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, ret; 103 unsigned long flags; 104 struct bcm_kona_wdt *wdt = s->private; 105 106 if (!wdt) 107 return seq_puts(s, "No device pointer\n"); 108 109 spin_lock_irqsave(&wdt->lock, flags); 110 ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG); 111 cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG); 112 spin_unlock_irqrestore(&wdt->lock, flags); 113 114 if (ctl_val < 0 || cur_val < 0) { 115 ret = seq_puts(s, "Error accessing hardware\n"); 116 } else { 117 int ctl, cur, ctl_sec, cur_sec, res; 118 119 ctl = ctl_val & SECWDOG_COUNT_MASK; 120 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT; 121 cur = cur_val & SECWDOG_COUNT_MASK; 122 ctl_sec = TICKS_TO_SECS(ctl, wdt); 123 cur_sec = TICKS_TO_SECS(cur, wdt); 124 ret = seq_printf(s, "Resolution: %d / %d\n" 125 "Control: %d s / %d (%#x) ticks\n" 126 "Current: %d s / %d (%#x) ticks\n" 127 "Busy count: %lu\n", res, 128 wdt->resolution, ctl_sec, ctl, ctl, cur_sec, 129 cur, cur, wdt->busy_count); 130 } 131 132 return ret; 133 } 134 135 static int bcm_kona_dbg_open(struct inode *inode, struct file *file) 136 { 137 return single_open(file, bcm_kona_wdt_dbg_show, inode->i_private); 138 } 139 140 static const struct file_operations bcm_kona_dbg_operations = { 141 .open = bcm_kona_dbg_open, 142 .read = seq_read, 143 .llseek = seq_lseek, 144 .release = single_release, 145 }; 146 147 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) 148 { 149 struct dentry *dir; 150 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 151 152 if (!wdt) 153 return; 154 155 wdt->debugfs = NULL; 156 157 dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL); 158 if (IS_ERR_OR_NULL(dir)) 159 return; 160 161 if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt, 162 &bcm_kona_dbg_operations)) 163 wdt->debugfs = dir; 164 else 165 debugfs_remove_recursive(dir); 166 } 167 168 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) 169 { 170 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 171 172 if (wdt && wdt->debugfs) { 173 debugfs_remove_recursive(wdt->debugfs); 174 wdt->debugfs = NULL; 175 } 176 } 177 178 #else 179 180 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {} 181 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {} 182 183 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */ 184 185 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, 186 unsigned mask, unsigned newval) 187 { 188 int val; 189 unsigned long flags; 190 int ret = 0; 191 192 spin_lock_irqsave(&wdt->lock, flags); 193 194 val = secure_register_read(wdt, SECWDOG_CTRL_REG); 195 if (val < 0) { 196 ret = val; 197 } else { 198 val &= ~mask; 199 val |= newval; 200 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); 201 } 202 203 spin_unlock_irqrestore(&wdt->lock, flags); 204 205 return ret; 206 } 207 208 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) 209 { 210 if (wdt->resolution > SECWDOG_MAX_RES) 211 return -EINVAL; 212 213 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, 214 wdt->resolution << SECWDOG_CLKS_SHIFT); 215 } 216 217 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, 218 unsigned watchdog_flags) 219 { 220 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 221 222 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, 223 SECS_TO_TICKS(wdog->timeout, wdt) | 224 watchdog_flags); 225 } 226 227 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, 228 unsigned int t) 229 { 230 wdog->timeout = t; 231 return 0; 232 } 233 234 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) 235 { 236 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 237 int val; 238 unsigned long flags; 239 240 spin_lock_irqsave(&wdt->lock, flags); 241 val = secure_register_read(wdt, SECWDOG_COUNT_REG); 242 spin_unlock_irqrestore(&wdt->lock, flags); 243 244 if (val < 0) 245 return val; 246 247 return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); 248 } 249 250 static int bcm_kona_wdt_start(struct watchdog_device *wdog) 251 { 252 return bcm_kona_wdt_set_timeout_reg(wdog, 253 SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); 254 } 255 256 static int bcm_kona_wdt_stop(struct watchdog_device *wdog) 257 { 258 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 259 260 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | 261 SECWDOG_SRSTEN_MASK, 0); 262 } 263 264 static struct watchdog_ops bcm_kona_wdt_ops = { 265 .owner = THIS_MODULE, 266 .start = bcm_kona_wdt_start, 267 .stop = bcm_kona_wdt_stop, 268 .set_timeout = bcm_kona_wdt_set_timeout, 269 .get_timeleft = bcm_kona_wdt_get_timeleft, 270 }; 271 272 static struct watchdog_info bcm_kona_wdt_info = { 273 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 274 WDIOF_KEEPALIVEPING, 275 .identity = "Broadcom Kona Watchdog Timer", 276 }; 277 278 static struct watchdog_device bcm_kona_wdt_wdd = { 279 .info = &bcm_kona_wdt_info, 280 .ops = &bcm_kona_wdt_ops, 281 .min_timeout = 1, 282 .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 283 .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 284 }; 285 286 static void bcm_kona_wdt_shutdown(struct platform_device *pdev) 287 { 288 bcm_kona_wdt_stop(&bcm_kona_wdt_wdd); 289 } 290 291 static int bcm_kona_wdt_probe(struct platform_device *pdev) 292 { 293 struct device *dev = &pdev->dev; 294 struct bcm_kona_wdt *wdt; 295 struct resource *res; 296 int ret; 297 298 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 299 if (!wdt) 300 return -ENOMEM; 301 302 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 303 wdt->base = devm_ioremap_resource(dev, res); 304 if (IS_ERR(wdt->base)) 305 return -ENODEV; 306 307 wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; 308 ret = bcm_kona_wdt_set_resolution_reg(wdt); 309 if (ret) { 310 dev_err(dev, "Failed to set resolution (error: %d)", ret); 311 return ret; 312 } 313 314 spin_lock_init(&wdt->lock); 315 platform_set_drvdata(pdev, wdt); 316 watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); 317 318 ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); 319 if (ret) { 320 dev_err(dev, "Failed set watchdog timeout"); 321 return ret; 322 } 323 324 ret = watchdog_register_device(&bcm_kona_wdt_wdd); 325 if (ret) { 326 dev_err(dev, "Failed to register watchdog device"); 327 return ret; 328 } 329 330 bcm_kona_wdt_debug_init(pdev); 331 dev_dbg(dev, "Broadcom Kona Watchdog Timer"); 332 333 return 0; 334 } 335 336 static int bcm_kona_wdt_remove(struct platform_device *pdev) 337 { 338 bcm_kona_wdt_debug_exit(pdev); 339 bcm_kona_wdt_shutdown(pdev); 340 watchdog_unregister_device(&bcm_kona_wdt_wdd); 341 dev_dbg(&pdev->dev, "Watchdog driver disabled"); 342 343 return 0; 344 } 345 346 static const struct of_device_id bcm_kona_wdt_of_match[] = { 347 { .compatible = "brcm,kona-wdt", }, 348 {}, 349 }; 350 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); 351 352 static struct platform_driver bcm_kona_wdt_driver = { 353 .driver = { 354 .name = BCM_KONA_WDT_NAME, 355 .owner = THIS_MODULE, 356 .of_match_table = bcm_kona_wdt_of_match, 357 }, 358 .probe = bcm_kona_wdt_probe, 359 .remove = bcm_kona_wdt_remove, 360 .shutdown = bcm_kona_wdt_shutdown, 361 }; 362 363 module_platform_driver(bcm_kona_wdt_driver); 364 365 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); 366 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); 367 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); 368 MODULE_LICENSE("GPL v2"); 369