1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * SBSA(Server Base System Architecture) Generic Watchdog driver 4 * 5 * Copyright (c) 2015, Linaro Ltd. 6 * Author: Fu Wei <fu.wei@linaro.org> 7 * Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> 8 * Al Stone <al.stone@linaro.org> 9 * Timur Tabi <timur@codeaurora.org> 10 * 11 * ARM SBSA Generic Watchdog has two stage timeouts: 12 * the first signal (WS0) is for alerting the system by interrupt, 13 * the second one (WS1) is a real hardware reset. 14 * More details about the hardware specification of this device: 15 * ARM DEN0029B - Server Base System Architecture (SBSA) 16 * 17 * This driver can operate ARM SBSA Generic Watchdog as a single stage watchdog 18 * or a two stages watchdog, it's set up by the module parameter "action". 19 * In the single stage mode, when the timeout is reached, your system 20 * will be reset by WS1. The first signal (WS0) is ignored. 21 * In the two stages mode, when the timeout is reached, the first signal (WS0) 22 * will trigger panic. If the system is getting into trouble and cannot be reset 23 * by panic or restart properly by the kdump kernel(if supported), then the 24 * second stage (as long as the first stage) will be reached, system will be 25 * reset by WS1. This function can help administrator to backup the system 26 * context info by panic console output or kdump. 27 * 28 * SBSA GWDT: 29 * if action is 1 (the two stages mode): 30 * |--------WOR-------WS0--------WOR-------WS1 31 * |----timeout-----(panic)----timeout-----reset 32 * 33 * if action is 0 (the single stage mode): 34 * |------WOR-----WS0(ignored)-----WOR------WS1 35 * |--------------timeout-------------------reset 36 * 37 * Note: Since this watchdog timer has two stages, and each stage is determined 38 * by WOR, in the single stage mode, the timeout is (WOR * 2); in the two 39 * stages mode, the timeout is WOR. The maximum timeout in the two stages mode 40 * is half of that in the single stage mode. 41 */ 42 43 #include <linux/io.h> 44 #include <linux/io-64-nonatomic-lo-hi.h> 45 #include <linux/interrupt.h> 46 #include <linux/module.h> 47 #include <linux/moduleparam.h> 48 #include <linux/of.h> 49 #include <linux/of_device.h> 50 #include <linux/platform_device.h> 51 #include <linux/uaccess.h> 52 #include <linux/watchdog.h> 53 #include <asm/arch_timer.h> 54 55 #define DRV_NAME "sbsa-gwdt" 56 #define WATCHDOG_NAME "SBSA Generic Watchdog" 57 58 /* SBSA Generic Watchdog register definitions */ 59 /* refresh frame */ 60 #define SBSA_GWDT_WRR 0x000 61 62 /* control frame */ 63 #define SBSA_GWDT_WCS 0x000 64 #define SBSA_GWDT_WOR 0x008 65 #define SBSA_GWDT_WCV 0x010 66 67 /* refresh/control frame */ 68 #define SBSA_GWDT_W_IIDR 0xfcc 69 #define SBSA_GWDT_IDR 0xfd0 70 71 /* Watchdog Control and Status Register */ 72 #define SBSA_GWDT_WCS_EN BIT(0) 73 #define SBSA_GWDT_WCS_WS0 BIT(1) 74 #define SBSA_GWDT_WCS_WS1 BIT(2) 75 76 #define SBSA_GWDT_VERSION_MASK 0xF 77 #define SBSA_GWDT_VERSION_SHIFT 16 78 79 /** 80 * struct sbsa_gwdt - Internal representation of the SBSA GWDT 81 * @wdd: kernel watchdog_device structure 82 * @clk: store the System Counter clock frequency, in Hz. 83 * @version: