linux-kernel - [PATCH 6/6] platform/x86/intel-uncore-freq: Process read/write blocked feature status

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Date:   Tue, 28 Nov 2023 10:56:05 -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 6/6] platform/x86/intel-uncore-freq: Process read/write blocked feature status

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

When the feature is write blocked, continue to offer read interface but
block setting uncore limits.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
---
 .../uncore-frequency/uncore-frequency-tpmi.c      | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-tpmi.c b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-tpmi.c
index 4fb790552c47..de5db49a9afe 100644
--- a/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-tpmi.c
+++ b/drivers/platform/x86/intel/uncore-frequency/uncore-frequency-tpmi.c
@@ -66,6 +66,7 @@ struct tpmi_uncore_struct {
 	int min_ratio;
 	struct tpmi_uncore_power_domain_info *pd_info;
 	struct tpmi_uncore_cluster_info root_cluster;
+	bool write_blocked;
 };
 
 #define UNCORE_GENMASK_MIN_RATIO	GENMASK_ULL(21, 15)
@@ -157,6 +158,9 @@ static int uncore_write_control_freq(struct uncore_data *data, unsigned int inpu
 	cluster_info = container_of(data, struct tpmi_uncore_cluster_info, uncore_data);
 	uncore_root = cluster_info->uncore_root;
 
+	if (uncore_root->write_blocked)
+		return -EPERM;
+
 	/* Update each cluster in a package */
 	if (cluster_info->root_domain) {
 		struct tpmi_uncore_struct *uncore_root = cluster_info->uncore_root;
@@ -233,11 +237,21 @@ static void remove_cluster_entries(struct tpmi_uncore_struct *tpmi_uncore)
 
 static int uncore_probe(struct auxiliary_device *auxdev, const struct auxiliary_device_id *id)
 {
+	int read_blocked = 0, write_blocked = 0;
 	struct intel_tpmi_plat_info *plat_info;
 	struct tpmi_uncore_struct *tpmi_uncore;
 	int ret, i, pkg = 0;
 	int num_resources;
 
+	ret = tpmi_get_feature_status(auxdev, TPMI_ID_UNCORE, &read_blocked, &write_blocked);
+	if (ret)
+		dev_info(&auxdev->dev, "Can't read feature status: ignoring blocked status\n");
+
+	if (read_blocked) {
+		dev_info(&auxdev->dev, "Firmware has blocked reads, exiting\n");
+		return -ENODEV;
+	}
+
 	/* Get number of power domains, which is equal to number of resources */
 	num_resources = tpmi_get_resource_count(auxdev);
 	if (!num_resources)
@@ -266,6 +280,7 @@ static int uncore_probe(struct auxiliary_device *auxdev, const struct auxiliary_
 	}
 
 	tpmi_uncore->power_domain_count = num_resources;
+	tpmi_uncore->write_blocked = write_blocked;
 
 	/* Get the package ID from the TPMI core */
 	plat_info = tpmi_get_platform_data(auxdev);
-- 
2.41.0