1 /* 2 * Imagination Technologies PowerDown Controller Watchdog Timer. 3 * 4 * Copyright (c) 2014 Imagination Technologies Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 as published by 8 * the Free Software Foundation. 9 * 10 * Based on drivers/watchdog/sunxi_wdt.c Copyright (c) 2013 Carlo Caione 11 * 2012 Henrik Nordstrom 12 * 13 * Notes 14 * ----- 15 * The timeout value is rounded to the next power of two clock cycles. 16 * This is configured using the PDC_WDT_CONFIG register, according to this 17 * formula: 18 * 19 * timeout = 2^(delay + 1) clock cycles 20 * 21 * Where 'delay' is the value written in PDC_WDT_CONFIG register. 22 * 23 * Therefore, the hardware only allows to program watchdog timeouts, expressed 24 * as a power of two number of watchdog clock cycles. The current implementation 25 * guarantees that the actual watchdog timeout will be _at least_ the value 26 * programmed in the imgpdg_wdt driver. 27 * 28 * The following table shows how the user-configured timeout relates 29 * to the actual hardware timeout (watchdog clock @ 40000 Hz): 30 * 31 * input timeout | WD_DELAY | actual timeout 32 * ----------------------------------- 33 * 10 | 18 | 13 seconds 34 * 20 | 19 | 26 seconds 35 * 30 | 20 | 52 seconds 36 * 60 | 21 | 104 seconds 37 * 38 * Albeit coarse, this granularity would suffice most watchdog uses. 39 * If the platform allows it, the user should be able to change the watchdog 40 * clock rate and achieve a finer timeout granularity. 41 */ 42 43 #include <linux/clk.h> 44 #include <linux/io.h> 45 #include <linux/log2.h> 46 #include <linux/module.h> 47 #include <linux/platform_device.h> 48 #include <linux/reboot.h> 49 #include <linux/slab.h> 50 #include <linux/watchdog.h> 51 52 /* registers */ 53 #define PDC_WDT_SOFT_RESET 0x00 54 #define PDC_WDT_CONFIG 0x04 55 #define PDC_WDT_CONFIG_ENABLE BIT(31) 56 #define PDC_WDT_CONFIG_DELAY_MASK 0x1f 57 58 #define PDC_WDT_TICKLE1 0x08 59 #define PDC_WDT_TICKLE1_MAGIC 0xabcd1234 60 #define PDC_WDT_TICKLE2 0x0c 61 #define PDC_WDT_TICKLE2_MAGIC 0x4321dcba 62 63 #define PDC_WDT_TICKLE_STATUS_MASK 0x7 64 #define PDC_WDT_TICKLE_STATUS_SHIFT 0 65 #define PDC_WDT_TICKLE_STATUS_HRESET 0x0 /* Hard reset */ 66 #define PDC_WDT_TICKLE_STATUS_TIMEOUT 0x1 /* Timeout */ 67 #define PDC_WDT_TICKLE_STATUS_TICKLE 0x2 /* Tickled incorrectly */ 68 #define PDC_WDT_TICKLE_STATUS_SRESET 0x3 /* Soft reset */ 69 #define PDC_WDT_TICKLE_STATUS_USER 0x4 /* User reset */ 70 71 /* Timeout values are in seconds */ 72 #define PDC_WDT_MIN_TIMEOUT 1 73 #define PDC_WDT_DEF_TIMEOUT 64 74 75 static int heartbeat; 76 module_param(heartbeat, int, 0); 77 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds " 78 "(default=" __MODULE_STRING(PDC_WDT_DEF_TIMEOUT) ")"); 79 80 static bool nowayout = WATCHDOG_NOWAYOUT; 81 module_param(nowayout, bool, 0); 82 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " 83 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 84 85 struct pdc_wdt_dev { 86 struct watchdog_device wdt_dev; 87 struct clk *wdt_clk; 88 struct clk *sys_clk; 89 void __iomem *base; 90 struct notifier_block restart_handler; 91 }; 92 93 static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev) 94 { 95 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev); 96 97 writel(PDC_WDT_TICKLE1_MAGIC, wdt->base + PDC_WDT_TICKLE1); 98 writel(PDC_WDT_TICKLE2_MAGIC, wdt->base + PDC_WDT_TICKLE2); 99 100 return 0; 101 } 102 103 static int pdc_wdt_stop(struct watchdog_device *wdt_dev) 104 { 105 unsigned int val; 106 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev); 