1 /* 2 * Copyright (C) 2013 Broadcom Corporation 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation version 2. 7 * 8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any 9 * kind, whether express or implied; without even the implied warranty 10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <linux/debugfs.h> 15 #include <linux/delay.h> 16 #include <linux/err.h> 17 #include <linux/io.h> 18 #include <linux/module.h> 19 #include <linux/of_address.h> 20 #include <linux/platform_device.h> 21 #include <linux/watchdog.h> 22 23 #define SECWDOG_CTRL_REG 0x00000000 24 #define SECWDOG_COUNT_REG 0x00000004 25 26 #define SECWDOG_RESERVED_MASK 0x1dffffff 27 #define SECWDOG_WD_LOAD_FLAG 0x10000000 28 #define SECWDOG_EN_MASK 0x08000000 29 #define SECWDOG_SRSTEN_MASK 0x04000000 30 #define SECWDOG_RES_MASK 0x00f00000 31 #define SECWDOG_COUNT_MASK 0x000fffff 32 33 #define SECWDOG_MAX_COUNT SECWDOG_COUNT_MASK 34 #define SECWDOG_CLKS_SHIFT 20 35 #define SECWDOG_MAX_RES 15 36 #define SECWDOG_DEFAULT_RESOLUTION 4 37 #define SECWDOG_MAX_TRY 1000 38 39 #define SECS_TO_TICKS(x, w) ((x) << (w)->resolution) 40 #define TICKS_TO_SECS(x, w) ((x) >> (w)->resolution) 41 42 #define BCM_KONA_WDT_NAME "bcm_kona_wdt" 43 44 struct bcm_kona_wdt { 45 void __iomem *base; 46 /* 47 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take 48 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default 49 * resolution of 4 means one tick is 62.5ms. 50 * 51 * The watchdog counter is 20 bits. Depending on resolution, the maximum 52 * counter value of 0xfffff expires after about 12 days (resolution 0) 53 * down to only 32s (resolution 15). The default resolution of 4 gives 54 * us a maximum of about 18 hours and 12 minutes before the watchdog 55 * times out. 56 */ 57 int resolution; 58 spinlock_t lock; 59 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 60 unsigned long busy_count; 61 struct dentry *debugfs; 62 #endif 63 }; 64 65 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset) 66 { 67 uint32_t val; 68 unsigned count = 0; 69 70 /* 71 * If the WD_LOAD_FLAG is set, the watchdog counter field is being 72 * updated in hardware. Once the WD timer is updated in hardware, it 73 * gets cleared. 74 */ 75 do { 76 if (unlikely(count > 1)) 77 udelay(5); 78 val = readl_relaxed(wdt->base + offset); 79 count++; 80 } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); 81 82 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 83 /* Remember the maximum number iterations due to WD_LOAD_FLAG */ 84 if (count > wdt->busy_count) 85 wdt->busy_count = count; 86 #endif 87 88 /* This is the only place we return a negative value. */ 89 if (val & SECWDOG_WD_LOAD_FLAG) 90 return -ETIMEDOUT; 91 92 /* We always mask out reserved bits. */ 93 val &= SECWDOG_RESERVED_MASK; 94 95 return val; 96 } 97 98 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 99 100 static int bcm_kona_wdt_dbg_show(struct seq_file *s, void *data) 101 { 102 int ctl_val, cur_val; 103 unsigned long flags; 104 struct bcm_kona_wdt *wdt = s->private; 105 106 if (!wdt) { 107 seq_puts(s, "No device pointer\n"); 108 return 0; 109 } 110 111 spin_lock_irqsave(&wdt->lock, flags); 112 ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG); 113 cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG); 114 spin_unlock_irqrestore(&wdt->lock, flags); 115 116 if (ctl_val < 0 || cur_val < 0) { 117 seq_puts(s, "Error accessing hardware\n"); 118 } else { 119 int ctl, cur, ctl_sec, cur_sec, res; 120 121 ctl = ctl_val & SECWDOG_COUNT_MASK; 122 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT; 123 cur = cur_val & SECWDOG_COUNT_MASK; 124 ctl_sec = TICKS_TO_SECS(ctl, wdt); 125 cur_sec = TICKS_TO_SECS(cur, wdt); 126 seq_printf(s, 127 "Resolution: %d / %d\n" 128 "Control: %d s / %d (%#x) ticks\n" 129 "Current: %d s / %d (%#x) ticks\n" 130 "Busy count: %lu\n", 131 res, wdt->resolution, 132 ctl_sec, ctl, ctl, 133 cur_sec, cur, cur, 134 wdt->busy_count); 135 } 136 137 return 0; 138 } 139 140 static int bcm_kona_dbg_open(struct inode *inode, struct file *file) 141 { 142 return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private); 143 } 144 145 static const struct file_operations bcm_kona_dbg_operations = { 146 .open = bcm_kona_dbg_open, 147 .read = seq_read, 148 .llseek = seq_lseek, 149 .release = single_release, 150 }; 151 152 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) 153 { 154 struct dentry *dir; 155 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 156 157 if (!wdt) 158 return; 159 160 wdt->debugfs = NULL; 161 162 dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL); 163 if (IS_ERR_OR_NULL(dir)) 164 return; 165 166 if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt, 167 &bcm_kona_dbg_operations)) 168 wdt->debugfs = dir; 169 else 170 debugfs_remove_recursive(dir); 171 } 172 173 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) 174 { 175 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 176 177 if (wdt && wdt->debugfs) { 178 debugfs_remove_recursive(wdt->debugfs); 179 wdt->debugfs = NULL; 180 } 181 } 182 183 #else 184 185 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {} 186 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {} 