linux/drivers/watchdog/meson_wdt.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *      Meson Watchdog Driver
   4 *
   5 *      Copyright (c) 2014 Carlo Caione
   6 */
   7
   8#include <linux/clk.h>
   9#include <linux/delay.h>
  10#include <linux/err.h>
  11#include <linux/init.h>
  12#include <linux/io.h>
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/moduleparam.h>
  16#include <linux/of.h>
  17#include <linux/of_device.h>
  18#include <linux/platform_device.h>
  19#include <linux/types.h>
  20#include <linux/watchdog.h>
  21
  22#define DRV_NAME                "meson_wdt"
  23
  24#define MESON_WDT_TC            0x00
  25#define MESON_WDT_DC_RESET      (3 << 24)
  26
  27#define MESON_WDT_RESET         0x04
  28
  29#define MESON_WDT_TIMEOUT       30
  30#define MESON_WDT_MIN_TIMEOUT   1
  31
  32#define MESON_SEC_TO_TC(s, c)   ((s) * (c))
  33
  34static bool nowayout = WATCHDOG_NOWAYOUT;
  35static unsigned int timeout;
  36
  37struct meson_wdt_data {
  38        unsigned int enable;
  39        unsigned int terminal_count_mask;
  40        unsigned int count_unit;
  41};
  42
  43static struct meson_wdt_data meson6_wdt_data = {
  44        .enable                 = BIT(22),
  45        .terminal_count_mask    = 0x3fffff,
  46        .count_unit             = 100000, /* 10 us */
  47};
  48
  49static struct meson_wdt_data meson8b_wdt_data = {
  50        .enable                 = BIT(19),
  51        .terminal_count_mask    = 0xffff,
  52        .count_unit             = 7812, /* 128 us */
  53};
  54
  55struct meson_wdt_dev {
  56        struct watchdog_device wdt_dev;
  57        void __iomem *wdt_base;
  58        const struct meson_wdt_data *data;
  59};
  60
  61static int meson_wdt_restart(struct watchdog_device *wdt_dev,
  62                             unsigned long action, void *data)
  63{
  64        struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  65        u32 tc_reboot = MESON_WDT_DC_RESET;
  66
  67        tc_reboot |= meson_wdt->data->enable;
  68
  69        while (1) {
  70                writel(tc_reboot, meson_wdt->wdt_base + MESON_WDT_TC);
  71                mdelay(5);
  72        }
  73
  74        return 0;
  75}
  76
  77static int meson_wdt_ping(struct watchdog_device *wdt_dev)
  78{
  79        struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  80
  81        writel(0, meson_wdt->wdt_base + MESON_WDT_RESET);
  82
  83        return 0;
  84}
  85
  86static void meson_wdt_change_timeout(struct watchdog_device *wdt_dev,
  87                                     unsigned int timeout)
  88{
  89        struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
  90        u32 reg;
  91
  92        reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
  93        reg &= ~meson_wdt->data->terminal_count_mask;
  94        reg |= MESON_SEC_TO_TC(timeout, meson_wdt->data->count_unit);
  95        writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
  96}
  97
  98static int meson_wdt_set_timeout(struct watchdog_device *wdt_dev,
  99                                 unsigned int timeout)
 100{
 101        wdt_dev->timeout = timeout;
 102
 103        meson_wdt_change_timeout(wdt_dev, timeout);
 104        meson_wdt_ping(wdt_dev);
 105
 106        return 0;
 107}
 108
 109static int meson_wdt_stop(struct watchdog_device *wdt_dev)
 110{
 111        struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 112        u32 reg;
 113
 114        reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 115        reg &= ~meson_wdt->data->enable;
 116        writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 117
 118        return 0;
 119}
 120
 121static int meson_wdt_start(struct watchdog_device *wdt_dev)
 122{
 123        struct meson_wdt_dev *meson_wdt = watchdog_get_drvdata(wdt_dev);
 124        u32 reg;
 125
 126        meson_wdt_change_timeout(wdt_dev, meson_wdt->wdt_dev.timeout);
 127        meson_wdt_ping(wdt_dev);
 128
 129        reg = readl(meson_wdt->wdt_base + MESON_WDT_TC);
