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 void bcm7038_clk_disable_unprepare(void *data) 111 { 112 clk_disable_unprepare(data); 113 } 114 115 static int bcm7038_wdt_probe(struct platform_device *pdev) 116 { 117 struct device *dev = &pdev->dev; 118 struct bcm7038_watchdog *wdt; 119 int err; 120 121 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 122 if (!wdt) 123 return -ENOMEM; 124 125 platform_set_drvdata(pdev, wdt); 126 127 wdt->base = devm_platform_ioremap_resource(pdev, 0); 128 if (IS_ERR(wdt->base)) 129 return PTR_ERR(wdt->base); 130 131 wdt->clk = devm_clk_get(dev, NULL); 132 /* If unable to get clock, use default frequency */ 133 if (!IS_ERR(wdt->clk)) { 134 err = clk_prepare_enable(wdt->clk); 135 if (err) 136 return err; 137 err = devm_add_action_or_reset(dev, 138 bcm7038_clk_disable_unprepare, 139 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 watchdog_stop_on_reboot(&wdt->wdd); 160 watchdog_stop_on_unregister(&wdt->wdd); 161 err = devm_watchdog_register_device(dev, &wdt->wdd); 162 if (err) { 163 dev_err(dev, "Failed to register watchdog device\n"); 164 return err; 165 } 166 167 dev_info(dev, "Registered BCM7038 Watchdog\n"); 168 169 return 0; 170 } 171 172 #ifdef CONFIG_PM_SLEEP 173 static int bcm7038_wdt_suspend(struct device *dev) 174 { 175 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 176 177 if (watchdog_active(&wdt->wdd)) 178 return bcm7038_wdt_stop(&wdt->wdd); 179 180 return 0; 181 } 182 183 static int bcm7038_wdt_resume(struct device *dev) 184 { 185 struct bcm7038_watchdog *wdt = dev_get_drvdata(dev); 186 187 if (watchdog_active(&wdt->wdd)) 188 return bcm7038_wdt_start(&wdt->wdd); 189 190 return 0; 191 } 192 #endif 193 194 static SIMPLE_DEV_PM_OPS(bcm7038_wdt_pm_ops, bcm7038_wdt_suspend, 195 bcm7038_wdt_resume); 196 197 static const struct of_device_id bcm7038_wdt_match[] = { 198 { .compatible = "brcm,bcm7038-wdt" }, 199 {}, 200 }; 201 MODULE_DEVICE_TABLE(of, bcm7038_wdt_match); 202 203 static struct platform_driver bcm7038_wdt_driver = { 204 .probe = bcm7038_wdt_probe, 205 .driver = { 206 .name = "bcm7038-wdt", 207 .of_match_table = bcm7038_wdt_match, 208 .pm = &bcm7038_wdt_pm_ops, 209 } 210 }; 211 module_platform_driver(bcm7038_wdt_driver); 212 213 module_param(nowayout, bool, 0); 214 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 215 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 216 MODULE_LICENSE("GPL"); 217 MODULE_DESCRIPTION("Driver for Broadcom 7038 SoCs Watchdog"); 218 MODULE_AUTHOR("Justin Chen"); 219