From: Perry Yuan <Perry.Yuan@amd.com>

There are some firmware parameters that need to be configured
when a CPU core is brought online or offline.

when CPU is online, it will initialize the workload classification
parameters to CPU firmware which will trigger the workload class ID
updating function.

Once the CPU is going to offline, it will need to disable the workload
classification function and clear the history.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/platform/x86/amd/hfi/hfi.c | 79 ++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/x86/amd/hfi/hfi.c
index 986ea056fa022..70ddde37f283f 100644
--- a/drivers/platform/x86/amd/hfi/hfi.c
+++ b/drivers/platform/x86/amd/hfi/hfi.c
@@ -245,6 +245,80 @@ static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
 	return 0;
 }
 
+static int amd_hfi_set_state(unsigned int cpu, bool state)
+{
+	int ret;
+
+	ret = wrmsrl_on_cpu(cpu, AMD_WORKLOAD_CLASS_CONFIG, state);
+	if (ret)
+		return ret;
+
+	return wrmsrl_on_cpu(cpu, AMD_WORKLOAD_HRST, 0x1);
+}
+
+/**
+ * amd_hfi_online() - Enable workload classification on @cpu
+ * @cpu: CPU in which the workload classification will be enabled
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int amd_hfi_online(unsigned int cpu)
+{
+	struct amd_hfi_cpuinfo *hfi_info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);
+	struct amd_hfi_classes *hfi_classes;
+	int ret;
+
+	if (WARN_ON_ONCE(!hfi_info))
+		return -EINVAL;
+
+	/*
+	 * Check if @cpu as an associated, initialized and ranking data must be filled
+	 */
+	hfi_classes = hfi_info->amd_hfi_classes;
+	if (!hfi_classes)
+		return -EINVAL;
+
+	guard(mutex)(&hfi_cpuinfo_lock);
+
+	if (!zalloc_cpumask_var(&hfi_info->cpus, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_set_cpu(cpu, hfi_info->cpus);
+
+	ret = amd_hfi_set_state(cpu, true);
+	if (ret)
+		pr_err("WCT enable failed for CPU %d\n", cpu);
+
+	return ret;
+}
+
+/**
+ * amd_hfi_offline() - Disable workload classification on @cpu
+ * @cpu: CPU in which the workload classification will be disabled
+ *
+ * Remove @cpu from those covered by its HFI instance.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int amd_hfi_offline(unsigned int cpu)
+{
+	struct amd_hfi_cpuinfo *hfi_info = &per_cpu(amd_hfi_cpuinfo, cpu);
+	int ret;
+
+	if (WARN_ON_ONCE(!hfi_info))
+		return -EINVAL;
+
+	guard(mutex)(&hfi_cpuinfo_lock);
+
+	ret = amd_hfi_set_state(cpu, false);
+	if (ret)
+		pr_err("WCT disable failed for CPU %d\n", cpu);
+
+	free_cpumask_var(hfi_info->cpus);
+
+	return ret;
+}
+
 static int update_hfi_ipcc_scores(void)
 {
 	int cpu;
@@ -348,6 +422,11 @@ static int amd_hfi_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/amd_hfi:online",
+				amd_hfi_online, amd_hfi_offline);
+	if (ret < 0)
+		return ret;
+
 	return 0;
 }
 
-- 
2.43.0