store the architecture version 84 * @refresh_base: Virtual address of the watchdog refresh frame 85 * @control_base: Virtual address of the watchdog control frame 86 */ 87 struct sbsa_gwdt { 88 struct watchdog_device wdd; 89 u32 clk; 90 int version; 91 void __iomem *refresh_base; 92 void __iomem *control_base; 93 }; 94 95 #define DEFAULT_TIMEOUT 10 /* seconds */ 96 97 static unsigned int timeout; 98 module_param(timeout, uint, 0); 99 MODULE_PARM_DESC(timeout, 100 "Watchdog timeout in seconds. (>=0, default=" 101 __MODULE_STRING(DEFAULT_TIMEOUT) ")"); 102 103 /* 104 * action refers to action taken when watchdog gets WS0 105 * 0 = skip 106 * 1 = panic 107 * defaults to skip (0) 108 */ 109 static int action; 110 module_param(action, int, 0); 111 MODULE_PARM_DESC(action, "after watchdog gets WS0 interrupt, do: " 112 "0 = skip(*) 1 = panic"); 113 114 static bool nowayout = WATCHDOG_NOWAYOUT; 115 module_param(nowayout, bool, S_IRUGO); 116 MODULE_PARM_DESC(nowayout, 117 "Watchdog cannot be stopped once started (default=" 118 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 119 120 /* 121 * Arm Base System Architecture 1.0 introduces watchdog v1 which 122 * increases the length watchdog offset register to 48 bits. 123 * - For version 0: WOR is 32 bits; 124 * - For version 1: WOR is 48 bits which comprises the register 125 * offset 0x8 and 0xC, and the bits [63:48] are reserved which are 126 * Read-As-Zero and Writes-Ignored. 127 */ 128 static u64 sbsa_gwdt_reg_read(struct sbsa_gwdt *gwdt) 129 { 130 if (gwdt->version == 0) 131 return readl(gwdt->control_base + SBSA_GWDT_WOR); 132 else 133 return readq(gwdt->control_base + SBSA_GWDT_WOR); 134 } 135 136 static void sbsa_gwdt_reg_write(u64 val, struct sbsa_gwdt *gwdt) 137 { 138 if (gwdt->version == 0) 139 writel((u32)val, gwdt->control_base + SBSA_GWDT_WOR); 140 else 141 writeq(val, gwdt->control_base + SBSA_GWDT_WOR); 142 } 143 144 /* 145 * watchdog operation functions 146 */ 147 static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd, 148 unsigned int timeout) 149 { 150 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 151 152 wdd->timeout = timeout; 153 154 if (action) 155 sbsa_gwdt_reg_write(gwdt->clk * timeout, gwdt); 156 else 157 /* 158 * In the single stage mode, The first signal (WS0) is ignored, 159 * the timeout is (WOR * 2), so the WOR should be configured 160 * to half value of timeout. 161 */ 162 sbsa_gwdt_reg_write(gwdt->clk / 2 * timeout, gwdt); 163 164 return 0; 165 } 166 167 static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd) 168 { 169 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 170 u64 timeleft = 0; 171 172 /* 173 * In the single stage mode, if WS0 is deasserted 174 * (watchdog is in the first stage), 175 * timeleft = WOR + (WCV - system counter) 176 */ 177 if (!action && 178 !(readl(gwdt->control_base + SBSA_GWDT_WCS) & SBSA_GWDT_WCS_WS0)) 179 timeleft += sbsa_gwdt_reg_read(gwdt); 180 181 timeleft += lo_hi_readq(gwdt->control_base + SBSA_GWDT_WCV) - 182 arch_timer_read_counter(); 183 184 do_div(timeleft, gwdt->clk); 185 186 return timeleft; 187 } 188 189 static int sbsa_gwdt_keepalive(struct watchdog_device *wdd) 190 { 191 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 192 193 /* 194 * Writing WRR for an explicit watchdog refresh. 