David Müller | 8112622 | 2022-09-14 11:46:05 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0+ |
| 2 | /* |
| 3 | * exar_wdt.c - Driver for the watchdog present in some |
| 4 | * Exar/MaxLinear UART chips like the XR28V38x. |
| 5 | * |
| 6 | * (c) Copyright 2022 D. Müller <d.mueller@elsoft.ch>. |
| 7 | * |
| 8 | */ |
| 9 | |
| 10 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 11 | |
| 12 | #include <linux/io.h> |
| 13 | #include <linux/list.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/platform_device.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/watchdog.h> |
| 18 | |
| 19 | #define DRV_NAME "exar_wdt" |
| 20 | |
| 21 | static const unsigned short sio_config_ports[] = { 0x2e, 0x4e }; |
| 22 | static const unsigned char sio_enter_keys[] = { 0x67, 0x77, 0x87, 0xA0 }; |
| 23 | #define EXAR_EXIT_KEY 0xAA |
| 24 | |
| 25 | #define EXAR_LDN 0x07 |
| 26 | #define EXAR_DID 0x20 |
| 27 | #define EXAR_VID 0x23 |
| 28 | #define EXAR_WDT 0x26 |
| 29 | #define EXAR_ACT 0x30 |
| 30 | #define EXAR_RTBASE 0x60 |
| 31 | |
| 32 | #define EXAR_WDT_LDEV 0x08 |
| 33 | |
| 34 | #define EXAR_VEN_ID 0x13A8 |
| 35 | #define EXAR_DEV_382 0x0382 |
| 36 | #define EXAR_DEV_384 0x0384 |
| 37 | |
| 38 | /* WDT runtime registers */ |
| 39 | #define WDT_CTRL 0x00 |
| 40 | #define WDT_VAL 0x01 |
| 41 | |
| 42 | #define WDT_UNITS_10MS 0x0 /* the 10 millisec unit of the HW is not used */ |
| 43 | #define WDT_UNITS_SEC 0x2 |
| 44 | #define WDT_UNITS_MIN 0x4 |
| 45 | |
| 46 | /* default WDT control for WDTOUT signal activ / rearm by read */ |
| 47 | #define EXAR_WDT_DEF_CONF 0 |
| 48 | |
| 49 | struct wdt_pdev_node { |
| 50 | struct list_head list; |
| 51 | struct platform_device *pdev; |
| 52 | const char name[16]; |
| 53 | }; |
| 54 | |
| 55 | struct wdt_priv { |
| 56 | /* the lock for WDT io operations */ |
| 57 | spinlock_t io_lock; |
| 58 | struct resource wdt_res; |
| 59 | struct watchdog_device wdt_dev; |
| 60 | unsigned short did; |
| 61 | unsigned short config_port; |
| 62 | unsigned char enter_key; |
| 63 | unsigned char unit; |
| 64 | unsigned char timeout; |
| 65 | }; |
| 66 | |
| 67 | #define WATCHDOG_TIMEOUT 60 |
| 68 | |
| 69 | static int timeout = WATCHDOG_TIMEOUT; |
| 70 | module_param(timeout, int, 0); |
| 71 | MODULE_PARM_DESC(timeout, |
| 72 | "Watchdog timeout in seconds. 1<=timeout<=15300, default=" |
| 73 | __MODULE_STRING(WATCHDOG_TIMEOUT) "."); |
| 74 | |
| 75 | static bool nowayout = WATCHDOG_NOWAYOUT; |
| 76 | module_param(nowayout, bool, 0); |
| 77 | MODULE_PARM_DESC(nowayout, |
| 78 | "Watchdog cannot be stopped once started (default=" |
| 79 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
| 80 | |
| 81 | static int exar_sio_enter(const unsigned short config_port, |
| 82 | const unsigned char key) |
| 83 | { |
| 84 | if (!request_muxed_region(config_port, 2, DRV_NAME)) |
| 85 | return -EBUSY; |
| 86 | |
| 87 | /* write the ENTER-KEY twice */ |
| 88 | outb(key, config_port); |
| 89 | outb(key, config_port); |
| 90 | |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | static void exar_sio_exit(const unsigned short config_port) |
| 95 | { |
| 96 | outb(EXAR_EXIT_KEY, config_port); |
| 97 | release_region(config_port, 2); |
| 98 | } |
| 99 | |
| 100 | static unsigned char exar_sio_read(const unsigned short config_port, |
| 101 | const unsigned char reg) |
| 102 | { |
| 103 | outb(reg, config_port); |
| 104 | return inb(config_port + 1); |
| 105 | } |
| 106 | |
