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); 146 147 debugfs_create_file("info", S_IFREG | S_IRUGO, dir, wdt, 148 &bcm_kona_fops); 149 wdt->debugfs = dir; 150 } 151 152 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) 153 { 154 struct bcm_kona_wdt *wdt = platform_get_drvdata(pdev); 155 156 if (wdt) 157 debugfs_remove_recursive(wdt->debugfs); 158 } 159 160 #else 161 162 static void bcm_kona_wdt_debug_init(struct platform_device *pdev) {} 163 static void bcm_kona_wdt_debug_exit(struct platform_device *pdev) {} 164 165 #endif /* CONFIG_BCM_KONA_WDT_DEBUG */ 166 167 static int bcm_kona_wdt_ctrl_reg_modify(struct bcm_kona_wdt *wdt, 168 unsigned mask, unsigned newval) 169 { 170 int val; 171 unsigned long flags; 172 int ret = 0; 173 174 spin_lock_irqsave(&wdt->lock, flags); 175 176 val = secure_register_read(wdt, SECWDOG_CTRL_REG); 177 if (val < 0) { 178 ret = val; 179 } else { 180 val &= ~mask; 181 val |= newval; 182 writel_relaxed(val, wdt->base + SECWDOG_CTRL_REG); 183 } 184 185 spin_unlock_irqrestore(&wdt->lock, flags); 186 187 return ret; 188 } 189 190 static int bcm_kona_wdt_set_resolution_reg(struct bcm_kona_wdt *wdt) 191 { 192 if (wdt->resolution > SECWDOG_MAX_RES) 193 return -EINVAL; 194 195 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_RES_MASK, 196 wdt->resolution << SECWDOG_CLKS_SHIFT); 197 } 198 199 static int bcm_kona_wdt_set_timeout_reg(struct watchdog_device *wdog, 200 unsigned watchdog_flags) 201 { 202 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 203 204 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_COUNT_MASK, 205 SECS_TO_TICKS(wdog->timeout, wdt) | 206 watchdog_flags); 207 } 208 209 static int bcm_kona_wdt_set_timeout(struct watchdog_device *wdog, 210 unsigned int t) 211 { 212 wdog->timeout = t; 213 return 0; 214 } 215 216 static unsigned int bcm_kona_wdt_get_timeleft(struct watchdog_device *wdog) 217 { 218 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 219 int val; 220 unsigned long flags; 221 222 spin_lock_irqsave(&wdt->lock, flags); 223 val = secure_register_read(wdt, SECWDOG_COUNT_REG); 224 spin_unlock_irqrestore(&wdt->lock, flags); 225 226 if (val < 0) 227 return val; 228 229 return TICKS_TO_SECS(val & SECWDOG_COUNT_MASK, wdt); 230 } 231 232 static int bcm_kona_wdt_start(struct watchdog_device *wdog) 233 { 234 return bcm_kona_wdt_set_timeout_reg(wdog, 235 SECWDOG_EN_MASK | SECWDOG_SRSTEN_MASK); 236 } 237 238 static int bcm_kona_wdt_stop(struct watchdog_device *wdog) 239 { 240 struct bcm_kona_wdt *wdt = watchdog_get_drvdata(wdog); 241 242 return bcm_kona_wdt_ctrl_reg_modify(wdt, SECWDOG_EN_MASK | 243 SECWDOG_SRSTEN_MASK, 0); 244 } 245 246 static const struct watchdog_ops bcm_kona_wdt_ops = { 247 .owner = THIS_MODULE, 248 .start = bcm_kona_wdt_start, 249 .stop = bcm_kona_wdt_stop, 250 .set_timeout = bcm_kona_wdt_set_timeout, 251 .get_timeleft = bcm_kona_wdt_get_timeleft, 252 }; 253 254 static const struct watchdog_info bcm_kona_wdt_info = { 255 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | 256 WDIOF_KEEPALIVEPING, 257 .identity = "Broadcom Kona Watchdog Timer", 258 }; 259 260 static struct watchdog_device bcm_kona_wdt_wdd = { 261 .info = &bcm_kona_wdt_info, 262 .ops = &bcm_kona_wdt_ops, 263 .min_timeout = 1, 264 .max_timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 265 .timeout = SECWDOG_MAX_COUNT >> SECWDOG_DEFAULT_RESOLUTION, 266 }; 267 268 static int bcm_kona_wdt_probe(struct platform_device *pdev) 269 { 270 struct device *dev = &pdev->dev; 271 struct bcm_kona_wdt *wdt; 272 int ret; 273 274 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 275 if (!wdt) 276 return -ENOMEM; 277 278 spin_lock_init(&wdt->lock); 279 280 wdt->base = devm_platform_ioremap_resource(pdev, 0); 281 if (IS_ERR(wdt->base)) 282 return -ENODEV; 283 284 wdt->resolution = SECWDOG_DEFAULT_RESOLUTION; 285 ret = bcm_kona_wdt_set_resolution_reg(wdt); 286 if (ret) { 287 dev_err(dev, "Failed to set resolution (error: %d)", ret); 288 return ret; 289 } 290 291 platform_set_drvdata(pdev, wdt); 292 watchdog_set_drvdata(&bcm_kona_wdt_wdd, wdt); 293 bcm_kona_wdt_wdd.parent = dev; 294 295 ret = bcm_kona_wdt_set_timeout_reg(&bcm_kona_wdt_wdd, 0); 296 if (ret) { 297 dev_err(dev, "Failed set watchdog timeout"); 298 return ret; 299 } 300 301 watchdog_stop_on_reboot(&bcm_kona_wdt_wdd); 302 watchdog_stop_on_unregister(&bcm_kona_wdt_wdd); 303 ret = devm_watchdog_register_device(dev, &bcm_kona_wdt_wdd); 304 if (ret) 305 return ret; 306 307 bcm_kona_wdt_debug_init(pdev); 308 dev_dbg(dev, "Broadcom Kona Watchdog Timer"); 309 310 return 0; 311 } 312 313 static int bcm_kona_wdt_remove(struct platform_device *pdev) 314 { 315 bcm_kona_wdt_debug_exit(pdev); 316 dev_dbg(&pdev->dev, "Watchdog driver disabled"); 317 318 return 0; 319 } 320 321 static const struct of_device_id bcm_kona_wdt_of_match[] = { 322 { .compatible = "brcm,kona-wdt", }, 323 {}, 324 }; 325 MODULE_DEVICE_TABLE(of, bcm_kona_wdt_of_match); 326 327 static struct platform_driver bcm_kona_wdt_driver = { 328 .driver = { 329 .name = BCM_KONA_WDT_NAME, 330 .of_match_table = bcm_kona_wdt_of_match, 331 }, 332 .probe = bcm_kona_wdt_probe, 333 .remove = bcm_kona_wdt_remove, 334 }; 335 336 module_platform_driver(bcm_kona_wdt_driver); 337 338 MODULE_ALIAS("platform:" BCM_KONA_WDT_NAME); 339 MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); 340 MODULE_DESCRIPTION("Broadcom Kona Watchdog Driver"); 341 MODULE_LICENSE("GPL v2"); 342