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