| 107 | static void exar_sio_write(const unsigned short config_port, |
| 108 | const unsigned char reg, const unsigned char val) |
| 109 | { |
| 110 | outb(reg, config_port); |
| 111 | outb(val, config_port + 1); |
| 112 | } |
| 113 | |
| 114 | static unsigned short exar_sio_read16(const unsigned short config_port, |
| 115 | const unsigned char reg) |
| 116 | { |
| 117 | unsigned char msb, lsb; |
| 118 | |
| 119 | msb = exar_sio_read(config_port, reg); |
| 120 | lsb = exar_sio_read(config_port, reg + 1); |
| 121 | |
| 122 | return (msb << 8) | lsb; |
| 123 | } |
| 124 | |
| 125 | static void exar_sio_select_wdt(const unsigned short config_port) |
| 126 | { |
| 127 | exar_sio_write(config_port, EXAR_LDN, EXAR_WDT_LDEV); |
| 128 | } |
| 129 | |
| 130 | static void exar_wdt_arm(const struct wdt_priv *priv) |
| 131 | { |
| 132 | unsigned short rt_base = priv->wdt_res.start; |
| 133 | |
| 134 | /* write timeout value twice to arm watchdog */ |
| 135 | outb(priv->timeout, rt_base + WDT_VAL); |
| 136 | outb(priv->timeout, rt_base + WDT_VAL); |
| 137 | } |
| 138 | |
| 139 | static void exar_wdt_disarm(const struct wdt_priv *priv) |
| 140 | { |
| 141 | unsigned short rt_base = priv->wdt_res.start; |
| 142 | |
| 143 | /* |
| 144 | * use two accesses with different values to make sure |
| 145 | * that a combination of a previous single access and |
| 146 | * the ones below with the same value are not falsely |
| 147 | * interpreted as "arm watchdog" |
| 148 | */ |
| 149 | outb(0xFF, rt_base + WDT_VAL); |
| 150 | outb(0, rt_base + WDT_VAL); |
| 151 | } |
| 152 | |
| 153 | static int exar_wdt_start(struct watchdog_device *wdog) |
| 154 | { |
| 155 | struct wdt_priv *priv = watchdog_get_drvdata(wdog); |
| 156 | unsigned short rt_base = priv->wdt_res.start; |
| 157 | |
| 158 | spin_lock(&priv->io_lock); |
| 159 | |
| 160 | exar_wdt_disarm(priv); |
| 161 | outb(priv->unit, rt_base + WDT_CTRL); |
| 162 | exar_wdt_arm(priv); |
| 163 | |
| 164 | spin_unlock(&priv->io_lock); |
| 165 | return 0; |
| 166 | } |
| 167 | |
| 168 | static int exar_wdt_stop(struct watchdog_device *wdog) |
| 169 | { |
| 170 | struct wdt_priv *priv = watchdog_get_drvdata(wdog); |
| 171 | |
| 172 | spin_lock(&priv->io_lock); |
| 173 | |
| 174 | exar_wdt_disarm(priv); |
| 175 | |
| 176 | spin_unlock(&priv->io_lock); |
| 177 | return 0; |
| 178 | } |
| 179 | |
| 180 | static int exar_wdt_keepalive(struct watchdog_device *wdog) |
| 181 | { |
| 182 | struct wdt_priv *priv = watchdog_get_drvdata(wdog); |
| 183 | unsigned short rt_base = priv->wdt_res.start; |
| 184 | |
| 185 | spin_lock(&priv->io_lock); |
| 186 | |
| 187 | /* reading the WDT_VAL reg will feed the watchdog */ |
| 188 | inb(rt_base + WDT_VAL); |
| 189 | |
| 190 | spin_unlock(&priv->io_lock); |
| 191 | return 0; |
| 192 | } |
| 193 | |
| 194 | static int exar_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) |
| 195 | { |
| 196 | struct wdt_priv *priv = watchdog_get_drvdata(wdog); |
| 197 | bool unit_min = false; |
| 198 | |
| 199 | /* |
| 200 | * if new timeout is bigger then 255 seconds, change the |
| 201 | * unit to minutes and round the timeout up to the next whole minute |
| 202 | */ |
| 203 | if (t > 255) { |
| 204 | unit_min = true; |
| 205 | t = DIV_ROUND_UP(t, 60); |
| 206 | } |
| 207 | |
| 208 | /* save for later use in exar_wdt_start() */ |
| 209 | priv->unit = unit_min ? WDT_UNITS_MIN : WDT_UNITS_SEC; |
| 210 | priv->timeout = t; |
| 211 | |
