drivers/watchdog/bcm7038_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2015 Broadcom Corporation
   4  *
   5  */
   6
   7 #include <linux/clk.h>
   8 #include <linux/init.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/platform_data/bcm7038_wdt.h>
  14 #include <linux/pm.h>
  15 #include <linux/watchdog.h>
  16
  17 #define WDT_START_1             0xff00
  18 #define WDT_START_2             0x00ff
  19 #define WDT_STOP_1              0xee00
  20 #define WDT_STOP_2              0x00ee
  21
  22 #define WDT_TIMEOUT_REG         0x0
  23 #define WDT_CMD_REG             0x4
  24
  25 #define WDT_MIN_TIMEOUT         1 /* seconds */
  26 #define WDT_DEFAULT_TIMEOUT     30 /* seconds */
  27 #define WDT_DEFAULT_RATE        27000000
  28
  29 struct bcm7038_watchdog {
  30         void __iomem            *base;
  31         struct watchdog_device  wdd;
  32         u32                     rate;
  33         struct clk              *clk;
  34 };
  35
  36 static bool nowayout = WATCHDOG_NOWAYOUT;
  37
  38 static inline void bcm7038_wdt_write(u32 value, void __iomem *addr)
  39 {
  40         /* MIPS chips strapped for BE will automagically configure the
  41          * peripheral registers for CPU-native byte order.
  42          */
  43         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  44                 __raw_writel(value, addr);
  45         else
  46                 writel_relaxed(value, addr);
  47 }
  48
  49 static inline u32 bcm7038_wdt_read(void __iomem *addr)
  50 {
  51         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  52                 return __raw_readl(addr);
  53         else
  54                 return readl_relaxed(addr);
  55 }
  56
  57 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
  58 {
  59         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  60         u32 timeout;
  61
  62         timeout = wdt->rate * wdog->timeout;
  63
  64         bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
  65 }
  66
  67 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
  68 {
  69         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  70
  71         bcm7038_wdt_write(WDT_START_1, wdt->base + WDT_CMD_REG);
  72         bcm7038_wdt_write(WDT_START_2, wdt->base + WDT_CMD_REG);
  73
  74         return 0;
  75 }
  76
  77 static int bcm7038_wdt_start(struct watchdog_device *wdog)
  78 {
  79         bcm7038_wdt_set_timeout_reg(wdog);
  80         bcm7038_wdt_ping(wdog);
  81
  82         return 0;
  83 }
  84
  85 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
  86 {
  87         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
  88
  89         bcm7038_wdt_write(WDT_STOP_1, wdt->base + WDT_CMD_REG);
  90         bcm7038_wdt_write(WDT_STOP_2, wdt->base + WDT_CMD_REG);
  91
  92         return 0;
  93 }
  94
  95 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
  96                                    unsigned int t)
  97 {
  98         /* Can't modify timeout value if watchdog timer is running */
  99         bcm7038_wdt_stop(wdog);
 100         wdog->timeout = t;
 101         bcm7038_wdt_start(wdog);
 102
 103         return 0;
 104 }
 105
 106 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
 107 {
 108         struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
 109         u32 time_left;
 110
 111         time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
 112
 113         return time_left / wdt->rate;
 114 }
 115
 116 static const struct watchdog_info bcm7038_wdt_info = {
 117         .identity       = "Broadcom BCM7038 Watchdog Timer",
 118         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 119                                 WDIOF_MAGICCLOSE
 120 };
 121
 122 static const struct watchdog_ops bcm7038_wdt_ops = {
 123         .owner          = THIS_MODULE,
 124         .start          = bcm7038_wdt_start,
 125         .stop           = bcm7038_wdt_stop,
 126         .set_timeout    = bcm7038_wdt_set_timeout,
 127         .get_timeleft   = bcm7038_wdt_get_timeleft,
 128 };
 129
 130 static void bcm7038_clk_disable_unprepare(void *data)
 131 {
 132         clk_disable_unprepare(data);
 133 }
 134
 135 static int bcm7038_wdt_probe(struct platform_device *pdev)
