drivers/watchdog/rt2880_wdt.c

   1 /*
   2  * Ralink RT288x/RT3xxx/MT76xx built-in hardware watchdog timer
   3  *
   4  * Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
   5  * Copyright (C) 2013 John Crispin <john@phrozen.org>
   6  *
   7  * This driver was based on: drivers/watchdog/softdog.c
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU General Public License version 2 as published
  11  * by the Free Software Foundation.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/reset.h>
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/watchdog.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/mod_devicetable.h>
  22
  23 #include <asm/mach-ralink/ralink_regs.h>
  24
  25 #define SYSC_RSTSTAT                    0x38
  26 #define WDT_RST_CAUSE                   BIT(1)
  27
  28 #define RALINK_WDT_TIMEOUT              30
  29 #define RALINK_WDT_PRESCALE             65536
  30
  31 #define TIMER_REG_TMR1LOAD              0x00
  32 #define TIMER_REG_TMR1CTL               0x08
  33
  34 #define TMRSTAT_TMR1RST                 BIT(5)
  35
  36 #define TMR1CTL_ENABLE                  BIT(7)
  37 #define TMR1CTL_MODE_SHIFT              4
  38 #define TMR1CTL_MODE_MASK               0x3
  39 #define TMR1CTL_MODE_FREE_RUNNING       0x0
  40 #define TMR1CTL_MODE_PERIODIC           0x1
  41 #define TMR1CTL_MODE_TIMEOUT            0x2
  42 #define TMR1CTL_MODE_WDT                0x3
  43 #define TMR1CTL_PRESCALE_MASK           0xf
  44 #define TMR1CTL_PRESCALE_65536          0xf
  45
  46 static struct clk *rt288x_wdt_clk;
  47 static unsigned long rt288x_wdt_freq;
  48 static void __iomem *rt288x_wdt_base;
  49 static struct reset_control *rt288x_wdt_reset;
  50
  51 static bool nowayout = WATCHDOG_NOWAYOUT;
  52 module_param(nowayout, bool, 0);
  53 MODULE_PARM_DESC(nowayout,
  54                 "Watchdog cannot be stopped once started (default="
  55                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  56
  57 static inline void rt_wdt_w32(unsigned reg, u32 val)
  58 {
  59         iowrite32(val, rt288x_wdt_base + reg);
  60 }
  61
  62 static inline u32 rt_wdt_r32(unsigned reg)
  63 {
  64         return ioread32(rt288x_wdt_base + reg);
  65 }
  66
  67 static int rt288x_wdt_ping(struct watchdog_device *w)
  68 {
  69         rt_wdt_w32(TIMER_REG_TMR1LOAD, w->timeout * rt288x_wdt_freq);
  70
  71         return 0;
  72 }
  73
  74 static int rt288x_wdt_start(struct watchdog_device *w)
  75 {
  76         u32 t;
  77
  78         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
  79         t &= ~(TMR1CTL_MODE_MASK << TMR1CTL_MODE_SHIFT |
  80                 TMR1CTL_PRESCALE_MASK);
  81         t |= (TMR1CTL_MODE_WDT << TMR1CTL_MODE_SHIFT |
  82                 TMR1CTL_PRESCALE_65536);
  83         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
  84
  85         rt288x_wdt_ping(w);
  86
  87         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
  88         t |= TMR1CTL_ENABLE;
  89         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
  90
  91         return 0;
  92 }
  93
  94 static int rt288x_wdt_stop(struct watchdog_device *w)
  95 {
  96         u32 t;
  97
  98         rt288x_wdt_ping(w);
  99
 100         t = rt_wdt_r32(TIMER_REG_TMR1CTL);
 101         t &= ~TMR1CTL_ENABLE;
 102         rt_wdt_w32(TIMER_REG_TMR1CTL, t);
 103
 104         return 0;
 105 }
 106
 107 static int rt288x_wdt_set_timeout(struct watchdog_device *w, unsigned int t)
