[PATCH] hw/char/bcm2835_aux: Allow less than 32-bit accesses

[Philippe Mathieu-Daudé]

The "BCM2835 ARM Peripherals" datasheet [*] chapter 2
("Auxiliaries: UART1 & SPI1, SPI2"), list the register
sizes as 3/8/16/32 bits. We assume this means this
peripheral allows 8-bit accesses.

This was not an issue until commit 5d971f9e67 which reverted
("memory: accept mismatching sizes in memory_region_access_valid").

The model is implemented as 32-bit accesses (see commit 97398d900c,
all registers are 32-bit) so replace MemoryRegionOps.valid as
MemoryRegionOps.impl, and re-introduce MemoryRegionOps.valid
with a 8/32-bit range.

[*] https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf

Fixes: 97398d900c ("bcm2835_aux: add emulation of BCM2835 AUX (aka UART1) 
block")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
Noticed while running Trusted Firmware-A on the raspi3:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg680115.html
---
 hw/char/bcm2835_aux.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/char/bcm2835_aux.c b/hw/char/bcm2835_aux.c
index ee3dd40e3c..dade2ab5fd 100644
--- a/hw/char/bcm2835_aux.c
+++ b/hw/char/bcm2835_aux.c
@@ -249,7 +249,9 @@ static const MemoryRegionOps bcm2835_aux_ops = {
     .read = bcm2835_aux_read,
     .write = bcm2835_aux_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
-    .valid.min_access_size = 4,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
+    .valid.min_access_size = 1,
     .valid.max_access_size = 4,
 };
 
-- 
2.26.2