drivers/watchdog/uniphier_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog driver for the UniPhier watchdog timer
   4  *
   5  * (c) Copyright 2014 Panasonic Corporation
   6  * (c) Copyright 2016 Socionext Inc.
   7  * All rights reserved.
   8  */
   9
  10 #include <linux/bitops.h>
  11 #include <linux/mfd/syscon.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/regmap.h>
  16 #include <linux/watchdog.h>
  17
  18 /* WDT timer setting register */
  19 #define WDTTIMSET                       0x3004
  20 #define   WDTTIMSET_PERIOD_MASK         (0xf << 0)
  21 #define   WDTTIMSET_PERIOD_1_SEC        (0x3 << 0)
  22
  23 /* WDT reset selection register */
  24 #define WDTRSTSEL                       0x3008
  25 #define   WDTRSTSEL_RSTSEL_MASK         (0x3 << 0)
  26 #define   WDTRSTSEL_RSTSEL_BOTH         (0x0 << 0)
  27 #define   WDTRSTSEL_RSTSEL_IRQ_ONLY     (0x2 << 0)
  28
  29 /* WDT control register */
  30 #define WDTCTRL                         0x300c
  31 #define   WDTCTRL_STATUS                BIT(8)
  32 #define   WDTCTRL_CLEAR                 BIT(1)
  33 #define   WDTCTRL_ENABLE                BIT(0)
  34
  35 #define SEC_TO_WDTTIMSET_PRD(sec) \
  36                 (ilog2(sec) + WDTTIMSET_PERIOD_1_SEC)
  37
  38 #define WDTST_TIMEOUT                   1000 /* usec */
  39
  40 #define WDT_DEFAULT_TIMEOUT             64   /* Default is 64 seconds */
  41 #define WDT_PERIOD_MIN                  1
  42 #define WDT_PERIOD_MAX                  128
  43
  44 static unsigned int timeout = 0;
  45 static bool nowayout = WATCHDOG_NOWAYOUT;
  46
  47 struct uniphier_wdt_dev {
  48         struct watchdog_device wdt_dev;
  49         struct regmap   *regmap;
  50 };
  51
  52 /*
  53  * UniPhier Watchdog operations
  54  */
  55 static int uniphier_watchdog_ping(struct watchdog_device *w)
  56 {
  57         struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
  58         unsigned int val;
  59         int ret;
  60
  61         /* Clear counter */
  62         ret = regmap_write_bits(wdev->regmap, WDTCTRL,
  63                                 WDTCTRL_CLEAR, WDTCTRL_CLEAR);
  64         if (!ret)
  65                 /*
  66                  * As SoC specification, after clear counter,
  67                  * it needs to wait until counter status is 1.
  68                  */
  69                 ret = regmap_read_poll_timeout(wdev->regmap, WDTCTRL, val,
  70                                                (val & WDTCTRL_STATUS),
  71                                                0, WDTST_TIMEOUT);
  72
  73         return ret;
  74 }
  75
  76 static int __uniphier_watchdog_start(struct regmap *regmap, unsigned int sec)
  77 {
  78         unsigned int val;
  79         int ret;
  80
  81         ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
  82                                        !(val & WDTCTRL_STATUS),
  83                                        0, WDTST_TIMEOUT);
  84         if (ret)
  85                 return ret;
  86
  87         /* Setup period */
  88         ret = regmap_write(regmap, WDTTIMSET,
  89                            SEC_TO_WDTTIMSET_PRD(sec));
  90         if (ret)
  91                 return ret;
  92
  93         /* Enable and clear watchdog */
  94         ret = regmap_write(regmap, WDTCTRL, WDTCTRL_ENABLE | WDTCTRL_CLEAR);
  95         if (!ret)
  96                 /*
  97                  * As SoC specification, after clear counter,
  98                  * it needs to wait until counter status is 1.
