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         { .compatible = "aspeed,ast2600-wdt", .data = &ast2500_config },
  42         { },
  43 };
  44 MODULE_DEVICE_TABLE(of, aspeed_wdt_of_table);
  45
  46 #define WDT_STATUS              0x00
  47 #define WDT_RELOAD_VALUE        0x04
  48 #define WDT_RESTART             0x08
  49 #define WDT_CTRL                0x0C
  50 #define   WDT_CTRL_BOOT_SECONDARY       BIT(7)
  51 #define   WDT_CTRL_RESET_MODE_SOC       (0x00 << 5)
  52 #define   WDT_CTRL_RESET_MODE_FULL_CHIP (0x01 << 5)
  53 #define   WDT_CTRL_RESET_MODE_ARM_CPU   (0x10 << 5)
  54 #define   WDT_CTRL_1MHZ_CLK             BIT(4)
  55 #define   WDT_CTRL_WDT_EXT              BIT(3)
  56 #define   WDT_CTRL_WDT_INTR             BIT(2)
  57 #define   WDT_CTRL_RESET_SYSTEM         BIT(1)
  58 #define   WDT_CTRL_ENABLE               BIT(0)
  59 #define WDT_TIMEOUT_STATUS      0x10
  60 #define   WDT_TIMEOUT_STATUS_BOOT_SECONDARY     BIT(1)
  61
  62 /*
  63  * WDT_RESET_WIDTH controls the characteristics of the external pulse (if
  64  * enabled), specifically:
  65  *
  66  * * Pulse duration
  67  * * Drive mode: push-pull vs open-drain
  68  * * Polarity: Active high or active low
  69  *
  70  * Pulse duration configuration is available on both the AST2400 and AST2500,
  71  * though the field changes between SoCs:
  72  *
  73  * AST2400: Bits 7:0
  74  * AST2500: Bits 19:0
  75  *
  76  * This difference is captured in struct aspeed_wdt_config.
  77  *
  78  * The AST2500 exposes the drive mode and polarity options, but not in a
  79  * regular fashion. For read purposes, bit 31 represents active high or low,
  80  * and bit 30 represents push-pull or open-drain. With respect to write, magic
  81  * values need to be written to the top byte to change the state of the drive
  82  * mode and polarity bits. Any other value written to the top byte has no
  83  * effect on the state of the drive mode or polarity bits. However, the pulse
  84  * width value must be preserved (as desired) if written.
  85  */
  86 #define WDT_RESET_WIDTH         0x18
  87 #define   WDT_RESET_WIDTH_ACTIVE_HIGH   BIT(31)
  88 #define     WDT_ACTIVE_HIGH_MAGIC       (0xA5 << 24)
  89 #define     WDT_ACTIVE_LOW_MAGIC        (0x5A << 24)
  90 #define   WDT_RESET_WIDTH_PUSH_PULL     BIT(30)
  91 #define     WDT_PUSH_PULL_MAGIC         (0xA8 << 24)
  92 #define     WDT_OPEN_DRAIN_MAGIC        (0x8A << 24)
  93
  94 #define WDT_RESTART_MAGIC       0x4755
  95
  96 /* 32 bits at 1MHz, in milliseconds */
  97 #define WDT_MAX_TIMEOUT_MS      4294967
  98 #define WDT_DEFAULT_TIMEOUT     30
  99 #define WDT_RATE_1MHZ           1000000
 100
 101 static struct aspeed_wdt *to_aspeed_wdt(struct watchdog_device *wdd)
 102 {
 103         return container_of(wdd, struct aspeed_wdt, wdd);
 104 }
 105
 106 static void aspeed_wdt_enable(struct aspeed_wdt *wdt, int count)
 107 {
 108         wdt->ctrl |= WDT_CTRL_ENABLE;
 109
 110         writel(0, wdt->base + WDT_CTRL);
 111         writel(count, wdt->base + WDT_RELOAD_VALUE);
 112         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 113         writel(wdt->ctrl, wdt->base + WDT_CTRL);
 114 }
 115
 116 static int aspeed_wdt_start(struct watchdog_device *wdd)
 117 {
 118         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 119
 120         aspeed_wdt_enable(wdt, wdd->timeout * WDT_RATE_1MHZ);
 121
 122         return 0;
 123 }
 124
 125 static int aspeed_wdt_stop(struct watchdog_device *wdd)
 126 {
 127         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 128
 129         wdt->ctrl &= ~WDT_CTRL_ENABLE;
 130         writel(wdt->ctrl, wdt->base + WDT_CTRL);
 131
 132         return 0;
 133 }
 134
 135 static int aspeed_wdt_ping(struct watchdog_device *wdd)
 136 {
 137         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 138
 139         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 140
 141         return 0;
 142 }
 143
 144 static int aspeed_wdt_set_timeout(struct watchdog_device *wdd,
 145                                   unsigned int timeout)
 146 {
 147         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 148         u32 actual;
 149
 150         wdd->timeout = timeout;
 151
 152         actual = min(timeout, wdd->max_hw_heartbeat_ms / 1000);
 153
 154         writel(actual * WDT_RATE_1MHZ, wdt->base + WDT_RELOAD_VALUE);
 155         writel(WDT_RESTART_MAGIC, wdt->base + WDT_RESTART);
 156
 157         return 0;
 158 }