 136 {
 137         struct bcm7038_wdt_platform_data *pdata = pdev->dev.platform_data;
 138         struct device *dev = &pdev->dev;
 139         struct bcm7038_watchdog *wdt;
 140         const char *clk_name = NULL;
 141         int err;
 142
 143         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 144         if (!wdt)
 145                 return -ENOMEM;
 146
 147         platform_set_drvdata(pdev, wdt);
 148
 149         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 150         if (IS_ERR(wdt->base))
 151                 return PTR_ERR(wdt->base);
 152
 153         if (pdata && pdata->clk_name)
 154                 clk_name = pdata->clk_name;
 155
 156         wdt->clk = devm_clk_get(dev, clk_name);
 157         /* If unable to get clock, use default frequency */
 158         if (!IS_ERR(wdt->clk)) {
 159                 err = clk_prepare_enable(wdt->clk);
 160                 if (err)
 161                         return err;
 162                 err = devm_add_action_or_reset(dev,
 163                                                bcm7038_clk_disable_unprepare,
 164                                                wdt->clk);
 165                 if (err)
 166                         return err;
 167                 wdt->rate = clk_get_rate(wdt->clk);
 168                 /* Prevent divide-by-zero exception */
 169                 if (!wdt->rate)
 170                         wdt->rate = WDT_DEFAULT_RATE;
 171         } else {
 172                 wdt->rate = WDT_DEFAULT_RATE;
 173                 wdt->clk = NULL;
 174         }
 175
 176         wdt->wdd.info           = &bcm7038_wdt_info;
 177         wdt->wdd.ops            = &bcm7038_wdt_ops;
 178         wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
 179         wdt->wdd.timeout        = WDT_DEFAULT_TIMEOUT;
 180         wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
 181         wdt->wdd.parent         = dev;
 182         watchdog_set_drvdata(&wdt->wdd, wdt);
 183
 184         watchdog_stop_on_reboot(&wdt->wdd);
 185         watchdog_stop_on_unregister(&wdt->wdd);
 186         err = devm_watchdog_register_device(dev, &wdt->wdd);
 187         if (err)
 188                 return err;
 189
 190         dev_info(dev, "Registered BCM7038 Watchdog\n");
 191
 192         return 0;
 193 }
 194
 195 #ifdef CONFIG_PM_SLEEP
 196 static int bcm7038_wdt_suspend(struct device *dev)
 197 {
 198         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 199
 200         if (watchdog_active(&wdt->wdd))
 201                 return bcm7038_wdt_stop(&wdt->wdd);
 202
 203         return 0;
 204 }
 205
 206 static int bcm7038_wdt_resume(struct device *dev)
 207 {
 208         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 209
 210         if (watchdog_active(&wdt->wdd))
 211                 return bcm7038_wdt_start(&wdt->wdd);
 212
 213         return 0;
 214 }
 215 #endif
 216
 217 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend,
 218                          bcm7038_wdt_resume);
 219
 220 static const struct of_device_id bcm7038_wdt_match[] = {
 221         { .compatible = "brcm,bcm6345-wdt" },
 222         { .compatible = "brcm,bcm7038-wdt" },
 223         {},
 224 };
 225 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
 226
 227 static const struct platform_device_id bcm7038_wdt_devtype[] = {
 228         { .name = "bcm63xx-wdt" },
 229         { /* sentinel */ },
 230 };
 231 MODULE_DEVICE_TABLE(platform, bcm7038_wdt_devtype);
 232
 233 static struct platform_driver bcm7038_wdt_driver = {
 234         .probe          = bcm7038_wdt_probe,
 235         .id_table       = bcm7038_wdt_devtype,
 236         .driver         = {
 237                 .name           = "bcm7038-wdt",
 238                 .of_match_table = bcm7038_wdt_match,
 239                 .pm             = &bcm7038_wdt_pm_ops,
 240         }
 241 };
 242 module_platform_driver(bcm7038_wdt_driver);
 243
 244 module_param(nowayout, bool, 0);
 245 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 246         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 247 MODULE_LICENSE("GPL");
 248 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
 249 MODULE_AUTHOR("Justin Chen");