107 108 val = readl(wdt->base + PDC_WDT_CONFIG); 109 val &= ~PDC_WDT_CONFIG_ENABLE; 110 writel(val, wdt->base + PDC_WDT_CONFIG); 111 112 /* Must tickle to finish the stop */ 113 pdc_wdt_keepalive(wdt_dev); 114 115 return 0; 116 } 117 118 static void __pdc_wdt_set_timeout(struct pdc_wdt_dev *wdt) 119 { 120 unsigned long clk_rate = clk_get_rate(wdt->wdt_clk); 121 unsigned int val; 122 123 val = readl(wdt->base + PDC_WDT_CONFIG) & ~PDC_WDT_CONFIG_DELAY_MASK; 124 val |= order_base_2(wdt->wdt_dev.timeout * clk_rate) - 1; 125 writel(val, wdt->base + PDC_WDT_CONFIG); 126 } 127 128 static int pdc_wdt_set_timeout(struct watchdog_device *wdt_dev, 129 unsigned int new_timeout) 130 { 131 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev); 132 133 wdt->wdt_dev.timeout = new_timeout; 134 135 __pdc_wdt_set_timeout(wdt); 136 137 return 0; 138 } 139 140 /* Start the watchdog timer (delay should already be set) */ 141 static int pdc_wdt_start(struct watchdog_device *wdt_dev) 142 { 143 unsigned int val; 144 struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev); 145 146 __pdc_wdt_set_timeout(wdt); 147 148 val = readl(wdt->base + PDC_WDT_CONFIG); 149 val |= PDC_WDT_CONFIG_ENABLE; 150 writel(val, wdt->base + PDC_WDT_CONFIG); 151 152 return 0; 153 } 154 155 static struct watchdog_info pdc_wdt_info = { 156 .identity = "IMG PDC Watchdog", 157 .options = WDIOF_SETTIMEOUT | 158 WDIOF_KEEPALIVEPING | 159 WDIOF_MAGICCLOSE, 160 }; 161 162 static const struct watchdog_ops pdc_wdt_ops = { 163 .owner = THIS_MODULE, 164 .start = pdc_wdt_start, 165 .stop = pdc_wdt_stop, 166 .ping = pdc_wdt_keepalive, 167 .set_timeout = pdc_wdt_set_timeout, 168 }; 169 170 static int pdc_wdt_restart(struct notifier_block *this, unsigned long mode, 171 void *cmd) 172 { 173 struct pdc_wdt_dev *wdt = container_of(this, struct pdc_wdt_dev, 174 restart_handler); 175 176 /* Assert SOFT_RESET */ 177 writel(0x1, wdt->base + PDC_WDT_SOFT_RESET); 178 179 return NOTIFY_OK; 180 } 181 182 static int pdc_wdt_probe(struct platform_device *pdev) 183 { 184 u64 div; 185 int ret, val; 186 unsigned long clk_rate; 187 struct resource *res; 188 struct pdc_wdt_dev *pdc_wdt; 189 190 pdc_wdt = devm_kzalloc(&pdev->dev, sizeof(*pdc_wdt), GFP_KERNEL); 191 if (!pdc_wdt) 192 return -ENOMEM; 193 194 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 195 pdc_wdt->base = devm_ioremap_resource(&pdev->dev, res); 196 if (IS_ERR(pdc_wdt->base)) 197 return PTR_ERR(pdc_wdt->base); 198 199 pdc_wdt->sys_clk = devm_clk_get(&pdev->dev, "sys"); 200 if (IS_ERR(pdc_wdt->sys_clk)) { 201 dev_err(&pdev->dev, "failed to get the sys clock\n"); 202 return PTR_ERR(pdc_wdt->sys_clk); 203 } 204 205 pdc_wdt->wdt_clk = devm_clk_get(&pdev->dev, "wdt"); 206 if (IS_ERR(pdc_wdt->wdt_clk)) { 207 dev_err(&pdev->dev, "failed to get the wdt clock\n"); 208 return PTR_ERR(pdc_wdt->wdt_clk); 209 } 210 211 ret = clk_prepare_enable(pdc_wdt->sys_clk); 212 if (ret) { 213 dev_err(&pdev->dev, "could not prepare or enable sys clock\n"); 214 return ret; 215 } 216 217 ret = clk_prepare_enable(pdc_wdt->wdt_clk); 218 if (ret) { 219 dev_err(&pdev->dev, "could not prepare or enable wdt clock\n"); 220 goto disable_sys_clk; 221 } 222 223 /* We use the clock rate to calculate the max timeout */ 224 clk_rate = clk_get_rate(pdc_wdt->wdt_clk); 225 if (clk_rate == 0) { 226 dev_err(&pdev->dev, "failed to get clock rate\n"); 227 ret = -EINVAL; 228 goto disable_wdt_clk; 229 } 230 231 if (order_base_2(clk_rate) > PDC_WDT_CONFIG_DELAY_MASK + 1) { 232 dev_err(&pdev->dev, "invalid clock