hw/misc/imx2_wdt.c

   1 /*
   2  * Copyright (c) 2018, Impinj, Inc.
   3  *
   4  * i.MX2 Watchdog IP block
   5  *
   6  * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   9  * See the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include "qemu/bitops.h"
  14 #include "sysemu/watchdog.h"
  15
  16 #include "hw/misc/imx2_wdt.h"
  17
  18 #define IMX2_WDT_WCR_WDA    BIT(5)      /* -> External Reset WDOG_B */
  19 #define IMX2_WDT_WCR_SRS    BIT(4)      /* -> Software Reset Signal */
  20
  21 static uint64_t imx2_wdt_read(void *opaque, hwaddr addr,
  22                               unsigned int size)
  23 {
  24     return 0;
  25 }
  26
  27 static void imx2_wdt_write(void *opaque, hwaddr addr,
  28                            uint64_t value, unsigned int size)
  29 {
  30     if (addr == IMX2_WDT_WCR &&
  31         (value & (IMX2_WDT_WCR_WDA | IMX2_WDT_WCR_SRS))) {
  32         watchdog_perform_action();
  33     }
  34 }
  35
  36 static const MemoryRegionOps imx2_wdt_ops = {
  37     .read  = imx2_wdt_read,
  38     .write = imx2_wdt_write,
  39     .endianness = DEVICE_NATIVE_ENDIAN,
  40     .impl = {
  41         /*
  42          * Our device would not work correctly if the guest was doing
  43          * unaligned access. This might not be a limitation on the
  44          * real device but in practice there is no reason for a guest
  45          * to access this device unaligned.
  46          */
  47         .min_access_size = 4,
  48         .max_access_size = 4,
  49         .unaligned = false,
  50     },
  51 };
  52
  53 static void imx2_wdt_realize(DeviceState *dev, Error **errp)
  54 {
  55     IMX2WdtState *s = IMX2_WDT(dev);
  56
  57     memory_region_init_io(&s->mmio, OBJECT(dev),
  58                           &imx2_wdt_ops, s,
  59                           TYPE_IMX2_WDT".mmio",
  60                           IMX2_WDT_REG_NUM * sizeof(uint16_t));
  61     sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->mmio);
  62 }
  63
  64 static void imx2_wdt_class_init(ObjectClass *klass, void *data)
  65 {
  66     DeviceClass *dc = DEVICE_CLASS(klass);
  67
  68     dc->realize = imx2_wdt_realize;
  69     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
  70 }
  71
  72 static const TypeInfo imx2_wdt_info = {
  73     .name          = TYPE_IMX2_WDT,
  74     .parent        = TYPE_SYS_BUS_DEVICE,
  75     .instance_size = sizeof(IMX2WdtState),
  76     .class_init    = imx2_wdt_class_init,
  77 };
  78
  79 static WatchdogTimerModel model = {
  80     .wdt_name = "imx2-watchdog",
  81     .wdt_description = "i.MX2 Watchdog",
  82 };
  83
  84 static void imx2_wdt_register_type(void)
  85 {
  86     watchdog_add_model(&model);
  87     type_register_static(&imx2_wdt_info);
  88 }
  89 type_init(imx2_wdt_register_type)