drivers/watchdog/txx9wdt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
   4  *
   5  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/types.h>
  13 #include <linux/watchdog.h>
  14 #include <linux/init.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/clk.h>
  17 #include <linux/err.h>
  18 #include <linux/io.h>
  19 #include <asm/txx9tmr.h>
  20
  21 #define WD_TIMER_CCD    7               /* 1/256 */
  22 #define WD_TIMER_CLK    (clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  23 #define WD_MAX_TIMEOUT  ((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  24 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  25
  26 static unsigned int timeout = TIMER_MARGIN;     /* in seconds */
  27 module_param(timeout, uint, 0);
  28 MODULE_PARM_DESC(timeout,
  29         "Watchdog timeout in seconds. "
  30         "(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  31         "default=" __MODULE_STRING(TIMER_MARGIN) ")");
  32
  33 static bool nowayout = WATCHDOG_NOWAYOUT;
  34 module_param(nowayout, bool, 0);
  35 MODULE_PARM_DESC(nowayout,
  36         "Watchdog cannot be stopped once started "
  37         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  38
  39 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  40 static struct clk *txx9_imclk;
  41 static DEFINE_SPINLOCK(txx9_lock);
  42
  43 static int txx9wdt_ping(struct watchdog_device *wdt_dev)
  44 {
  45         spin_lock(&txx9_lock);
  46         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  47         spin_unlock(&txx9_lock);
  48         return 0;
  49 }
  50
  51 static int txx9wdt_start(struct watchdog_device *wdt_dev)
  52 {
  53         spin_lock(&txx9_lock);
  54         __raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
  55         __raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  56         __raw_writel(0, &txx9wdt_reg->tisr);    /* clear pending interrupt */
  57         __raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  58                      &txx9wdt_reg->tcr);
  59         __raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
  60         spin_unlock(&txx9_lock);
  61         return 0;
  62 }
  63
  64 static int txx9wdt_stop(struct watchdog_device *wdt_dev)
  65 {
  66         spin_lock(&txx9_lock);
  67         __raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  68         __raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  69                      &txx9wdt_reg->tcr);
  70         spin_unlock(&txx9_lock);
  71         return 0;
  72 }
  73
  74 static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
  75                                unsigned int new_timeout)
  76 {
  77         wdt_dev->timeout = new_timeout;
  78         txx9wdt_stop(wdt_dev);
  79         txx9wdt_start(wdt_dev);
  80         return 0;
  81 }
  82
  83 static const struct watchdog_info txx9wdt_info = {
  84         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  85         .identity = "Hardware Watchdog for TXx9",
  86 };
  87
  88 static const struct watchdog_ops txx9wdt_ops = {
  89         .owner = THIS_MODULE,
  90         .start = txx9wdt_start,
  91         .stop = txx9wdt_stop,
  92         .ping = txx9wdt_ping,
  93         .set_timeout = txx9wdt_set_timeout,
  94 };
  95
  96 static struct watchdog_device txx9wdt = {
  97         .info = &txx9wdt_info,
  98         .ops = &txx9wdt_ops,
  99 };
 100
 101 static int __init txx9wdt_probe(struct platform_device *dev)
 102 {
 103         int ret;
 104
 105         txx9_imclk = clk_get(NULL, "imbus_clk");
 106         if (IS_ERR(txx9_imclk)) {
 107                 ret = PTR_ERR(txx9_imclk);
 108                 txx9_imclk = NULL;
 109                 goto exit;
 110         }
 111         ret = clk_prepare_enable(txx9_imclk);
 112         if (ret) {
 113                 clk_put(txx9_imclk);
 114                 txx9_imclk = NULL;
 115                 goto exit;
 116         }
 117
 118         txx9wdt_reg = devm_platform_ioremap_resource(dev, 0);
 119         if (IS_ERR(txx9wdt_reg)) {
 120                 ret = PTR_ERR(txx9wdt_reg);
 121                 goto exit;
 122         }
 123
 124         if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
 125                 timeout = TIMER_MARGIN;
 126         txx9wdt.timeout = timeout;
 127         txx9wdt.min_timeout = 1;
 128         txx9wdt.max_timeout = WD_MAX_TIMEOUT;
 129         txx9wdt.parent = &dev->dev;
 130         watchdog_set_nowayout(&txx9wdt, nowayout);
 131
 132         ret = watchdog_register_device(&txx9wdt);
 133         if (ret)
 134                 goto exit;
 135
 136         pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
 137                 timeout, WD_MAX_TIMEOUT, nowayout);
 138
 139         return 0;
 140 exit:
 141         if (txx9_imclk) {
 142                 clk_disable_unprepare(txx9_imclk);
 143                 clk_put(txx9_imclk);
 144         }
 145         return ret;
 146 }
 147
 148 static int __exit txx9wdt_remove(struct platform_device *dev)
 149 {
 150         watchdog_unregister_device(&txx9wdt);
 151         clk_disable_unprepare(txx9_imclk);
 152         clk_put(txx9_imclk);
 153         return 0;
 154 }
 155
 156 static void txx9wdt_shutdown(struct platform_device *dev)
 157 {
 158         txx9wdt_stop(&txx9wdt);
 159 }
 160
 161 static struct platform_driver txx9wdt_driver = {
 162         .remove = __exit_p(txx9wdt_remove),
 163         .shutdown = txx9wdt_shutdown,
 164         .driver = {
 165                 .name = "txx9wdt",
 166         },
 167 };
 168
 169 module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);
 170
 171 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
 172 MODULE_LICENSE("GPL");
 173 MODULE_ALIAS("platform:txx9wdt");