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 void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog) 38 { 39 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 40 u32 timeout; 41 42 timeout = wdt->rate * wdog->timeout; 43 44 writel(timeout, wdt->base + WDT_TIMEOUT_REG); 45 } 46 47 static int bcm7038_wdt_ping(struct watchdog_device *wdog) 48 { 49 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 50 51 writel(WDT_START_1, wdt->base + WDT_CMD_REG); 52 writel(WDT_START_2, wdt->base + WDT_CMD_REG); 53 54 return 0; 55 } 56 57 static int bcm7038_wdt_start(struct watchdog_device *wdog) 58 { 59 bcm7038_wdt_set_timeout_reg(wdog); 60 bcm7038_wdt_ping(wdog); 61 62 return 0; 63 } 64 65 static int bcm7038_wdt_stop(struct watchdog_device *wdog) 66 { 67 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 68 69 writel(WDT_STOP_1, wdt->base + WDT_CMD_REG); 70 writel(WDT_STOP_2, wdt->base + WDT_CMD_REG); 71 72 return 0; 73 } 74 75 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog, 76 unsigned int t) 77 { 78 /* Can't modify timeout value if watchdog timer is running */ 79 bcm7038_wdt_stop(wdog); 80 wdog->timeout = t; 81 bcm7038_wdt_start(wdog); 82 83 return 0; 84 } 85 86 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog) 87 { 88 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 89 u32 time_left; 90 91 time_left = readl(wdt->base + WDT_CMD_REG); 92 93 return time_left / wdt->rate; 94 } 95 96 static const struct watchdog_info bcm7038_wdt_info = { 97 .identity = "Broadcom BCM7038 Watchdog Timer", 98 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 99 WDIOF_MAGICCLOSE 100 }; 101 102 static const struct watchdog_ops bcm7038_wdt_ops = { 103 .owner = THIS_MODULE, 104 .start = bcm7038_wdt_start, 105 .stop = bcm7038_wdt_stop, 106 .set_timeout = bcm7038_wdt_set_timeout, 107 .get_timeleft = bcm7038_wdt_get_timeleft, 108 }; 109 110 static int bcm7038_wdt_probe(struct platform_device *pdev) 111 { 112 struct device *dev = &pdev->dev; 113 struct bcm7038_watchdog *wdt; 114 struct resource *res; 115 int err; 116 117 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 118 if (!wdt) 119 return -ENOMEM; 120 121 platform_set_drvdata(pdev, wdt); 122 123 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 124 wdt->base = devm_ioremap_resource(dev, res); 125 if (IS_ERR(wdt->base)) 126 return PTR_ERR(wdt->base); 127 128 wdt->clk = devm_clk_get(dev, NULL); 129 /* If unable to get clock, use default frequency */ 130 if (!IS_ERR(wdt->clk)) { 131 err = clk_prepare_enable(wdt->clk); 132 if (err) 133 return err; 134 wdt->rate = clk_get_rate(wdt->clk); 135 /* Prevent divide-by-zero exception */ 136 if (!wdt->rate) 137 wdt->rate = WDT_DEFAULT_RATE; 138 } else { 139 wdt->rate = WDT_DEFAULT_RATE; 140 wdt->clk = NULL; 141 } 142 143 wdt->wdd.info = &bcm7038_wdt_info; 144 wdt->wdd.ops = &bcm7038_wdt_ops; 145 wdt->wdd.min_timeout = WDT_MIN_TIMEOUT; 146 wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT; 147 wdt->wdd.max_timeout = 0xffffffff / wdt->rate; 148 wdt->wdd.parent = dev; 149 watchdog_set_drvdata(&wdt->wdd, wdt); 150 151 err = watchdog_register_device(&wdt->wdd); 152 if (err) { 153 dev_err(dev, "Failed to register watchdog device\n"); 154 clk_disable_unprepare(wdt->clk); 155 return err; 156 } 157 158 dev_info(dev, "Registered BCM7038 Watchdog\n"); 159 160 return 0; 161 } 162 163 static int bcm7038_wdt_remove(struct platform_device *pdev) 164 { 165 struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev); 166 167 if (!nowayout) 168 bcm7038_wdt_stop(&wdt->wdd); 169 170 watchdog_unregister_device(&wdt->wdd); 171 clk_disable_unprepare(wdt->clk); 172 173 return 0; 174 } 175 176 #ifdef CONFIG_PM_SLEEP 177 static int bcm7038_wdt_suspend(struct device *dev) 178 { 179 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 180 181 if (watchdog_active(&wdt->wdd)) 182 return bcm7038_wdt_stop(&wdt->wdd); 183 184 return 0; 185 } 186 187 static int bcm7038_wdt_resume(struct device *dev) 188 { 189 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 190 191 if (watchdog_active(&wdt->wdd)) 192 return bcm7038_wdt_start(&wdt->wdd); 193 194 return 0; 195 } 196 #endif 197 198 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend, 199 bcm7038_wdt_resume); 200 201 static void bcm7038_wdt_shutdown(struct platform_device *pdev) 202 { 203 struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev); 204 205 if (watchdog_active(&wdt->wdd)) 206 bcm7038_wdt_stop(&wdt->wdd); 207 } 208 209 static const struct of_device_id bcm7038_wdt_match[] = { 210 { .compatible = "brcm,bcm7038-wdt" }, 211 {}, 212 }; 213 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match); 214 215 static struct platform_driver bcm7038_wdt_driver = { 216 .probe = bcm7038_wdt_probe, 217 .remove = bcm7038_wdt_remove, 218 .shutdown = bcm7038_wdt_shutdown, 219 .driver = { 220 .name = "bcm7038-wdt", 221 .of_match_table = bcm7038_wdt_match, 222 .pm = &bcm7038_wdt_pm_ops, 223 } 224 }; 225 module_platform_driver(bcm7038_wdt_driver); 226 227 module_param(nowayout, bool, 0); 228 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 229 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 230 MODULE_LICENSE("GPL"); 231 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog"); 232 MODULE_AUTHOR("Justin Chen"); 233