1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Watchdog driver for the K3 RTI module 4 * 5 * (c) Copyright 2019-2020 Texas Instruments Inc. 6 * All rights reserved. 7 */ 8 9 #include <linux/clk.h> 10 #include <linux/device.h> 11 #include <linux/err.h> 12 #include <linux/io.h> 13 #include <linux/kernel.h> 14 #include <linux/mod_devicetable.h> 15 #include <linux/module.h> 16 #include <linux/moduleparam.h> 17 #include <linux/platform_device.h> 18 #include <linux/pm_runtime.h> 19 #include <linux/types.h> 20 #include <linux/watchdog.h> 21 22 #define DEFAULT_HEARTBEAT 60 23 24 /* Max heartbeat is calculated at 32kHz source clock */ 25 #define MAX_HEARTBEAT 1000 26 27 /* Timer register set definition */ 28 #define RTIDWDCTRL 0x90 29 #define RTIDWDPRLD 0x94 30 #define RTIWDSTATUS 0x98 31 #define RTIWDKEY 0x9c 32 #define RTIDWDCNTR 0xa0 33 #define RTIWWDRXCTRL 0xa4 34 #define RTIWWDSIZECTRL 0xa8 35 36 #define RTIWWDRX_NMI 0xa 37 38 #define RTIWWDSIZE_50P 0x50 39 #define RTIWWDSIZE_25P 0x500 40 #define RTIWWDSIZE_12P5 0x5000 41 #define RTIWWDSIZE_6P25 0x50000 42 #define RTIWWDSIZE_3P125 0x500000 43 44 #define WDENABLE_KEY 0xa98559da 45 46 #define WDKEY_SEQ0 0xe51a 47 #define WDKEY_SEQ1 0xa35c 48 49 #define WDT_PRELOAD_SHIFT 13 50 51 #define WDT_PRELOAD_MAX 0xfff 52 53 #define DWDST BIT(1) 54 55 static int heartbeat = DEFAULT_HEARTBEAT; 56 57 /* 58 * struct to hold data for each WDT device 59 * @base - base io address of WD device 60 * @freq - source clock frequency of WDT 61 * @wdd - hold watchdog device as is in WDT core 62 */ 63 struct rti_wdt_device { 64 void __iomem *base; 65 unsigned long freq; 66 struct watchdog_device wdd; 67 }; 68 69 static int rti_wdt_start(struct watchdog_device *wdd) 70 { 71 u32 timer_margin; 72 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd); 73 74 /* set timeout period */ 75 timer_margin = (u64)wdd->timeout * wdt->freq; 76 timer_margin >>= WDT_PRELOAD_SHIFT; 77 if (timer_margin > WDT_PRELOAD_MAX) 78 timer_margin = WDT_PRELOAD_MAX; 79 writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD); 80 81 /* 82 * RTI only supports a windowed mode, where the watchdog can only 83 * be petted during the open window; not too early or not too late. 84 * The HW configuration options only allow for the open window size 85 * to be 50% or less than that; we obviouly want to configure the open 86 * window as large as possible so we select the 50% option. 87 */ 88 wdd->min_hw_heartbeat_ms = 500 * wdd->timeout; 89 90 /* Generate NMI when wdt expires */ 91 writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL); 92 93 /* Open window size 50%; this is the largest window size available */ 94 writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL); 95 96 readl_relaxed(wdt->base + RTIWWDSIZECTRL); 97 98 /* enable watchdog */ 99 writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL); 100 return 0; 101 } 102 103 static int rti_wdt_ping(struct watchdog_device *wdd) 104 { 105 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd); 106 107 /* put watchdog in service state */ 108 writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY); 109 /* put watchdog in active state */ 110 writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY); 111 112 return 0; 113 } 114 115 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize) 116 { 117 /* 118 * RTI only supports a windowed mode, where the watchdog can only 119 * be petted during the open window; not too early or not too late. 120 * The HW configuration options only allow for the open window size 121 * to be 50% or less than that. 122 */ 123 switch (wsize) { 124 case RTIWWDSIZE_50P: 125 /* 50% open window => 50% min heartbeat */ 126 wdd->min_hw_heartbeat_ms = 500 * heartbeat; 127 break; 128 129 case RTIWWDSIZE_25P: 130 /* 25% open window => 75% min heartbeat */ 131 wdd->min_hw_heartbeat_ms = 750 * heartbeat; 132 break; 133 134 case RTIWWDSIZE_12P5: 135 /* 12.5% open window => 87.5% min heartbeat */ 136 wdd->min_hw_heartbeat_ms = 875 * heartbeat; 137 break; 138 139 case RTIWWDSIZE_6P25: 140 /* 6.5% open window => 93.5% min heartbeat */ 141 wdd->min_hw_heartbeat_ms = 935 * heartbeat; 142 break; 143 144 case RTIWWDSIZE_3P125: 145 /* 3.125% open window => 96.9% min heartbeat */ 146 wdd->min_hw_heartbeat_ms = 969 * heartbeat; 147 break; 148 149 default: 150 return -EINVAL; 151 } 152 153 return 0; 154 } 155 156 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd) 157 { 158 u64 timer_counter; 159 u32 val; 160 struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd); 161 162 /* if timeout has occurred then return 0 */ 163 val = readl_relaxed(wdt->base + RTIWDSTATUS); 164 if (val & DWDST) 165 return 