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 "qemu/module.h"
  23#include "hw/i2c/microbit_i2c.h"
  24#include "migration/vmstate.h"
  25
  26static const uint32_t twi_read_sequence[] = {0x5A, 0x5A, 0x40};
  27
  28static uint64_t microbit_i2c_read(void *opaque, hwaddr addr, unsigned int size)
  29{
  30    MicrobitI2CState *s = opaque;
  31    uint64_t data = 0x00;
  32
  33    switch (addr) {
  34    case NRF51_TWI_EVENT_STOPPED:
  35        data = 0x01;
  36        break;
  37    case NRF51_TWI_EVENT_RXDREADY:
  38        data = 0x01;
  39        break;
  40    case NRF51_TWI_EVENT_TXDSENT:
  41        data = 0x01;
  42        break;
  43    case NRF51_TWI_REG_RXD:
  44        data = twi_read_sequence[s->read_idx];
  45        if (s->read_idx < G_N_ELEMENTS(twi_read_sequence)) {
  46            s->read_idx++;
  47        }
  48        break;
  49    default:
  50        data = s->regs[addr / sizeof(s->regs[0])];
  51        break;
  52    }
  53
  54    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u] = %" PRIx32 "\n",
  55                  __func__, addr, size, (uint32_t)data);
  56
  57
  58    return data;
  59}
  60
  61static void microbit_i2c_write(void *opaque, hwaddr addr, uint64_t data,
  62                               unsigned int size)
  63{
  64    MicrobitI2CState *s = opaque;
  65
  66    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n",
  67                  __func__, addr, data, size);
  68    s->regs[addr / sizeof(s->regs[0])] = data;
  69}
  70
  71static const MemoryRegionOps microbit_i2c_ops = {
  72    .read = microbit_i2c_read,
  73    .write = microbit_i2c_write,
  74    .endianness = DEVICE_LITTLE_ENDIAN,
  75    .impl.min_access_size = 4,
  76    .impl.max_access_size = 4,
  77};
  78
  79static const VMStateDescription microbit_i2c_vmstate = {
  80    .name = TYPE_MICROBIT_I2C,
  81    .version_id = 1,
  82    .minimum_version_id = 1,
  83    .fields = (VMStateField[]) {
  84        VMSTATE_UINT32_ARRAY(regs, MicrobitI2CState, MICROBIT_I2C_NREGS),
  85        VMSTATE_UINT32(read_idx, MicrobitI2CState),
  86        VMSTATE_END_OF_LIST()
  87    },
  88};
  89
  90static void microbit_i2c_reset(DeviceState *dev)
  91{
  92    MicrobitI2CState *s = MICROBIT_I2C(dev);
  93
  94    memset(s->regs, 0, sizeof(s->regs));
  95    s->read_idx = 0;
  96}
  97
  98static void microbit_i2c_realize(DeviceState *dev, Error **errp)
  99{
 100    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
 101    MicrobitI2CState *s = MICROBIT_I2C(dev);
 102
 103    memory_region_init_io(&s->iomem, OBJECT(s), &microbit_i2c_ops, s,
 104                          "microbit.twi", NRF51_PERIPHERAL_SIZE);
 105    sysbus_init_mmio(sbd, &s->iomem);
 106}
 107
 108static void microbit_i2c_class_init(ObjectClass *klass, void *data)
 109{
 110    DeviceClass *dc = DEVICE_CLASS(klass);
 111
 112    dc->vmsd = &microbit_i2c_vmstate;
 113    dc->reset = microbit_i2c_reset;
 114    dc->realize = microbit_i2c_realize;
 115    dc->desc = "Microbit I2C controller";
 116}
 117
 118static const TypeInfo microbit_i2c_info = {
 119    .name = TYPE_MICROBIT_I2C,
 120    .parent = TYPE_SYS_BUS_DEVICE,
 121    .instance_size = sizeof(MicrobitI2CState),
 122    .class_init = microbit_i2c_class_init,
 123};
 124
 125static void microbit_i2c_register_types(void)
 126{
 127    type_register_static(&microbit_i2c_info);
 128}
 129
 130type_init(microbit_i2c_register_types)
 131