drm/msm: add support to take dpu snapshot

Add the msm_disp_snapshot module which adds supports to dump dpu
registers and capture the drm atomic state which can be used in
case of error conditions.

changes in v5:
 - start storing disp_state in msm_kms instead of dpu_kms
 - get rid of MSM_DISP_SNAPSHOT_IN_* enum by simplifying the functions
 - move snprintf inside the snapshot core by using varargs
 - get rid of some stale code comments
 - allow snapshot module for non-DPU targets

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Abhinav Kumar <abhinavk@codeaurora.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/1618606645-19695-3-git-send-email-abhinavk@codeaurora.org
Signed-off-by: Rob Clark <robdclark@chromium.org>

1 files changed, 161 insertions, 0 deletions

diff --git a/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
new file mode 100644
index 000000000000..70fd5a1fe13e
--- /dev/null
+++ b/drivers/gpu/drm/msm/disp/msm_disp_snapshot.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020-2021, The Linux Foundation. All rights reserved.
+ */
+
+#define pr_fmt(fmt)	"[drm:%s:%d] " fmt, __func__, __LINE__
+
+#include "msm_disp_snapshot.h"
+
+#ifdef CONFIG_DEV_COREDUMP
+static ssize_t disp_devcoredump_read(char *buffer, loff_t offset,
+		size_t count, void *data, size_t datalen)
+{
+	struct drm_print_iterator iter;
+	struct drm_printer p;
+	struct msm_disp_state *disp_state;
+
+	disp_state = data;
+
+	iter.data = buffer;
+	iter.offset = 0;
+	iter.start = offset;
+	iter.remain = count;
+
+	p = drm_coredump_printer(&iter);
+
+	msm_disp_state_print(disp_state, &p);
+
+	return count - iter.remain;
+}
+
+static void disp_devcoredump_free(void *data)
+{
+	struct msm_disp_state *disp_state;
+
+	disp_state = data;
+
+	msm_disp_state_free(disp_state);
+
+	disp_state->coredump_pending = false;
+}
+#endif /* CONFIG_DEV_COREDUMP */
+
+static void _msm_disp_snapshot_work(struct kthread_work *work)
+{
+	struct msm_disp_state *disp_state = container_of(work, struct msm_disp_state, dump_work);
+	struct drm_printer p;
+
+	mutex_lock(&disp_state->mutex);
+
+	msm_disp_snapshot_capture_state(disp_state);
+
+	if (MSM_DISP_SNAPSHOT_DUMP_IN_CONSOLE) {
+		p = drm_info_printer(disp_state->drm_dev->dev);
+		msm_disp_state_print(disp_state, &p);
+	}
+
+	/*
+	 * if devcoredump is not defined free the state immediately
+	 * otherwise it will be freed in the free handler.
+	 */
+#ifdef CONFIG_DEV_COREDUMP
+	dev_coredumpm(disp_state->dev, THIS_MODULE, disp_state, 0, GFP_KERNEL,
+			disp_devcoredump_read, disp_devcoredump_free);
+	disp_state->coredump_pending = true;
+#else
+	msm_disp_state_free(disp_state);
+#endif
+
+	mutex_unlock(&disp_state->mutex);
+}
+
+void msm_disp_snapshot_state(struct drm_device *drm_dev)
+{
+	struct msm_drm_private *priv;
+	struct msm_kms *kms;
+	struct msm_disp_state *disp_state;
+
+	if (!drm_dev) {
+		DRM_ERROR("invalid params\n");
+		return;
+	}
+
+	priv = drm_dev->dev_private;
+	kms = priv->kms;
+	disp_state = kms->disp_state;
+
+	if (!disp_state) {
+		DRM_ERROR("invalid params\n");
+		return;
+	}
+
+	/*
+	 * if there is a coredump pending return immediately till dump
+	 * if read by userspace or timeout happens
+	 */
+	if (disp_state->coredump_pending) {
+		DRM_DEBUG("coredump is pending read\n");
+		return;
+	}
+
+	kthread_queue_work(disp_state->dump_worker,
+			&disp_state->dump_work);
+}
+
+int msm_disp_snapshot_init(struct drm_device *drm_dev)
+{
+	struct msm_drm_private *priv;
+	struct msm_disp_state *disp_state;
+	struct msm_kms *kms;
+
+	if (!drm_dev) {
+		DRM_ERROR("invalid params\n");
+		return -EINVAL;
+	}
+
+	priv = drm_dev->dev_private;
+	kms = priv->kms;
+
+	disp_state = devm_kzalloc(drm_dev->dev, sizeof(struct msm_disp_state), GFP_KERNEL);
+
+	mutex_init(&disp_state->mutex);
+
+	disp_state->dev = drm_dev->dev;
+	disp_state->drm_dev = drm_dev;
+
+	INIT_LIST_HEAD(&disp_state->blocks);
+
+	disp_state->dump_worker = kthread_create_worker(0, "%s", "disp_snapshot");
+	if (IS_ERR(disp_state->dump_worker))
+		DRM_ERROR("failed to create disp state task\n");
+
+	kthread_init_work(&disp_state->dump_work, _msm_disp_snapshot_work);
+
+	kms->disp_state = disp_state;
+
+	return 0;
+}
+
+void msm_disp_snapshot_destroy(struct drm_device *drm_dev)
+{
+	struct msm_kms *kms;
+	struct msm_drm_private *priv;
+	struct msm_disp_state *disp_state;
+
+	if (!drm_dev) {
+		DRM_ERROR("invalid params\n");
+		return;
+	}
+
+	priv = drm_dev->dev_private;
+	kms = priv->kms;
+	disp_state = kms->disp_state;
+
+	if (disp_state->dump_worker)
+		kthread_destroy_worker(disp_state->dump_worker);
+
+	list_del(&disp_state->blocks);
+
+	mutex_destroy(&disp_state->mutex);
+}