195 * You can write anyting (like 0). 196 */ 197 writel(0, gwdt->refresh_base + SBSA_GWDT_WRR); 198 199 return 0; 200 } 201 202 static void sbsa_gwdt_get_version(struct watchdog_device *wdd) 203 { 204 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 205 int ver; 206 207 ver = readl(gwdt->control_base + SBSA_GWDT_W_IIDR); 208 ver = (ver >> SBSA_GWDT_VERSION_SHIFT) & SBSA_GWDT_VERSION_MASK; 209 210 gwdt->version = ver; 211 } 212 213 static int sbsa_gwdt_start(struct watchdog_device *wdd) 214 { 215 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 216 217 /* writing WCS will cause an explicit watchdog refresh */ 218 writel(SBSA_GWDT_WCS_EN, gwdt->control_base + SBSA_GWDT_WCS); 219 220 return 0; 221 } 222 223 static int sbsa_gwdt_stop(struct watchdog_device *wdd) 224 { 225 struct sbsa_gwdt *gwdt = watchdog_get_drvdata(wdd); 226 227 /* Simply write 0 to WCS to clean WCS_EN bit */ 228 writel(0, gwdt->control_base + SBSA_GWDT_WCS); 229 230 return 0; 231 } 232 233 static irqreturn_t sbsa_gwdt_interrupt(int irq, void *dev_id) 234 { 235 panic(WATCHDOG_NAME " timeout"); 236 237 return IRQ_HANDLED; 238 } 239 240 static const struct watchdog_info sbsa_gwdt_info = { 241 .identity = WATCHDOG_NAME, 242 .options = WDIOF_SETTIMEOUT | 243 WDIOF_KEEPALIVEPING | 244 WDIOF_MAGICCLOSE | 245 WDIOF_CARDRESET, 246 }; 247 248 static const struct watchdog_ops sbsa_gwdt_ops = { 249 .owner = THIS_MODULE, 250 .start = sbsa_gwdt_start, 251 .stop = sbsa_gwdt_stop, 252 .ping = sbsa_gwdt_keepalive, 253 .set_timeout = sbsa_gwdt_set_timeout, 254 .get_timeleft = sbsa_gwdt_get_timeleft, 255 }; 256 257 static int sbsa_gwdt_probe(struct platform_device *pdev) 258 { 259 void __iomem *rf_base, *cf_base; 260 struct device *dev = &pdev->dev; 261 struct watchdog_device *wdd; 262 struct sbsa_gwdt *gwdt; 263 int ret, irq; 264 u32 status; 265 266 gwdt = devm_kzalloc(dev, sizeof(*gwdt), GFP_KERNEL); 267 if (!gwdt) 268 return -ENOMEM; 269 platform_set_drvdata(pdev, gwdt); 270 271 cf_base = devm_platform_ioremap_resource(pdev, 0); 272 if (IS_ERR(cf_base)) 273 return PTR_ERR(cf_base); 274 275 rf_base = devm_platform_ioremap_resource(pdev, 1); 276 if (IS_ERR(rf_base)) 277 return PTR_ERR(rf_base); 278 279 /* 280 * Get the frequency of system counter from the cp15 interface of ARM 281 * Generic timer. We don't need to check it, because if it returns "0", 282 * system would panic in very early stage. 283 */ 284 gwdt->clk = arch_timer_get_cntfrq(); 285 gwdt->refresh_base = rf_base; 286 gwdt->control_base = cf_base; 287 288 wdd = &gwdt->wdd; 289 wdd->parent = dev; 290 wdd->info = &sbsa_gwdt_info; 291 wdd->ops = &sbsa_gwdt_ops; 292 wdd->min_timeout = 1; 293 wdd->timeout = DEFAULT_TIMEOUT; 294 watchdog_set_drvdata(wdd, gwdt); 295 watchdog_set_nowayout(wdd, nowayout); 296 sbsa_gwdt_get_version(wdd); 297 if (gwdt->version == 0) 298 wdd->max_hw_heartbeat_ms = U32_MAX / gwdt->clk * 1000; 299 else 300 wdd->max_hw_heartbeat_ms = GENMASK_ULL(47, 0) / gwdt->clk * 1000; 301 302 status = readl(cf_base + SBSA_GWDT_WCS); 303 if (status & SBSA_GWDT_WCS_WS1) { 304 dev_warn(dev, "System reset by WDT.