[PATCH 02/10] drm: crc: Introduce get_crc_sources callback

[Mahesh Kumar]

This patch introduce a callback function "get_crc_sources" which
will be called during read of control node. It is an optional
callback function and if driver implements this callback, driver
should print list of available CRC sources in seq_file privided
as an input to the callback.

Changes Since V1: (Daniel)
 - return const pointer to an array of crc sources list
 - do validation of sources in CRC-core

Signed-off-by: Mahesh Kumar <mahesh1.kumar at intel.com>
Cc: dri-devel at lists.freedesktop.org
Reviewed-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/drm_debugfs_crc.c | 20 +++++++++++++++++++-
 include/drm/drm_crtc.h            | 16 ++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
index c6a725b79ac6..f4d76528d24c 100644
--- a/drivers/gpu/drm/drm_debugfs_crc.c
+++ b/drivers/gpu/drm/drm_debugfs_crc.c
@@ -67,9 +67,27 @@
 static int crc_control_show(struct seq_file *m, void *data)
 {
 	struct drm_crtc *crtc = m->private;
+	size_t count;
+
+	if (crtc->funcs->get_crc_sources) {
+		const char *const *sources = crtc->funcs->get_crc_sources(crtc,
+									&count);
+		size_t values_cnt;
+		int i;
+
+		if (count <= 0 || !sources)
+			goto out;
+
+		seq_puts(m, "[");
+		for (i = 0; i < count; i++)
+			if (!crtc->funcs->verify_crc_source(crtc, sources[i],
+							    &values_cnt))
+				seq_printf(m, "%s ", sources[i]);
+		seq_puts(m, "] ");
+	}
 
+out:
 	seq_printf(m, "%s\n", crtc->crc.source);
-
 	return 0;
 }
 
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 1a6dcbf91744..ffaec138aeee 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -676,6 +676,22 @@ struct drm_crtc_funcs {
 	 */
 	int (*verify_crc_source)(struct drm_crtc *crtc, const char *source,
 				 size_t *values_cnt);
+	/**
+	 * @get_crc_sources:
+	 *
+	 * Driver callback for getting a list of all the available sources for
+	 * CRC generation.
+	 *
+	 * This callback is optional if the driver does not support exporting of
+	 * possible CRC sources list. CRC-core does the verification of sources.
+	 *
+	 * RETURNS:
+	 *
+	 * a constant character pointer to the list of all the available CRC
+	 * sources
+	 */
+	const char *const *(*get_crc_sources)(struct drm_crtc *crtc,
+					      size_t *count);
 
 	/**
 	 * @atomic_print_state:
-- 
2.16.2