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,bcm7038-wdt" }, 222 {}, 223 }; 224 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match); 225 226 static const struct platform_device_id bcm7038_wdt_devtype[] = { 227 { .name = "bcm63xx-wdt" }, 228 { /* sentinel */ }, 229 }; 230 MODULE_DEVICE_TABLE(platform, bcm7038_wdt_devtype); 231 232 static struct platform_driver bcm7038_wdt_driver = { 233 .probe = bcm7038_wdt_probe, 234 .id_table = bcm7038_wdt_devtype, 235 .driver = { 236 .name = "bcm7038-wdt", 237 .of_match_table = bcm7038_wdt_match, 238 .pm = &bcm7038_wdt_pm_ops, 239 } 240 }; 241 module_platform_driver(bcm7038_wdt_driver); 242 243 module_param(nowayout, bool, 0); 244 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 245 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 246 MODULE_LICENSE("GPL"); 247 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog"); 248 MODULE_AUTHOR("Justin Chen"); 249