drivers/watchdog/imgpdc_wdt.c

   1 /*
   2  * Imagination Technologies PowerDown Controller Watchdog Timer.
   3  *
   4  * Copyright (c) 2014 Imagination Technologies Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  *
  10  * Based on drivers/watchdog/sunxi_wdt.c Copyright (c) 2013 Carlo Caione
  11  *                                                     2012 Henrik Nordstrom
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/io.h>
  16 #include <linux/log2.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/slab.h>
  20 #include <linux/watchdog.h>
  21
  22 /* registers */
  23 #define PDC_WDT_SOFT_RESET              0x00
  24 #define PDC_WDT_CONFIG                  0x04
  25   #define PDC_WDT_CONFIG_ENABLE         BIT(31)
  26   #define PDC_WDT_CONFIG_DELAY_MASK     0x1f
  27
  28 #define PDC_WDT_TICKLE1                 0x08
  29 #define PDC_WDT_TICKLE1_MAGIC           0xabcd1234
  30 #define PDC_WDT_TICKLE2                 0x0c
  31 #define PDC_WDT_TICKLE2_MAGIC           0x4321dcba
  32
  33 #define PDC_WDT_TICKLE_STATUS_MASK      0x7
  34 #define PDC_WDT_TICKLE_STATUS_SHIFT     0
  35 #define PDC_WDT_TICKLE_STATUS_HRESET    0x0  /* Hard reset */
  36 #define PDC_WDT_TICKLE_STATUS_TIMEOUT   0x1  /* Timeout */
  37 #define PDC_WDT_TICKLE_STATUS_TICKLE    0x2  /* Tickled incorrectly */
  38 #define PDC_WDT_TICKLE_STATUS_SRESET    0x3  /* Soft reset */
  39 #define PDC_WDT_TICKLE_STATUS_USER      0x4  /* User reset */
  40
  41 /* Timeout values are in seconds */
  42 #define PDC_WDT_MIN_TIMEOUT             1
  43 #define PDC_WDT_DEF_TIMEOUT             64
  44
  45 static int heartbeat;
  46 module_param(heartbeat, int, 0);
  47 MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds "
  48         "(default=" __MODULE_STRING(PDC_WDT_DEF_TIMEOUT) ")");
  49
  50 static bool nowayout = WATCHDOG_NOWAYOUT;
  51 module_param(nowayout, bool, 0);
  52 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  53         "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  54
  55 struct pdc_wdt_dev {
  56         struct watchdog_device wdt_dev;
  57         struct clk *wdt_clk;
  58         struct clk *sys_clk;
  59         void __iomem *base;
  60 };
  61
  62 static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev)
  63 {
  64         struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
  65
  66         writel(PDC_WDT_TICKLE1_MAGIC, wdt->base + PDC_WDT_TICKLE1);
  67         writel(PDC_WDT_TICKLE2_MAGIC, wdt->base + PDC_WDT_TICKLE2);
  68
  69         return 0;
  70 }
  71
  72 static int pdc_wdt_stop(struct watchdog_device *wdt_dev)
  73 {
  74         unsigned int val;
  75         struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
  76
  77         val = readl(wdt->base + PDC_WDT_CONFIG);
  78         val &= ~PDC_WDT_CONFIG_ENABLE;
  79         writel(val, wdt->base + PDC_WDT_CONFIG);
  80
  81         /* Must tickle to finish the stop */
  82         pdc_wdt_keepalive(wdt_dev);
  83
  84         return 0;
  85 }
  86
  87 static int pdc_wdt_set_timeout(struct watchdog_device *wdt_dev,
  88                                unsigned int new_timeout)
  89 {
  90         unsigned int val;
  91         struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
  92         unsigned long clk_rate = clk_get_rate(wdt->wdt_clk);
  93
  94         wdt->wdt_dev.timeout = new_timeout;
  95
  96         val = readl(wdt->base + PDC_WDT_CONFIG) & ~PDC_WDT_CONFIG_DELAY_MASK;
  97         val |= order_base_2(new_timeout * clk_rate) - 1;
  98         writel(val, wdt->base + PDC_WDT_CONFIG);
