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Subject[PATCH v2 08/13] ACPICA: Hardware: Add optimized access bit width support
Date
ACPICA commit c49a751b4dae7baec1790748a2b4b6e8ab599f51

For Access Size = 0, it actually can use user expected access bit width.
This patch implements this.

Besides of the ACPICA upstream commit, this patch also includes a fix fixing
the issue reported by the FreeBSD community.
The old register descriptors are translated in acpi_tb_init_generic_address()
with access_width being filled with 0. This breaks code in
acpi_hw_get_access_bit_width() when the registers are 16-bit IO ports and their
bit_width fields are filled with 16. The rapid fix is meant to make code
written for acpi_hw_get_access_bit_width() regression safer before the issue is
correctly fixed from acpi_tb_init_generic_address(). Reported by
John Baldwin <jhb@freebsd.org>, fixed by Lv Zheng <lv.zheng@intel.com>, tested
by Jung-uk Kim <jkim@freebsd.org>.

Link: https://github.com/acpica/acpica/commit/c49a751b
Reported-by: John Baldwin <jhb@freebsd.org>
Tested-by Jung-uk Kim <jkim@freebsd.org>.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
---
drivers/acpi/acpica/hwregs.c | 49 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c
index 035fb52..892e677 100644
--- a/drivers/acpi/acpica/hwregs.c
+++ b/drivers/acpi/acpica/hwregs.c
@@ -51,6 +51,10 @@ ACPI_MODULE_NAME("hwregs")

#if (!ACPI_REDUCED_HARDWARE)
/* Local Prototypes */
+static u8
+acpi_hw_get_access_bit_width(struct acpi_generic_address *reg,
+ u8 max_bit_width);
+
static acpi_status
acpi_hw_read_multiple(u32 *value,
struct acpi_generic_address *register_a,
@@ -65,6 +69,48 @@ acpi_hw_write_multiple(u32 value,

/******************************************************************************
*
+ * FUNCTION: acpi_hw_get_access_bit_width
+ *
+ * PARAMETERS: reg - GAS register structure
+ * max_bit_width - Max bit_width supported (32 or 64)
+ *
+ * RETURN: Status
+ *
+ * DESCRIPTION: Obtain optimal access bit width
+ *
+ ******************************************************************************/
+
+static u8
+acpi_hw_get_access_bit_width(struct acpi_generic_address *reg, u8 max_bit_width)
+{
+ u64 address;
+
+ if (!reg->access_width) {
+ /*
+ * Detect old register descriptors where only the bit_width field
+ * makes senses. The target address is copied to handle possible
+ * alignment issues.
+ */
+ ACPI_MOVE_64_TO_64(&address, &reg->address);
+ if (!reg->bit_offset && reg->bit_width &&
+ ACPI_IS_POWER_OF_TWO(reg->bit_width) &&
+ ACPI_IS_ALIGNED(reg->bit_width, 8) &&
+ ACPI_IS_ALIGNED(address, reg->bit_width)) {
+ return (reg->bit_width);
+ } else {
+ if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
+ return (32);
+ } else {
+ return (max_bit_width);
+ }
+ }
+ } else {
+ return (1 << (reg->access_width + 2));
+ }
+}
+
+/******************************************************************************
+ *
* FUNCTION: acpi_hw_validate_register
*
* PARAMETERS: reg - GAS register structure
@@ -122,8 +168,7 @@ acpi_hw_validate_register(struct acpi_generic_address *reg,

/* Validate the bit_width, convert access_width into number of bits */

- access_width = reg->access_width ? reg->access_width : 1;
- access_width = 1 << (access_width + 2);
+ access_width = acpi_hw_get_access_bit_width(reg, max_bit_width);
bit_width =
ACPI_ROUND_UP(reg->bit_offset + reg->bit_width, access_width);
if (max_bit_width < bit_width) {
--
1.7.10
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