On 08/03/2018 11:47 AM, Stefan Hajnoczi wrote:
> Some ARM CPUs have bitbanded IO, a memory region that allows convenient
> bit access via 32-bit memory loads/stores. This eliminates the need for
> read-modify-update instruction sequences.
>
> This patch makes this optional feature an ARMv7MState qdev property,
> allowing boards to choose whether they want bitbanding or not.
>
> Status of boards:
> * iotkit (Cortex M33), no bitband
> * mps2 (Cortex M3), bitband
> * msf2 (Cortex M3), bitband
> * stellaris (Cortex M3), bitband
> * stm32f205 (Cortex M3), bitband
>
> As a side-effect of this patch, Peter Maydell noted that the Ethernet
> controller on mps2 board is now accessible. Previously they were hidden
> by the bitband region (which does not exist on the real board).
>
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
> ---
> include/hw/arm/armv7m.h | 2 ++
> hw/arm/armv7m.c | 37 ++++++++++++++++++++-----------------
> hw/arm/mps2.c | 1 +
> hw/arm/msf2-soc.c | 1 +
> hw/arm/stellaris.c | 1 +
> hw/arm/stm32f205_soc.c | 1 +
> 6 files changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/include/hw/arm/armv7m.h b/include/hw/arm/armv7m.h
> index 78308d1484..2ba24953b6 100644
> --- a/include/hw/arm/armv7m.h
> +++ b/include/hw/arm/armv7m.h
> @@ -43,6 +43,7 @@ typedef struct {
> * devices will be automatically layered on top of this view.)
> * + Property "idau": IDAU interface (forwarded to CPU object)
> * + Property "init-svtor": secure VTOR reset value (forwarded to CPU object)
> + * + Property "enable-bitband": expose bitbanded IO
> */
> typedef struct ARMv7MState {
> /*< private >*/
> @@ -63,6 +64,7 @@ typedef struct ARMv7MState {
> MemoryRegion *board_memory;
> Object *idau;
> uint32_t init_svtor;
> + bool enable_bitband;
> } ARMv7MState;
>
> #endif
> diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
> index 6b07666057..878613994d 100644
> --- a/hw/arm/armv7m.c
> +++ b/hw/arm/armv7m.c
> @@ -211,25 +211,27 @@ static void armv7m_realize(DeviceState *dev, Error
> **errp)
> memory_region_add_subregion(&s->container, 0xe000e000,
> sysbus_mmio_get_region(sbd, 0));
>
> - for (i = 0; i < ARRAY_SIZE(s->bitband); i++) {
> - Object *obj = OBJECT(&s->bitband[i]);
> - SysBusDevice *sbd = SYS_BUS_DEVICE(&s->bitband[i]);
> + if (s->enable_bitband) {
> + for (i = 0; i < ARRAY_SIZE(s->bitband); i++) {
> + Object *obj = OBJECT(&s->bitband[i]);
> + SysBusDevice *sbd = SYS_BUS_DEVICE(&s->bitband[i]);
>
> - object_property_set_int(obj, bitband_input_addr[i], "base", &err);
> - if (err != NULL) {
> - error_propagate(errp, err);
> - return;
> - }
> - object_property_set_link(obj, OBJECT(s->board_memory),
> - "source-memory", &error_abort);
> - object_property_set_bool(obj, true, "realized", &err);
> - if (err != NULL) {
> - error_propagate(errp, err);
> - return;
> - }
> + object_property_set_int(obj, bitband_input_addr[i], "base",
> &err);
> + if (err != NULL) {
> + error_propagate(errp, err);
> + return;
> + }
> + object_property_set_link(obj, OBJECT(s->board_memory),
> + "source-memory", &error_abort);
