linux/drivers/watchdog/bd70528_wdt.c
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   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (C) 2018 ROHM Semiconductors
   3// ROHM BD70528MWV watchdog driver
   4
   5#include <linux/bcd.h>
   6#include <linux/kernel.h>
   7#include <linux/mfd/rohm-bd70528.h>
   8#include <linux/module.h>
   9#include <linux/of.h>
  10#include <linux/platform_device.h>
  11#include <linux/regmap.h>
  12#include <linux/watchdog.h>
  13
  14/*
  15 * Max time we can set is 1 hour, 59 minutes and 59 seconds
  16 * and Minimum time is 1 second
  17 */
  18#define WDT_MAX_MS      ((2 * 60 * 60 - 1) * 1000)
  19#define WDT_MIN_MS      1000
  20#define DEFAULT_TIMEOUT 60
  21
  22#define WD_CTRL_MAGIC1 0x55
  23#define WD_CTRL_MAGIC2 0xAA
  24
  25struct wdtbd70528 {
  26        struct device *dev;
  27        struct regmap *regmap;
  28        struct rohm_regmap_dev *mfd;
  29        struct watchdog_device wdt;
  30};
  31
  32/**
  33 * bd70528_wdt_set - arm or disarm watchdog timer
  34 *
  35 * @data:       device data for the PMIC instance we want to operate on
  36 * @enable:     new state of WDT. zero to disable, non zero to enable
  37 * @old_state:  previous state of WDT will be filled here
  38 *
  39 * Arm or disarm WDT on BD70528 PMIC. Expected to be called only by
  40 * BD70528 RTC and BD70528 WDT drivers. The rtc_timer_lock must be taken
  41 * by calling bd70528_wdt_lock before calling bd70528_wdt_set.
  42 */
  43int bd70528_wdt_set(struct rohm_regmap_dev *data, int enable, int *old_state)
  44{
  45        int ret, i;
  46        unsigned int tmp;
  47        struct bd70528_data *bd70528 = container_of(data, struct bd70528_data,
  48                                                 chip);
  49        u8 wd_ctrl_arr[3] = { WD_CTRL_MAGIC1, WD_CTRL_MAGIC2, 0 };
  50        u8 *wd_ctrl = &wd_ctrl_arr[2];
  51
  52        ret = regmap_read(bd70528->chip.regmap, BD70528_REG_WDT_CTRL, &tmp);
  53        if (ret)
  54                return ret;
  55
  56        *wd_ctrl = (u8)tmp;
  57
  58        if (old_state) {
  59                if (*wd_ctrl & BD70528_MASK_WDT_EN)
  60                        *old_state |= BD70528_WDT_STATE_BIT;
  61                else
  62                        *old_state &= ~BD70528_WDT_STATE_BIT;
  63                if ((!enable) == (!(*old_state & BD70528_WDT_STATE_BIT)))
  64                        return 0;
  65        }
  66
  67        if (enable) {
  68                if (*wd_ctrl & BD70528_MASK_WDT_EN)
  69                        return 0;
  70                *wd_ctrl |= BD70528_MASK_WDT_EN;
  71        } else {
  72                if (*wd_ctrl & BD70528_MASK_WDT_EN)
  73                        *wd_ctrl &= ~BD70528_MASK_WDT_EN;
  74                else
  75                        return 0;
  76        }
  77
  78        for (i = 0; i < 3; i++) {
  79                ret = regmap_write(bd70528->chip.regmap, BD70528_REG_WDT_CTRL,
  80                                   wd_ctrl_arr[i]);
  81                if (ret)
  82                        return ret;
  83        }
  84
  85        ret = regmap_read(bd70528->chip.regmap, BD70528_REG_WDT_CTRL, &tmp);
  86        if ((tmp & BD70528_MASK_WDT_EN) != (*wd_ctrl & BD70528_MASK_WDT_EN)) {
  87                dev_err(bd70528->chip.dev,
  88                        "Watchdog ctrl mismatch (hw) 0x%x (set) 0x%x\n",
  89                        tmp, *wd_ctrl);
  90                ret = -EIO;
  91        }
  92
  93        return ret;
  94}
  95EXPORT_SYMBOL(bd70528_wdt_set);
  96
  97/**
  98 * bd70528_wdt_lock - take WDT lock
  99 *
 100 * @data:       device data for the PMIC instance we want to operate on
 101 *
 102 * Lock WDT for arming/disarming in order to avoid race condition caused
 103 * by WDT state changes initiated by WDT and RTC drivers.
