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