[PATCH for-5.1] acpi: allow accessing acpi-cnt register by byte

[Michael Tokarev]

>From the ACPI spec (4.8.3.2.1 PM1 Control Registers):

Register Location: <PM1a_CNT_BLK / PM1b_CNT_BLK> System I/O or Memory Space
Default Value:     00h
Attribute:         Read/Write
Size:              PM1_CNT_LEN (2 bytes)
The PM1 control registers contain the fixed hardware feature control bits.
These bits can be split between two registers: PM1a_CNT or PM1b_CNT.
Each register grouping can be at a different 32-bit aligned address
and is pointed to by the PM1a_CNT_BLK or PM1b_CNT_BLK. The values
for these pointers to the register space are found in the FADT.
Accesses to PM1 control registers are accessed through byte
and word accesses.

So allow 1-byte access too, not only 2-byte.

Fixes: afafe4bbe0cf7d3318e1ac7b40925561f86a6bd4
Fixes: 5d971f9e672507210e77d020d89e0e89165c8fc9
Buglink: 
https://lore.kernel.org/xen-devel/20200630170913.123646-1-anthony.perard@citrix.com/T/
Buglink: https://bugs.debian.org/964793
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 hw/acpi/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/core.c b/hw/acpi/core.c
index f6d9ec4f13..2c1199d9dc 100644
--- a/hw/acpi/core.c
+++ b/hw/acpi/core.c
@@ -599,7 +599,8 @@ static void acpi_pm_cnt_write(void *opaque, hwaddr addr, 
uint64_t val,
 static const MemoryRegionOps acpi_pm_cnt_ops = {
     .read = acpi_pm_cnt_read,
     .write = acpi_pm_cnt_write,
-    .valid.min_access_size = 2,
+    .impl.min_access_size = 2,
+    .valid.min_access_size = 1,
     .valid.max_access_size = 2,
     .endianness = DEVICE_LITTLE_ENDIAN,
 };
-- 
2.20.1