 104 */
 105void bd70528_wdt_lock(struct rohm_regmap_dev *data)
 106{
 107        struct bd70528_data *bd70528 = container_of(data, struct bd70528_data,
 108                                                 chip);
 109
 110        mutex_lock(&bd70528->rtc_timer_lock);
 111}
 112EXPORT_SYMBOL(bd70528_wdt_lock);
 113
 114/**
 115 * bd70528_wdt_unlock - unlock WDT lock
 116 *
 117 * @data:       device data for the PMIC instance we want to operate on
 118 *
 119 * Unlock WDT lock which has previously been taken by call to
 120 * bd70528_wdt_lock.
 121 */
 122void bd70528_wdt_unlock(struct rohm_regmap_dev *data)
 123{
 124        struct bd70528_data *bd70528 = container_of(data, struct bd70528_data,
 125                                                 chip);
 126
 127        mutex_unlock(&bd70528->rtc_timer_lock);
 128}
 129EXPORT_SYMBOL(bd70528_wdt_unlock);
 130
 131static int bd70528_wdt_set_locked(struct wdtbd70528 *w, int enable)
 132{
 133        return bd70528_wdt_set(w->mfd, enable, NULL);
 134}
 135
 136static int bd70528_wdt_change(struct wdtbd70528 *w, int enable)
 137{
 138        int ret;
 139
 140        bd70528_wdt_lock(w->mfd);
 141        ret = bd70528_wdt_set_locked(w, enable);
 142        bd70528_wdt_unlock(w->mfd);
 143
 144        return ret;
 145}
 146
 147static int bd70528_wdt_start(struct watchdog_device *wdt)
 148{
 149        struct wdtbd70528 *w = watchdog_get_drvdata(wdt);
 150
 151        dev_dbg(w->dev, "WDT ping...\n");
 152        return bd70528_wdt_change(w, 1);
 153}
 154
 155static int bd70528_wdt_stop(struct watchdog_device *wdt)
 156{
 157        struct wdtbd70528 *w = watchdog_get_drvdata(wdt);
 158
 159        dev_dbg(w->dev, "WDT stopping...\n");
 160        return bd70528_wdt_change(w, 0);
 161}
 162
 163static int bd70528_wdt_set_timeout(struct watchdog_device *wdt,
 164                                   unsigned int timeout)
 165{
 166        unsigned int hours;
 167        unsigned int minutes;
 168        unsigned int seconds;
 169        int ret;
 170        struct wdtbd70528 *w = watchdog_get_drvdata(wdt);
 171
 172        seconds = timeout;
 173        hours = timeout / (60 * 60);
 174        /* Maximum timeout is 1h 59m 59s => hours is 1 or 0 */
 175        if (hours)
 176                seconds -= (60 * 60);
 177        minutes = seconds / 60;
 178        seconds = seconds % 60;
 179
 180        bd70528_wdt_lock(w->mfd);
 181
 182        ret = bd70528_wdt_set_locked(w, 0);
 183        if (ret)
 184                goto out_unlock;
 185
 186        ret = regmap_update_bits(w->regmap, BD70528_REG_WDT_HOUR,
 187                                 BD70528_MASK_WDT_HOUR, hours);
 188        if (ret) {
 189                dev_err(w->dev, "Failed to set WDT hours\n");
 190                goto out_en_unlock;
 191        }
 192        ret = regmap_update_bits(w->regmap, BD70528_REG_WDT_MINUTE,
 193                                 BD70528_MASK_WDT_MINUTE, bin2bcd(minutes));
 194        if (ret) {
 195                dev_err(w->dev, "Failed to set WDT minutes\n");
 196                goto out_en_unlock;
 197        }
 198        ret = regmap_update_bits(w->regmap, BD70528_REG_WDT_SEC,
