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"); 236