  99                  */
 100                 ret = regmap_read_poll_timeout(regmap, WDTCTRL, val,
 101                                                (val & WDTCTRL_STATUS),
 102                                                0, WDTST_TIMEOUT);
 103
 104         return ret;
 105 }
 106
 107 static int __uniphier_watchdog_stop(struct regmap *regmap)
 108 {
 109         /* Disable and stop watchdog */
 110         return regmap_write_bits(regmap, WDTCTRL, WDTCTRL_ENABLE, 0);
 111 }
 112
 113 static int __uniphier_watchdog_restart(struct regmap *regmap, unsigned int sec)
 114 {
 115         int ret;
 116
 117         ret = __uniphier_watchdog_stop(regmap);
 118         if (ret)
 119                 return ret;
 120
 121         return __uniphier_watchdog_start(regmap, sec);
 122 }
 123
 124 static int uniphier_watchdog_start(struct watchdog_device *w)
 125 {
 126         struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
 127         unsigned int tmp_timeout;
 128
 129         tmp_timeout = roundup_pow_of_two(w->timeout);
 130
 131         return __uniphier_watchdog_start(wdev->regmap, tmp_timeout);
 132 }
 133
 134 static int uniphier_watchdog_stop(struct watchdog_device *w)
 135 {
 136         struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
 137
 138         return __uniphier_watchdog_stop(wdev->regmap);
 139 }
 140
 141 static int uniphier_watchdog_set_timeout(struct watchdog_device *w,
 142                                          unsigned int t)
 143 {
 144         struct uniphier_wdt_dev *wdev = watchdog_get_drvdata(w);
 145         unsigned int tmp_timeout;
 146         int ret;
 147
 148         tmp_timeout = roundup_pow_of_two(t);
 149         if (tmp_timeout == w->timeout)
 150                 return 0;
 151
 152         if (watchdog_active(w)) {
 153                 ret = __uniphier_watchdog_restart(wdev->regmap, tmp_timeout);
 154                 if (ret)
 155                         return ret;
 156         }
 157
 158         w->timeout = tmp_timeout;
 159
 160         return 0;
 161 }
 162
 163 /*
 164  * Kernel Interfaces
 165  */
 166 static const struct watchdog_info uniphier_wdt_info = {
 167         .identity       = "uniphier-wdt",
 168         .options        = WDIOF_SETTIMEOUT |
 169                           WDIOF_KEEPALIVEPING |
 170                           WDIOF_MAGICCLOSE |
 171                           WDIOF_OVERHEAT,
 172 };
 173
 174 static const struct watchdog_ops uniphier_wdt_ops = {
 175         .owner          = THIS_MODULE,
 176         .start          = uniphier_watchdog_start,
 177         .stop           = uniphier_watchdog_stop,
 178         .ping           = uniphier_watchdog_ping,
 179         .set_timeout    = uniphier_watchdog_set_timeout,
 180 };
 181
 182 static int uniphier_wdt_probe(struct platform_device *pdev)
 183 {
 184         struct device *dev = &pdev->dev;
 185         struct uniphier_wdt_dev *wdev;
 186         struct regmap *regmap;
 187         struct device_node *parent;
 188         int ret;
 189
 190         wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
 191         if (!wdev)
 192                 return -ENOMEM;
 193
 194         parent = of_get_parent(dev->of_node); /* parent should be syscon node */
 195         regmap = syscon_node_to_regmap(parent);
 196         of_node_put(parent);
 197         if (IS_ERR(regmap))
 198                 return PTR_ERR(regmap);
 199
 200         wdev->regmap = regmap;
 201         wdev->wdt_dev.info = &uniphier_wdt_info;
 202         wdev->wdt_dev.ops = &uniphier_wdt_ops;
 203         wdev->wdt_dev.max_timeout = WDT_PERIOD_MAX;
 204         wdev->wdt_dev.min_timeout = WDT_PERIOD_MIN;
 205         wdev->wdt_dev.timeout = WDT_DEFAULT_TIMEOUT;
 206         wdev->wdt_dev.parent = dev;
 207
 208         watchdog_init_timeout(&wdev->wdt_dev, timeout, dev);
 209         watchdog_set_nowayout(&wdev->wdt_dev, nowayout);
 210         watchdog_stop_on_reboot(&wdev->wdt_dev);
 211
 212         watchdog_set_drvdata(&wdev->wdt_dev, wdev);
 213
 214         uniphier_watchdog_stop(&wdev->wdt_dev);
 215         ret = regmap_write(wdev->regmap, WDTRSTSEL, WDTRSTSEL_RSTSEL_BOTH);
 216         if (ret)
 217                 return ret;
 218
 219         ret = devm_watchdog_register_device(dev, &wdev->wdt_dev);
 220         if (ret)
 221                 return ret;
 222
 223         dev_info(dev, "watchdog driver (timeout=%d sec, nowayout=%d)\n",
 224                  wdev->wdt_dev.timeout, nowayout);
 225
 226         return 0;
 227 }
 228
 229 static const struct of_device_id uniphier_wdt_dt_ids[] = {
 230         { .compatible = "socionext,uniphier-wdt" },
 231         { /* sentinel */ }
 232 };
 233 MODULE_DEVICE_TABLE(of, uniphier_wdt_dt_ids);
 234
 235 static struct platform_driver uniphier_wdt_driver = {
 236         .probe          = uniphier_wdt_probe,
 237         .driver         = {
 238                 .name           = "uniphier-wdt",
 239                 .of_match_table = uniphier_wdt_dt_ids,
 240         },
 241 };
 242
 243 module_platform_driver(uniphier_wdt_driver);
 244
 245 module_param(timeout, uint, 0000);
 246 MODULE_PARM_DESC(timeout,
 247         "Watchdog timeout seconds in power of 2. (0 < timeout < 128, default="
 248                                 __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
 249
 250 module_param(nowayout, bool, 0000);
 251 MODULE_PARM_DESC(nowayout,
 252         "Watchdog cannot be stopped once started (default="
 253                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 254
 255 MODULE_AUTHOR("Keiji Hayashibara <hayashibara.keiji@socionext.com>");
 256 MODULE_DESCRIPTION("UniPhier Watchdog Device Driver");
 257 MODULE_LICENSE("GPL v2");