drivers/watchdog/bcm7038_wdt.c

0001 // SPDX-License-Identifier: GPL-2.0+
0002 /*
0003  * Copyright (C) 2015 Broadcom Corporation
0004  *
0005  */
0006
0007 #include <linux/clk.h>
0008 #include <linux/init.h>
0009 #include <linux/io.h>
0010 #include <linux/module.h>
0011 #include <linux/of.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/platform_data/bcm7038_wdt.h>
0014 #include <linux/pm.h>
0015 #include <linux/watchdog.h>
0016
0017 #define WDT_START_1     0xff00
0018 #define WDT_START_2     0x00ff
0019 #define WDT_STOP_1      0xee00
0020 #define WDT_STOP_2      0x00ee
0021
0022 #define WDT_TIMEOUT_REG     0x0
0023 #define WDT_CMD_REG     0x4
0024
0025 #define WDT_MIN_TIMEOUT     1 /* seconds */
0026 #define WDT_DEFAULT_TIMEOUT 30 /* seconds */
0027 #define WDT_DEFAULT_RATE    27000000
0028
0029 struct bcm7038_watchdog {
0030     void __iomem        *base;
0031     struct watchdog_device  wdd;
0032     u32         rate;
0033     struct clk      *clk;
0034 };
0035
0036 static bool nowayout = WATCHDOG_NOWAYOUT;
0037
0038 static inline void bcm7038_wdt_write(u32 value, void __iomem *addr)
0039 {
0040     /* MIPS chips strapped for BE will automagically configure the
0041      * peripheral registers for CPU-native byte order.
0042      */
0043     if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
0044         __raw_writel(value, addr);
0045     else
0046         writel_relaxed(value, addr);
0047 }
0048
0049 static inline u32 bcm7038_wdt_read(void __iomem *addr)
0050 {
0051     if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
0052         return __raw_readl(addr);
0053     else
0054         return readl_relaxed(addr);
0055 }
0056
0057 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog)
0058 {
0059     struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
0060     u32 timeout;
0061
0062     timeout = wdt->rate * wdog->timeout;
0063
0064     bcm7038_wdt_write(timeout, wdt->base + WDT_TIMEOUT_REG);
0065 }
0066
0067 static int bcm7038_wdt_ping(struct watchdog_device *wdog)
0068 {
0069     struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
0070
0071     bcm7038_wdt_write(WDT_START_1, wdt->base + WDT_CMD_REG);
0072     bcm7038_wdt_write(WDT_START_2, wdt->base + WDT_CMD_REG);
0073
0074     return 0;
0075 }
0076
0077 static int bcm7038_wdt_start(struct watchdog_device *wdog)
0078 {
0079     bcm7038_wdt_set_timeout_reg(wdog);
0080     bcm7038_wdt_ping(wdog);
0081
0082     return 0;
0083 }
0084
0085 static int bcm7038_wdt_stop(struct watchdog_device *wdog)
0086 {
0087     struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
0088
0089     bcm7038_wdt_write(WDT_STOP_1, wdt->base + WDT_CMD_REG);
0090     bcm7038_wdt_write(WDT_STOP_2, wdt->base + WDT_CMD_REG);
0091
0092     return 0;
0093 }
0094
0095 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog,
0096                    unsigned int t)
0097 {
0098     /* Can't modify timeout value if watchdog timer is running */
0099     bcm7038_wdt_stop(wdog);
0100     wdog->timeout = t;
0101     bcm7038_wdt_start(wdog);
0102
0103     return 0;
0104 }
0105
0106 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog)
0107 {
0108     struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog);
0109     u32 time_left;
0110
0111     time_left = bcm7038_wdt_read(wdt->base + WDT_CMD_REG);
0112
0113     return time_left / wdt->rate;
0114 }
0115
0116 static const struct watchdog_info bcm7038_wdt_info = {
0117     .identity   = "Broadcom BCM7038 Watchdog Timer",
0118     .options    = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
0119                 WDIOF_MAGICCLOSE
0120 };
0121
0122 static const struct watchdog_ops bcm7038_wdt_ops = {
0123     .owner      = THIS_MODULE,
0124     .start      = bcm7038_wdt_start,
0125     .stop       = bcm7038_wdt_stop,
0126     .set_timeout    = bcm7038_wdt_set_timeout,
0127     .get_timeleft   = bcm7038_wdt_get_timeleft,
0128 };
0129
0130 static void bcm7038_clk_disable_unprepare(void *data)