 159
 160 static int aspeed_wdt_restart(struct watchdog_device *wdd,
 161                               unsigned long action, void *data)
 162 {
 163         struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
 164
 165         wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY;
 166         aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
 167
 168         mdelay(1000);
 169
 170         return 0;
 171 }
 172
 173 static const struct watchdog_ops aspeed_wdt_ops = {
 174         .start          = aspeed_wdt_start,
 175         .stop           = aspeed_wdt_stop,
 176         .ping           = aspeed_wdt_ping,
 177         .set_timeout    = aspeed_wdt_set_timeout,
 178         .restart        = aspeed_wdt_restart,
 179         .owner          = THIS_MODULE,
 180 };
 181
 182 static const struct watchdog_info aspeed_wdt_info = {
 183         .options        = WDIOF_KEEPALIVEPING
 184                         | WDIOF_MAGICCLOSE
 185                         | WDIOF_SETTIMEOUT,
 186         .identity       = KBUILD_MODNAME,
 187 };
 188
 189 static int aspeed_wdt_probe(struct platform_device *pdev)
 190 {
 191         const struct aspeed_wdt_config *config;
 192         const struct of_device_id *ofdid;
 193         struct aspeed_wdt *wdt;
 194         struct resource *res;
 195         struct device_node *np;
 196         const char *reset_type;
 197         u32 duration;
 198         u32 status;
 199         int ret;
 200
 201         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
 202         if (!wdt)
 203                 return -ENOMEM;
 204
 205         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 206         wdt->base = devm_ioremap_resource(&pdev->dev, res);
 207         if (IS_ERR(wdt->base))
 208                 return PTR_ERR(wdt->base);
 209
 210         wdt->wdd.info = &aspeed_wdt_info;
 211         wdt->wdd.ops = &aspeed_wdt_ops;
 212         wdt->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
 213         wdt->wdd.parent = &pdev->dev;
 214
 215         wdt->wdd.timeout = WDT_DEFAULT_TIMEOUT;
 216         watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
 217
 218         np = pdev->dev.of_node;
 219
 220         ofdid = of_match_node(aspeed_wdt_of_table, np);
 221         if (!ofdid)
 222                 return -EINVAL;
 223         config = ofdid->data;
 224
 225         /*
 226          * On clock rates:
 227          *  - ast2400 wdt can run at PCLK, or 1MHz
 228          *  - ast2500 only runs at 1MHz, hard coding bit 4 to 1
 229          *  - ast2600 always runs at 1MHz
 230          *
 231          * Set the ast2400 to run at 1MHz as it simplifies the driver.
 232          */
 233         if (of_device_is_compatible(np, "aspeed,ast2400-wdt"))
 234                 wdt->ctrl = WDT_CTRL_1MHZ_CLK;
 235
 236         /*
 237          * Control reset on a per-device basis to ensure the
 238          * host is not affected by a BMC reboot
 239          */
 240         ret = of_property_read_string(np, "aspeed,reset-type", &reset_type);
 241         if (ret) {
 242                 wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC | WDT_CTRL_RESET_SYSTEM;
 243         } else {
 244                 if (!strcmp(reset_type, "cpu"))
 245                         wdt->ctrl |= WDT_CTRL_RESET_MODE_ARM_CPU |
 246                                      WDT_CTRL_RESET_SYSTEM;
 247                 else if (!strcmp(reset_type, "soc"))
 248                         wdt->ctrl |= WDT_CTRL_RESET_MODE_SOC |
 249                                      WDT_CTRL_RESET_SYSTEM;
 250                 else if (!strcmp(reset_type, "system"))
 251                         wdt->ctrl |= WDT_CTRL_RESET_MODE_FULL_CHIP |
 252                                      WDT_CTRL_RESET_SYSTEM;
 253                 else if (strcmp(reset_type, "none"))
 254                         return -EINVAL;
 255         }
 256         if (of_property_read_bool(np, "aspeed,external-signal"))
 257                 wdt->ctrl |= WDT_CTRL_WDT_EXT;
 258         if (of_property_read_bool(np, "aspeed,alt-boot"))
 259                 wdt->ctrl |= WDT_CTRL_BOOT_SECONDARY;
 260
 261         if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
 262                 /*
 263                  * The watchdog is running, but invoke aspeed_wdt_start() to
 264                  * write wdt->ctrl to WDT_CTRL to ensure the watchdog's
 265                  * configuration conforms to the driver's expectations.
