drivers/watchdog/mt7621_wdt.c

   1 /*
   2  * Ralink MT7621/MT7628 built-in hardware watchdog timer
   3  *
   4  * Copyright (C) 2014 John Crispin <john@phrozen.org>
   5  *
   6  * This driver was based on: drivers/watchdog/rt2880_wdt.c
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published
  10  * by the Free Software Foundation.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/reset.h>
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/watchdog.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/platform_device.h>
  20
  21 #include <asm/mach-ralink/ralink_regs.h>
  22
  23 #define SYSC_RSTSTAT                    0x38
  24 #define WDT_RST_CAUSE                   BIT(1)
  25
  26 #define RALINK_WDT_TIMEOUT              30
  27
  28 #define TIMER_REG_TMRSTAT               0x00
  29 #define TIMER_REG_TMR1LOAD              0x24
  30 #define TIMER_REG_TMR1CTL               0x20
  31
  32 #define TMR1CTL_ENABLE                  BIT(7)
  33 #define TMR1CTL_RESTART                 BIT(9)
  34 #define TMR1CTL_PRESCALE_SHIFT          16
  35
  36 static void __iomem *mt7621_wdt_base;
  37 static struct reset_control *mt7621_wdt_reset;
  38
  39 static bool nowayout = WATCHDOG_NOWAYOUT;
  40 module_param(nowayout, bool, 0);
  41 MODULE_PARM_DESC(nowayout,
  42                  "Watchdog cannot be stopped once started (default="
  43                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  44
  45 static inline void rt_wdt_w32(unsigned reg, u32 val)
  46 {
  47         iowrite32(val, mt7621_wdt_base + reg);
  48 }
  49
  50 static inline u32 rt_wdt_r32(unsigned reg)
  51 {
  52         return ioread32(mt7621_wdt_base + reg);
  53 }
  54
  55 static int mt7621_wdt_ping(struct watchdog_device *w)
  56 {
  57         rt_wdt_w32(TIMER_REG_TMRSTAT, TMR1CTL_RESTART);
  58
  59         return 0;
  60 }
  61
  62 static int mt7621_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
  63 {
  64         w->timeout = t;
  65         rt_wdt_w32(TIMER_REG_TMR1LOAD, t * 1000);
  66         mt7621_wdt_ping(w);
  67
  68         return 0;
  69 }
  70
  71 static int mt7621_wdt_start(struct watchdog_device *w)
  72 {
  73         u32 t;
  74
  75         /* set the prescaler to 1ms == 1000us */
  76         rt_wdt_w32(TIMER_REG_TMR1CTL, 1000 << TMR1CTL_PRESCALE_SHIFT);
  77
  78         mt7621_wdt_set_timeout(w, w->timeout);
  79
  80         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
  81         t |= TMR1CTL_ENABLE;
  82         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
  83
  84         return 0;
  85 }
  86
  87 static int mt7621_wdt_stop(struct watchdog_device *w)
  88 {
  89         u32 t;
  90
  91         mt7621_wdt_ping(w);
  92
  93         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
  94         t &= ~TMR1CTL_ENABLE;
  95         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
  96
  97         return 0;
  98 }
  99
 100 static int mt7621_wdt_bootcause(void)
 101 {
 102         if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
 103                 return WDIOF_CARDRESET;
 104
 105         return 0;
 106 }
 107
 108 static int mt7621_wdt_is_running(struct watchdog_device *w)
 109 {
 110         return !!(rt_wdt_r32(TIMER_REG_TMR1CTL) & TMR1CTL_ENABLE);
 111 }
 112
 113 static const struct watchdog_info mt7621_wdt_info = {
 114         .identity = "Mediatek Watchdog",
 115         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 116 };
 117
 118 static const struct watchdog_ops mt7621_wdt_ops = {
 119         .owner = THIS_MODULE,
 120         .start = mt7621_wdt_start,
 121         .stop = mt7621_wdt_stop,
 122         .ping = mt7621_wdt_ping,
 123         .set_timeout = mt7621_wdt_set_timeout,
 124 };
 125
 126 static struct watchdog_device mt7621_wdt_dev = {
 127         .info = &mt7621_wdt_info,
 128         .ops = &mt7621_wdt_ops,
 129         .min_timeout = 1,
 130         .max_timeout = 0xfffful / 1000,
 131 };
 132
 133 static int mt7621_wdt_probe(struct platform_device *pdev)
 134 {
 135         struct resource *res;
 136
 137         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 138         mt7621_wdt_base = devm_ioremap_resource(&pdev->dev, res);
 139         if (IS_ERR(mt7621_wdt_base))
 140                 return PTR_ERR(mt7621_wdt_base);
 141
 142         mt7621_wdt_reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
 143         if (!IS_ERR(mt7621_wdt_reset))
 144                 reset_control_deassert(mt7621_wdt_reset);
 145
 146         mt7621_wdt_dev.bootstatus = mt7621_wdt_bootcause();
 147
 148         watchdog_init_timeout(&mt7621_wdt_dev, mt7621_wdt_dev.max_timeout,
 149                               &pdev->dev);
 150         watchdog_set_nowayout(&mt7621_wdt_dev, nowayout);
 151         if (mt7621_wdt_is_running(&mt7621_wdt_dev)) {
 152                 /*
 153                  * Make sure to apply timeout from watchdog core, taking
 154                  * the prescaler of this driver here into account (the
 155                  * boot loader might be using a different prescaler).
 156                  *
 157                  * To avoid spurious resets because of different scaling,
 158                  * we first disable the watchdog, set the new prescaler
 159                  * and timeout, and then re-enable the watchdog.
 160                  */
 161                 mt7621_wdt_stop(&mt7621_wdt_dev);
 162                 mt7621_wdt_start(&mt7621_wdt_dev);
 163                 set_bit(WDOG_HW_RUNNING, &mt7621_wdt_dev.status);
 164         }
 165
 166         return devm_watchdog_register_device(&pdev->dev, &mt7621_wdt_dev);
 167 }
 168
 169 static void mt7621_wdt_shutdown(struct platform_device *pdev)
 170 {
 171         mt7621_wdt_stop(&mt7621_wdt_dev);
 172 }
 173
 174 static const struct of_device_id mt7621_wdt_match[] = {
 175         { .compatible = "mediatek,mt7621-wdt" },
 176         {},
 177 };
 178 MODULE_DEVICE_TABLE(of, mt7621_wdt_match);
 179
 180 static struct platform_driver mt7621_wdt_driver = {
 181         .probe          = mt7621_wdt_probe,
 182         .shutdown       = mt7621_wdt_shutdown,
 183         .driver         = {
 184                 .name           = KBUILD_MODNAME,
 185                 .of_match_table = mt7621_wdt_match,
 186         },
 187 };
 188
 189 module_platform_driver(mt7621_wdt_driver);
 190
 191 MODULE_DESCRIPTION("MediaTek MT762x hardware watchdog driver");
 192 MODULE_AUTHOR("John Crispin <john@phrozen.org");
 193 MODULE_LICENSE("GPL v2");