0131 {
0132     clk_disable_unprepare(data);
0133 }
0134
0135 static int bcm7038_wdt_probe(struct platform_device *pdev)
0136 {
0137     struct bcm7038_wdt_platform_data *pdata = pdev->dev.platform_data;
0138     struct device *dev = &pdev->dev;
0139     struct bcm7038_watchdog *wdt;
0140     const char *clk_name = NULL;
0141     int err;
0142
0143     wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
0144     if (!wdt)
0145         return -ENOMEM;
0146
0147     platform_set_drvdata(pdev, wdt);
0148
0149     wdt->base = devm_platform_ioremap_resource(pdev, 0);
0150     if (IS_ERR(wdt->base))
0151         return PTR_ERR(wdt->base);
0152
0153     if (pdata && pdata->clk_name)
0154         clk_name = pdata->clk_name;
0155
0156     wdt->clk = devm_clk_get(dev, clk_name);
0157     /* If unable to get clock, use default frequency */
0158     if (!IS_ERR(wdt->clk)) {
0159         err = clk_prepare_enable(wdt->clk);
0160         if (err)
0161             return err;
0162         err = devm_add_action_or_reset(dev,
0163                            bcm7038_clk_disable_unprepare,
0164                            wdt->clk);
0165         if (err)
0166             return err;
0167         wdt->rate = clk_get_rate(wdt->clk);
0168         /* Prevent divide-by-zero exception */
0169         if (!wdt->rate)
0170             wdt->rate = WDT_DEFAULT_RATE;
0171     } else {
0172         wdt->rate = WDT_DEFAULT_RATE;
0173         wdt->clk = NULL;
0174     }
0175
0176     wdt->wdd.info       = &bcm7038_wdt_info;
0177     wdt->wdd.ops        = &bcm7038_wdt_ops;
0178     wdt->wdd.min_timeout    = WDT_MIN_TIMEOUT;
0179     wdt->wdd.timeout    = WDT_DEFAULT_TIMEOUT;
0180     wdt->wdd.max_timeout    = 0xffffffff / wdt->rate;
0181     wdt->wdd.parent     = dev;
0182     watchdog_set_drvdata(&wdt->wdd, wdt);
0183
0184     watchdog_stop_on_reboot(&wdt->wdd);
0185     watchdog_stop_on_unregister(&wdt->wdd);
0186     err = devm_watchdog_register_device(dev, &wdt->wdd);
0187     if (err)
0188         return err;
0189
0190     dev_info(dev, "Registered BCM7038 Watchdog\n");
0191
0192     return 0;
0193 }
0194
0195 static int bcm7038_wdt_suspend(struct device *dev)
0196 {
0197     struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
0198
0199     if (watchdog_active(&wdt->wdd))
0200         return bcm7038_wdt_stop(&wdt->wdd);
0201
0202     return 0;
0203 }
0204
0205 static int bcm7038_wdt_resume(struct device *dev)
0206 {
0207     struct bcm7038_watchdog *wdt = dev_get_drvdata(dev);
0208
0209     if (watchdog_active(&wdt->wdd))
0210         return bcm7038_wdt_start(&wdt->wdd);
0211
0212     return 0;
0213 }
0214
0215 static DEFINE_SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops,
0216                 bcm7038_wdt_suspend, bcm7038_wdt_resume);
0217
0218 static const struct of_device_id bcm7038_wdt_match[] = {
0219     { .compatible = "brcm,bcm6345-wdt" },
0220     { .compatible = "brcm,bcm7038-wdt" },
0221     {},
0222 };
0223 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match);
0224
0225 static const struct platform_device_id bcm7038_wdt_devtype[] = {
0226     { .name = "bcm63xx-wdt" },
0227     { /* sentinel */ },
0228 };
0229 MODULE_DEVICE_TABLE(platform, bcm7038_wdt_devtype);
0230
0231 static struct platform_driver bcm7038_wdt_driver = {
0232     .probe      = bcm7038_wdt_probe,
0233     .id_table   = bcm7038_wdt_devtype,
0234     .driver     = {
0235         .name       = "bcm7038-wdt",
0236         .of_match_table = bcm7038_wdt_match,
0237         .pm     = pm_sleep_ptr(&bcm7038_wdt_pm_ops),
0238     }
0239 };
0240 module_platform_driver(bcm7038_wdt_driver);
0241
0242 module_param(nowayout, bool, 0);
0243 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
0244     __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
0245 MODULE_LICENSE("GPL");
0246 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog");
0247 MODULE_AUTHOR("Justin Chen");