LXR linux/drivers/watchdog/menz69

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Watchdog driver for the MEN z069 IP-Core
   4 *
   5 * Copyright (C) 2018 Johannes Thumshirn <jth@kernel.org>
   6 */
   7#include <linux/io.h>
   8#include <linux/kernel.h>
   9#include <linux/mcb.h>
  10#include <linux/module.h>
  11#include <linux/watchdog.h>
  12
  13struct men_z069_drv {
  14        struct watchdog_device wdt;
  15        void __iomem *base;
  16        struct resource *mem;
  17};
  18
  19#define MEN_Z069_WTR                    0x10
  20#define MEN_Z069_WTR_WDEN               BIT(15)
  21#define MEN_Z069_WTR_WDET_MASK          0x7fff
  22#define MEN_Z069_WVR                    0x14
  23
  24#define MEN_Z069_TIMER_FREQ             500 /* 500 Hz */
  25#define MEN_Z069_WDT_COUNTER_MIN        1
  26#define MEN_Z069_WDT_COUNTER_MAX        0x7fff
  27#define MEN_Z069_DEFAULT_TIMEOUT        30
  28
  29static bool nowayout = WATCHDOG_NOWAYOUT;
  30module_param(nowayout, bool, 0);
  31MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  32                            __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  33
  34static int men_z069_wdt_start(struct watchdog_device *wdt)
  35{
  36        struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
  37        u16 val;
  38
  39        val = readw(drv->base + MEN_Z069_WTR);
  40        val |= MEN_Z069_WTR_WDEN;
  41        writew(val, drv->base + MEN_Z069_WTR);
  42
  43        return 0;
  44}
  45
  46static int men_z069_wdt_stop(struct watchdog_device *wdt)
  47{
  48        struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
  49        u16 val;
  50
  51        val = readw(drv->base + MEN_Z069_WTR);
  52        val &= ~MEN_Z069_WTR_WDEN;
  53        writew(val, drv->base + MEN_Z069_WTR);
  54
  55        return 0;
  56}
  57
  58static int men_z069_wdt_ping(struct watchdog_device *wdt)
  59{
  60        struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
  61        u16 val;
  62
  63        /* The watchdog trigger value toggles between 0x5555 and 0xaaaa */
  64        val = readw(drv->base + MEN_Z069_WVR);
  65        val ^= 0xffff;
  66        writew(val, drv->base + MEN_Z069_WVR);
  67
  68        return 0;
  69}
  70
  71static int men_z069_wdt_set_timeout(struct watchdog_device *wdt,
  72                                    unsigned int timeout)
  73{
  74        struct men_z069_drv *drv = watchdog_get_drvdata(wdt);
  75        u16 reg, val, ena;
  76
  77        wdt->timeout = timeout;
  78        val = timeout * MEN_Z069_TIMER_FREQ;
  79
  80        reg = readw(drv->base + MEN_Z069_WVR);
  81        ena = reg & MEN_Z069_WTR_WDEN;
  82        reg = ena | val;
  83        writew(reg, drv->base + MEN_Z069_WTR);
  84
  85        return 0;
  86}
  87
  88static const struct watchdog_info men_z069_info = {
  89        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  90        .identity = "MEN z069 Watchdog",
  91};
  92
  93static const struct watchdog_ops men_z069_ops = {
  94        .owner = THIS_MODULE,
  95        .start = men_z069_wdt_start,
  96        .stop = men_z069_wdt_stop,
  97        .ping = men_z069_wdt_ping,
  98        .set_timeout = men_z069_wdt_set_timeout,
  99};
 100
 101static struct watchdog_device men_z069_wdt = {
 102        .info = &men_z069_info,
 103        .ops = &men_z069_ops,
 104        .timeout = MEN_Z069_DEFAULT_TIMEOUT,
 105        .min_timeout = 1,
 106        .max_timeout = MEN_Z069_WDT_COUNTER_MAX / MEN_Z069_TIMER_FREQ,
 107};
 108
 109static int men_z069_probe(struct mcb_device *dev,
 110                          const struct mcb_device_id *id)
 111{
 112        struct men_z069_drv *drv;
 113        struct resource *mem;
 114
 115        drv = devm_kzalloc(&dev->dev, sizeof(struct men_z069_drv), GFP_KERNEL);
 116        if (!drv)
 117                return -ENOMEM;
 118
 119        mem = mcb_request_mem(dev, "z069-wdt");
 120        if (IS_ERR(mem))
 121                return PTR_ERR(mem);
 122
 123        drv->base = devm_ioremap(&dev->dev, mem->start, resource_size(mem));
 124        if (drv->base == NULL)
 125                goto release_mem;
 126
 127        drv->mem = mem;
 128
 129        drv->wdt = men_z069_wdt;
 130        watchdog_init_timeout(&drv->wdt, 0, &dev->dev);
 131        watchdog_set_nowayout(&drv->wdt, nowayout);
 132        watchdog_set_drvdata(&drv->wdt, drv);
 133        drv->wdt.parent = &dev->dev;
 134        mcb_set_drvdata(dev, drv);
 135
 136        return watchdog_register_device(&men_z069_wdt);
 137
 138release_mem:
 139        mcb_release_mem(mem);
 140        return -ENOMEM;
 141}
 142
 143static void men_z069_remove(struct mcb_device *dev)
 144{
 145        struct men_z069_drv *drv = mcb_get_drvdata(dev);
 146
 147        watchdog_unregister_device(&drv->wdt);
 148        mcb_release_mem(drv->mem);
 149}
 150
 151static const struct mcb_device_id men_z069_ids[] = {
 152        { .device = 0x45 },
 153        { }
 154};
 155MODULE_DEVICE_TABLE(mcb, men_z069_ids);
 156
 157static struct mcb_driver men_z069_driver = {
 158        .driver = {
 159                .name = "z069-wdt",
 160                .owner = THIS_MODULE,
 161        },
 162        .probe = men_z069_probe,
 163        .remove = men_z069_remove,
 164        .id_table = men_z069_ids,
 165};
 166module_mcb_driver(men_z069_driver);
 167
 168MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
 169MODULE_LICENSE("GPL v2");
 170MODULE_ALIAS("mcb:16z069");
 171MODULE_IMPORT_NS(MCB);
 172