[PATCH 5/9] platform/x86: intel_pmc_core: Get LPM requirements for Tiger Lake

David E. Box
2021-04-01T03:07:16Z

From: Gayatri Kammela <gayatri.kammela@intel.com>

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>
---
drivers/platform/x86/intel_pmc_core.c | 49 +++++++++++++++++++++++++++
drivers/platform/x86/intel_pmc_core.h | 2 ++
2 files changed, 51 insertions(+)

diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
index ba0db301f07b..0ec26a4c715e 100644
--- a/drivers/platform/x86/intel_pmc_core.c
+++ b/drivers/platform/x86/intel_pmc_core.c
@@ -23,7 +23,9 @@
#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>
@@ -31,6 +33,9 @@

#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},
@@ -587,6 +592,46 @@ static const struct pmc_reg_map tgl_reg_map = {
.lpm_live_status_offset = TGL_LPM_LIVE_STATUS_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;
+
+ adev = ACPI_COMPANION(&pdev->dev);
+ if (!adev)
+ return;
+
+ lpm_req_regs = devm_kzalloc(&pdev->dev, lpm_size * sizeof(u32),
+ GFP_KERNEL);
+ if (!lpm_req_regs)
+ 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) {
+ u32 *addr = (u32 *)out_obj->buffer.pointer;
+ int size = out_obj->buffer.length;
+
+ if (size != lpm_size)
+ return;
+
+ memcpy_fromio(lpm_req_regs, addr, lpm_size);
+ } else
+ acpi_handle_debug(adev->handle,
+ "_DSM function 0 evaluation failed\n");
+
+ ACPI_FREE(out_obj);
+
+ pmcdev->lpm_req_regs = lpm_req_regs;
+}
+
static inline u32 pmc_core_reg_read(struct pmc_dev *pmcdev, int reg_offset)
{
return readl(pmcdev->regbase + reg_offset);
@@ -1312,10 +1357,14 @@ 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.
diff --git a/drivers/platform/x86/intel_pmc_core.h b/drivers/platform/x86/intel_pmc_core.h
index 3800c1ba6fb7..81d797feed33 100644
--- a/drivers/platform/x86/intel_pmc_core.h
+++ b/drivers/platform/x86/intel_pmc_core.h
@@ -288,6 +288,7 @@ struct pmc_reg_map {
* @s0ix_counter: S0ix residency (step adjusted)
* @num_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.
*/
@@ -304,6 +305,7 @@ struct pmc_dev {
u64 s0ix_counter;
int num_modes;
int lpm_en_modes[LPM_MAX_NUM_MODES];
+ u32 *lpm_req_regs;
};

#define pmc_for_each_mode(i, mode, pmcdev) \
--
2.25.1