1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2013 Broadcom Corporation 4 * 5 */ 6 7 #include <linux/debugfs.h> 8 #include <linux/delay.h> 9 #include <linux/err.h> 10 #include <linux/io.h> 11 #include <linux/module.h> 12 #include <linux/of_address.h> 13 #include <linux/platform_device.h> 14 #include <linux/watchdog.h> 15 16 #define SECWDOG_CTRL_REG 0x00000000 17 #define SECWDOG_COUNT_REG 0x00000004 18 19 #define SECWDOG_RESERVED_MASK 0x1dffffff 20 #define SECWDOG_WD_LOAD_FLAG 0x10000000 21 #define SECWDOG_EN_MASK 0x08000000 22 #define SECWDOG_SRSTEN_MASK 0x04000000 23 #define SECWDOG_RES_MASK 0x00f00000 24 #define SECWDOG_COUNT_MASK 0x000fffff 25 26 #define SECWDOG_MAX_COUNT SECWDOG_COUNT_MASK 27 #define SECWDOG_CLKS_SHIFT 20 28 #define SECWDOG_MAX_RES 15 29 #define SECWDOG_DEFAULT_RESOLUTION 4 30 #define SECWDOG_MAX_TRY 1000 31 32 #define SECS_TO_TICKS(x, w) ((x) << (w)->resolution) 33 #define TICKS_TO_SECS(x, w) ((x) >> (w)->resolution) 34 35 #define BCM_KONA_WDT_NAME "bcm_kona_wdt" 36 37 struct bcm_kona_wdt { 38 void __iomem *base; 39 /* 40 * One watchdog tick is 1/(2^resolution) seconds. Resolution can take 41 * the values 0-15, meaning one tick can be 1s to 30.52us. Our default 42 * resolution of 4 means one tick is 62.5ms. 43 * 44 * The watchdog counter is 20 bits. Depending on resolution, the maximum 45 * counter value of 0xfffff expires after about 12 days (resolution 0) 46 * down to only 32s (resolution 15). The default resolution of 4 gives 47 * us a maximum of about 18 hours and 12 minutes before the watchdog 48 * times out. 49 */ 50 int resolution; 51 spinlock_t lock; 52 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 53 unsigned long busy_count; 54 struct dentry *debugfs; 55 #endif 56 }; 57 58 static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset) 59 { 60 uint32_t val; 61 unsigned count = 0; 62 63 /* 64 * If the WD_LOAD_FLAG is set, the watchdog counter field is being 65 * updated in hardware. Once the WD timer is updated in hardware, it 66 * gets cleared. 67 */ 68 do { 69 if (unlikely(count > 1)) 70 udelay(5); 71 val = readl_relaxed(wdt->base + offset); 72 count++; 73 } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); 74 75 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 76 /* Remember the maximum number iterations due to WD_LOAD_FLAG */ 77 if (count > wdt->busy_count) 78 wdt->busy_count = count; 79 #endif 80 81 /* This is the only place we return a negative value. */ 82 if (val & SECWDOG_WD_LOAD_FLAG) 83 return -ETIMEDOUT; 84 85 /* We always mask out reserved bits. */ 86 val &= SECWDOG_RESERVED_MASK; 87 88 return val; 89 } 90 91 #ifdef CONFIG_BCM_KONA_WDT_DEBUG 92 93 static int bcm_kona_show(struct seq_file *s, void *data) 94 { 95 int ctl_val, cur_val; 96 unsigned long flags; 97 struct bcm_kona_wdt *wdt = s->private; 98 99 if (!wdt) { 100 seq_puts(s, "No device pointer\n"); 101 return 0; 102 } 103 104 spin_lock_irqsave(&wdt->lock, flags); 105 ctl_val = secure_register_read(wdt, SECWDOG_CTRL_REG); 106 cur_val = secure_register_read(wdt, SECWDOG_COUNT_REG); 107 spin_unlock_irqrestore(&wdt->lock, flags); 108 109 if (ctl_val < 0 || cur_val < 0) { 110 seq_puts(s, "Error accessing hardware\n"); 111 } else { 112 int ctl, cur, ctl_sec, cur_sec, res; 113 114 ctl = ctl_val & SECWDOG_COUNT_MASK; 115 res = (ctl_val & SECWDOG_RES_MASK) >> SECWDOG_CLKS_SHIFT; 116 cur = cur_val & SECWDOG_COUNT_MASK; 117 ctl_sec = TICKS_TO_SECS(ctl, wdt); 118 cur_sec = TICKS_TO_SECS(cur, wdt); 119 seq_printf(s, 120 "Resolution: %d / %d\n" 121 "Control: %d s / %d (%#x) ticks\n" 122 "Current: %d s / %d (%#x) ticks\n" 123 "Busy count: %lu\n", 124 res, wdt->resolution, 125 ctl_sec, ctl, ctl, 126 cur_sec, cur, cur, 127 wdt->busy_count); 128 } 129 130 return 0; 131 } 132 133 DEFINE_SHOW_ATTRIBUTE(bcm_kona); 134 135 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) 136 { 137 struct dentry *dir; 138 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 139 140 if (!wdt) 141 return; 142 143 wdt->debugfs = NULL; 144 145 dir = debugfs_create_dir(BCM_KONA_WDT_NAME, NULL); 146 if (IS_ERR_OR_NULL(dir)) 147 return; 148 149 if (debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt, 150 &bcm_kona_fops)) 151 wdt->debugfs = dir; 152 else 153 debugfs_remove_recursive(dir); 154 } 155 156 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) 157 { 158 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 159 160 if (wdt && wdt->debugfs) { 161 debugfs_remove_recursive(wdt->debugfs); 162 wdt->debugfs = NULL; 163 } 164 } 165 166 #else 167 168 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {} 169 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {} 170 171 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */ 172 173 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, 174 unsigned