drivers/watchdog/aspeed_wdt.c

   1 /*
   2  * Copyright 2016 IBM Corporation
   3  *
   4  * Joel Stanley <joel@jms.id.au>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/delay.h>
  13 #include <linux/io.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/watchdog.h>
  19
  20 struct aspeed_wdt {
  21         struct watchdog_device  wdd;
  22         void __iomem            *base;
  23         u32                     ctrl;
  24 };
  25
  26 struct aspeed_wdt_config {
  27         u32 ext_pulse_width_mask;
  28 };
  29
  30 static const struct aspeed_wdt_config ast2400_config = {
  31         .ext_pulse_width_mask = 0xff,
  32 };
  33
  34 static const struct aspeed_wdt_config ast2500_config = {
  35         .ext_pulse_width_mask = 0xfffff,
  36 };
  37
  38 static const struct of_device_id aspeed_wdt_of_table[] = {
  39         { .compatible = "aspeed,ast2400-wdt", .data = &ast2400_config },
  40         { .compatible = "aspeed,ast2500-wdt", .data = &ast2500_config },
  41         { },
  42 };
  43 MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
  44
  45 #define WDT_STATUS              0x00
  46 #define WDT_RELOAD_VALUE        0x04
  47 #define WDT_RESTART             0x08
  48 #define WDT_CTRL                0x0C
  49 #define   WDT_CTRL_RESET_MODE_SOC       (0x00 << 5)
  50 #define   WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
  51 #define   WDT_CTRL_RESET_MODE_ARM_CPU   (0x10 << 5)
  52 #define   WDT_CTRL_1MHZ_CLK             BIT(4)
  53 #define   WDT_CTRL_WDT_EXT              BIT(3)
  54 #define   WDT_CTRL_WDT_INTR             BIT(2)
  55 #define   WDT_CTRL_RESET_SYSTEM         BIT(1)
  56 #define   WDT_CTRL_ENABLE               BIT(0)
  57
  58 /*
  59  * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
  60  * enabled), specifically:
  61  *
  62  * * Pulse duration
  63  * * Drive mode: push-pull vs open-drain
  64  * * Polarity: Active high or active low
  65  *
  66  * Pulse duration configuration is available on both the AST2400 and AST2500,
  67  * though the field changes between SoCs:
  68  *
  69  * AST2400: Bits 7:0
  70  * AST2500: Bits 19:0
  71  *
  72  * This difference is captured in struct aspeed_wdt_config.
  73  *
  74  * The AST2500 exposes the drive mode and polarity options, but not in a
  75  * regular fashion. For read purposes, bit 31 represents active high or low,
  76  * and bit 30 represents push-pull or open-drain. With respect to write, magic
  77  * values need to be written to the top byte to change the state of the drive
  78  * mode and polarity bits. Any other value written to the top byte has no
  79  * effect on the state of the drive mode or polarity bits. However, the pulse
  80  * width value must be preserved (as desired) if written.
