Signed-off-by: Anju T Sudhakar <redacted>
---
  arch/powerpc/perf/imc-pmu.c               | 91 +++++++++++++++++++++++
  arch/powerpc/platforms/powernv/opal-imc.c |  3 +
  include/linux/cpuhotplug.h                |  1 +
  3 files changed, 95 insertions(+)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index 5ca80545a849..1f09265c8fb0 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c

@@ -43,6 +43,10 @@ static DEFINE_PER_CPU(u64 *, thread_imc_mem);
  static struct imc_pmu *thread_imc_pmu;
  static int thread_imc_mem_size;

+/* Trace IMC data structures */
+static DEFINE_PER_CPU(u64 *, trace_imc_mem);
+static int trace_imc_mem_size;
+
  static struct imc_pmu *imc_event_to_pmu(struct perf_event *event)
  {
  	return container_of(event->pmu, struct imc_pmu, pmu);

@@ -1068,6 +1072,54 @@ static void thread_imc_event_del(struct perf_event *event, int flags)
  	imc_event_update(event);
  }

+/*
+ * Allocate a page of memory for each cpu, and load LDBAR with 0.
+ */
+static int trace_imc_mem_alloc(int cpu_id, int size)
+{
+	u64 *local_mem = per_cpu(trace_imc_mem, cpu_id);
+	int phys_id = cpu_to_node(cpu_id), rc = 0;
+
+	if (!local_mem) {
+		local_mem = page_address(alloc_pages_node(phys_id,
+					GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE |
+					__GFP_NOWARN, get_order(size)));
+		if (!local_mem)
+			return -ENOMEM;
+		per_cpu(trace_imc_mem, cpu_id) = local_mem;
+
+		/* Initialise the counters for trace mode */
+		rc = opal_imc_counters_init(OPAL_IMC_COUNTERS_TRACE, __pa((void *)local_mem),
+					    get_hard_smp_processor_id(cpu_id));
+		if (rc) {
+			pr_info("IMC:opal init failed for trace imc\n");
+			return rc;
+		}
+	}
+
+	mtspr(SPRN_LDBAR, 0);
+	return 0;
+}
+
+static int ppc_trace_imc_cpu_online(unsigned int cpu)
+{
+	return trace_imc_mem_alloc(cpu, trace_imc_mem_size);
+}
+
+static int ppc_trace_imc_cpu_offline(unsigned int cpu)
+{
+	mtspr(SPRN_LDBAR, 0);
+	return 0;
+}
+
+static int trace_imc_cpu_init(void)
+{
+	return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
+			  "perf/powerpc/imc_trace:online",
+			  ppc_trace_imc_cpu_online,
+			  ppc_trace_imc_cpu_offline);
+}
+
  /* update_pmu_ops : Populate the appropriate operations for "pmu" */
  static int update_pmu_ops(struct imc_pmu *pmu)
  {

@@ -1189,6 +1241,17 @@ static void cleanup_all_thread_imc_memory(void)
  	}
  }

+static void cleanup_all_trace_imc_memory(void)
+{
+	int i, order = get_order(trace_imc_mem_size);
+
+	for_each_online_cpu(i) {
+		if (per_cpu(trace_imc_mem, i))
+			free_pages((u64)per_cpu(trace_imc_mem, i), order);
+
+	}
+}
+
  /* Function to free the attr_groups which are dynamically allocated */
  static void imc_common_mem_free(struct imc_pmu *pmu_ptr)
  {

@@ -1230,6 +1293,11 @@ static void imc_common_cpuhp_mem_free(struct imc_pmu *pmu_ptr)
  		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE);
  		cleanup_all_thread_imc_memory();
  	}
+
+	if (pmu_ptr->domain == IMC_DOMAIN_TRACE) {
+		cpuhp_remove_state(CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE);
+		cleanup_all_trace_imc_memory();
+	}
  }

  /*

@@ -1312,6 +1380,21 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct device_node *parent,

  		thread_imc_pmu = pmu_ptr;
  		break;
+	case IMC_DOMAIN_TRACE:
+		/* Update the pmu name */
+		pmu_ptr->pmu.name = kasprintf(GFP_KERNEL, "%s%s", s, "_imc");
+		if (!pmu_ptr->pmu.name)
+			return -ENOMEM;
+
+		trace_imc_mem_size = pmu_ptr->counter_mem_size;
+		for_each_online_cpu(cpu) {
+			res = trace_imc_mem_alloc(cpu, trace_imc_mem_size);
+			if (res) {
+				cleanup_all_trace_imc_memory();
+				goto err;
+			}
+		}
+		break;
  	default:
  		return -EINVAL;
  	}

@@ -1384,6 +1467,14 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id
  			goto err_free_mem;
  		}

+		break;
+	case IMC_DOMAIN_TRACE:
+		ret = trace_imc_cpu_init();
+		if (ret) {
+			cleanup_all_trace_imc_memory();
+			goto err_free_mem;
+		}
+
  		break;
  	default:
  		return  -EINVAL;	/* Unknown domain */

diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
index 58a07948c76e..dedc9ae22662 100644
--- a/arch/powerpc/platforms/powernv/opal-imc.c
+++ b/arch/powerpc/platforms/powernv/opal-imc.c

@@ -284,6 +284,9 @@ static int opal_imc_counters_probe(struct platform_device *pdev)
  		case IMC_TYPE_THREAD:
  			domain = IMC_DOMAIN_THREAD;
  			break;
+		case IMC_TYPE_TRACE:
+			domain = IMC_DOMAIN_TRACE;
+			break;
  		default:
  			pr_warn("IMC Unknown Device type \n");
  			domain = -1;

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index e0cd2baa8380..c471f2de878b 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h

@@ -167,6 +167,7 @@ enum cpuhp_state {
  	CPUHP_AP_PERF_POWERPC_NEST_IMC_ONLINE,
  	CPUHP_AP_PERF_POWERPC_CORE_IMC_ONLINE,
  	CPUHP_AP_PERF_POWERPC_THREAD_IMC_ONLINE,
+	CPUHP_AP_PERF_POWERPC_TRACE_IMC_ONLINE,
  	CPUHP_AP_WATCHDOG_ONLINE,
  	CPUHP_AP_WORKQUEUE_ONLINE,
  	CPUHP_AP_RCUTREE_ONLINE,