rate\n"); 233 ret = -EINVAL; 234 goto disable_wdt_clk; 235 } 236 237 if (order_base_2(clk_rate) == 0) 238 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT + 1; 239 else 240 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT; 241 242 pdc_wdt->wdt_dev.info = &pdc_wdt_info; 243 pdc_wdt->wdt_dev.ops = &pdc_wdt_ops; 244 245 div = 1ULL << (PDC_WDT_CONFIG_DELAY_MASK + 1); 246 do_div(div, clk_rate); 247 pdc_wdt->wdt_dev.max_timeout = div; 248 pdc_wdt->wdt_dev.timeout = PDC_WDT_DEF_TIMEOUT; 249 pdc_wdt->wdt_dev.parent = &pdev->dev; 250 watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt); 251 252 watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, &pdev->dev); 253 254 pdc_wdt_stop(&pdc_wdt->wdt_dev); 255 256 /* Find what caused the last reset */ 257 val = readl(pdc_wdt->base + PDC_WDT_TICKLE1); 258 val = (val & PDC_WDT_TICKLE_STATUS_MASK) >> PDC_WDT_TICKLE_STATUS_SHIFT; 259 switch (val) { 260 case PDC_WDT_TICKLE_STATUS_TICKLE: 261 case PDC_WDT_TICKLE_STATUS_TIMEOUT: 262 pdc_wdt->wdt_dev.bootstatus |= WDIOF_CARDRESET; 263 dev_info(&pdev->dev, 264 "watchdog module last reset due to timeout\n"); 265 break; 266 case PDC_WDT_TICKLE_STATUS_HRESET: 267 dev_info(&pdev->dev, 268 "watchdog module last reset due to hard reset\n"); 269 break; 270 case PDC_WDT_TICKLE_STATUS_SRESET: 271 dev_info(&pdev->dev, 272 "watchdog module last reset due to soft reset\n"); 273 break; 274 case PDC_WDT_TICKLE_STATUS_USER: 275 dev_info(&pdev->dev, 276 "watchdog module last reset due to user reset\n"); 277 break; 278 default: 279 dev_info(&pdev->dev, 280 "contains an illegal status code (%08x)\n", val); 281 break; 282 } 283 284 watchdog_set_nowayout(&pdc_wdt->wdt_dev, nowayout); 285 286 platform_set_drvdata(pdev, pdc_wdt); 287 288 ret = watchdog_register_device(&pdc_wdt->wdt_dev); 289 if (ret) 290 goto disable_wdt_clk; 291 292 pdc_wdt->restart_handler.notifier_call = pdc_wdt_restart; 293 pdc_wdt->restart_handler.priority = 128; 294 ret = register_restart_handler(&pdc_wdt->restart_handler); 295 if (ret) 296 dev_warn(&pdev->dev, "failed to register restart handler: %d\n", 297 ret); 298 299 return 0; 300 301 disable_wdt_clk: 302 clk_disable_unprepare(pdc_wdt->wdt_clk); 303 disable_sys_clk: 304 clk_disable_unprepare(pdc_wdt->sys_clk); 305 return ret; 306 } 307 308 static void pdc_wdt_shutdown(struct platform_device *pdev) 309 { 310 struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev); 311 312 pdc_wdt_stop(&pdc_wdt->wdt_dev); 313 } 314 315 static int pdc_wdt_remove(struct platform_device *pdev) 316 { 317 struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev); 318 319 unregister_restart_handler(&pdc_wdt->restart_handler); 320 pdc_wdt_stop(&pdc_wdt->wdt_dev); 321 watchdog_unregister_device(&pdc_wdt->wdt_dev); 322 clk_disable_unprepare(pdc_wdt->wdt_clk); 323 clk_disable_unprepare(pdc_wdt->sys_clk); 324 325 return 0; 326 } 327 328 static const struct of_device_id pdc_wdt_match[] = { 329 { .compatible = "img,pdc-wdt" }, 330 {} 331 }; 332 MODULE_DEVICE_TABLE(of, pdc_wdt_match); 333 334 static struct platform_driver pdc_wdt_driver = { 335 .driver = { 336 .name = "imgpdc-wdt", 337 .of_match_table = pdc_wdt_match, 338 }, 339 .probe = pdc_wdt_probe, 340 .remove = pdc_wdt_remove, 341 .shutdown = pdc_wdt_shutdown, 342 }; 343 module_platform_driver(pdc_wdt_driver); 344 345 MODULE_AUTHOR("Jude Abraham <Jude.Abraham@imgtec.com>"); 346 MODULE_AUTHOR("Naidu Tellapati <Naidu.Tellapati@imgtec.com>"); 347 MODULE_DESCRIPTION("Imagination Technologies PDC Watchdog Timer Driver"); 348 MODULE_LICENSE("GPL v2"); 349