platform/x86:intel/pmc: Create Intel PMC SSRAM Telemetry driver

JIRA: https://issues.redhat.com/browse/RHEL-110838

commit b5d4653
Author: Xi Pardee <xi.pardee@linux.intel.com>
Date:   Fri Apr 25 12:52:30 2025 -0700

    platform/x86:intel/pmc: Create Intel PMC SSRAM Telemetry driver

    Convert ssram device related functionalities to a new driver named Intel
    PMC SSRAM Telemetry driver. Modify PMC Core driver to use API exported by
    the driver to discover and achieve devid and PWRMBASE address information
    for each available PMC. PMC Core driver needs to get PCI device when
    reading from telemetry regions.

    The new SSRAM driver binds to the SSRAM device and provides the following
    functionalities:
    1. Look for and register telemetry regions available in SSRAM device.
    2. Provide devid and PWRMBASE address information for the corresponding
       PMCs.

    Signed-off-by: Xi Pardee <xi.pardee@linux.intel.com>
    Link: https://lore.kernel.org/r/20250425195237.493129-3-xi.pardee@linux.intel.com
    Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
    Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Signed-off-by: Steve Best <sbest@redhat.com>

Author: sfbest

drivers/platform/x86/intel/pmc/Kconfig

@@ -8,6 +8,7 @@ config INTEL_PMC_CORE
 	depends on PCI
 	depends on ACPI
 	depends on INTEL_PMT_TELEMETRY
+	select INTEL_PMC_SSRAM_TELEMETRY
 	help
 	  The Intel Platform Controller Hub for Intel Core SoCs provides access
 	  to Power Management Controller registers via various interfaces. This
@@ -24,3 +25,6 @@ config INTEL_PMC_CORE
 		- SLPS0 Debug registers (Cannonlake/Icelake PCH)
 		- Low Power Mode registers (Tigerlake and beyond)
 		- PMC quirks as needed to enable SLPS0/S0ix
+
+config INTEL_PMC_SSRAM_TELEMETRY
+	tristate

drivers/platform/x86/intel/pmc/Makefile

@@ -3,8 +3,12 @@
 # Intel x86 Platform-Specific Drivers
 #
 
-intel_pmc_core-y			:= core.o ssram_telemetry.o spt.o cnp.o \
-					   icl.o tgl.o adl.o mtl.o arl.o lnl.o ptl.o
+intel_pmc_core-y			:= core.o spt.o cnp.o icl.o \
+					   tgl.o adl.o mtl.o arl.o lnl.o ptl.o
 obj-$(CONFIG_INTEL_PMC_CORE)		+= intel_pmc_core.o
 intel_pmc_core_pltdrv-y			:= pltdrv.o
 obj-$(CONFIG_INTEL_PMC_CORE)		+= intel_pmc_core_pltdrv.o
+
+# Intel PMC SSRAM driver
+intel_pmc_ssram_telemetry-y		+= ssram_telemetry.o
+obj-$(CONFIG_INTEL_PMC_SSRAM_TELEMETRY)	+= intel_pmc_ssram_telemetry.o

drivers/platform/x86/intel/pmc/core.c

@@ -29,6 +29,7 @@
 #include <asm/tsc.h>
 
 #include "core.h"
+#include "ssram_telemetry.h"
 #include "../pmt/telemetry.h"
 
 /* Maximum number of modes supported by platfoms that has low power mode capability */
@@ -1354,7 +1355,7 @@ static u32 pmc_core_find_guid(struct pmc_info *list, const struct pmc_reg_map *m
 	return 0;
 }
 
-static int pmc_core_get_lpm_req(struct pmc_dev *pmcdev, struct pmc *pmc)
+static int pmc_core_get_lpm_req(struct pmc_dev *pmcdev, struct pmc *pmc, struct pci_dev *pcidev)
 {
 	struct telem_endpoint *ep;
 	const u8 *lpm_indices;
@@ -1371,7 +1372,7 @@ static int pmc_core_get_lpm_req(struct pmc_dev *pmcdev, struct pmc *pmc)
 	if (!guid)
 		return -ENXIO;
 