 108 {
 109         w->timeout = t;
 110         rt288x_wdt_ping(w);
 111
 112         return 0;
 113 }
 114
 115 static int rt288x_wdt_bootcause(void)
 116 {
 117         if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
 118                 return WDIOF_CARDRESET;
 119
 120         return 0;
 121 }
 122
 123 static const struct watchdog_info rt288x_wdt_info = {
 124         .identity = "Ralink Watchdog",
 125         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 126 };
 127
 128 static const struct watchdog_ops rt288x_wdt_ops = {
 129         .owner = THIS_MODULE,
 130         .start = rt288x_wdt_start,
 131         .stop = rt288x_wdt_stop,
 132         .ping = rt288x_wdt_ping,
 133         .set_timeout = rt288x_wdt_set_timeout,
 134 };
 135
 136 static struct watchdog_device rt288x_wdt_dev = {
 137         .info = &rt288x_wdt_info,
 138         .ops = &rt288x_wdt_ops,
 139         .min_timeout = 1,
 140 };
 141
 142 static int rt288x_wdt_probe(struct platform_device *pdev)
 143 {
 144         struct resource *res;
 145         int ret;
 146
 147         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 148         rt288x_wdt_base = devm_ioremap_resource(&pdev->dev, res);
 149         if (IS_ERR(rt288x_wdt_base))
 150                 return PTR_ERR(rt288x_wdt_base);
 151
 152         rt288x_wdt_clk = devm_clk_get(&pdev->dev, NULL);
 153         if (IS_ERR(rt288x_wdt_clk))
 154                 return PTR_ERR(rt288x_wdt_clk);
 155
 156         rt288x_wdt_reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
 157         if (!IS_ERR(rt288x_wdt_reset))
 158                 reset_control_deassert(rt288x_wdt_reset);
 159
 160         rt288x_wdt_freq = clk_get_rate(rt288x_wdt_clk) / RALINK_WDT_PRESCALE;
 161
 162         rt288x_wdt_dev.bootstatus = rt288x_wdt_bootcause();
 163         rt288x_wdt_dev.max_timeout = (0xfffful / rt288x_wdt_freq);
 164         rt288x_wdt_dev.parent = &pdev->dev;
 165
 166         watchdog_init_timeout(&rt288x_wdt_dev, rt288x_wdt_dev.max_timeout,
 167                               &pdev->dev);
 168         watchdog_set_nowayout(&rt288x_wdt_dev, nowayout);
 169
 170         ret = watchdog_register_device(&rt288x_wdt_dev);
 171         if (!ret)
 172                 dev_info(&pdev->dev, "Initialized\n");
 173
 174         return 0;
 175 }
 176
 177 static int rt288x_wdt_remove(struct platform_device *pdev)
 178 {
 179         watchdog_unregister_device(&rt288x_wdt_dev);
 180
 181         return 0;
 182 }
 183
 184 static void rt288x_wdt_shutdown(struct platform_device *pdev)
 185 {
 186         rt288x_wdt_stop(&rt288x_wdt_dev);
 187 }
 188
 189 static const struct of_device_id rt288x_wdt_match[] = {
 190         { .compatible = "ralink,rt2880-wdt" },
 191         {},
 192 };
 193 MODULE_DEVICE_TABLE(of, rt288x_wdt_match);
 194
 195 static struct platform_driver rt288x_wdt_driver = {
 196         .probe          = rt288x_wdt_probe,
 197         .remove         = rt288x_wdt_remove,
 198         .shutdown       = rt288x_wdt_shutdown,
 199         .driver         = {
 200                 .name           = KBUILD_MODNAME,
 201                 .of_match_table = rt288x_wdt_match,
 202         },
 203 };
 204
 205 module_platform_driver(rt288x_wdt_driver);
 206
 207 MODULE_DESCRIPTION("MediaTek/Ralink RT288x/RT3xxx hardware watchdog driver");
 208 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org");
 209 MODULE_LICENSE("GPL v2");