  81  */
  82 #define WDT_RESET_WIDTH         0x18
  83 #define   WDT_RESET_WIDTH_ACTIVE_HIGH   BIT(31)
  84 #define     WDT_ACTIVE_HIGH_MAGIC       (0xA5 << 24)
  85 #define     WDT_ACTIVE_LOW_MAGIC        (0x5A << 24)
  86 #define   WDT_RESET_WIDTH_PUSH_PULL     BIT(30)
  87 #define     WDT_PUSH_PULL_MAGIC         (0xA8 << 24)
  88 #define     WDT_OPEN_DRAIN_MAGIC        (0x8A << 24)
  89
  90 #define WDT_RESTART_MAGIC       0x4755
  91
  92 /* 32 bits at 1MHz, in milliseconds */
  93 #define WDT_MAX_TIMEOUT_MS      4294967
  94 #define WDT_DEFAULT_TIMEOUT     30
  95 #define WDT_RATE_1MHZ           1000000
  96
  97 static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd)
  98 {
  99         return container_of(wdd, struct aspeed_wdt, wdd);
 100 }
 101
 102 static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count)
 103 {
 104         wdt->ctrl |= WDT_CTRL_ENABLE;
 105
 106         writel(0, wdt->base + WDT_CTRL);
 107         writel(count, wdt->base + WDT_RELOAD_VALUE);
 108         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 109         writel(wdt->ctrl, wdt->base + WDT_CTRL);
 110 }
 111
 112 static int aspeed_wdt_start(struct watchdog_device *wdd)
 113 {
 114         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 115
 116         aspeed_wdt_enable(wdt, wdd->timeout * WDT_RATE_1MHZ);
 117
 118         return 0;
 119 }
 120
 121 static int aspeed_wdt_stop(struct watchdog_device *wdd)
 122 {
 123         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 124
 125         wdt->ctrl &= ~WDT_CTRL_ENABLE;
 126         writel(wdt->ctrl, wdt->base + WDT_CTRL);
 127
 128         return 0;
 129 }
 130
 131 static int aspeed_wdt_ping(struct watchdog_device *wdd)
 132 {
 133         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 134
 135         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 136
 137         return 0;
 138 }
 139
 140 static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
 141                                   unsigned int timeout)
 142 {
 143         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 144         u32 actual;
 145
 146         wdd->timeout = timeout;
 147
 148         actual = min(timeout, wdd->max_hw_heartbeat_ms * 1000);
 149
 150         writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE);
 151         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 152
 153         return 0;
 154 }
 155
 156 static int aspeed_wdt_restart(struct watchdog_device *wdd,
 157                               unsigned long action, void *data)
 158 {
 159         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 160
 161         aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
 162
 163         mdelay(1000);
 164
 165         return 0;
 166 }
 167
 168 static const struct watchdog_ops aspeed_wdt_ops = {
 169         .start          = aspeed_wdt_start,
 170         .stop           = aspeed_wdt_stop,
 171         .ping           = aspeed_wdt_ping,
 172         .set_timeout    = aspeed_wdt_set_timeout,
 173         .restart        = aspeed_wdt_restart,
 174         .owner          = THIS_MODULE,
 175 };
 176
 177 static const struct watchdog_info aspeed_wdt_info = {
 178         .options        = WDIOF_KEEPALIVEPING
 179                         | WDIOF_MAGICCLOSE
 180                         | WDIOF_SETTIMEOUT,
 181         .identity       = KBUILD_MODNAME,
 182 };
 183
 184 static int aspeed_wdt_probe(struct platform_device *pdev)
 185 {
 186         const struct aspeed_wdt_config *config;
 187         const struct of_device_id *ofdid;
 188         struct aspeed_wdt *wdt;
 189         struct resource *res;
 190         struct device_node *np;
 191         const char *reset_type;
 192         u32 duration;
 193         int ret;
 194
 195         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 196         if (!wdt)
 197                 return -ENOMEM;
 198
 199         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 200         wdt->base = devm_ioremap_resource(&pdev->dev, res);
 201         if (IS_ERR(wdt->base))
 202                 return PTR_ERR(wdt->base);
 203
 204         /*
 205          * The ast2400 wdt can run at PCLK, or 1MHz. The ast2500 only
 206          * runs at 1MHz. We chose to always run at 1MHz, as there's no
 207          * good reason to have a faster watchdog counter.
