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