1 /* 2 * drivers/char/watchdog/sp805-wdt.c 3 * 4 * Watchdog driver for ARM SP805 watchdog module 5 * 6 * Copyright (C) 2010 ST Microelectronics 7 * Viresh Kumar <viresh.linux@gmail.com> 8 * 9 * This file is licensed under the terms of the GNU General Public 10 * License version 2 or later. This program is licensed "as is" without any 11 * warranty of any kind, whether express or implied. 12 */ 13 14 #include <linux/device.h> 15 #include <linux/resource.h> 16 #include <linux/amba/bus.h> 17 #include <linux/bitops.h> 18 #include <linux/clk.h> 19 #include <linux/io.h> 20 #include <linux/ioport.h> 21 #include <linux/kernel.h> 22 #include <linux/math64.h> 23 #include <linux/module.h> 24 #include <linux/moduleparam.h> 25 #include <linux/pm.h> 26 #include <linux/slab.h> 27 #include <linux/spinlock.h> 28 #include <linux/types.h> 29 #include <linux/watchdog.h> 30 31 /* default timeout in seconds */ 32 #define DEFAULT_TIMEOUT 60 33 34 #define MODULE_NAME "sp805-wdt" 35 36 /* watchdog register offsets and masks */ 37 #define WDTLOAD 0x000 38 #define LOAD_MIN 0x00000001 39 #define LOAD_MAX 0xFFFFFFFF 40 #define WDTVALUE 0x004 41 #define WDTCONTROL 0x008 42 /* control register masks */ 43 #define INT_ENABLE (1 << 0) 44 #define RESET_ENABLE (1 << 1) 45 #define WDTINTCLR 0x00C 46 #define WDTRIS 0x010 47 #define WDTMIS 0x014 48 #define INT_MASK (1 << 0) 49 #define WDTLOCK 0xC00 50 #define UNLOCK 0x1ACCE551 51 #define LOCK 0x00000001 52 53 /** 54 * struct sp805_wdt: sp805 wdt device structure 55 * @wdd: instance of struct watchdog_device 56 * @lock: spin lock protecting dev structure and io access 57 * @base: base address of wdt 58 * @clk: clock structure of wdt 59 * @adev: amba device structure of wdt 60 * @status: current status of wdt 61 * @load_val: load value to be set for current timeout 62 * @timeout: current programmed timeout 63 */ 64 struct sp805_wdt { 65 struct watchdog_device wdd; 66 spinlock_t lock; 67 void __iomem *base; 68 struct clk *clk; 69 struct amba_device *adev; 70 unsigned int load_val; 71 unsigned int timeout; 72 }; 73 74 static bool nowayout = WATCHDOG_NOWAYOUT; 75 module_param(nowayout, bool, 0); 76 MODULE_PARM_DESC(nowayout, 77 "Set to 1 to keep watchdog running after device release"); 78 79 /* This routine finds load value that will reset system in required timout */ 80 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout) 81 { 82 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd); 83 u64 load, rate; 84 85 rate = clk_get_rate(wdt->clk); 86 87 /* 88 * sp805 runs counter with given value twice, after the end of first 89 * counter it gives an interrupt and then starts counter again. If 90 * interrupt already occurred then it resets the system. This is why 91 * load is half of what should be required. 92 */ 93 load = div_u64(rate, 2) * timeout - 1; 94 95 load = (load > LOAD_MAX) ? LOAD_MAX : load; 96 load = (load < LOAD_MIN) ? LOAD_MIN : load; 97 98 spin_lock(&wdt->lock); 99 wdt->load_val = load; 100 /* roundup timeout to closest positive integer value */ 101 wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate); 102 spin_unlock(&wdt->lock); 103 104 return 0; 105 } 106 107 /* returns number of seconds left for reset to occur */ 108 static unsigned int wdt_timeleft(struct watchdog_device *wdd) 109 { 110 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd); 111 u64 load, rate; 112 113 rate = clk_get_rate(wdt->clk); 114 115 spin_lock(&wdt->lock); 116 load = readl_relaxed(wdt->base + WDTVALUE); 117 118 /*If the interrupt is inactive then time left is WDTValue + WDTLoad. */ 119 if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK)) 120 load += wdt->load_val + 1; 121 spin_unlock(&wdt->lock); 122 123 return div_u64(load, rate); 124 } 125 126 static int wdt_config(struct watchdog_device *wdd, bool ping) 127 { 128 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd); 129 int ret; 130 131 if (!ping) { 132 133 ret = clk_prepare_enable(wdt->clk); 134 if (ret) { 135 dev_err(&wdt->adev->dev, "clock enable fail"); 136 return ret; 137 } 138 } 139 140 spin_lock(&wdt->lock); 141 142 writel_relaxed(UNLOCK, wdt->base + WDTLOCK); 