| 212 | wdog->timeout = unit_min ? t * 60 : t; |
| 213 | |
| 214 | if (watchdog_hw_running(wdog)) |
| 215 | exar_wdt_start(wdog); |
| 216 | |
| 217 | return 0; |
| 218 | } |
| 219 | |
| 220 | static const struct watchdog_info exar_wdt_info = { |
| 221 | .options = WDIOF_KEEPALIVEPING | |
| 222 | WDIOF_SETTIMEOUT | |
| 223 | WDIOF_MAGICCLOSE, |
| 224 | .identity = "Exar/MaxLinear XR28V38x Watchdog", |
| 225 | }; |
| 226 | |
| 227 | static const struct watchdog_ops exar_wdt_ops = { |
| 228 | .owner = THIS_MODULE, |
| 229 | .start = exar_wdt_start, |
| 230 | .stop = exar_wdt_stop, |
| 231 | .ping = exar_wdt_keepalive, |
| 232 | .set_timeout = exar_wdt_set_timeout, |
| 233 | }; |
| 234 | |
| 235 | static int exar_wdt_config(struct watchdog_device *wdog, |
| 236 | const unsigned char conf) |
| 237 | { |
| 238 | struct wdt_priv *priv = watchdog_get_drvdata(wdog); |
| 239 | int ret; |
| 240 | |
| 241 | ret = exar_sio_enter(priv->config_port, priv->enter_key); |
| 242 | if (ret) |
| 243 | return ret; |
| 244 | |
| 245 | exar_sio_select_wdt(priv->config_port); |
| 246 | exar_sio_write(priv->config_port, EXAR_WDT, conf); |
| 247 | |
| 248 | exar_sio_exit(priv->config_port); |
| 249 | |
| 250 | return 0; |
| 251 | } |
| 252 | |
| 253 | static int __init exar_wdt_probe(struct platform_device *pdev) |
| 254 | { |
| 255 | struct device *dev = &pdev->dev; |
| 256 | struct wdt_priv *priv = dev->platform_data; |
| 257 | struct watchdog_device *wdt_dev = &priv->wdt_dev; |
| 258 | struct resource *res; |
| 259 | int ret; |
| 260 | |
| 261 | res = platform_get_resource(pdev, IORESOURCE_IO, 0); |
| 262 | if (!res) |
| 263 | return -ENXIO; |
| 264 | |
| 265 | spin_lock_init(&priv->io_lock); |
| 266 | |
| 267 | wdt_dev->info = &exar_wdt_info; |
| 268 | wdt_dev->ops = &exar_wdt_ops; |
| 269 | wdt_dev->min_timeout = 1; |
| 270 | wdt_dev->max_timeout = 255 * 60; |
| 271 | |
| 272 | watchdog_init_timeout(wdt_dev, timeout, NULL); |
| 273 | watchdog_set_nowayout(wdt_dev, nowayout); |
| 274 | watchdog_stop_on_reboot(wdt_dev); |
| 275 | watchdog_stop_on_unregister(wdt_dev); |
| 276 | watchdog_set_drvdata(wdt_dev, priv); |
| 277 | |
| 278 | ret = exar_wdt_config(wdt_dev, EXAR_WDT_DEF_CONF); |
| 279 | if (ret) |
| 280 | return ret; |
| 281 | |
| 282 | exar_wdt_set_timeout(wdt_dev, timeout); |
| 283 | /* Make sure that the watchdog is not running */ |
| 284 | exar_wdt_stop(wdt_dev); |
| 285 | |
| 286 | ret = devm_watchdog_register_device(dev, wdt_dev); |
| 287 | if (ret) |
| 288 | return ret; |
| 289 | |
| 290 | dev_info(dev, "XR28V%X WDT initialized. timeout=%d sec (nowayout=%d)\n", |
| 291 | priv->did, timeout, nowayout); |
| 292 | |
| 293 | return 0; |
| 294 | } |
| 295 | |
| 296 | static unsigned short __init exar_detect(const unsigned short config_port, |
| 297 | const unsigned char key, |
| 298 | unsigned short *rt_base) |
| 299 | { |
| 300 | int ret; |
| 301 | unsigned short base = 0; |
| 302 | unsigned short vid, did; |
| 303 | |
| 304 | ret = exar_sio_enter(config_port, key); |
| 305 | if (ret) |
| 306 | return 0; |
| 307 | |
| 308 | vid = exar_sio_read16(config_port, EXAR_VID); |
| 309 | did = exar_sio_read16(config_port, EXAR_DID); |
| 310 | |
| 311 | /* check for the vendor and device IDs we currently know about */ |
| 312 | if (vid == EXAR_VEN_ID && |
| 313 | (did == EXAR_DEV_382 || |
| 314 | did == EXAR_DEV_384)) { |
| 315 | exar_sio_select_wdt(config_port); |
| 316 | /* is device active? */ |