 266                  * Primarily, ensure we're using the 1MHz clock source.
 267                  */
 268                 aspeed_wdt_start(&wdt->wdd);
 269                 set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
 270         }
 271
 272         if ((of_device_is_compatible(np, "aspeed,ast2500-wdt")) ||
 273                 (of_device_is_compatible(np, "aspeed,ast2600-wdt"))) {
 274                 u32 reg = readl(wdt->base + WDT_RESET_WIDTH);
 275
 276                 reg &= config->ext_pulse_width_mask;
 277                 if (of_property_read_bool(np, "aspeed,ext-push-pull"))
 278                         reg |= WDT_PUSH_PULL_MAGIC;
 279                 else
 280                         reg |= WDT_OPEN_DRAIN_MAGIC;
 281
 282                 writel(reg, wdt->base + WDT_RESET_WIDTH);
 283
 284                 reg &= config->ext_pulse_width_mask;
 285                 if (of_property_read_bool(np, "aspeed,ext-active-high"))
 286                         reg |= WDT_ACTIVE_HIGH_MAGIC;
 287                 else
 288                         reg |= WDT_ACTIVE_LOW_MAGIC;
 289
 290                 writel(reg, wdt->base + WDT_RESET_WIDTH);
 291         }
 292
 293         if (!of_property_read_u32(np, "aspeed,ext-pulse-duration", &duration)) {
 294                 u32 max_duration = config->ext_pulse_width_mask + 1;
 295
 296                 if (duration == 0 || duration > max_duration) {
 297                         dev_err(&pdev->dev, "Invalid pulse duration: %uus\n",
 298                                         duration);
 299                         duration = max(1U, min(max_duration, duration));
 300                         dev_info(&pdev->dev, "Pulse duration set to %uus\n",
 301                                         duration);
 302                 }
 303
 304                 /*
 305                  * The watchdog is always configured with a 1MHz source, so
 306                  * there is no need to scale the microsecond value. However we
 307                  * need to offset it - from the datasheet:
 308                  *
 309                  * "This register decides the asserting duration of wdt_ext and
 310                  * wdt_rstarm signal. The default value is 0xFF. It means the
 311                  * default asserting duration of wdt_ext and wdt_rstarm is
 312                  * 256us."
 313                  *
 314                  * This implies a value of 0 gives a 1us pulse.
 315                  */
 316                 writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
 317         }
 318
 319         status = readl(wdt->base + WDT_TIMEOUT_STATUS);
 320         if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY)
 321                 wdt->wdd.bootstatus = WDIOF_CARDRESET;
 322
 323         ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
 324         if (ret) {
 325                 dev_err(&pdev->dev, "failed to register\n");
 326                 return ret;
 327         }
 328
 329         return 0;
 330 }
 331
 332 static struct platform_driver aspeed_watchdog_driver = {
 333         .probe = aspeed_wdt_probe,
 334         .driver = {
 335                 .name = KBUILD_MODNAME,
 336                 .of_match_table = of_match_ptr(aspeed_wdt_of_table),
 337         },
 338 };
 339
 340 static int __init aspeed_wdt_init(void)
 341 {
 342         return platform_driver_register(&aspeed_watchdog_driver);
 343 }
 344 arch_initcall(aspeed_wdt_init);
 345
 346 static void __exit aspeed_wdt_exit(void)
 347 {
 348         platform_driver_unregister(&aspeed_watchdog_driver);
 349 }
 350 module_exit(aspeed_wdt_exit);
 351
 352 MODULE_DESCRIPTION("Aspeed Watchdog Driver");
 353 MODULE_LICENSE("GPL");