 130        reg |= meson_wdt->data->enable;
 131        writel(reg, meson_wdt->wdt_base + MESON_WDT_TC);
 132
 133        return 0;
 134}
 135
 136static const struct watchdog_info meson_wdt_info = {
 137        .identity       = DRV_NAME,
 138        .options        = WDIOF_SETTIMEOUT |
 139                          WDIOF_KEEPALIVEPING |
 140                          WDIOF_MAGICCLOSE,
 141};
 142
 143static const struct watchdog_ops meson_wdt_ops = {
 144        .owner          = THIS_MODULE,
 145        .start          = meson_wdt_start,
 146        .stop           = meson_wdt_stop,
 147        .ping           = meson_wdt_ping,
 148        .set_timeout    = meson_wdt_set_timeout,
 149        .restart        = meson_wdt_restart,
 150};
 151
 152static const struct of_device_id meson_wdt_dt_ids[] = {
 153        { .compatible = "amlogic,meson6-wdt", .data = &meson6_wdt_data },
 154        { .compatible = "amlogic,meson8-wdt", .data = &meson6_wdt_data },
 155        { .compatible = "amlogic,meson8b-wdt", .data = &meson8b_wdt_data },
 156        { .compatible = "amlogic,meson8m2-wdt", .data = &meson8b_wdt_data },
 157        { /* sentinel */ }
 158};
 159MODULE_DEVICE_TABLE(of, meson_wdt_dt_ids);
 160
 161static int meson_wdt_probe(struct platform_device *pdev)
 162{
 163        struct device *dev = &pdev->dev;
 164        struct meson_wdt_dev *meson_wdt;
 165        const struct of_device_id *of_id;
 166        int err;
 167
 168        meson_wdt = devm_kzalloc(dev, sizeof(*meson_wdt), GFP_KERNEL);
 169        if (!meson_wdt)
 170                return -ENOMEM;
 171
 172        meson_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);
 173        if (IS_ERR(meson_wdt->wdt_base))
 174                return PTR_ERR(meson_wdt->wdt_base);
 175
 176        of_id = of_match_device(meson_wdt_dt_ids, dev);
 177        if (!of_id) {
 178                dev_err(dev, "Unable to initialize WDT data\n");
 179                return -ENODEV;
 180        }
 181        meson_wdt->data = of_id->data;
 182
 183        meson_wdt->wdt_dev.parent = dev;
 184        meson_wdt->wdt_dev.info = &meson_wdt_info;
 185        meson_wdt->wdt_dev.ops = &meson_wdt_ops;
 186        meson_wdt->wdt_dev.max_timeout =
 187                meson_wdt->data->terminal_count_mask / meson_wdt->data->count_unit;
 188        meson_wdt->wdt_dev.min_timeout = MESON_WDT_MIN_TIMEOUT;
 189        meson_wdt->wdt_dev.timeout = min_t(unsigned int,
 190                                           MESON_WDT_TIMEOUT,
 191                                           meson_wdt->wdt_dev.max_timeout);
 192
 193        watchdog_set_drvdata(&meson_wdt->wdt_dev, meson_wdt);
 194
 195        watchdog_init_timeout(&meson_wdt->wdt_dev, timeout, dev);
 196        watchdog_set_nowayout(&meson_wdt->wdt_dev, nowayout);
 197        watchdog_set_restart_priority(&meson_wdt->wdt_dev, 128);
 198
 199        meson_wdt_stop(&meson_wdt->wdt_dev);
 200
 201        watchdog_stop_on_reboot(&meson_wdt->wdt_dev);
 202        err = devm_watchdog_register_device(dev, &meson_wdt->wdt_dev);
 203        if (err)
 204                return err;
 205
 206        dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
 207                 meson_wdt->wdt_dev.timeout, nowayout);
 208
 209        return 0;
 210}
 211
 212static struct platform_driver meson_wdt_driver = {
 213        .probe          = meson_wdt_probe,
 214        .driver         = {
 215                .name           = DRV_NAME,
 216                .of_match_table = meson_wdt_dt_ids,
 217        },
 218};
 219
 220module_platform_driver(meson_wdt_driver);
 221
 222module_param(timeout, uint, 0);
 223MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
 224
 225module_param(nowayout, bool, 0);
 226MODULE_PARM_DESC(nowayout,
 227                 "Watchdog cannot be stopped once started (default="
 228                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 229
 230MODULE_LICENSE("GPL");
 231MODULE_AUTHOR("Carlo Caione <carlo@caione.org>");
 232MODULE_DESCRIPTION("Meson Watchdog Timer Driver");
 233