LXR qemu/hw/i2c/microbit

   1/*
   2 * Microbit stub for Nordic Semiconductor nRF51 SoC Two-Wire Interface
   3 * http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.1.pdf
   4 *
   5 * This is a microbit-specific stub for the TWI controller on the nRF51 SoC.
   6 * We don't emulate I2C devices but the firmware probes the
   7 * accelerometer/magnetometer on startup and panics if they are not found.
   8 * Therefore we stub out the probing.
   9 *
  10 * In the future this file could evolve into a full nRF51 TWI controller
  11 * device.
  12 *
  13 * Copyright 2018 Steffen Görtz <contrib@steffen-goertz.de>
  14 * Copyright 2019 Red Hat, Inc.
  15 *
  16 * This code is licensed under the GPL version 2 or later.  See
  17 * the COPYING file in the top-level directory.
  18 */
  19
  20#include "qemu/osdep.h"
  21#include "qemu/log.h"
  22#include "hw/i2c/microbit_i2c.h"
  23
  24static const uint32_t twi_read_sequence[] = {0x5A, 0x5A, 0x40};
  25
  26static uint64_t microbit_i2c_read(void *opaque, hwaddr addr, unsigned int size)
  27{
  28    MicrobitI2CState *s = opaque;
  29    uint64_t data = 0x00;
  30
  31    switch (addr) {
  32    case NRF51_TWI_EVENT_STOPPED:
  33        data = 0x01;
  34        break;
  35    case NRF51_TWI_EVENT_RXDREADY:
  36        data = 0x01;
  37        break;
  38    case NRF51_TWI_EVENT_TXDSENT:
  39        data = 0x01;
  40        break;
  41    case NRF51_TWI_REG_RXD:
  42        data = twi_read_sequence[s->read_idx];
  43        if (s->read_idx < G_N_ELEMENTS(twi_read_sequence)) {
  44            s->read_idx++;
  45        }
  46        break;
  47    default:
  48        data = s->regs[addr / sizeof(s->regs[0])];
  49        break;
  50    }
  51
  52    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u] = %" PRIx32 "\n",
  53                  __func__, addr, size, (uint32_t)data);
  54
  55
  56    return data;
  57}
  58
  59static void microbit_i2c_write(void *opaque, hwaddr addr, uint64_t data,
  60                               unsigned int size)
  61{
  62    MicrobitI2CState *s = opaque;
  63
  64    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n",
  65                  __func__, addr, data, size);
  66    s->regs[addr / sizeof(s->regs[0])] = data;
  67}
  68
  69static const MemoryRegionOps microbit_i2c_ops = {
  70    .read = microbit_i2c_read,
  71    .write = microbit_i2c_write,
  72    .endianness = DEVICE_LITTLE_ENDIAN,
  73    .impl.min_access_size = 4,
  74    .impl.max_access_size = 4,
  75};
  76
  77static const VMStateDescription microbit_i2c_vmstate = {
  78    .name = TYPE_MICROBIT_I2C,
  79    .version_id = 1,
  80    .minimum_version_id = 1,
  81    .fields = (VMStateField[]) {
  82        VMSTATE_UINT32_ARRAY(regs, MicrobitI2CState, MICROBIT_I2C_NREGS),
  83        VMSTATE_UINT32(read_idx, MicrobitI2CState),
  84    },
  85};
  86
  87static void microbit_i2c_reset(DeviceState *dev)
  88{
  89    MicrobitI2CState *s = MICROBIT_I2C(dev);
  90
  91    memset(s->regs, 0, sizeof(s->regs));
  92    s->read_idx = 0;
  93}
  94
  95static void microbit_i2c_realize(DeviceState *dev, Error **errp)
  96{
  97    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
  98    MicrobitI2CState *s = MICROBIT_I2C(dev);
  99
 100    memory_region_init_io(&s->iomem, OBJECT(s), &microbit_i2c_ops, s,
 101                          "microbit.twi", NRF51_TWI_SIZE);
 102    sysbus_init_mmio(sbd, &s->iomem);
 103}
 104
 105static void microbit_i2c_class_init(ObjectClass *klass, void *data)
 106{
 107    DeviceClass *dc = DEVICE_CLASS(klass);
 108
 109    dc->vmsd = &microbit_i2c_vmstate;
 110    dc->reset = microbit_i2c_reset;
 111    dc->realize = microbit_i2c_realize;
 112    dc->desc = "Microbit I2C controller";
 113}
 114
 115static const TypeInfo microbit_i2c_info = {
 116    .name = TYPE_MICROBIT_I2C,
 117    .parent = TYPE_SYS_BUS_DEVICE,
 118    .instance_size = sizeof(MicrobitI2CState),
 119    .class_init = microbit_i2c_class_init,
 120};
 121
 122static void microbit_i2c_register_types(void)
 123{
 124    type_register_static(&microbit_i2c_info);
 125}
 126
 127type_init(microbit_i2c_register_types)
 128