  99
 100         return 0;
 101 }
 102
 103 /* Start the watchdog timer (delay should already be set) */
 104 static int pdc_wdt_start(struct watchdog_device *wdt_dev)
 105 {
 106         unsigned int val;
 107         struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
 108
 109         val = readl(wdt->base + PDC_WDT_CONFIG);
 110         val |= PDC_WDT_CONFIG_ENABLE;
 111         writel(val, wdt->base + PDC_WDT_CONFIG);
 112
 113         return 0;
 114 }
 115
 116 static struct watchdog_info pdc_wdt_info = {
 117         .identity       = "IMG PDC Watchdog",
 118         .options        = WDIOF_SETTIMEOUT |
 119                           WDIOF_KEEPALIVEPING |
 120                           WDIOF_MAGICCLOSE,
 121 };
 122
 123 static const struct watchdog_ops pdc_wdt_ops = {
 124         .owner          = THIS_MODULE,
 125         .start          = pdc_wdt_start,
 126         .stop           = pdc_wdt_stop,
 127         .ping           = pdc_wdt_keepalive,
 128         .set_timeout    = pdc_wdt_set_timeout,
 129 };
 130
 131 static int pdc_wdt_probe(struct platform_device *pdev)
 132 {
 133         int ret, val;
 134         unsigned long clk_rate;
 135         struct resource *res;
 136         struct pdc_wdt_dev *pdc_wdt;
 137
 138         pdc_wdt = devm_kzalloc(&pdev->dev, sizeof(*pdc_wdt), GFP_KERNEL);
 139         if (!pdc_wdt)
 140                 return -ENOMEM;
 141
 142         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 143         pdc_wdt->base = devm_ioremap_resource(&pdev->dev, res);
 144         if (IS_ERR(pdc_wdt->base))
 145                 return PTR_ERR(pdc_wdt->base);
 146
 147         pdc_wdt->sys_clk = devm_clk_get(&pdev->dev, "sys");
 148         if (IS_ERR(pdc_wdt->sys_clk)) {
 149                 dev_err(&pdev->dev, "failed to get the sys clock\n");
 150                 return PTR_ERR(pdc_wdt->sys_clk);
 151         }
 152
 153         pdc_wdt->wdt_clk = devm_clk_get(&pdev->dev, "wdt");
 154         if (IS_ERR(pdc_wdt->wdt_clk)) {
 155                 dev_err(&pdev->dev, "failed to get the wdt clock\n");
 156                 return PTR_ERR(pdc_wdt->wdt_clk);
 157         }
 158
 159         ret = clk_prepare_enable(pdc_wdt->sys_clk);
 160         if (ret) {
 161                 dev_err(&pdev->dev, "could not prepare or enable sys clock\n");
 162                 return ret;
 163         }
 164
 165         ret = clk_prepare_enable(pdc_wdt->wdt_clk);
 166         if (ret) {
 167                 dev_err(&pdev->dev, "could not prepare or enable wdt clock\n");
 168                 goto disable_sys_clk;
 169         }
 170
 171         /* We use the clock rate to calculate the max timeout */
 172         clk_rate = clk_get_rate(pdc_wdt->wdt_clk);
 173         if (clk_rate == 0) {
 174                 dev_err(&pdev->dev, "failed to get clock rate\n");
 175                 ret = -EINVAL;
 176                 goto disable_wdt_clk;
 177         }
 178
 179         if (order_base_2(clk_rate) > PDC_WDT_CONFIG_DELAY_MASK + 1) {
 180                 dev_err(&pdev->dev, "invalid clock rate\n");
 181                 ret = -EINVAL;
 182                 goto disable_wdt_clk;
 183         }
 184
 185         if (order_base_2(clk_rate) == 0)
 186                 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT + 1;
 187         else
 188                 pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT;
 189
 190         pdc_wdt->wdt_dev.info = &pdc_wdt_info;
 191         pdc_wdt->wdt_dev.ops = &pdc_wdt_ops;
 192         pdc_wdt->wdt_dev.max_timeout = 1 << PDC_WDT_CONFIG_DELAY_MASK;
