drivers/watchdog/menz69_wdt.c

   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
  13 struct 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
  29 static bool nowayout = WATCHDOG_NOWAYOUT;
  30 module_param(nowayout, bool, 0);
  31 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  32                             __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  33
  34 static 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
  46 static 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
  58 static 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
  71 static 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
  88 static const struct watchdog_info men_z069_info = {
  89         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  90         .identity = "MEN z069 Watchdog",
  91 };
  92
  93 static 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
 101 static 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
 109 static 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
 138 release_mem:
 139         mcb_release_mem(mem);
 140         return -ENOMEM;
 141 }
 142
 143 static 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
 151 static const struct mcb_device_id men_z069_ids[] = {
 152         { .device = 0x45 },
 153         { }
 154 };
 155 MODULE_DEVICE_TABLE(mcb, men_z069_ids);
 156
 157 static 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 };
 166 module_mcb_driver(men_z069_driver);
 167
 168 MODULE_AUTHOR("Johannes Thumshirn <jth@kernel.org>");
 169 MODULE_LICENSE("GPL v2");
 170 MODULE_ALIAS("mcb:16z069");