linux-kernel - [PATCH 5/6] platform/x86: ISST: Process read/write blocked feature status

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Message-Id: <20231128185605.3027653-6-srinivas.pandruvada@linux.intel.com>
Date:   Tue, 28 Nov 2023 10:56:04 -0800
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     hdegoede@...hat.com, markgross@...nel.org,
        ilpo.jarvinen@...ux.intel.com, andriy.shevchenko@...ux.intel.com
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH 5/6] platform/x86: ISST: Process read/write blocked feature status

When a feature is read blocked, don't continue to read SST information
and register with SST core.

When the feature is write blocked, continue to offer read interface for
SST parameters, but don't allow any operation to change state. A state
change results from SST level change, feature change or class of service
change.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
---
 .../intel/speed_select_if/isst_tpmi_core.c    | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
index 0b6d2c864437..ed3a04d6c99c 100644
--- a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
+++ b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
@@ -234,6 +234,7 @@ struct perf_level {
  * @saved_clos_configs:	Save SST-CP CLOS configuration to store restore for suspend/resume
  * @saved_clos_assocs:	Save SST-CP CLOS association to store restore for suspend/resume
  * @saved_pp_control:	Save SST-PP control information to store restore for suspend/resume
+ * @write_blocked:	Write operation is blocked, so can't change SST state
  *
  * This structure is used store complete SST information for a power_domain. This information
  * is used to read/write request for any SST IOCTL. Each physical CPU package can have multiple
@@ -259,6 +260,7 @@ struct tpmi_per_power_domain_info {
 	u64 saved_clos_configs[4];
 	u64 saved_clos_assocs[4];
 	u64 saved_pp_control;
+	bool write_blocked;
 };
 
 /**
@@ -514,6 +516,9 @@ static long isst_if_clos_param(void __user *argp)
 	if (!power_domain_info)
 		return -EINVAL;
 
+	if (power_domain_info->write_blocked)
+		return -EPERM;
+
 	if (clos_param.get_set) {
 		_write_cp_info("clos.min_freq", clos_param.min_freq_mhz,
 			       (SST_CLOS_CONFIG_0_OFFSET + clos_param.clos * SST_REG_SIZE),
@@ -602,6 +607,9 @@ static long isst_if_clos_assoc(void __user *argp)
 
 		power_domain_info = &sst_inst->power_domain_info[punit_id];
 
+		if (power_domain_info->write_blocked)
+			return -EPERM;
+
 		offset = SST_CLOS_ASSOC_0_OFFSET +
 				(punit_cpu_no / SST_CLOS_ASSOC_CPUS_PER_REG) * SST_REG_SIZE;
 		shift = punit_cpu_no % SST_CLOS_ASSOC_CPUS_PER_REG;
@@ -752,6 +760,9 @@ static int isst_if_set_perf_level(void __user *argp)
 	if (!power_domain_info)
 		return -EINVAL;
 
+	if (power_domain_info->write_blocked)
+		return -EPERM;
+
 	if (!(power_domain_info->pp_header.allowed_level_mask & BIT(perf_level.level)))
 		return -EINVAL;
 
@@ -809,6 +820,9 @@ static int isst_if_set_perf_feature(void __user *argp)
 	if (!power_domain_info)
 		return -EINVAL;
 
+	if (power_domain_info->write_blocked)
+		return -EPERM;
+
 	_write_pp_info("perf_feature", perf_feature.feature, SST_PP_CONTROL_OFFSET,
 		       SST_PP_FEATURE_STATE_START, SST_PP_FEATURE_STATE_WIDTH,
 		       SST_MUL_FACTOR_NONE)
@@ -1257,11 +1271,21 @@ static long isst_if_def_ioctl(struct file *file, unsigned int cmd,
 
 int tpmi_sst_dev_add(struct auxiliary_device *auxdev)
 {
+	int read_blocked = 0, write_blocked = 0;
 	struct intel_tpmi_plat_info *plat_info;
 	struct tpmi_sst_struct *tpmi_sst;
 	int i, ret, pkg = 0, inst = 0;
 	int num_resources;
 
+	ret = tpmi_get_feature_status(auxdev, TPMI_ID_SST, &read_blocked, &write_blocked);
+	if (ret)
+		dev_info(&auxdev->dev, "Can't read feature status: ignoring read/write blocked status\n");
+
+	if (read_blocked) {
+		dev_info(&auxdev->dev, "Firmware has blocked reads, exiting\n");
+		return -ENODEV;
+	}
+
 	plat_info = tpmi_get_platform_data(auxdev);
 	if (!plat_info) {
 		dev_err(&auxdev->dev, "No platform info\n");
@@ -1306,6 +1330,7 @@ int tpmi_sst_dev_add(struct auxiliary_device *auxdev)
 		tpmi_sst->power_domain_info[i].package_id = pkg;
 		tpmi_sst->power_domain_info[i].power_domain_id = i;
 		tpmi_sst->power_domain_info[i].auxdev = auxdev;
+		tpmi_sst->power_domain_info[i].write_blocked = write_blocked;
 		tpmi_sst->power_domain_info[i].sst_base = devm_ioremap_resource(&auxdev->dev, res);
 		if (IS_ERR(tpmi_sst->power_domain_info[i].sst_base))
 			return PTR_ERR(tpmi_sst->power_domain_info[i].sst_base);
-- 
2.41.0