> + object_property_set_bool(obj, true, "realized", &err);
> + if (err != NULL) {
> + error_propagate(errp, err);
> + return;
> + }
>
> - memory_region_add_subregion(&s->container, bitband_output_addr[i],
> - sysbus_mmio_get_region(sbd, 0));
> + memory_region_add_subregion(&s->container,
> bitband_output_addr[i],
> + sysbus_mmio_get_region(sbd, 0));
> + }
> }
> }
>
> @@ -239,6 +241,7 @@ static Property armv7m_properties[] = {
> MemoryRegion *),
> DEFINE_PROP_LINK("idau", ARMv7MState, idau, TYPE_IDAU_INTERFACE, Object
> *),
> DEFINE_PROP_UINT32("init-svtor", ARMv7MState, init_svtor, 0),
> + DEFINE_PROP_BOOL("enable-bitband", ARMv7MState, enable_bitband, false),
> DEFINE_PROP_END_OF_LIST(),
> };
>
> diff --git a/hw/arm/mps2.c b/hw/arm/mps2.c
> index c3946da317..0a0ae867d9 100644
> --- a/hw/arm/mps2.c
> +++ b/hw/arm/mps2.c
> @@ -186,6 +186,7 @@ static void mps2_common_init(MachineState *machine)
> g_assert_not_reached();
> }
> qdev_prop_set_string(armv7m, "cpu-type", machine->cpu_type);
> + qdev_prop_set_bit(armv7m, "enable-bitband", true);
> object_property_set_link(OBJECT(&mms->armv7m), OBJECT(system_memory),
> "memory", &error_abort);
> object_property_set_bool(OBJECT(&mms->armv7m), true, "realized",
> diff --git a/hw/arm/msf2-soc.c b/hw/arm/msf2-soc.c
> index dbefade644..2702e90b45 100644
> --- a/hw/arm/msf2-soc.c
> +++ b/hw/arm/msf2-soc.c
> @@ -117,6 +117,7 @@ static void m2sxxx_soc_realize(DeviceState *dev_soc,
> Error **errp)
> armv7m = DEVICE(&s->armv7m);
> qdev_prop_set_uint32(armv7m, "num-irq", 81);
> qdev_prop_set_string(armv7m, "cpu-type", s->cpu_type);
> + qdev_prop_set_bit(armv7m, "enable-bitband", true);
> object_property_set_link(OBJECT(&s->armv7m), OBJECT(get_system_memory()),
> "memory", &error_abort);
> object_property_set_bool(OBJECT(&s->armv7m), true, "realized", &err);
> diff --git a/hw/arm/stellaris.c b/hw/arm/stellaris.c
> index dc521b4a5a..6c69ce79b2 100644
> --- a/hw/arm/stellaris.c
> +++ b/hw/arm/stellaris.c
> @@ -1304,6 +1304,7 @@ static void stellaris_init(MachineState *ms,
> stellaris_board_info *board)
> nvic = qdev_create(NULL, TYPE_ARMV7M);
> qdev_prop_set_uint32(nvic, "num-irq", NUM_IRQ_LINES);
> qdev_prop_set_string(nvic, "cpu-type", ms->cpu_type);
> + qdev_prop_set_bit(nvic, "enable-bitband", true);
> object_property_set_link(OBJECT(nvic), OBJECT(get_system_memory()),
> "memory", &error_abort);
> /* This will exit with an error if the user passed us a bad cpu_type */
> diff --git a/hw/arm/stm32f205_soc.c b/hw/arm/stm32f205_soc.c
> index c486d06a8b..980e5af13c 100644
> --- a/hw/arm/stm32f205_soc.c
> +++ b/hw/arm/stm32f205_soc.c
> @@ -109,6 +109,7 @@ static void stm32f205_soc_realize(DeviceState *dev_soc,
> Error **errp)
> armv7m = DEVICE(&s->armv7m);
> qdev_prop_set_uint32(armv7m, "num-irq", 96);
> qdev_prop_set_string(armv7m, "cpu-type", s->cpu_type);
> + qdev_prop_set_bit(armv7m, "enable-bitband", true);
> object_property_set_link(OBJECT(&s->armv7m), OBJECT(get_system_memory()),
> "memory", &error_abort);
> object_property_set_bool(OBJECT(&s->armv7m), true, "realized", &err);
>
