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 int bcm7038_wdt_probe(struct platform_device *pdev)
 131 {
 132         struct bcm7038_wdt_platform_data *pdata = pdev->dev.platform_data;
 133         struct device *dev = &pdev->dev;
 134         struct bcm7038_watchdog *wdt;
 135         const char *clk_name = NULL;
 136         int err;
 137
 138         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 139         if (!wdt)
 140                 return -ENOMEM;
 141
 142         platform_set_drvdata(pdev, wdt);
 143
 144         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 145         if (IS_ERR(wdt->base))
 146                 return PTR_ERR(wdt->base);
 147
 148         if (pdata && pdata->clk_name)
 149                 clk_name = pdata->clk_name;
 150
 151         wdt->clk = devm_clk_get_enabled(dev, clk_name);
 152         /* If unable to get clock, use default frequency */
 153         if (!IS_ERR(wdt->clk)) {
 154                 wdt->rate = clk_get_rate(wdt->clk);
 155                 /* Prevent divide-by-zero exception */
 156                 if (!wdt->rate)
 157                         wdt->rate = WDT_DEFAULT_RATE;
 158         } else {
 159                 wdt->rate = WDT_DEFAULT_RATE;
 160                 wdt->clk = NULL;
 161         }
 162
 163         wdt->wdd.info           = &bcm7038_wdt_info;
 164         wdt->wdd.ops            = &bcm7038_wdt_ops;
 165         wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
 166         wdt->wdd.timeout        = WDT_DEFAULT_TIMEOUT;
 167         wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
 168         wdt->wdd.parent         = dev;
 169         watchdog_set_drvdata(&wdt->wdd, wdt);
 170
 171         watchdog_stop_on_reboot(&wdt->wdd);
 172         watchdog_stop_on_unregister(&wdt->wdd);
 173         err = devm_watchdog_register_device(dev, &wdt->wdd);
 174         if (err)
 175                 return err;
 176
 177         dev_info(dev, "Registered BCM7038 Watchdog\n");
 178
 179         return 0;
 180 }
 181
 182 static int bcm7038_wdt_suspend(struct device *dev)
 183 {
 184         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 185
 186         if (watchdog_active(&wdt->wdd))
 187                 return bcm7038_wdt_stop(&wdt->wdd);
 188
 189         return 0;
 190 }
 191
 192 static int bcm7038_wdt_resume(struct device *dev)
 193 {
 194         struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
 195
 196         if (watchdog_active(&wdt->wdd))
 197                 return bcm7038_wdt_start(&wdt->wdd);
 198
 199         return 0;
 200 }
 201
 202 static DEFINE_SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops,
 203                                 bcm7038_wdt_suspend, bcm7038_wdt_resume);
 204
 205 static const struct of_device_id bcm7038_wdt_match[] = {
 206         { .compatible = "brcm,bcm6345-wdt" },
 207         { .compatible = "brcm,bcm7038-wdt" },
 208         {},
 209 };
 210 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
 211
 212 static const struct platform_device_id bcm7038_wdt_devtype[] = {
 213         { .name = "bcm63xx-wdt" },
 214         { /* sentinel */ },
 215 };
 216 MODULE_DEVICE_TABLE(platform, bcm7038_wdt_devtype);
 217
 218 static struct platform_driver bcm7038_wdt_driver = {
 219         .probe          = bcm7038_wdt_probe,
 220         .id_table       = bcm7038_wdt_devtype,
 221         .driver         = {
 222                 .name           = "bcm7038-wdt",
 223                 .of_match_table = bcm7038_wdt_match,
 224                 .pm             = pm_sleep_ptr(&bcm7038_wdt_pm_ops),
 225         }
 226 };
 227 module_platform_driver(bcm7038_wdt_driver);
 228
 229 module_param(nowayout, bool, 0);
 230 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 231         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 232 MODULE_LICENSE("GPL");
 233 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
 234 MODULE_AUTHOR("Justin Chen");