mask, unsigned newval) 175 { 176 int val; 177 unsigned long flags; 178 int ret = 0; 179 180 spin_lock_irqsave(&wdt->lock, flags); 181 182 val = secure_register_read(wdt, SECWDOG_CTRL_REG); 183 if (val < 0) { 184 ret = val; 185 } else { 186 val &= ~mask; 187 val |= newval; 188 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); 189 } 190 191 spin_unlock_irqrestore(&wdt->lock, flags); 192 193 return ret; 194 } 195 196 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) 197 { 198 if (wdt->resolution > SECWDOG_MAX_RES) 199 return -EINVAL; 200 201 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, 202 wdt->resolution << SECWDOG_CLKS_SHIFT); 203 } 204 205 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, 206 unsigned watchdog_flags) 207 { 208 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 209 210 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, 211 SECS_TO_TICKS(wdog->timeout, wdt) | 212 watchdog_flags); 213 } 214 215 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, 216 unsigned int t) 217 { 218 wdog->timeout = t; 219 return 0; 220 } 221 222 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) 223 { 224 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 225 int val; 226 unsigned long flags; 227 228 spin_lock_irqsave(&wdt->lock, flags); 229 val = secure_register_read(wdt, SECWDOG_COUNT_REG); 230 spin_unlock_irqrestore(&wdt->lock, flags); 231 232 if (val < 0) 233 return val; 234 235 return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); 236 } 237 238 static int bcm_kona_wdt_start(struct watchdog_device *wdog) 239 { 240 return bcm_kona_wdt_set_timeout_reg(wdog, 241 SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); 242 } 243 244 static int bcm_kona_wdt_stop(struct watchdog_device *wdog) 245 { 246 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 247 248 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | 249 SECWDOG_SRSTEN_MASK, 0); 250 } 251 252 static const struct watchdog_ops bcm_kona_wdt_ops = { 253 .owner = THIS_MODULE, 254 .start = bcm_kona_wdt_start, 255 .stop = bcm_kona_wdt_stop, 256 .set_timeout = bcm_kona_wdt_set_timeout, 257 .get_timeleft = bcm_kona_wdt_get_timeleft, 258 }; 259 260 static const struct watchdog_info bcm_kona_wdt_info = { 261 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 262 WDIOF_KEEPALIVEPING, 263 .identity = "Broadcom Kona Watchdog Timer", 264 }; 265 266 static struct watchdog_device bcm_kona_wdt_wdd = { 267 .info = &bcm_kona_wdt_info, 268 .ops = &bcm_kona_wdt_ops, 269 .min_timeout = 1, 270 .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 271 .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 272 }; 273 274 static int bcm_kona_wdt_probe(struct platform_device *pdev) 275 { 276 struct device *dev = &pdev->dev; 277 struct bcm_kona_wdt *wdt; 278 int ret; 279 280 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 281 if (!wdt) 282 return -ENOMEM; 283 284 spin_lock_init(&wdt->lock); 285 286 wdt->base = devm_platform_ioremap_resource(pdev, 0); 287 if (IS_ERR(wdt->base)) 288 return -ENODEV; 289 290 wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; 291 ret = bcm_kona_wdt_set_resolution_reg(wdt); 292 if (ret) { 293 dev_err(dev, "Failed to set resolution (error: %d)", ret); 294 return ret; 295 } 296 297 platform_set_drvdata(pdev, wdt); 298 watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); 299 bcm_kona_wdt_wdd.parent = dev; 300 301 ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); 302 if (ret) { 303 dev_err(dev, "Failed set watchdog timeout"); 304 return ret; 305 } 306 307 watchdog_stop_on_reboot(&bcm_kona_wdt_wdd); 308 watchdog_stop_on_unregister(&bcm_kona_wdt_wdd); 309 ret = devm_watchdog_register_device(dev, &bcm_kona_wdt_wdd); 310 if (ret) { 311 dev_err(dev, "Failed to register watchdog device"); 312 return ret; 313 } 314 315 bcm_kona_wdt_debug_init(pdev); 316 dev_dbg(dev, "Broadcom Kona Watchdog Timer"); 317 318 return 0; 319 } 320 321 static int bcm_kona_wdt_remove(struct platform_device *pdev) 322 { 323 bcm_kona_wdt_debug_exit(pdev); 324 dev_dbg(&pdev->dev, "Watchdog driver disabled"); 325 326 return 0; 327 } 328 329 static const struct of_device_id bcm_kona_wdt_of_match[] = { 330 { .compatible = "brcm,kona-wdt", }, 331 {}, 332 }; 333 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); 334 335 static struct platform_driver bcm_kona_wdt_driver = { 336 .driver = { 337 .name = BCM_KONA_WDT_NAME, 338 .of_match_table = bcm_kona_wdt_of_match, 339 }, 340 .probe = bcm_kona_wdt_probe, 341 .remove = bcm_kona_wdt_remove, 342 }; 343 344 module_platform_driver(bcm_kona_wdt_driver); 345 346 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); 347 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); 348 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); 349 MODULE_LICENSE("GPL v2"); 350