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