-	ep = pmt_telem_find_and_register_endpoint(pmcdev->ssram_pcidev, guid, 0);
+	ep = pmt_telem_find_and_register_endpoint(pcidev, guid, 0);
 	if (IS_ERR(ep)) {
 		dev_dbg(&pmcdev->pdev->dev, "couldn't get telem endpoint %ld",
 			PTR_ERR(ep));
@@ -1455,27 +1456,29 @@ static int pmc_core_get_lpm_req(struct pmc_dev *pmcdev, struct pmc *pmc)
 	return ret;
 }
 
-static int pmc_core_ssram_get_lpm_reqs(struct pmc_dev *pmcdev)
+static int pmc_core_ssram_get_lpm_reqs(struct pmc_dev *pmcdev, int func)
 {
+	struct pci_dev *pcidev __free(pci_dev_put) = NULL;
 	unsigned int i;
 	int ret;
 
-	if (!pmcdev->ssram_pcidev)
+	pcidev = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(20, func));
+	if (!pcidev)
 		return -ENODEV;
 
 	for (i = 0; i < ARRAY_SIZE(pmcdev->pmcs); ++i) {
 		if (!pmcdev->pmcs[i])
 			continue;
 
-		ret = pmc_core_get_lpm_req(pmcdev, pmcdev->pmcs[i]);
+		ret = pmc_core_get_lpm_req(pmcdev, pmcdev->pmcs[i], pcidev);
 		if (ret)
 			return ret;
 	}
 
 	return 0;
 }
 
-const struct pmc_reg_map *pmc_core_find_regmap(struct pmc_info *list, u16 devid)
+static const struct pmc_reg_map *pmc_core_find_regmap(struct pmc_info *list, u16 devid)
 {
 	for (; list->map; ++list)
 		if (devid == list->devid)
@@ -1484,23 +1487,32 @@ const struct pmc_reg_map *pmc_core_find_regmap(struct pmc_info *list, u16 devid)
 	return NULL;
 }
 
-int pmc_core_pmc_add(struct pmc_dev *pmcdev, u64 pwrm_base,
-		     const struct pmc_reg_map *reg_map, unsigned int pmc_index)
+static int pmc_core_pmc_add(struct pmc_dev *pmcdev, unsigned int pmc_index)
+
 {
-	struct pmc *pmc = pmcdev->pmcs[pmc_index];
+	struct pmc_ssram_telemetry pmc_ssram_telemetry;
+	const struct pmc_reg_map *map;
+	struct pmc *pmc;
+	int ret;
+
+	ret = pmc_ssram_telemetry_get_pmc_info(pmc_index, &pmc_ssram_telemetry);
+	if (ret)
+		return ret;
 
-	if (!pwrm_base)
+	map = pmc_core_find_regmap(pmcdev->regmap_list, pmc_ssram_telemetry.devid);
+	if (!map)
 		return -ENODEV;
 
-	/* Memory for primary PMC has been allocated in core.c */
+	pmc = pmcdev->pmcs[pmc_index];
+	/* Memory for primary PMC has been allocated */
 	if (!pmc) {
 		pmc = devm_kzalloc(&pmcdev->pdev->dev, sizeof(*pmc), GFP_KERNEL);
 		if (!pmc)
 			return -ENOMEM;
 	}
 
-	pmc->map = reg_map;
-	pmc->base_addr = pwrm_base;
+	pmc->map = map;
+	pmc->base_addr = pmc_ssram_telemetry.base_addr;
 	pmc->regbase = ioremap(pmc->base_addr, pmc->map->regmap_length);
 
 	if (!pmc->regbase) {
@@ -1513,6 +1525,20 @@ int pmc_core_pmc_add(struct pmc_dev *pmcdev, u64 pwrm_base,
 	return 0;
 }
 