 199                                 BD70528_MASK_WDT_SEC, bin2bcd(seconds));
 200        if (ret)
 201                dev_err(w->dev, "Failed to set WDT seconds\n");
 202        else
 203                dev_dbg(w->dev, "WDT tmo set to %u\n", timeout);
 204
 205out_en_unlock:
 206        ret = bd70528_wdt_set_locked(w, 1);
 207out_unlock:
 208        bd70528_wdt_unlock(w->mfd);
 209
 210        return ret;
 211}
 212
 213static const struct watchdog_info bd70528_wdt_info = {
 214        .identity = "bd70528-wdt",
 215        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 216};
 217
 218static const struct watchdog_ops bd70528_wdt_ops = {
 219        .start          = bd70528_wdt_start,
 220        .stop           = bd70528_wdt_stop,
 221        .set_timeout    = bd70528_wdt_set_timeout,
 222};
 223
 224static int bd70528_wdt_probe(struct platform_device *pdev)
 225{
 226        struct rohm_regmap_dev *bd70528;
 227        struct wdtbd70528 *w;
 228        int ret;
 229        unsigned int reg;
 230
 231        bd70528 = dev_get_drvdata(pdev->dev.parent);
 232        if (!bd70528) {
 233                dev_err(&pdev->dev, "No MFD driver data\n");
 234                return -EINVAL;
 235        }
 236        w = devm_kzalloc(&pdev->dev, sizeof(*w), GFP_KERNEL);
 237        if (!w)
 238                return -ENOMEM;
 239
 240        w->regmap = bd70528->regmap;
 241        w->mfd = bd70528;
 242        w->dev = &pdev->dev;
 243
 244        w->wdt.info = &bd70528_wdt_info;
 245        w->wdt.ops =  &bd70528_wdt_ops;
 246        w->wdt.min_hw_heartbeat_ms = WDT_MIN_MS;
 247        w->wdt.max_hw_heartbeat_ms = WDT_MAX_MS;
 248        w->wdt.parent = pdev->dev.parent;
 249        w->wdt.timeout = DEFAULT_TIMEOUT;
 250        watchdog_set_drvdata(&w->wdt, w);
 251        watchdog_init_timeout(&w->wdt, 0, pdev->dev.parent);
 252
 253        ret = bd70528_wdt_set_timeout(&w->wdt, w->wdt.timeout);
 254        if (ret) {
 255                dev_err(&pdev->dev, "Failed to set the watchdog timeout\n");
 256                return ret;
 257        }
 258
 259        bd70528_wdt_lock(w->mfd);
 260        ret = regmap_read(w->regmap, BD70528_REG_WDT_CTRL, &reg);
 261        bd70528_wdt_unlock(w->mfd);
 262
 263        if (ret) {
 264                dev_err(&pdev->dev, "Failed to get the watchdog state\n");
 265                return ret;
 266        }
 267        if (reg & BD70528_MASK_WDT_EN) {
 268                dev_dbg(&pdev->dev, "watchdog was running during probe\n");
 269                set_bit(WDOG_HW_RUNNING, &w->wdt.status);
 270        }
 271
 272        ret = devm_watchdog_register_device(&pdev->dev, &w->wdt);
 273        if (ret < 0)
 274                dev_err(&pdev->dev, "watchdog registration failed: %d\n", ret);
 275
 276        return ret;
 277}
 278
 279static struct platform_driver bd70528_wdt = {
 280        .driver = {
 281                .name = "bd70528-wdt"
 282        },
 283        .probe = bd70528_wdt_probe,
 284};
 285
 286module_platform_driver(bd70528_wdt);
 287
 288MODULE_AUTHOR("Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>");
 289MODULE_DESCRIPTION("BD70528 watchdog driver");
 290MODULE_LICENSE("GPL");
 291MODULE_ALIAS("platform:bd70528-wdt");
 292