[PATCH v1 1/5] ACPI: CPPC: Check _OSC for flexible address space

[Pierre Gondois <pierre.gondois@arm.com>]

ACPI 6.2 Section 6.2.11.2 'Platform-Wide OSPM Capabilities':
  Starting with ACPI Specification 6.2, all _CPC registers can be in
  PCC, System Memory, System IO, or Functional Fixed Hardware address
  spaces. OSPM support for this more flexible register space scheme is
  indicated by the “Flexible Address Space for CPPC Registers” _OSC bit

Otherwise (cf ACPI 6.1, s8.4.7.1.1.X), _CPC registers must be in:
- PCC or Functional Fixed Hardware address space if defined
- SystemMemory address space (NULL register) if not defined

Add the corresponding _OSC bit and check it when parsing _CPC objects.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
---
 drivers/acpi/bus.c       | 18 ++++++++++++++++++
 drivers/acpi/cppc_acpi.c |  9 +++++++++
 include/linux/acpi.h     |  2 ++
 3 files changed, 29 insertions(+)

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 3e58b613a2c4..a5d08de5d1e9 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -278,6 +278,20 @@ bool osc_sb_apei_support_acked;
 bool osc_pc_lpi_support_confirmed;
 EXPORT_SYMBOL_GPL(osc_pc_lpi_support_confirmed);
 
+/*
+ * ACPI 6.2 Section 6.2.11.2 'Platform-Wide OSPM Capabilities':
+ *   Starting with ACPI Specification 6.2, all _CPC registers can be in
+ *   PCC, System Memory, System IO, or Functional Fixed Hardware address
+ *   spaces. OSPM support for this more flexible register space scheme is
+ *   indicated by the “Flexible Address Space for CPPC Registers” _OSC bit.
+ *
+ * Otherwise (cf ACPI 6.1, s8.4.7.1.1.X), _CPC registers must be in:
+ * - PCC or Functional Fixed Hardware address space if defined
+ * - SystemMemory address space (NULL register) if not defined
+ */
+bool osc_cpc_flexible_adr_space_confirmed;
+EXPORT_SYMBOL_GPL(osc_cpc_flexible_adr_space_confirmed);
+
 /*
  * ACPI 6.4 Operating System Capabilities for USB.
  */
@@ -321,6 +335,8 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 	}
 #endif
 
+	capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPC_FLEXIBLE_ADR_SP;
+
 	if (IS_ENABLED(CONFIG_SCHED_MC_PRIO))
 		capbuf[OSC_SUPPORT_DWORD] |= OSC_SB_CPC_DIVERSE_HIGH_SUPPORT;
 
@@ -366,6 +382,8 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_PCLPI_SUPPORT;
 		osc_sb_native_usb4_support_confirmed =
 			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_NATIVE_USB4_SUPPORT;
+		osc_cpc_flexible_adr_space_confirmed =
+			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_CPC_FLEXIBLE_ADR_SP;
 	}
 
 	kfree(context.ret.pointer);
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index bc1454789a06..6f09fe011544 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -736,6 +736,11 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 				if (gas_t->address) {
 					void __iomem *addr;
 
+					if (!osc_cpc_flexible_adr_space_confirmed) {
+						pr_debug("Flexible address space capability not supported\n");
+						goto out_free;
+					}
+
 					addr = ioremap(gas_t->address, gas_t->bit_width/8);
 					if (!addr)
 						goto out_free;
@@ -758,6 +763,10 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 						 gas_t->address);
 					goto out_free;
 				}
+				if (!osc_cpc_flexible_adr_space_confirmed) {
+					pr_debug("Flexible address space capability not supported\n");
+					goto out_free;
+				}
 			} else {
 				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
 					/* Support only PCC, SystemMemory, SystemIO, and FFH type regs. */
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index d7136d13aa44..977d74d0465b 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -574,6 +574,7 @@ acpi_status acpi_run_osc(acpi_handle handle, struct acpi_osc_context *context);
 #define OSC_SB_OSLPI_SUPPORT			0x00000100
 #define OSC_SB_CPC_DIVERSE_HIGH_SUPPORT		0x00001000
 #define OSC_SB_GENERIC_INITIATOR_SUPPORT	0x00002000
+#define OSC_SB_CPC_FLEXIBLE_ADR_SP		0x00004000
 #define OSC_SB_NATIVE_USB4_SUPPORT		0x00040000
 #define OSC_SB_PRM_SUPPORT			0x00200000
 
@@ -581,6 +582,7 @@ extern bool osc_sb_apei_support_acked;
 extern bool osc_pc_lpi_support_confirmed;
 extern bool osc_sb_native_usb4_support_confirmed;
 extern bool osc_sb_cppc_not_supported;
+extern bool osc_cpc_flexible_adr_space_confirmed;
 
 /* USB4 Capabilities */
 #define OSC_USB_USB3_TUNNELING			0x00000001
-- 
2.25.1