[RFC v2 3/8] drm/panthor: Add panthor_perf_init and panthor_perf_unplug

[Lukas Zapolskas]

Added the panthor_perf system initialization and unplug code to allow
for the handling of userspace sessions to be added in follow-up patches.

Signed-off-by: Lukas Zapolskas <lukas.zapolskas at arm.com>
---
 drivers/gpu/drm/panthor/panthor_device.c |  7 +++
 drivers/gpu/drm/panthor/panthor_device.h |  5 +-
 drivers/gpu/drm/panthor/panthor_perf.c   | 77 ++++++++++++++++++++++++
 drivers/gpu/drm/panthor/panthor_perf.h   |  3 +
 4 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 00f7b8ce935a..1a81a436143b 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -19,6 +19,7 @@
 #include "panthor_fw.h"
 #include "panthor_gpu.h"
 #include "panthor_mmu.h"
+#include "panthor_perf.h"
 #include "panthor_regs.h"
 #include "panthor_sched.h"
 
@@ -97,6 +98,7 @@ 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);
@@ -262,6 +264,10 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		goto err_unplug_fw;
 
+	ret = panthor_perf_init(ptdev);
+	if (ret)
+		goto err_unplug_fw;
+
 	/* ~3 frames */
 	pm_runtime_set_autosuspend_delay(ptdev->base.dev, 50);
 	pm_runtime_use_autosuspend(ptdev->base.dev);
@@ -275,6 +281,7 @@ int panthor_device_init(struct panthor_device *ptdev)
 
 err_disable_autosuspend:
 	pm_runtime_dont_use_autosuspend(ptdev->base.dev);
+	panthor_perf_unplug(ptdev);
 	panthor_sched_unplug(ptdev);
 
 err_unplug_fw:
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index 636542c1dcbd..aca33d03036c 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -26,7 +26,7 @@ struct panthor_heap_pool;
 struct panthor_job;
 struct panthor_mmu;
 struct panthor_fw;
-struct panthor_perfcnt;
+struct panthor_perf;
 struct panthor_vm;
 struct panthor_vm_pool;
 
@@ -137,6 +137,9 @@ struct panthor_device {
 	/** @devfreq: Device frequency scaling management data. */
 	struct panthor_devfreq *devfreq;
 
+	/** @perf: Performance counter management data. */
+	struct panthor_perf *perf;
+
 	/** @unplug: Device unplug related fields. */
 	struct {
 		/** @lock: Lock used to serialize unplug operations. */
diff --git a/drivers/gpu/drm/panthor/panthor_perf.c b/drivers/gpu/drm/panthor/panthor_perf.c
index 0e3d769c1805..e0dc6c4b0cf1 100644
--- a/drivers/gpu/drm/panthor/panthor_perf.c
+++ b/drivers/gpu/drm/panthor/panthor_perf.c
@@ -13,6 +13,24 @@
 #include "panthor_perf.h"
 #include "panthor_regs.h"
 
+struct panthor_perf {
+	/**
+	 * @block_set: The global counter set configured onto the HW.
+	 */
+	u8 block_set;
+
+	/** @next_session: The ID of the next session. */
+	u32 next_session;
+
+	/** @session_range: The number of sessions supported at a time. */
+	struct xa_limit session_range;
+
+	/**
+	 * @sessions: Global map of sessions, accessed by their ID.
+	 */
+	struct xarray sessions;
+};
+
 /**
  * PANTHOR_PERF_COUNTERS_PER_BLOCK - On CSF architectures pre-11.x, the number of counters
  * per block was hardcoded to be 64. Arch 11.0 onwards supports the PRFCNT_FEATURES GPU register,
@@ -45,3 +63,62 @@ void panthor_perf_info_init(struct panthor_device *ptdev)
 	perf_info->shader_blocks = hweight64(ptdev->gpu_info.shader_present);
 }
 
+/**
+ * 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;
+
+	if (!ptdev)
+		return -EINVAL;
+
+	perf = devm_kzalloc(ptdev->base.dev, sizeof(*perf), GFP_KERNEL);
+	if (ZERO_OR_NULL_PTR(perf))
+		return -ENOMEM;
+
+	xa_init_flags(&perf->sessions, XA_FLAGS_ALLOC);
+
+	/* Currently, we only support a single session at a time. */
+	perf->session_range = (struct xa_limit) {
+		.min = 0,
+		.max = 1,
+	};
+
+	drm_info(&ptdev->base, "Performance counter subsystem initialized");
+
+	ptdev->perf = perf;
+
+	return 0;
+}
+
+/**
+ * panthor_perf_unplug - Terminate the performance counter subsystem.
+ * @ptdev: Panthor device.
+ *
+ * This function will terminate the performance counter control structures and any remaining
+ * sessions, after waiting for any pending interrupts.
+ */
+void panthor_perf_unplug(struct panthor_device *ptdev)
+{
+	struct panthor_perf *perf = ptdev->perf;
+
+	if (!perf)
+		return;
+
+	if (!xa_empty(&perf->sessions))
+		drm_err(&ptdev->base,
+				"Performance counter sessions active when unplugging the driver!");
+
+	xa_destroy(&perf->sessions);
+
+	devm_kfree(ptdev->base.dev, ptdev->perf);
+
+	ptdev->perf = NULL;
+}
diff --git a/drivers/gpu/drm/panthor/panthor_perf.h b/drivers/gpu/drm/panthor/panthor_perf.h
index cff537a370c9..90af8b18358c 100644
--- a/drivers/gpu/drm/panthor/panthor_perf.h
+++ b/drivers/gpu/drm/panthor/panthor_perf.h
@@ -9,4 +9,7 @@ struct panthor_device;
 
 void panthor_perf_info_init(struct panthor_device *ptdev);
 
+int panthor_perf_init(struct panthor_device *ptdev);
+void panthor_perf_unplug(struct panthor_device *ptdev);
+
 #endif /* __PANTHOR_PERF_H__ */
-- 
2.25.1