txx9_imclk);
 156         clk_put(txx9_imclk);
 157         return 0;
 158 }
 159
 160 static void txx9wdt_shutdown(struct platform_device *dev)
 161 {
 162         txx9wdt_stop(&txx9wdt);
 163 }
 164
 165 static struct platform_driver txx9wdt_driver = {
 166         .remove = __exit_p(txx9wdt_remove),
 167         .shutdown = txx9wdt_shutdown,
 168         .driver = {
 169                 .name = "txx9wdt",
 170         },
 171 };
 172
 173 module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);
 174
 175 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 176 MODULE_LICENSE("GPL");
 177 MODULE_ALIAS("platform:txx9wdt");