Commit 9d68bf56 authored by Steffen Görtz's avatar Steffen Görtz Committed by Peter Maydell
Browse files

arm: Stub out NRF51 TWI magnetometer/accelerometer detection 



Recent microbit firmwares panic if the TWI magnetometer/accelerometer
devices are not detected during startup.  We don't implement TWI (I2C)
so let's stub out these devices just to let the firmware boot.

Signed-off by: Steffen Görtz <contrib@steffen-goertz.de>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190110094020.18354-2-stefanha@redhat.com
Reviewed-by: default avatarPeter Maydell <peter.maydell@linaro.org>
[PMM: fixed comment style]
Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
parent ab65eed3

hw/arm/microbit.c

+16 −0
Original line number Diff line number Diff line
@@ -16,11 +16,13 @@ 
#include "exec/address-spaces.h"



#include "hw/arm/nrf51_soc.h"

#include "hw/i2c/microbit_i2c.h"



typedef struct {

    MachineState parent;



    NRF51State nrf51;

    MicrobitI2CState i2c;

} MicrobitMachineState;



#define TYPE_MICROBIT_MACHINE MACHINE_TYPE_NAME("microbit")
@@ -32,7 +34,9 @@ static void microbit_init(MachineState *machine) 
{

    MicrobitMachineState *s = MICROBIT_MACHINE(machine);

    MemoryRegion *system_memory = get_system_memory();

    MemoryRegion *mr;

    Object *soc = OBJECT(&s->nrf51);

    Object *i2c = OBJECT(&s->i2c);



    sysbus_init_child_obj(OBJECT(machine), "nrf51", soc, sizeof(s->nrf51),

                          TYPE_NRF51_SOC);
@@ -41,6 +45,18 @@ static void microbit_init(MachineState *machine) 
                             &error_fatal);

    object_property_set_bool(soc, true, "realized", &error_fatal);



    /*

     * Overlap the TWI stub device into the SoC.  This is a microbit-specific

     * hack until we implement the nRF51 TWI controller properly and the

     * magnetometer/accelerometer devices.

     */

    sysbus_init_child_obj(OBJECT(machine), "microbit.twi", i2c,

                          sizeof(s->i2c), TYPE_MICROBIT_I2C);

    object_property_set_bool(i2c, true, "realized", &error_fatal);

    mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(i2c), 0);

    memory_region_add_subregion_overlap(&s->nrf51.container, NRF51_TWI_BASE,

                                        mr, -1);



    armv7m_load_kernel(ARM_CPU(first_cpu), machine->kernel_filename,

                       NRF51_SOC(soc)->flash_size);

}

hw/i2c/Makefile.objs

+1 −0
Original line number Diff line number Diff line
@@ -7,5 +7,6 @@ common-obj-$(CONFIG_BITBANG_I2C) += bitbang_i2c.o 
common-obj-$(CONFIG_EXYNOS4) += exynos4210_i2c.o

common-obj-$(CONFIG_IMX_I2C) += imx_i2c.o

common-obj-$(CONFIG_ASPEED_SOC) += aspeed_i2c.o

common-obj-$(CONFIG_NRF51_SOC) += microbit_i2c.o

obj-$(CONFIG_OMAP) += omap_i2c.o

obj-$(CONFIG_PPC4XX) += ppc4xx_i2c.o

hw/i2c/microbit_i2c.c

0 → 100644
+127 −0
Original line number Diff line number Diff line 
/*

 * Microbit stub for Nordic Semiconductor nRF51 SoC Two-Wire Interface

 * http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.1.pdf

 *

 * This is a microbit-specific stub for the TWI controller on the nRF51 SoC.

 * We don't emulate I2C devices but the firmware probes the

 * accelerometer/magnetometer on startup and panics if they are not found.

 * Therefore we stub out the probing.

 *

 * In the future this file could evolve into a full nRF51 TWI controller

 * device.

 *

 * Copyright 2018 Steffen Görtz <contrib@steffen-goertz.de>

 * Copyright 2019 Red Hat, Inc.

 *

 * This code is licensed under the GPL version 2 or later.  See

 * the COPYING file in the top-level directory.

