[PATCH 5.15.y 3/3] ACPI: CPPC: Fix access width used for PCC registers

[Easwar Hariharan <eahariha@linux.microsoft.com>]

From: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>

commit f489c948028b69cea235d9c0de1cc10eeb26a172 upstream

commit 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for system
memory accesses") modified cpc_read()/cpc_write() to use access_width to
read CPC registers.

However, for PCC registers the access width field in the ACPI register
macro specifies the PCC subspace ID.  For non-zero PCC subspace ID it is
incorrectly treated as access width. This causes errors when reading
from PCC registers in the CPPC driver.

For PCC registers, base the size of read/write on the bit width field.
The debug message in cpc_read()/cpc_write() is updated to print relevant
information for the address space type used to read the register.

Fixes: 2f4a4d63a193 ("ACPI: CPPC: Use access_width over bit_width for system memory accesses")
Signed-off-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com>
Tested-by: Jarred White <jarredwhite@linux.microsoft.com>
Reviewed-by: Jarred White <jarredwhite@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Cc: 5.15+ <stable@vger.kernel.org> # 5.15+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[ eahariha: Backport to v5.15 by dropping SystemIO bits as commit
  a2c8f92bea5f is not present ]
Signed-off-by: Easwar Hariharan <eahariha@linux.microsoft.com>
---
 drivers/acpi/cppc_acpi.c | 48 ++++++++++++++++++++++++++++++----------
 1 file changed, 36 insertions(+), 12 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6aa456cda0ed..6dcce036adb9 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -955,17 +955,24 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 	}
 
 	*val = 0;
-	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+	size = GET_BIT_WIDTH(reg);
+
+	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
+		/*
+		 * For registers in PCC space, the register size is determined
+		 * by the bit width field; the access size is used to indicate
+		 * the PCC subspace id.
+		 */
+		size = reg->bit_width;
 		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+	}
 	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		vaddr = reg_res->sys_mem_vaddr;
 	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
 		return cpc_read_ffh(cpu, reg, val);
 	else
 		return acpi_os_read_memory((acpi_physical_address)reg->address,
-				val, reg->bit_width);
-
-	size = GET_BIT_WIDTH(reg);
+				val, size);
 
 	switch (size) {
 	case 8:
@@ -981,8 +988,13 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
 		*val = readq_relaxed(vaddr);
 		break;
 	default:
-		pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
-			 reg->bit_width, pcc_ss_id);
+		if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+			pr_debug("Error: Cannot read %u bit width from system memory: 0x%llx\n",
+				size, reg->address);
+		} else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
+			pr_debug("Error: Cannot read %u bit width from PCC for ss: %d\n",
+				size, pcc_ss_id);
+		}
 		ret_val = -EFAULT;
 	}
 
@@ -1000,17 +1012,24 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
 	struct cpc_reg *reg = &reg_res->cpc_entry.reg;
 
-	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
+	size = GET_BIT_WIDTH(reg);
+
+	if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0) {
+		/*
+		 * For registers in PCC space, the register size is determined
+		 * by the bit width field; the access size is used to indicate
+		 * the PCC subspace id.
+		 */
+		size = reg->bit_width;
 		vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
+	}
 	else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		vaddr = reg_res->sys_mem_vaddr;
 	else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
 		return cpc_write_ffh(cpu, reg, val);
 	else
 		return acpi_os_write_memory((acpi_physical_address)reg->address,
-				val, reg->bit_width);
-
-	size = GET_BIT_WIDTH(reg);
+				val, size);
 
 	if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
 		val = MASK_VAL(reg, val);
@@ -1029,8 +1048,13 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
 		writeq_relaxed(val, vaddr);
 		break;
 	default:
-		pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
-			 reg->bit_width, pcc_ss_id);
+		if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+			pr_debug("Error: Cannot write %u bit width to system memory: 0x%llx\n",
+				size, reg->address);
+		} else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
+			pr_debug("Error: Cannot write %u bit width to PCC for ss: %d\n",
+				size, pcc_ss_id);
+		}
 		ret_val = -EFAULT;
 		break;
 	}
-- 
2.34.1