0; 166 167 timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR); 168 169 timer_counter *= 1000; 170 171 do_div(timer_counter, wdt->freq); 172 173 return timer_counter; 174 } 175 176 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd) 177 { 178 return rti_wdt_get_timeleft_ms(wdd) / 1000; 179 } 180 181 static const struct watchdog_info rti_wdt_info = { 182 .options = WDIOF_KEEPALIVEPING, 183 .identity = "K3 RTI Watchdog", 184 }; 185 186 static const struct watchdog_ops rti_wdt_ops = { 187 .owner = THIS_MODULE, 188 .start = rti_wdt_start, 189 .ping = rti_wdt_ping, 190 .get_timeleft = rti_wdt_get_timeleft, 191 }; 192 193 static int rti_wdt_probe(struct platform_device *pdev) 194 { 195 int ret = 0; 196 struct device *dev = &pdev->dev; 197 struct watchdog_device *wdd; 198 struct rti_wdt_device *wdt; 199 struct clk *clk; 200 u32 last_ping = 0; 201 202 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 203 if (!wdt) 204 return -ENOMEM; 205 206 clk = clk_get(dev, NULL); 207 if (IS_ERR(clk)) 208 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n"); 209 210 wdt->freq = clk_get_rate(clk); 211 212 clk_put(clk); 213 214 if (!wdt->freq) { 215 dev_err(dev, "Failed to get fck rate.\n"); 216 return -EINVAL; 217 } 218 219 /* 220 * If watchdog is running at 32k clock, it is not accurate. 221 * Adjust frequency down in this case so that we don't pet 222 * the watchdog too often. 223 */ 224 if (wdt->freq < 32768) 225 wdt->freq = wdt->freq * 9 / 10; 226 227 pm_runtime_enable(dev); 228 ret = pm_runtime_resume_and_get(dev); 229 if (ret < 0) { 230 pm_runtime_disable(&pdev->dev); 231 return dev_err_probe(dev, ret, "runtime pm failed\n"); 232 } 233 234 platform_set_drvdata(pdev, wdt); 235 236 wdd = &wdt->wdd; 237 wdd->info = &rti_wdt_info; 238 wdd->ops = &rti_wdt_ops; 239 wdd->min_timeout = 1; 240 wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) / 241 wdt->freq * 1000; 242 wdd->parent = dev; 243 244 watchdog_set_drvdata(wdd, wdt); 245 watchdog_set_nowayout(wdd, 1); 246 watchdog_set_restart_priority(wdd, 128); 247 248 wdt->base = devm_platform_ioremap_resource(pdev, 0); 249 if (IS_ERR(wdt->base)) { 250 ret = PTR_ERR(wdt->base); 251 goto err_iomap; 252 } 253 254 if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) { 255 int preset_heartbeat; 256 u32 time_left_ms; 257 u64 heartbeat_ms; 258 u32 wsize; 259 260 set_bit(WDOG_HW_RUNNING, &wdd->status); 261 time_left_ms = rti_wdt_get_timeleft_ms(wdd); 262 heartbeat_ms = readl(wdt->base + RTIDWDPRLD); 263 heartbeat_ms <<= WDT_PRELOAD_SHIFT; 264 heartbeat_ms *= 1000; 265 do_div(heartbeat_ms, wdt->freq); 266 preset_heartbeat = heartbeat_ms + 500; 267 preset_heartbeat /= 1000; 268 if (preset_heartbeat != heartbeat) 269 dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n"); 270 271 heartbeat = preset_heartbeat; 272 273 wsize = readl(wdt->base + RTIWWDSIZECTRL); 274 ret = rti_wdt_setup_hw_hb(wdd, wsize); 275 if (ret) { 276 dev_err(dev, "bad window size.\n"); 277 goto err_iomap; 278 } 279 280 last_ping = heartbeat_ms - time_left_ms; 281 if (time_left_ms > heartbeat_ms) { 282 dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n"); 283 last_ping = 0; 284 } 285 } 286 287 watchdog_init_timeout(wdd, heartbeat, dev); 288 289 ret = watchdog_register_device(wdd); 290 if (ret) { 291 dev_err(dev, "cannot register watchdog device\n"); 292 goto err_iomap; 293 } 294 295 if (last_ping) 296 watchdog_set_last_hw_keepalive(wdd, last_ping); 297 298 return 0; 299 300 err_iomap: 301 pm_runtime_put_sync(&pdev->dev); 302 pm_runtime_disable(&pdev->dev); 303 304 return ret; 305 } 306 307 static int rti_wdt_remove(struct platform_device *pdev) 308 { 309 struct rti_wdt_device *wdt = platform_get_drvdata(pdev); 310 311 watchdog_unregister_device(&wdt->wdd); 312 pm_runtime_put(&pdev->dev); 313 pm_runtime_disable(&pdev->dev); 314 315 return 0; 316 } 317 318 static const struct of_device_id rti_wdt_of_match[] = { 319 { .compatible = "ti,j7-rti-wdt", }, 320 {}, 321 }; 322 MODULE_DEVICE_TABLE(of, rti_wdt_of_match); 323 324 static struct platform_driver rti_wdt_driver = { 325 .driver = { 326 .name = "rti-wdt", 327 .of_match_table = rti_wdt_of_match, 328 }, 329 .probe = rti_wdt_probe, 330 .remove = rti_wdt_remove, 331 }; 332 333 module_platform_driver(rti_wdt_driver); 334 335 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>"); 336 MODULE_DESCRIPTION("K3 RTI Watchdog Driver"); 337 338 module_param(heartbeat, int, 0); 339 MODULE_PARM_DESC(heartbeat, 340 "Watchdog heartbeat period in seconds from 1 to " 341 __MODULE_STRING(MAX_HEARTBEAT) ", default " 342 __MODULE_STRING(DEFAULT_HEARTBEAT)); 343 344 MODULE_LICENSE("GPL"); 345 MODULE_ALIAS("platform:rti-wdt"); 346