| 317 | if (exar_sio_read(config_port, EXAR_ACT) == 0x01) |
| 318 | base = exar_sio_read16(config_port, EXAR_RTBASE); |
| 319 | } |
| 320 | |
| 321 | exar_sio_exit(config_port); |
| 322 | |
| 323 | if (base) { |
| 324 | pr_debug("Found a XR28V%X WDT (conf: 0x%x / rt: 0x%04x)\n", |
| 325 | did, config_port, base); |
| 326 | *rt_base = base; |
| 327 | return did; |
| 328 | } |
| 329 | |
| 330 | return 0; |
| 331 | } |
| 332 | |
| 333 | static struct platform_driver exar_wdt_driver = { |
| 334 | .driver = { |
| 335 | .name = DRV_NAME, |
| 336 | }, |
| 337 | }; |
| 338 | |
| 339 | static LIST_HEAD(pdev_list); |
| 340 | |
| 341 | static int __init exar_wdt_register(struct wdt_priv *priv, const int idx) |
| 342 | { |
| 343 | struct wdt_pdev_node *n; |
| 344 | |
| 345 | n = kzalloc(sizeof(*n), GFP_KERNEL); |
| 346 | if (!n) |
| 347 | return -ENOMEM; |
| 348 | |
| 349 | INIT_LIST_HEAD(&n->list); |
| 350 | |
| 351 | scnprintf((char *)n->name, sizeof(n->name), DRV_NAME ".%d", idx); |
| 352 | priv->wdt_res.name = n->name; |
| 353 | |
| 354 | n->pdev = platform_device_register_resndata(NULL, DRV_NAME, idx, |
| 355 | &priv->wdt_res, 1, |
| 356 | priv, sizeof(*priv)); |
| 357 | if (IS_ERR(n->pdev)) { |
Manank Patel | 82ebbe6 | 2022-10-13 15:22:58 +0530 | [diff] [blame] | 358 | int err = PTR_ERR(n->pdev); |
| 359 | |
David Müller | 8112622 | 2022-09-14 11:46:05 +0200 | [diff] [blame] | 360 | kfree(n); |
Manank Patel | 82ebbe6 | 2022-10-13 15:22:58 +0530 | [diff] [blame] | 361 | return err; |
David Müller | 8112622 | 2022-09-14 11:46:05 +0200 | [diff] [blame] | 362 | } |
| 363 | |
| 364 | list_add_tail(&n->list, &pdev_list); |
| 365 | |
| 366 | return 0; |
| 367 | } |
| 368 | |
| 369 | static void exar_wdt_unregister(void) |
| 370 | { |
| 371 | struct wdt_pdev_node *n, *t; |
| 372 | |
| 373 | list_for_each_entry_safe(n, t, &pdev_list, list) { |
| 374 | platform_device_unregister(n->pdev); |
| 375 | list_del(&n->list); |
| 376 | kfree(n); |
| 377 | } |
| 378 | } |
| 379 | |
| 380 | static int __init exar_wdt_init(void) |
| 381 | { |
| 382 | int ret, i, j, idx = 0; |
| 383 | |
| 384 | /* search for active Exar watchdogs on all possible locations */ |
| 385 | for (i = 0; i < ARRAY_SIZE(sio_config_ports); i++) { |
| 386 | for (j = 0; j < ARRAY_SIZE(sio_enter_keys); j++) { |
| 387 | unsigned short did, rt_base = 0; |
| 388 | |
| 389 | did = exar_detect(sio_config_ports[i], |
| 390 | sio_enter_keys[j], |
| 391 | &rt_base); |
| 392 | |
| 393 | if (did) { |
| 394 | struct wdt_priv priv = { |
| 395 | .wdt_res = DEFINE_RES_IO(rt_base, 2), |
| 396 | .did = did, |
| 397 | .config_port = sio_config_ports[i], |
| 398 | .enter_key = sio_enter_keys[j], |
| 399 | }; |
| 400 | |
| 401 | ret = exar_wdt_register(&priv, idx); |
| 402 | if (!ret) |
| 403 | idx++; |
| 404 | } |
| 405 | } |
| 406 | } |
| 407 | |
| 408 | if (!idx) |
| 409 | return -ENODEV; |
| 410 | |
| 411 | ret = platform_driver_probe(&exar_wdt_driver, exar_wdt_probe); |
| 412 | if (ret) |
| 413 | exar_wdt_unregister(); |
| 414 | |
| 415 | return ret; |
| 416 | } |
| 417 | |
| 418 | static void __exit exar_wdt_exit(void) |
| 419 | { |
| 420 | exar_wdt_unregister(); |
| 421 | platform_driver_unregister(&exar_wdt_driver); |
| 422 | } |
| 423 | |
| 424 | module_init(exar_wdt_init); |
| 425 | module_exit(exar_wdt_exit); |
| 426 | |
| 427 | MODULE_AUTHOR("David Müller <d.mueller@elsoft.ch>"); |
| 428 | MODULE_DESCRIPTION("Exar/MaxLinear Watchdog Driver"); |
| 429 | MODULE_LICENSE("GPL"); |