platform/x86: intel_pmc_core: Get LPM requirements for Tiger Lake

Platforms that support low power modes (LPM) such as Tiger Lake maintain
requirements for each sub-state that a readable in the PMC. However, unlike
LPM status registers, requirement registers are not memory mapped but are
available from an ACPI _DSM. Collect the requirements for Tiger Lake using
the _DSM method and store in a buffer.

Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Co-developed-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/intel_pmc_core.c

@@ -23,14 +23,19 @@
 #include <linux/slab.h>
 #include <linux/suspend.h>
 #include <linux/uaccess.h>
+#include <linux/uuid.h>
 
+#include <acpi/acpi_bus.h>
 #include <asm/cpu_device_id.h>
 #include <asm/intel-family.h>
 #include <asm/msr.h>
 #include <asm/tsc.h>
 
 #include "intel_pmc_core.h"
 
+#define ACPI_S0IX_DSM_UUID		"57a6512e-3979-4e9d-9708-ff13b2508972"
+#define ACPI_GET_LOW_MODE_REGISTERS	1
+
 /* PKGC MSRs are common across Intel Core SoCs */
 static const struct pmc_bit_map msr_map[] = {
 	{"Package C2",                  MSR_PKG_C2_RESIDENCY},
@@ -590,6 +595,53 @@ static const struct pmc_reg_map tgl_reg_map = {
 	.etr3_offset = ETR3_OFFSET,
 };
 
+static void pmc_core_get_tgl_lpm_reqs(struct platform_device *pdev)
+{
+	struct pmc_dev *pmcdev = platform_get_drvdata(pdev);
+	const int num_maps = pmcdev->map->lpm_num_maps;
+	size_t lpm_size = LPM_MAX_NUM_MODES * num_maps * 4;
+	union acpi_object *out_obj;
+	struct acpi_device *adev;
+	guid_t s0ix_dsm_guid;
+	u32 *lpm_req_regs, *addr;
+
+	adev = ACPI_COMPANION(&pdev->dev);
+	if (!adev)
+		return;
+
+	guid_parse(ACPI_S0IX_DSM_UUID, &s0ix_dsm_guid);
+
+	out_obj = acpi_evaluate_dsm(adev->handle, &s0ix_dsm_guid, 0,
+				    ACPI_GET_LOW_MODE_REGISTERS, NULL);
+	if (out_obj && out_obj->type == ACPI_TYPE_BUFFER) {
+		int size = out_obj->buffer.length;
+
+		if (size != lpm_size) {
+			acpi_handle_debug(adev->handle,
+				"_DSM returned unexpected buffer size,"
+				" have %d, expect %ld\n", size, lpm_size);
+			goto free_acpi_obj;
+		}
+	} else {
+		acpi_handle_debug(adev->handle,
+				  "_DSM function 0 evaluation failed\n");
+		goto free_acpi_obj;
+	}
+
+	addr = (u32 *)out_obj->buffer.pointer;
+
+	lpm_req_regs = devm_kzalloc(&pdev->dev, lpm_size * sizeof(u32),
+				     GFP_KERNEL);
+	if (!lpm_req_regs)
+		goto free_acpi_obj;
+
+	memcpy(lpm_req_regs, addr, lpm_size);
+	pmcdev->lpm_req_regs = lpm_req_regs;
+
+free_acpi_obj:
+	ACPI_FREE(out_obj);
+}
+
 static inline u32 pmc_core_reg_read(struct pmc_dev *pmcdev, int reg_offset)
 {
 	return readl(pmcdev->regbase + reg_offset);
@@ -1424,10 +1476,14 @@ static int pmc_core_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	mutex_init(&pmcdev->lock);
+
 	pmcdev->pmc_xram_read_bit = pmc_core_check_read_lock_bit(pmcdev);
 	pmc_core_get_low_power_modes(pmcdev);
 	pmc_core_do_dmi_quirks(pmcdev);
 
+	if (pmcdev->map == &tgl_reg_map)
+		pmc_core_get_tgl_lpm_reqs(pdev);
+
 	/*
 	 * On TGL, due to a hardware limitation, the GBE LTR blocks PC10 when
 	 * a cable is attached. Tell the PMC to ignore it.

drivers/platform/x86/intel_pmc_core.h

@@ -294,6 +294,7 @@ struct pmc_reg_map {
  * @s0ix_counter:	S0ix residency (step adjusted)
  * @num_lpm_modes:	Count of enabled modes
  * @lpm_en_modes:	Array of enabled modes from lowest to highest priority
+ * @lpm_req_regs:	List of substate requirements
  *
  * pmc_dev contains info about power management controller device.
  */
@@ -310,6 +311,7 @@ struct pmc_dev {
 	u64 s0ix_counter;
 	int num_lpm_modes;
 	int lpm_en_modes[LPM_MAX_NUM_MODES];
+	u32 *lpm_req_regs;
 };
 
 #define pmc_for_each_mode(i, mode, pmcdev)		\