 */



#include "qemu/osdep.h"

#include "qemu/log.h"

#include "hw/i2c/microbit_i2c.h"



static const uint32_t twi_read_sequence[] = {0x5A, 0x5A, 0x40};



static uint64_t microbit_i2c_read(void *opaque, hwaddr addr, unsigned int size)

{

    MicrobitI2CState *s = opaque;

    uint64_t data = 0x00;



    switch (addr) {

    case NRF51_TWI_EVENT_STOPPED:

        data = 0x01;

        break;

    case NRF51_TWI_EVENT_RXDREADY:

        data = 0x01;

        break;

    case NRF51_TWI_EVENT_TXDSENT:

        data = 0x01;

        break;

    case NRF51_TWI_REG_RXD:

        data = twi_read_sequence[s->read_idx];

        if (s->read_idx < G_N_ELEMENTS(twi_read_sequence)) {

            s->read_idx++;

        }

        break;

    default:

        data = s->regs[addr / sizeof(s->regs[0])];

        break;

    }



    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u] = %" PRIx32 "\n",

                  __func__, addr, size, (uint32_t)data);





    return data;

}



static void microbit_i2c_write(void *opaque, hwaddr addr, uint64_t data,

                               unsigned int size)

{

    MicrobitI2CState *s = opaque;



    qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n",

                  __func__, addr, data, size);

    s->regs[addr / sizeof(s->regs[0])] = data;

}



static const MemoryRegionOps microbit_i2c_ops = {

    .read = microbit_i2c_read,

    .write = microbit_i2c_write,

    .endianness = DEVICE_LITTLE_ENDIAN,

    .impl.min_access_size = 4,

    .impl.max_access_size = 4,

};



static const VMStateDescription microbit_i2c_vmstate = {

    .name = TYPE_MICROBIT_I2C,

    .version_id = 1,

    .minimum_version_id = 1,

    .fields = (VMStateField[]) {

        VMSTATE_UINT32_ARRAY(regs, MicrobitI2CState, MICROBIT_I2C_NREGS),

        VMSTATE_UINT32(read_idx, MicrobitI2CState),

    },

};



static void microbit_i2c_reset(DeviceState *dev)

{

    MicrobitI2CState *s = MICROBIT_I2C(dev);



    memset(s->regs, 0, sizeof(s->regs));

    s->read_idx = 0;

}



static void microbit_i2c_realize(DeviceState *dev, Error **errp)

{

    SysBusDevice *sbd = SYS_BUS_DEVICE(dev);

    MicrobitI2CState *s = MICROBIT_I2C(dev);



    memory_region_init_io(&s->iomem, OBJECT(s), &microbit_i2c_ops, s,

                          "microbit.twi", NRF51_TWI_SIZE);

    sysbus_init_mmio(sbd, &s->iomem);

}



static void microbit_i2c_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);



    dc->vmsd = &microbit_i2c_vmstate;

    dc->reset = microbit_i2c_reset;

    dc->realize = microbit_i2c_realize;

    dc->desc = "Microbit I2C controller";

}



static const TypeInfo microbit_i2c_info = {

    .name = TYPE_MICROBIT_I2C,

    .parent = TYPE_SYS_BUS_DEVICE,

    .instance_size = sizeof(MicrobitI2CState),

    .class_init = microbit_i2c_class_init,

};



static void microbit_i2c_register_types(void)

{

    type_register_static(&microbit_i2c_info);

}



type_init(microbit_i2c_register_types)

include/hw/arm/nrf51.h

+2 −0
Original line number Diff line number Diff line
@@ -25,6 +25,8 @@ 
#define NRF51_IOMEM_SIZE      0x20000000



#define NRF51_UART_BASE       0x40002000

#define NRF51_TWI_BASE        0x40003000

#define NRF51_TWI_SIZE        0x00001000

#define NRF51_TIMER_BASE      0x40008000

#define NRF51_TIMER_SIZE      0x00001000

#define NRF51_RNG_BASE        0x4000D000

include/hw/arm/nrf51_soc.h

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ typedef struct NRF51State { 
    MemoryRegion sram;

    MemoryRegion flash;

    MemoryRegion clock;

    MemoryRegion twi;



    uint32_t sram_size;

    uint32_t flash_size;