[PATCH v7 4/8] drm/panthor: Add panthor perf initialization and termination

[Lukas Zapolskas <lukas.zapolskas@arm.com>]

Added the panthor_perf system initialization and unplug code for
subsystem-level handling in subsequent patches. Userspace session
handling is done at the pfile level, via a pool of sessions.

Signed-off-by: Lukas Zapolskas <lukas.zapolskas@arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.c |  2 +
 drivers/gpu/drm/panthor/panthor_device.h |  9 +++-
 drivers/gpu/drm/panthor/panthor_drv.c    |  9 ++++
 drivers/gpu/drm/panthor/panthor_perf.c   | 85 ++++++++++++++++++++++++++++++++
 drivers/gpu/drm/panthor/panthor_perf.h   |  6 +++
 5 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 2877d47c6717..535383ef629f 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -95,6 +95,7 @@ void panthor_device_unplug(struct panthor_device *ptdev)
 	/* Now, try to cleanly shutdown the GPU before the device resources
 	 * get reclaimed.
 	 */
+	panthor_perf_unplug(ptdev);
 	panthor_sched_unplug(ptdev);
 	panthor_fw_unplug(ptdev);
 	panthor_mmu_unplug(ptdev);
@@ -310,6 +311,7 @@ int panthor_device_init(struct panthor_device *ptdev)
 
 err_disable_autosuspend:
 	pm_runtime_dont_use_autosuspend(ptdev->base.dev);
+	panthor_perf_unplug(ptdev);
 
 err_unplug_sched:
 	panthor_sched_unplug(ptdev);
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index d93b182a3d9b..085254a60fc4 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -29,10 +29,11 @@ struct panthor_hw;
 struct panthor_job;
 struct panthor_mmu;
 struct panthor_fw;
-struct panthor_perfcnt;
 struct panthor_pwr;
+struct panthor_perf;
 struct panthor_vm;
 struct panthor_vm_pool;
+struct panthor_perf_pool;
 
 /**
  * struct panthor_soc_data - Panthor SoC Data
@@ -323,6 +324,9 @@ struct panthor_device {
 		atomic_t recovery_needed;
 	} pm;
 
+	/** @perf: Performance counter management data. */
+	struct panthor_perf *perf;
+
 	/** @profile_mask: User-set profiling flags for job accounting. */
 	u32 profile_mask;
 
@@ -377,6 +381,9 @@ struct panthor_file {
 	/** @groups: Scheduling group pool attached to this file. */
 	struct panthor_group_pool *groups;
 
+	/** @sessions: Perf session pool attached to this file. */
+	struct panthor_perf_pool *sessions;
+
 	/** @stats: cycle and timestamp measures for job execution. */
 	struct panthor_gpu_usage stats;
 };
diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
index b6b55b0f2ff5..3e62142d7ebd 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -37,6 +37,7 @@
 #include "panthor_gpu.h"
 #include "panthor_heap.h"
 #include "panthor_mmu.h"
+#include "panthor_perf.h"
 #include "panthor_sched.h"
 
 /**
@@ -1635,9 +1636,16 @@ panthor_open(struct drm_device *ddev, struct drm_file *file)
 	if (ret)
 		goto err_destroy_vm_pool;
 
+	ret = panthor_perf_pool_create(pfile);
+	if (ret)
+		goto err_destroy_group_pool;
+
 	file->driver_priv = pfile;
 	return 0;
 
+err_destroy_group_pool:
+	panthor_group_pool_destroy(pfile);
+
 err_destroy_vm_pool:
 	panthor_vm_pool_destroy(pfile);
 
@@ -1651,6 +1659,7 @@ panthor_postclose(struct drm_device *ddev, struct drm_file *file)
 {
 	struct panthor_file *pfile = file->driver_priv;
 
+	panthor_perf_pool_destroy(pfile);
 	panthor_group_pool_destroy(pfile);
 	panthor_vm_pool_destroy(pfile);
 
diff --git a/drivers/gpu/drm/panthor/panthor_perf.c b/drivers/gpu/drm/panthor/panthor_perf.c
index cbfe1ca5872d..ba466e22c50d 100644
--- a/drivers/gpu/drm/panthor/panthor_perf.c
+++ b/drivers/gpu/drm/panthor/panthor_perf.c
@@ -3,7 +3,9 @@
 /* Copyright 2025 Arm ltd. */
 