 193         pdc_wdt->wdt_dev.timeout = PDC_WDT_DEF_TIMEOUT;
 194         pdc_wdt->wdt_dev.parent = &pdev->dev;
 195         watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);
 196
 197         watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, &pdev->dev);
 198
 199         pdc_wdt_stop(&pdc_wdt->wdt_dev);
 200
 201         /* Find what caused the last reset */
 202         val = readl(pdc_wdt->base + PDC_WDT_TICKLE1);
 203         val = (val & PDC_WDT_TICKLE_STATUS_MASK) >> PDC_WDT_TICKLE_STATUS_SHIFT;
 204         switch (val) {
 205         case PDC_WDT_TICKLE_STATUS_TICKLE:
 206         case PDC_WDT_TICKLE_STATUS_TIMEOUT:
 207                 pdc_wdt->wdt_dev.bootstatus |= WDIOF_CARDRESET;
 208                 dev_info(&pdev->dev,
 209                          "watchdog module last reset due to timeout\n");
 210                 break;
 211         case PDC_WDT_TICKLE_STATUS_HRESET:
 212                 dev_info(&pdev->dev,
 213                          "watchdog module last reset due to hard reset\n");
 214                 break;
 215         case PDC_WDT_TICKLE_STATUS_SRESET:
 216                 dev_info(&pdev->dev,
 217                          "watchdog module last reset due to soft reset\n");
 218                 break;
 219         case PDC_WDT_TICKLE_STATUS_USER:
 220                 dev_info(&pdev->dev,
 221                          "watchdog module last reset due to user reset\n");
 222                 break;
 223         default:
 224                 dev_info(&pdev->dev,
 225                          "contains an illegal status code (%08x)\n", val);
 226                 break;
 227         }
 228
 229         watchdog_set_nowayout(&pdc_wdt->wdt_dev, nowayout);
 230
 231         platform_set_drvdata(pdev, pdc_wdt);
 232
 233         ret = watchdog_register_device(&pdc_wdt->wdt_dev);
 234         if (ret)
 235                 goto disable_wdt_clk;
 236
 237         return 0;
 238
 239 disable_wdt_clk:
 240         clk_disable_unprepare(pdc_wdt->wdt_clk);
 241 disable_sys_clk:
 242         clk_disable_unprepare(pdc_wdt->sys_clk);
 243         return ret;
 244 }
 245
 246 static void pdc_wdt_shutdown(struct platform_device *pdev)
 247 {
 248         struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev);
 249
 250         pdc_wdt_stop(&pdc_wdt->wdt_dev);
 251 }
 252
 253 static int pdc_wdt_remove(struct platform_device *pdev)
 254 {
 255         struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev);
 256
 257         pdc_wdt_stop(&pdc_wdt->wdt_dev);
 258         watchdog_unregister_device(&pdc_wdt->wdt_dev);
 259         clk_disable_unprepare(pdc_wdt->wdt_clk);
 260         clk_disable_unprepare(pdc_wdt->sys_clk);
 261
 262         return 0;
 263 }
 264
 265 static const struct of_device_id pdc_wdt_match[] = {
 266         { .compatible = "img,pdc-wdt" },
 267         {}
 268 };
 269 MODULE_DEVICE_TABLE(of, pdc_wdt_match);
 270
 271 static struct platform_driver pdc_wdt_driver = {
 272         .driver = {
 273                 .name = "imgpdc-wdt",
 274                 .of_match_table = pdc_wdt_match,
 275         },
 276         .probe = pdc_wdt_probe,
 277         .remove = pdc_wdt_remove,
 278         .shutdown = pdc_wdt_shutdown,
 279 };
 280 module_platform_driver(pdc_wdt_driver);
 281
 282 MODULE_AUTHOR("Jude Abraham <Jude.Abraham@imgtec.com>");
 283 MODULE_AUTHOR("Naidu Tellapati <Naidu.Tellapati@imgtec.com>");
 284 MODULE_DESCRIPTION("Imagination Technologies PDC Watchdog Timer Driver");
 285 MODULE_LICENSE("GPL v2");