 208          */
 209         wdt->wdd.info = &aspeed_wdt_info;
 210         wdt->wdd.ops = &aspeed_wdt_ops;
 211         wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
 212         wdt->wdd.parent = &pdev->dev;
 213
 214         wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
 215         watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 216
 217         np = pdev->dev.of_node;
 218
 219         ofdid = of_match_node(aspeed_wdt_of_table, np);
 220         if (!ofdid)
 221                 return -EINVAL;
 222         config = ofdid->data;
 223
 224         wdt->ctrl = WDT_CTRL_1MHZ_CLK;
 225
 226         /*
 227          * Control reset on a per-device basis to ensure the
 228          * host is not affected by a BMC reboot
 229          */
 230         ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
 231         if (ret) {
 232                 wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
 233         } else {
 234                 if (!strcmp(reset_type, "cpu"))
 235                         wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU;
 236                 else if (!strcmp(reset_type, "soc"))
 237                         wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC;
 238                 else if (!strcmp(reset_type, "system"))
 239                         wdt->ctrl |= WDT_CTRL_RESET_SYSTEM;
 240                 else if (strcmp(reset_type, "none"))
 241                         return -EINVAL;
 242         }
 243         if (of_property_read_bool(np, "aspeed,external-signal"))
 244                 wdt->ctrl |= WDT_CTRL_WDT_EXT;
 245
 246         if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
 247                 /*
 248                  * The watchdog is running, but invoke aspeed_wdt_start() to
 249                  * write wdt->ctrl to WDT_CTRL to ensure the watchdog's
 250                  * configuration conforms to the driver's expectations.
 251                  * Primarily, ensure we're using the 1MHz clock source.
 252                  */
 253                 aspeed_wdt_start(&wdt->wdd);
 254                 set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
 255         }
 256
 257         if (of_device_is_compatible(np, "aspeed,ast2500-wdt")) {
 258                 u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
 259
 260                 reg &= config->ext_pulse_width_mask;
 261                 if (of_property_read_bool(np, "aspeed,ext-push-pull"))
 262                         reg |= WDT_PUSH_PULL_MAGIC;
 263                 else
 264                         reg |= WDT_OPEN_DRAIN_MAGIC;
 265
 266                 writel(reg, wdt->base + WDT_RESET_WIDTH);
 267
 268                 reg &= config->ext_pulse_width_mask;
 269                 if (of_property_read_bool(np, "aspeed,ext-active-high"))
 270                         reg |= WDT_ACTIVE_HIGH_MAGIC;
 271                 else
 272                         reg |= WDT_ACTIVE_LOW_MAGIC;
 273
 274                 writel(reg, wdt->base + WDT_RESET_WIDTH);
 275         }
 276
 277         if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
 278                 u32 max_duration = config->ext_pulse_width_mask + 1;
 279
 280                 if (duration == 0 || duration > max_duration) {
 281                         dev_err(&pdev->dev, "Invalid pulse duration: %uus\n",
 282                                         duration);
 283                         duration = max(1U, min(max_duration, duration));
 284                         dev_info(&pdev->dev, "Pulse duration set to %uus\n",
 285                                         duration);
 286                 }
 287
 288                 /*
 289                  * The watchdog is always configured with a 1MHz source, so
 290                  * there is no need to scale the microsecond value. However we
 291                  * need to offset it - from the datasheet:
 292                  *
 293                  * "This register decides the asserting duration of wdt_ext and
 294                  * wdt_rstarm signal. The default value is 0xFF. It means the
 295                  * default asserting duration of wdt_ext and wdt_rstarm is
 296                  * 256us."
 297                  *
 298                  * This implies a value of 0 gives a 1us pulse.
 299                  */
 300                 writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
 301         }
 302
 303         ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
 304         if (ret) {
 305                 dev_err(&pdev->dev, "failed to register\n");
 306                 return ret;
 307         }
 308
 309         return 0;
 310 }
 311
 312 static struct platform_driver aspeed_watchdog_driver = {
 313         .probe = aspeed_wdt_probe,
 314         .driver = {
 315                 .name = KBUILD_MODNAME,
 316                 .of_match_table = of_match_ptr(aspeed_wdt_of_table),
 317         },
 318 };
 319
 320 static int __init aspeed_wdt_init(void)
 321 {
 322         return platform_driver_register(&aspeed_watchdog_driver);
 323 }
 324 arch_initcall(aspeed_wdt_init);
 325
 326 static void __exit aspeed_wdt_exit(void)
 327 {
 328         platform_driver_unregister(&aspeed_watchdog_driver);
 329 }
 330 module_exit(aspeed_wdt_exit);
 331
 332 MODULE_DESCRIPTION("Aspeed Watchdog Driver");
 333 MODULE_LICENSE("GPL");