 #include <linux/bitops.h>
+#include <drm/drm_managed.h>
 #include <drm/panthor_drm.h>
+#include <drm/drm_print.h>
 
 #include "panthor_device.h"
 #include "panthor_fw.h"
@@ -23,11 +25,26 @@
  */
 #define PANTHOR_HW_COUNTER_SIZE (sizeof(u32))
 
+#define MAX_SESSIONS_PER_FILE 1
+
 struct panthor_perf_counter_block {
 	struct drm_panthor_perf_block_header header;
 	u64 counters[];
 };
 
+struct panthor_perf {
+	/** @info: Pointer to the previously initialized perf info. */
+	struct drm_panthor_perf_info *info;
+};
+
+struct panthor_perf_pool {
+	/** @session_range: The number of sessions supported at a time. */
+	struct xa_limit session_range;
+
+	/** @xa: Xarray used to manage session handles. */
+	struct xarray xa;
+};
+
 static size_t get_annotated_block_size(size_t counters_per_block)
 {
 	return struct_size_t(struct panthor_perf_counter_block, counters, counters_per_block);
@@ -74,14 +91,82 @@ static void panthor_perf_info_init(struct panthor_device *const ptdev)
  * panthor_perf_init - Initialize the performance counter subsystem.
  * @ptdev: Panthor device
  *
+ * The performance counters require the FW interface to be available to setup the
+ * sampling ringbuffers, so this must be called only after FW is initialized.
+ *
  * Return: 0 on success, negative error code on failure.
  */
 int panthor_perf_init(struct panthor_device *ptdev)
 {
+	struct panthor_perf *perf;
+	int ret = 0;
+
 	if (!ptdev)
 		return -EINVAL;
 
 	panthor_perf_info_init(ptdev);
 
+	perf = drmm_kzalloc(&ptdev->base, sizeof(*perf), GFP_KERNEL);
+	if (!perf)
+		return -ENOMEM;
+
+	drm_info(&ptdev->base, "Performance counter subsystem initialized");
+
+	perf->info = &ptdev->perf_info;
+	ptdev->perf = perf;
+
+	return ret;
+}
+
+/**
+ * panthor_perf_unplug - Terminate the performance counter subsystem.
+ * @ptdev: Panthor device.
+ *
+ * Release the performance counter hardware resources. The control structure is
+ * released with the DRM device.
+ */
+void panthor_perf_unplug(struct panthor_device *ptdev)
+{
+	struct panthor_perf *perf = ptdev->perf;
+
+	if (!perf)
+		return;
+
+	ptdev->perf = NULL;
+}
+
+int panthor_perf_pool_create(struct panthor_file *pfile)
+{
+	struct panthor_perf_pool *pool;
+
+	pool = kzalloc_obj(*pool);
+	if (!pool)
+		return -ENOMEM;
+
+	xa_init_flags(&pool->xa, XA_FLAGS_ALLOC);
+
+	pool->session_range.min = 0;
+	pool->session_range.max = MAX_SESSIONS_PER_FILE - 1;
+
+	pfile->sessions = pool;
+
 	return 0;
 }
+
+void panthor_perf_pool_destroy(struct panthor_file *pfile)
+{
+	struct panthor_perf_pool *pool = pfile->sessions;
+
+	if (IS_ERR_OR_NULL(pool))
+		return;
+
+	if (!xa_empty(&pool->xa)) {
+		drm_err(&pfile->ptdev->base,
+			"Performance counter sessions active when unplugging the driver!");
+	}
+
+	xa_destroy(&pool->xa);
+	kfree(pool);
+
+	pfile->sessions = NULL;
+}
diff --git a/drivers/gpu/drm/panthor/panthor_perf.h b/drivers/gpu/drm/panthor/panthor_perf.h
index 3c32c24c164c..ad01fc88f18f 100644
--- a/drivers/gpu/drm/panthor/panthor_perf.h
+++ b/drivers/gpu/drm/panthor/panthor_perf.h
@@ -8,8 +8,14 @@
 #include <linux/types.h>
 
 struct panthor_device;
+struct panthor_file;
+struct panthor_perf_pool;
+
+int panthor_perf_pool_create(struct panthor_file *pfile);
+void panthor_perf_pool_destroy(struct panthor_file *pfile);
 
 int panthor_perf_init(struct panthor_device *ptdev);
+void panthor_perf_unplug(struct panthor_device *ptdev);
 
 #endif /* __PANTHOR_PERF_H__ */
 

-- 
2.43.0