From: Steffen Görtz <cont...@steffen-goertz.de>
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: Stefan Hajnoczi <stefa...@redhat.com>
Based-on: <20190103091119.9367-1-stefa...@redhat.com>
---
Steffen: Please post your Signed-off-by. I did some minor cleanups so
your patch can be merged. Thanks!
include/hw/arm/nrf51.h | 1 +
include/hw/arm/nrf51_soc.h | 1 +
hw/arm/nrf51_soc.c | 62 ++++++++++++++++++++++++++++++++++++++
3 files changed, 64 insertions(+)
diff --git a/include/hw/arm/nrf51.h b/include/hw/arm/nrf51.h
index 175bb6c301..5411121b66 100644
--- a/include/hw/arm/nrf51.h
+++ b/include/hw/arm/nrf51.h
@@ -25,6 +25,7 @@
#define NRF51_IOMEM_SIZE 0x20000000
#define NRF51_UART_BASE 0x40002000
+#define NRF51_TWI_BASE 0x40003000
#define NRF51_TIMER_BASE 0x40008000
#define NRF51_TIMER_SIZE 0x00001000
#define NRF51_RNG_BASE 0x4000D000
diff --git a/include/hw/arm/nrf51_soc.h b/include/hw/arm/nrf51_soc.h
index e06f0304b4..fbdefc07e4 100644
--- a/include/hw/arm/nrf51_soc.h
+++ b/include/hw/arm/nrf51_soc.h
@@ -39,6 +39,7 @@ typedef struct NRF51State {
MemoryRegion sram;
MemoryRegion flash;
MemoryRegion clock;
+ MemoryRegion twi;
uint32_t sram_size;
uint32_t flash_size;
diff --git a/hw/arm/nrf51_soc.c b/hw/arm/nrf51_soc.c
index 1630c27594..265438f916 100644
--- a/hw/arm/nrf51_soc.c
+++ b/hw/arm/nrf51_soc.c
@@ -32,6 +32,11 @@
#define NRF51822_FLASH_SIZE (256 * NRF51_PAGE_SIZE)
#define NRF51822_SRAM_SIZE (16 * NRF51_PAGE_SIZE)
+#define NRF51_TWI_EVENT_STOPPED 0x104
+#define NRF51_TWI_EVENT_RXDREADY 0x108
+#define NRF51_TWI_EVENT_TXDSENT 0x11c
+#define NRF51_TWI_REG_RXD 0x518
+
#define BASE_TO_IRQ(base) ((base >> 12) & 0x1F)
static uint64_t clock_read(void *opaque, hwaddr addr, unsigned int size)
@@ -53,6 +58,58 @@ static const MemoryRegionOps clock_ops = {
.write = clock_write
};
+/* Two-Wire Interface (TWI) is not implemented but the microbit-dal firmware
+ * panics if the TWI accelerometer and magnetometer WHO_AM_I registers cannot
+ * be read. Stub out this read sequence so microbit-dal starts up.
+ */
+static uint32_t twi_read_sequence[] = {0x5A, 0x5A, 0x40};
+static uint32_t twi_regs[0x1000 / 4];
+
+static uint64_t twi_read(void *opaque, hwaddr addr, unsigned int size)
+{
+ static int i;
+ 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[i];
+ if (i < ARRAY_SIZE(twi_read_sequence)) {
+ i++;
+ }
+ break;
+ default:
+ data = twi_regs[addr / 4];
+ break;
+ }
+
+ qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " [%u] = %" PRIx32 "\n",
+ __func__, addr, size, (uint32_t)data);
+
+
+ return data;
+}
+
+static void twi_write(void *opaque, hwaddr addr, uint64_t data,
+ unsigned int size)
+{
+ qemu_log_mask(LOG_UNIMP, "%s: 0x%" HWADDR_PRIx " <- 0x%" PRIx64 " [%u]\n",
+ __func__, addr, data, size);
+ twi_regs[addr / 4] = data;
+}
+
+static const MemoryRegionOps twi_ops = {
+ .read = twi_read,
+ .write = twi_write
+};
static void nrf51_soc_realize(DeviceState *dev_soc, Error **errp)
{
@@ -156,6 +213,11 @@ static void nrf51_soc_realize(DeviceState *dev_soc, Error
**errp)
memory_region_add_subregion_overlap(&s->container,
NRF51_IOMEM_BASE, &s->clock, -1);
+ memory_region_init_io(&s->twi, NULL, &twi_ops, NULL,
+ "nrf51_soc.twi", 0x1000);
+ memory_region_add_subregion_overlap(&s->container,
+ NRF51_TWI_BASE, &s->twi, -1);
+
create_unimplemented_device("nrf51_soc.io", NRF51_IOMEM_BASE,
NRF51_IOMEM_SIZE);
create_unimplemented_device("nrf51_soc.ficr", NRF51_FICR_BASE,
--
2.20.1
