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