187 188 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */ 189 190 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, 191 unsigned mask, unsigned newval) 192 { 193 int val; 194 unsigned long flags; 195 int ret = 0; 196 197 spin_lock_irqsave(&wdt->lock, flags); 198 199 val = secure_register_read(wdt, SECWDOG_CTRL_REG); 200 if (val < 0) { 201 ret = val; 202 } else { 203 val &= ~mask; 204 val |= newval; 205 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); 206 } 207 208 spin_unlock_irqrestore(&wdt->lock, flags); 209 210 return ret; 211 } 212 213 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) 214 { 215 if (wdt->resolution > SECWDOG_MAX_RES) 216 return -EINVAL; 217 218 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, 219 wdt->resolution << SECWDOG_CLKS_SHIFT); 220 } 221 222 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, 223 unsigned watchdog_flags) 224 { 225 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 226 227 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, 228 SECS_TO_TICKS(wdog->timeout, wdt) | 229 watchdog_flags); 230 } 231 232 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, 233 unsigned int t) 234 { 235 wdog->timeout = t; 236 return 0; 237 } 238 239 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) 240 { 241 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 242 int val; 243 unsigned long flags; 244 245 spin_lock_irqsave(&wdt->lock, flags); 246 val = secure_register_read(wdt, SECWDOG_COUNT_REG); 247 spin_unlock_irqrestore(&wdt->lock, flags); 248 249 if (val < 0) 250 return val; 251 252 return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); 253 } 254 255 static int bcm_kona_wdt_start(struct watchdog_device *wdog) 256 { 257 return bcm_kona_wdt_set_timeout_reg(wdog, 258 SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); 259 } 260 261 static int bcm_kona_wdt_stop(struct watchdog_device *wdog) 262 { 263 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 264 265 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | 266 SECWDOG_SRSTEN_MASK, 0); 267 } 268 269 static struct watchdog_ops bcm_kona_wdt_ops = { 270 .owner = THIS_MODULE, 271 .start = bcm_kona_wdt_start, 272 .stop = bcm_kona_wdt_stop, 273 .set_timeout = bcm_kona_wdt_set_timeout, 274 .get_timeleft = bcm_kona_wdt_get_timeleft, 275 }; 276 277 static struct watchdog_info bcm_kona_wdt_info = { 278 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 279 WDIOF_KEEPALIVEPING, 280 .identity = "Broadcom Kona Watchdog Timer", 281 }; 282 283 static struct watchdog_device bcm_kona_wdt_wdd = { 284 .info = &bcm_kona_wdt_info, 285 .ops = &bcm_kona_wdt_ops, 286 .min_timeout = 1, 287 .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 288 .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 289 }; 290 291 static void bcm_kona_wdt_shutdown(struct platform_device *pdev) 292 { 293 bcm_kona_wdt_stop(&bcm_kona_wdt_wdd); 294 } 295 296 static int bcm_kona_wdt_probe(struct platform_device *pdev) 297 { 298 struct device *dev = &pdev->dev; 299 struct bcm_kona_wdt *wdt; 300 struct resource *res; 301 int ret; 302 303 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 304 if (!wdt) 305 return -ENOMEM; 306 307 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 308 wdt->base = devm_ioremap_resource(dev, res); 309 if (IS_ERR(wdt->base)) 310 return -ENODEV; 311 312 wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; 313 ret = bcm_kona_wdt_set_resolution_reg(wdt); 314 if (ret) { 315 dev_err(dev, "Failed to set resolution (error: %d)", ret); 316 return ret; 317 } 318 319 spin_lock_init(&wdt->lock); 320 platform_set_drvdata(pdev, wdt); 321 watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); 322 bcm_kona_wdt_wdd.parent = &pdev->dev; 323 324 ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); 325 if (ret) { 326 dev_err(dev, "Failed set watchdog timeout"); 327 return ret; 328 } 329 330 ret = watchdog_register_device(&bcm_kona_wdt_wdd); 331 if (ret) { 332 dev_err(dev, "Failed to register watchdog device"); 333 return ret; 334 } 335 336 bcm_kona_wdt_debug_init(pdev); 337 dev_dbg(dev, "Broadcom Kona Watchdog Timer"); 338 339 return 0; 340 } 341 342 static int bcm_kona_wdt_remove(struct platform_device *pdev) 343 { 344 bcm_kona_wdt_debug_exit(pdev); 345 bcm_kona_wdt_shutdown(pdev); 346 watchdog_unregister_device(&bcm_kona_wdt_wdd); 347 dev_dbg(&pdev->dev, "Watchdog driver disabled"); 348 349 return 0; 350 } 351 352 static const struct of_device_id bcm_kona_wdt_of_match[] = { 353 { .compatible = "brcm,kona-wdt", }, 354 {}, 355 }; 356 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); 357 358 static struct platform_driver bcm_kona_wdt_driver = { 359 .driver = { 360 .name = BCM_KONA_WDT_NAME, 361 .of_match_table = bcm_kona_wdt_of_match, 362 }, 363 .probe = bcm_kona_wdt_probe, 364 .remove = bcm_kona_wdt_remove, 365 .shutdown = bcm_kona_wdt_shutdown, 366 }; 367 368 module_platform_driver(bcm_kona_wdt_driver); 369 370 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); 371 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); 372 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); 373 MODULE_LICENSE("GPL v2"); 374