Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 14 | #include <linux/debugfs.h> |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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; |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 59 | #ifdef CONFIG_BCM_KONA_WDT_DEBUG |
| 60 | unsigned long busy_count; |
| 61 | struct dentry *debugfs; |
| 62 | #endif |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 63 | }; |
| 64 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 65 | static int secure_register_read(struct bcm_kona_wdt *wdt, uint32_t offset) |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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); |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 78 | val = readl_relaxed(wdt->base + offset); |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 79 | count++; |
| 80 | } while ((val & SECWDOG_WD_LOAD_FLAG) && count < SECWDOG_MAX_TRY); |
| 81 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 194 | val = secure_register_read(wdt, SECWDOG_CTRL_REG); |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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); |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 241 | val = secure_register_read(wdt, SECWDOG_COUNT_REG); |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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 | |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 330 | bcm_kona_wdt_debug_init(pdev); |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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 | { |
Markus Mayer | 6e2ac20 | 2014-01-06 13:56:10 -0800 | [diff] [blame] | 338 | bcm_kona_wdt_debug_exit(pdev); |
Markus Mayer | 6adb730 | 2013-11-22 14:56:03 -0800 | [diff] [blame] | 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"); |