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 <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Reviewed-by: Ilpo Järvinen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Hans de Goede <[e-mail]>

drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c

···
  * @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
···
 	u64 saved_clos_configs[4];
 	u64 saved_clos_assocs[4];
 	u64 saved_pp_control;
+	bool write_blocked;
 };
 
 /**
···
 		return -EINVAL;
 
 	if (clos_param.get_set) {
+		if (power_domain_info->write_blocked)
+			return -EPERM;
+
 		_write_cp_info("clos.min_freq", clos_param.min_freq_mhz,
 			       (SST_CLOS_CONFIG_0_OFFSET + clos_param.clos * SST_REG_SIZE),
 			       SST_CLOS_CONFIG_MIN_START, SST_CLOS_CONFIG_MIN_WIDTH,
···
 			return -EINVAL;
 
 		power_domain_info = &sst_inst->power_domain_info[punit_id];
+
+		if (assoc_cmds.get_set && 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;
···
 	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;
 
···
 	power_domain_info = get_instance(perf_feature.socket_id, perf_feature.power_domain_id);
 	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,
···
 
 int tpmi_sst_dev_add(struct auxiliary_device *auxdev)
 {
+	bool 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) {
···
 		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);