\n"); 305 wdd->bootstatus |= WDIOF_CARDRESET; 306 } 307 if (status & SBSA_GWDT_WCS_EN) 308 set_bit(WDOG_HW_RUNNING, &wdd->status); 309 310 if (action) { 311 irq = platform_get_irq(pdev, 0); 312 if (irq < 0) { 313 action = 0; 314 dev_warn(dev, "unable to get ws0 interrupt.\n"); 315 } else { 316 /* 317 * In case there is a pending ws0 interrupt, just ping 318 * the watchdog before registering the interrupt routine 319 */ 320 writel(0, rf_base + SBSA_GWDT_WRR); 321 if (devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0, 322 pdev->name, gwdt)) { 323 action = 0; 324 dev_warn(dev, "unable to request IRQ %d.\n", 325 irq); 326 } 327 } 328 if (!action) 329 dev_warn(dev, "falling back to single stage mode.\n"); 330 } 331 /* 332 * In the single stage mode, The first signal (WS0) is ignored, 333 * the timeout is (WOR * 2), so the maximum timeout should be doubled. 334 */ 335 if (!action) 336 wdd->max_hw_heartbeat_ms *= 2; 337 338 watchdog_init_timeout(wdd, timeout, dev); 339 /* 340 * Update timeout to WOR. 341 * Because of the explicit watchdog refresh mechanism, 342 * it's also a ping, if watchdog is enabled. 343 */ 344 sbsa_gwdt_set_timeout(wdd, wdd->timeout); 345 346 watchdog_stop_on_reboot(wdd); 347 ret = devm_watchdog_register_device(dev, wdd); 348 if (ret) 349 return ret; 350 351 dev_info(dev, "Initialized with %ds timeout @ %u Hz, action=%d.%s\n", 352 wdd->timeout, gwdt->clk, action, 353 status & SBSA_GWDT_WCS_EN ? " [enabled]" : ""); 354 355 return 0; 356 } 357 358 /* Disable watchdog if it is active during suspend */ 359 static int __maybe_unused sbsa_gwdt_suspend(struct device *dev) 360 { 361 struct sbsa_gwdt *gwdt = dev_get_drvdata(dev); 362 363 if (watchdog_active(&gwdt->wdd)) 364 sbsa_gwdt_stop(&gwdt->wdd); 365 366 return 0; 367 } 368 369 /* Enable watchdog if necessary */ 370 static int __maybe_unused sbsa_gwdt_resume(struct device *dev) 371 { 372 struct sbsa_gwdt *gwdt = dev_get_drvdata(dev); 373 374 if (watchdog_active(&gwdt->wdd)) 375 sbsa_gwdt_start(&gwdt->wdd); 376 377 return 0; 378 } 379 380 static const struct dev_pm_ops sbsa_gwdt_pm_ops = { 381 SET_SYSTEM_SLEEP_PM_OPS(sbsa_gwdt_suspend, sbsa_gwdt_resume) 382 }; 383 384 static const struct of_device_id sbsa_gwdt_of_match[] = { 385 { .compatible = "arm,sbsa-gwdt", }, 386 {}, 387 }; 388 MODULE_DEVICE_TABLE(of, sbsa_gwdt_of_match); 389 390 static const struct platform_device_id sbsa_gwdt_pdev_match[] = { 391 { .name = DRV_NAME, }, 392 {}, 393 }; 394 MODULE_DEVICE_TABLE(platform, sbsa_gwdt_pdev_match); 395 396 static struct platform_driver sbsa_gwdt_driver = { 397 .driver = { 398 .name = DRV_NAME, 399 .pm = &sbsa_gwdt_pm_ops, 400 .of_match_table = sbsa_gwdt_of_match, 401 }, 402 .probe = sbsa_gwdt_probe, 403 .id_table = sbsa_gwdt_pdev_match, 404 }; 405 406 module_platform_driver(sbsa_gwdt_driver); 407 408 MODULE_DESCRIPTION("SBSA Generic Watchdog Driver"); 409 MODULE_AUTHOR("Fu Wei <fu.wei@linaro.org>"); 410 MODULE_AUTHOR("Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>"); 411 MODULE_AUTHOR("Al Stone <al.stone@linaro.org>"); 412 MODULE_AUTHOR("Timur Tabi <timur@codeaurora.org>"); 413 MODULE_LICENSE("GPL v2"); 414 MODULE_ALIAS("platform:" DRV_NAME); 415