1 /* 2 * Copyright (c) 2014, NVIDIA CORPORATION. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms and conditions of the GNU General Public License, 6 * version 2, as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 11 * more details. 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/interrupt.h> 17 #include <linux/io.h> 18 #include <linux/of.h> 19 #include <linux/platform_device.h> 20 #include <linux/watchdog.h> 21 22 /* minimum and maximum watchdog trigger timeout, in seconds */ 23 #define MIN_WDT_TIMEOUT 1 24 #define MAX_WDT_TIMEOUT 255 25 26 /* 27 * Base of the WDT registers, from the timer base address. There are 28 * actually 5 watchdogs that can be configured (by pairing with an available 29 * timer), at bases 0x100 + (WDT ID) * 0x20, where WDT ID is 0 through 4. 30 * This driver only configures the first watchdog (WDT ID 0). 31 */ 32 #define WDT_BASE 0x100 33 #define WDT_ID 0 34 35 /* 36 * Register base of the timer that's selected for pairing with the watchdog. 37 * This driver arbitrarily uses timer 5, which is currently unused by 38 * other drivers (in particular, the Tegra clocksource driver). If this 39 * needs to change, take care that the new timer is not used by the 40 * clocksource driver. 41 */ 42 #define WDT_TIMER_BASE 0x60 43 #define WDT_TIMER_ID 5 44 45 /* WDT registers */ 46 #define WDT_CFG 0x0 47 #define WDT_CFG_PERIOD_SHIFT 4 48 #define WDT_CFG_PERIOD_MASK 0xff 49 #define WDT_CFG_INT_EN (1 << 12) 50 #define WDT_CFG_PMC2CAR_RST_EN (1 << 15) 51 #define WDT_STS 0x4 52 #define WDT_STS_COUNT_SHIFT 4 53 #define WDT_STS_COUNT_MASK 0xff 54 #define WDT_STS_EXP_SHIFT 12 55 #define WDT_STS_EXP_MASK 0x3 56 #define WDT_CMD 0x8 57 #define WDT_CMD_START_COUNTER (1 << 0) 58 #define WDT_CMD_DISABLE_COUNTER (1 << 1) 59 #define WDT_UNLOCK (0xc) 60 #define WDT_UNLOCK_PATTERN (0xc45a << 0) 61 62 /* Timer registers */ 63 #define TIMER_PTV 0x0 64 #define TIMER_EN (1 << 31) 65 #define TIMER_PERIODIC (1 << 30) 66 67 struct tegra_wdt { 68 struct watchdog_device wdd; 69 void __iomem *wdt_regs; 70 void __iomem *tmr_regs; 71 }; 72 73 #define WDT_HEARTBEAT 120 74 static int heartbeat = WDT_HEARTBEAT; 75 module_param(heartbeat, int, 0); 76 MODULE_PARM_DESC(heartbeat, 77 "Watchdog heartbeats in seconds. (default = " 78 __MODULE_STRING(WDT_HEARTBEAT) ")"); 79 80 static bool nowayout = WATCHDOG_NOWAYOUT; 81 module_param(nowayout, bool, 0); 82 MODULE_PARM_DESC(nowayout, 83 "Watchdog cannot be stopped once started (default=" 84 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 85 86 static int tegra_wdt_start(struct watchdog_device *wdd) 87 { 88 struct tegra_wdt *wdt = watchdog_get_drvdata(wdd); 89 u32 val; 90 91 /* 92 * This thing has a fixed 1MHz clock. Normally, we would set the 93 * period to 1 second by writing 1000000ul, but the watchdog system 94 * reset actually occurs on the 4th expiration of this counter, 95 * so we set the period to 1/4 of this amount. 96 */ 97 val = 1000000ul / 4; 98 val |= (TIMER_EN | TIMER_PERIODIC); 99 writel(val, wdt->tmr_regs + TIMER_PTV); 100 101 /* 102 * Set number of periods and start counter. 103 * 104 * Interrupt handler is not required for user space 105 * WDT accesses, since the caller is responsible to ping the 106 * WDT to reset the counter before expiration, through ioctls. 107 */ 108 val = WDT_TIMER_ID | 109 (wdd->timeout << WDT_CFG_PERIOD_SHIFT) | 110 WDT_CFG_PMC2CAR_RST_EN; 111 writel(val, wdt->wdt_regs + WDT_CFG); 112 113 writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD); 114 115 return 0; 116 } 117 118 static int tegra_wdt_stop(struct watchdog_device *wdd) 119 { 120 struct tegra_wdt *wdt = watchdog_get_drvdata(wdd); 121 122 writel(WDT_UNLOCK_PATTERN, wdt->wdt_regs + WDT_UNLOCK); 123 writel(WDT_CMD_DISABLE_COUNTER, wdt->wdt_regs + WDT_CMD); 124 writel(0, wdt->tmr_regs + TIMER_PTV); 125 126 return 0; 127 } 128 129 static int tegra_wdt_ping(struct watchdog_device *wdd) 130 { 131 struct tegra_wdt *wdt = watchdog_get_drvdata(wdd); 132 133 writel(WDT_CMD_START_COUNTER, wdt->wdt_regs + WDT_CMD); 134 135 return 0; 136 } 137 138 static int tegra_wdt_set_timeout(struct watchdog_device *wdd, 139 unsigned int timeout) 140 { 141 wdd->timeout = timeout; 142 143 if (watchdog_active(wdd)) { 144 tegra_wdt_stop(wdd); 145 return tegra_wdt_start(wdd); 146 } 147 148 return 0; 149 } 150 151 static unsigned int tegra_wdt_get_timeleft(struct watchdog_device *wdd) 152 { 153 struct tegra_wdt *wdt = watchdog_get_drvdata(wdd); 154 u32 val; 155 int count; 156 int exp; 157 158 val = readl(wdt->wdt_regs + WDT_STS); 159 160 /* Current countdown (from timeout) */ 161 count = (val >> WDT_STS_COUNT_SHIFT) & WDT_STS_COUNT_MASK; 162 163 /* Number of expirations (we are waiting for the 4th expiration) */ 164 exp = (val >> WDT_STS_EXP_SHIFT) & WDT_STS_EXP_MASK; 165 166 /* 167 * The entire thing is divided by 4 because we are ticking down 4 times 168 * faster due to needing to wait for the 4th expiration. 169 */ 170 return (((3 - exp) * wdd->timeout) + count) / 4; 171 } 172 173 static const struct watchdog_info tegra_wdt_info = { 174 .options = WDIOF_SETTIMEOUT | 175 WDIOF_MAGICCLOSE | 176 WDIOF_KEEPALIVEPING, 177 .firmware_version = 0, 178 .identity = "Tegra Watchdog", 179 }; 180 181 static const struct watchdog_ops tegra_wdt_ops = { 182 .owner = THIS_MODULE, 183 .start = tegra_wdt_start, 184 .stop = tegra_wdt_stop, 185 .ping = tegra_wdt_ping, 186 .set_timeout = tegra_wdt_set_timeout, 187 .get_timeleft = tegra_wdt_get_timeleft, 188 }; 189 190 static int tegra_wdt_probe(struct platform_device *pdev) 191 { 192 struct watchdog_device *wdd; 193 struct tegra_wdt *wdt; 194 struct resource *res; 195 void __iomem *regs; 196 int ret; 197 198 /* This is the timer base. */ 199 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 200 regs = devm_ioremap_resource(&pdev->dev, res); 201 if (IS_ERR(regs)) 202 return PTR_ERR(regs); 203 204 /* 205 * Allocate our watchdog driver data, which has the 206 * struct watchdog_device nested within it. 207 */ 208 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); 209 if (!wdt) 210 return -ENOMEM; 211 212 /* Initialize struct tegra_wdt. */ 213 wdt->wdt_regs = regs + WDT_BASE; 214 wdt->tmr_regs = regs + WDT_TIMER_BASE; 215 216 /* Initialize struct watchdog_device. */ 217 wdd = &wdt->wdd; 218 wdd->timeout = heartbeat; 219 wdd->info = &tegra_wdt_info; 220 wdd->ops = &tegra_wdt_ops; 221 wdd->min_timeout = MIN_WDT_TIMEOUT; 222 wdd->max_timeout = MAX_WDT_TIMEOUT; 223 wdd->parent = &pdev->dev; 224 225 watchdog_set_drvdata(wdd, wdt); 226 227 watchdog_set_nowayout(wdd, nowayout); 228 229 ret = devm_watchdog_register_device(&pdev->dev, wdd); 230 if (ret) { 231 dev_err(&pdev->dev, 232 "failed to register watchdog device\n"); 233 return ret; 234 } 235 236 platform_set_drvdata(pdev, wdt); 237 238 dev_info(&pdev->dev, 239 "initialized (heartbeat = %d sec, nowayout = %d)\n", 240 heartbeat, nowayout); 241 242 return 0; 243 } 244 245 static int tegra_wdt_remove(struct platform_device *pdev) 246 { 247 struct tegra_wdt *wdt = platform_get_drvdata(pdev); 248 249 tegra_wdt_stop(&wdt->wdd); 250 251 dev_info(&pdev->dev, "removed wdt\n"); 252 253 return 0; 254 } 255 256 #ifdef CONFIG_PM_SLEEP 257 static int tegra_wdt_runtime_suspend(struct device *dev) 258 { 259 struct tegra_wdt *wdt = dev_get_drvdata(dev); 260 261 if (watchdog_active(&wdt->wdd)) 262 tegra_wdt_stop(&wdt->wdd); 263 264 return 0; 265 } 266 267 static int tegra_wdt_runtime_resume(struct device *dev) 268 { 269 struct tegra_wdt *wdt = dev_get_drvdata(dev); 270 271 if (watchdog_active(&wdt->wdd)) 272 tegra_wdt_start(&wdt->wdd); 273 274 return 0; 275 } 276 #endif 277 278 static const struct of_device_id tegra_wdt_of_match[] = { 279 { .compatible = "nvidia,tegra30-timer", }, 280 { }, 281 }; 282 MODULE_DEVICE_TABLE(of, tegra_wdt_of_match); 283 284 static const struct dev_pm_ops tegra_wdt_pm_ops = { 285 SET_SYSTEM_SLEEP_PM_OPS(tegra_wdt_runtime_suspend, 286 tegra_wdt_runtime_resume) 287 }; 288 289 static struct platform_driver tegra_wdt_driver = { 290 .probe = tegra_wdt_probe, 291 .remove = tegra_wdt_remove, 292 .driver = { 293 .name = "tegra-wdt", 294 .pm = &tegra_wdt_pm_ops, 295 .of_match_table = tegra_wdt_of_match, 296 }, 297 }; 298 module_platform_driver(tegra_wdt_driver); 299 300 MODULE_AUTHOR("NVIDIA Corporation"); 301 MODULE_DESCRIPTION("Tegra Watchdog Driver"); 302 MODULE_LICENSE("GPL v2"); 303