143 writel_relaxed(wdt->load_val, wdt->base + WDTLOAD); 144 145 if (!ping) { 146 writel_relaxed(INT_MASK, wdt->base + WDTINTCLR); 147 writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + 148 WDTCONTROL); 149 } 150 151 writel_relaxed(LOCK, wdt->base + WDTLOCK); 152 153 /* Flush posted writes. */ 154 readl_relaxed(wdt->base + WDTLOCK); 155 spin_unlock(&wdt->lock); 156 157 return 0; 158 } 159 160 static int wdt_ping(struct watchdog_device *wdd) 161 { 162 return wdt_config(wdd, true); 163 } 164 165 /* enables watchdog timers reset */ 166 static int wdt_enable(struct watchdog_device *wdd) 167 { 168 return wdt_config(wdd, false); 169 } 170 171 /* disables watchdog timers reset */ 172 static int wdt_disable(struct watchdog_device *wdd) 173 { 174 struct sp805_wdt *wdt = watchdog_get_drvdata(wdd); 175 176 spin_lock(&wdt->lock); 177 178 writel_relaxed(UNLOCK, wdt->base + WDTLOCK); 179 writel_relaxed(0, wdt->base + WDTCONTROL); 180 writel_relaxed(LOCK, wdt->base + WDTLOCK); 181 182 /* Flush posted writes. */ 183 readl_relaxed(wdt->base + WDTLOCK); 184 spin_unlock(&wdt->lock); 185 186 clk_disable_unprepare(wdt->clk); 187 188 return 0; 189 } 190 191 static const struct watchdog_info wdt_info = { 192 .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, 193 .identity = MODULE_NAME, 194 }; 195 196 static const struct watchdog_ops wdt_ops = { 197 .owner = THIS_MODULE, 198 .start = wdt_enable, 199 .stop = wdt_disable, 200 .ping = wdt_ping, 201 .set_timeout = wdt_setload, 202 .get_timeleft = wdt_timeleft, 203 }; 204 205 static int 206 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id) 207 { 208 struct sp805_wdt *wdt; 209 int ret = 0; 210 211 wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL); 212 if (!wdt) { 213 ret = -ENOMEM; 214 goto err; 215 } 216 217 wdt->base = devm_ioremap_resource(&adev->dev, &adev->res); 218 if (IS_ERR(wdt->base)) 219 return PTR_ERR(wdt->base); 220 221 wdt->clk = devm_clk_get(&adev->dev, NULL); 222 if (IS_ERR(wdt->clk)) { 223 dev_warn(&adev->dev, "Clock not found\n"); 224 ret = PTR_ERR(wdt->clk); 225 goto err; 226 } 227 228 wdt->adev = adev; 229 wdt->wdd.info = &wdt_info; 230 wdt->wdd.ops = &wdt_ops; 231 232 spin_lock_init(&wdt->lock); 233 watchdog_set_nowayout(&wdt->wdd, nowayout); 234 watchdog_set_drvdata(&wdt->wdd, wdt); 235 wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT); 236 237 ret = watchdog_register_device(&wdt->wdd); 238 if (ret) { 239 dev_err(&adev->dev, "watchdog_register_device() failed: %d\n", 240 ret); 241 goto err; 242 } 243 amba_set_drvdata(adev, wdt); 244 245 dev_info(&adev->dev, "registration successful\n"); 246 return 0; 247 248 err: 249 dev_err(&adev->dev, "Probe Failed!!!\n"); 250 return ret; 251 } 252 253 static int sp805_wdt_remove(struct amba_device *adev) 254 { 255 struct sp805_wdt *wdt = amba_get_drvdata(adev); 256 257 watchdog_unregister_device(&wdt->wdd); 258 watchdog_set_drvdata(&wdt->wdd, NULL); 259 260 return 0; 261 } 262 263 static int __maybe_unused sp805_wdt_suspend(struct device *dev) 264 { 265 struct sp805_wdt *wdt = dev_get_drvdata(dev); 266 267 if (watchdog_active(&wdt->wdd)) 268 return wdt_disable(&wdt->wdd); 269 270 return 0; 271 } 272 273 static int __maybe_unused sp805_wdt_resume(struct device *dev) 274 { 275 struct sp805_wdt *wdt = dev_get_drvdata(dev); 276 277 if (watchdog_active(&wdt->wdd)) 278 return wdt_enable(&wdt->wdd); 279 280 return 0; 281 } 282 283 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend, 284 sp805_wdt_resume); 285 286 static struct amba_id sp805_wdt_ids[] = { 287 { 288 .id = 0x00141805, 289 .mask = 0x00ffffff, 290 }, 291 { 0, 0 }, 292 }; 293 294 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids); 295 296 static struct amba_driver sp805_wdt_driver = { 297 .drv = { 298 .name = MODULE_NAME, 299 .pm = &sp805_wdt_dev_pm_ops, 300 }, 301 .id_table = sp805_wdt_ids, 302 .probe = sp805_wdt_probe, 303 .remove = sp805_wdt_remove, 304 }; 305 306 module_amba_driver(sp805_wdt_driver); 307 308 MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>"); 309 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver"); 310 MODULE_LICENSE("GPL"); 311