1 /* 2 * Copyright (C) 2015 Broadcom Corporation 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 2 7 * of the License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 */ 14 15 #include <linux/clk.h> 16 #include <linux/init.h> 17 #include <linux/io.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/platform_device.h> 21 #include <linux/pm.h> 22 #include <linux/watchdog.h> 23 24 #define WDT_START_1 0xff00 25 #define WDT_START_2 0x00ff 26 #define WDT_STOP_1 0xee00 27 #define WDT_STOP_2 0x00ee 28 29 #define WDT_TIMEOUT_REG 0x0 30 #define WDT_CMD_REG 0x4 31 32 #define WDT_MIN_TIMEOUT 1 /* seconds */ 33 #define WDT_DEFAULT_TIMEOUT 30 /* seconds */ 34 #define WDT_DEFAULT_RATE 27000000 35 36 struct bcm7038_watchdog { 37 void __iomem *base; 38 struct watchdog_device wdd; 39 u32 rate; 40 struct clk *clk; 41 }; 42 43 static bool nowayout = WATCHDOG_NOWAYOUT; 44 45 static void bcm7038_wdt_set_timeout_reg(struct watchdog_device *wdog) 46 { 47 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 48 u32 timeout; 49 50 timeout = wdt->rate * wdog->timeout; 51 52 writel(timeout, wdt->base + WDT_TIMEOUT_REG); 53 } 54 55 static int bcm7038_wdt_ping(struct watchdog_device *wdog) 56 { 57 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 58 59 writel(WDT_START_1, wdt->base + WDT_CMD_REG); 60 writel(WDT_START_2, wdt->base + WDT_CMD_REG); 61 62 return 0; 63 } 64 65 static int bcm7038_wdt_start(struct watchdog_device *wdog) 66 { 67 bcm7038_wdt_set_timeout_reg(wdog); 68 bcm7038_wdt_ping(wdog); 69 70 return 0; 71 } 72 73 static int bcm7038_wdt_stop(struct watchdog_device *wdog) 74 { 75 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 76 77 writel(WDT_STOP_1, wdt->base + WDT_CMD_REG); 78 writel(WDT_STOP_2, wdt->base + WDT_CMD_REG); 79 80 return 0; 81 } 82 83 static int bcm7038_wdt_set_timeout(struct watchdog_device *wdog, 84 unsigned int t) 85 { 86 /* Can't modify timeout value if watchdog timer is running */ 87 bcm7038_wdt_stop(wdog); 88 wdog->timeout = t; 89 bcm7038_wdt_start(wdog); 90 91 return 0; 92 } 93 94 static unsigned int bcm7038_wdt_get_timeleft(struct watchdog_device *wdog) 95 { 96 struct bcm7038_watchdog *wdt = watchdog_get_drvdata(wdog); 97 u32 time_left; 98 99 time_left = readl(wdt->base + WDT_CMD_REG); 100 101 return time_left / wdt->rate; 102 } 103 104 static const struct watchdog_info bcm7038_wdt_info = { 105 .identity = "Broadcom BCM7038 Watchdog Timer", 106 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 107 WDIOF_MAGICCLOSE 108 }; 109 110 static const struct watchdog_ops bcm7038_wdt_ops = { 111 .owner = THIS_MODULE, 112 .start = bcm7038_wdt_start, 113 .stop = bcm7038_wdt_stop, 114 .set_timeout = bcm7038_wdt_set_timeout, 115 .get_timeleft = bcm7038_wdt_get_timeleft, 116 }; 117 118 static int bcm7038_wdt_probe(struct platform_device *pdev) 119 { 120 struct device *dev = &pdev->dev; 121 struct bcm7038_watchdog *wdt; 122 struct resource *res; 123 int err; 124 125 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 126 if (!wdt) 127 return -ENOMEM; 128 129 platform_set_drvdata(pdev, wdt); 130 131 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 132 wdt->base = devm_ioremap_resource(dev, res); 133 if (IS_ERR(wdt->base)) 134 return PTR_ERR(wdt->base); 135 136 wdt->clk = devm_clk_get(dev, NULL); 137 /* If unable to get clock, use default frequency */ 138 if (!IS_ERR(wdt->clk)) { 139 err = clk_prepare_enable(wdt->clk); 140 if (err) 141 return err; 142 wdt->rate = clk_get_rate(wdt->clk); 143 /* Prevent divide-by-zero exception */ 144 if (!wdt->rate) 145 wdt->rate = WDT_DEFAULT_RATE; 146 } else { 147 wdt->rate = WDT_DEFAULT_RATE; 148 wdt->clk = NULL; 149 } 150 151 wdt->wdd.info = &bcm7038_wdt_info; 152 wdt->wdd.ops = &bcm7038_wdt_ops; 153 wdt->wdd.min_timeout = WDT_MIN_TIMEOUT; 154 wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT; 155 wdt->wdd.max_timeout = 0xffffffff / wdt->rate; 156 wdt->wdd.parent = dev; 157 watchdog_set_drvdata(&wdt->wdd, wdt); 158 159 err = watchdog_register_device(&wdt->wdd); 160 if (err) { 161 dev_err(dev, "Failed to register watchdog device\n"); 162 clk_disable_unprepare(wdt->clk); 163 return err; 164 } 165 166 dev_info(dev, "Registered BCM7038 Watchdog\n"); 167 168 return 0; 169 } 170 171 static int bcm7038_wdt_remove(struct platform_device *pdev) 172 { 173 struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev); 174 175 if (!nowayout) 176 bcm7038_wdt_stop(&wdt->wdd); 177 178 watchdog_unregister_device(&wdt->wdd); 179 clk_disable_unprepare(wdt->clk); 180 181 return 0; 182 } 183 184 #ifdef CONFIG_PM_SLEEP 185 static int bcm7038_wdt_suspend(struct device *dev) 186 { 187 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 188 189 if (watchdog_active(&wdt->wdd)) 190 return bcm7038_wdt_stop(&wdt->wdd); 191 192 return 0; 193 } 194 195 static int bcm7038_wdt_resume(struct device *dev) 196 { 197 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 198 199 if (watchdog_active(&wdt->wdd)) 200 return bcm7038_wdt_start(&wdt->wdd); 201 202 return 0; 203 } 204 #endif 205 206 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend, 207 bcm7038_wdt_resume); 208 209 static void bcm7038_wdt_shutdown(struct platform_device *pdev) 210 { 211 struct bcm7038_watchdog *wdt = platform_get_drvdata(pdev); 212 213 if (watchdog_active(&wdt->wdd)) 214 bcm7038_wdt_stop(&wdt->wdd); 215 } 216 217 static const struct of_device_id bcm7038_wdt_match[] = { 218 { .compatible = "brcm,bcm7038-wdt" }, 219 {}, 220 }; 221 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match); 222 223 static struct platform_driver bcm7038_wdt_driver = { 224 .probe = bcm7038_wdt_probe, 225 .remove = bcm7038_wdt_remove, 226 .shutdown = bcm7038_wdt_shutdown, 227 .driver = { 228 .name = "bcm7038-wdt", 229 .of_match_table = bcm7038_wdt_match, 230 .pm = &bcm7038_wdt_pm_ops, 231 } 232 }; 233 module_platform_driver(bcm7038_wdt_driver); 234 235 module_param(nowayout, bool, 0); 236 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 237 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 238 MODULE_LICENSE("GPL v2"); 239 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog"); 240 MODULE_AUTHOR("Justin Chen"); 241