ACPICA: Hardware: Add optimized access bit width support

[mirror_ubuntu-bionic-kernel.git] / drivers / acpi / acpica / hwregs.c

diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c
index 5ba0498412fd5773d07feadd44ca442d88211b91..892e677f524f87f3c78fe494a4c0230e7137b496 100644 (file)
--- 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,
@@ -63,6 +67,48 @@ acpi_hw_write_multiple(u32 value,
 
 #endif                         /* !ACPI_REDUCED_HARDWARE */
 
+/******************************************************************************
+ *
+ * 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
@@ -83,6 +129,8 @@ acpi_status
 acpi_hw_validate_register(struct acpi_generic_address *reg,
                          u8 max_bit_width, u64 *address)
 {
+       u8 bit_width;
+       u8 access_width;
 
        /* Must have a valid pointer to a GAS structure */
 
@@ -109,23 +157,25 @@ acpi_hw_validate_register(struct acpi_generic_address *reg,
                return (AE_SUPPORT);
        }
 
-       /* Validate the bit_width */
+       /* Validate the access_width */
 
-       if ((reg->bit_width != 8) &&
-           (reg->bit_width != 16) &&
-           (reg->bit_width != 32) && (reg->bit_width != max_bit_width)) {
+       if (reg->access_width > 4) {
                ACPI_ERROR((AE_INFO,
-                           "Unsupported register bit width: 0x%X",
-                           reg->bit_width));
+                           "Unsupported register access width: 0x%X",
+                           reg->access_width));
                return (AE_SUPPORT);
        }
 
-       /* Validate the bit_offset. Just a warning for now. */
+       /* Validate the bit_width, convert access_width into number of bits */
 
-       if (reg->bit_offset != 0) {
+       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) {
                ACPI_WARNING((AE_INFO,
-                             "Unsupported register bit offset: 0x%X",
-                             reg->bit_offset));
+                             "Requested bit width 0x%X is smaller than register bit width 0x%X",
+                             max_bit_width, bit_width));
+               return (AE_SUPPORT);
        }
 
        return (AE_OK);