+static int pmc_core_ssram_get_reg_base(struct pmc_dev *pmcdev)
+{
+	int ret;
+
+	ret = pmc_core_pmc_add(pmcdev, PMC_IDX_MAIN);
+	if (ret)
+		return ret;
+
+	pmc_core_pmc_add(pmcdev, PMC_IDX_IOE);
+	pmc_core_pmc_add(pmcdev, PMC_IDX_PCH);
+
+	return 0;
+}
+
 /*
  * When supported, ssram init is used to achieve all available PMCs.
  * If ssram init fails, this function uses legacy method to at least get the
@@ -1530,10 +1556,18 @@ int generic_core_init(struct pmc_dev *pmcdev, struct pmc_dev_info *pmc_dev_info)
 	ssram = pmc_dev_info->regmap_list != NULL;
 	if (ssram) {
 		pmcdev->regmap_list = pmc_dev_info->regmap_list;
-		ret = pmc_core_ssram_init(pmcdev, pmc_dev_info->pci_func);
+		ret = pmc_core_ssram_get_reg_base(pmcdev);
+		/*
+		 * EAGAIN error code indicates Intel PMC SSRAM Telemetry driver
+		 * has not finished probe and PMC info is not available yet. Try
+		 * again later.
+		 */
+		if (ret == -EAGAIN)
+			return -EPROBE_DEFER;
+
 		if (ret) {
 			dev_warn(&pmcdev->pdev->dev,
-				 "ssram init failed, %d, using legacy init\n", ret);
+				 "Failed to get PMC info from SSRAM, %d, using legacy init\n", ret);
 			ssram = false;
 		}
 	}
@@ -1550,7 +1584,7 @@ int generic_core_init(struct pmc_dev *pmcdev, struct pmc_dev_info *pmc_dev_info)
 		pmc_core_punit_pmt_init(pmcdev, pmc_dev_info->dmu_guid);
 
 	if (ssram)
-		return pmc_core_ssram_get_lpm_reqs(pmcdev);
+		return pmc_core_ssram_get_lpm_reqs(pmcdev, pmc_dev_info->pci_func);
 
 	return 0;
 }
@@ -1639,15 +1673,10 @@ static void pmc_core_clean_structure(struct platform_device *pdev)
 	for (i = 0; i < ARRAY_SIZE(pmcdev->pmcs); ++i) {
 		struct pmc *pmc = pmcdev->pmcs[i];
 
-		if (pmc)
+		if (pmc && pmc->regbase)
 			iounmap(pmc->regbase);
 	}
 
-	if (pmcdev->ssram_pcidev) {
-		pci_dev_put(pmcdev->ssram_pcidev);
-		pci_disable_device(pmcdev->ssram_pcidev);
-	}
-
 	if (pmcdev->punit_ep)
 		pmt_telem_unregister_endpoint(pmcdev->punit_ep);
 

drivers/platform/x86/intel/pmc/core.h

@@ -413,7 +413,6 @@ struct pmc {
  * struct pmc_dev - pmc device structure
  * @devs:		pointer to an array of pmc pointers
  * @pdev:		pointer to platform_device struct
- * @ssram_pcidev:	pointer to pci device struct for the PMC SSRAM
  * @crystal_freq:	crystal frequency from cpuid
  * @dbgfs_dir:		path to debugfs interface
  * @pmc_xram_read_bit:	flag to indicate whether PMC XRAM shadow registers
@@ -433,7 +432,6 @@ struct pmc_dev {
 	struct pmc *pmcs[MAX_NUM_PMC];
 	struct dentry *dbgfs_dir;
 	struct platform_device *pdev;
-	struct pci_dev *ssram_pcidev;
 	unsigned int crystal_freq;
 	int pmc_xram_read_bit;
 	struct mutex lock; /* generic mutex lock for PMC Core */
@@ -510,12 +508,7 @@ void pmc_core_get_low_power_modes(struct pmc_dev *pmcdev);
 void pmc_core_punit_pmt_init(struct pmc_dev *pmcdev, u32 guid);
 void pmc_core_set_device_d3(unsigned int device);
 
-int pmc_core_ssram_init(struct pmc_dev *pmcdev, int func);
-
 int generic_core_init(struct pmc_dev *pmcdev, struct pmc_dev_info *pmc_dev_info);
-const struct pmc_reg_map *pmc_core_find_regmap(struct pmc_info *list, u16 devid);
-int pmc_core_pmc_add(struct pmc_dev *pmcdev, u64 pwrm_base,
-		     const struct pmc_reg_map *reg_map, unsigned int pmc_index);
 
 extern struct pmc_dev_info spt_pmc_dev;
 extern struct pmc_dev_info cnp_pmc_dev;