[PATCH V6 1/4] drm: of: Add drm_of_get_dsi_bus helper function

Chris Morgan
2022-12-15T18:52:36Z

Add helper function to find DSI host for devices where DSI panel is not
a minor of a DSI bus (such as the Samsung AMS495QA01 panel or the
official Raspberry Pi touchscreen display).

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Signed-off-by: Maya Matuszczyk <maccraft123mc@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
---
drivers/gpu/drm/drm_of.c | 62 ++++++++++++++++++++++++++++++++++++++++
include/drm/drm_of.h | 11 +++++++
2 files changed, 73 insertions(+)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 7bbcb999bb75..7d89ac164069 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -10,6 +10,7 @@
#include <drm/drm_crtc.h>
#include <drm/drm_device.h>
#include <drm/drm_encoder.h>
+#include <drm/drm_mipi_dsi.h>
#include <drm/drm_of.h>
#include <drm/drm_panel.h>

@@ -493,3 +494,64 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
return ret;
}
EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);
+
+/**
+ * drm_of_get_dsi_bus - find the DSI bus for a given device
+ * @dev: parent device of display (SPI, I2C)
+ * @dsi_host: DSI host to be populated
+ * @info: DSI device info to be updated with correct DSI node
+ *
+ * Given a panel device parented to a non-DSI device, follow the
+ * devicetree to find the correct DSI host node and populate the
+ * dsi_host with the correct host and info with the correct node.
+ * Returns zero if successful, -EPROBE_DEFER if the DSI host is
+ * found but not available, or -ENODEV otherwise.
+ */
+int drm_of_get_dsi_bus(struct device *dev,
+ struct mipi_dsi_host **dsi_host,
+ struct mipi_dsi_device_info *info)
+{
+ struct device_node *endpoint, *dsi_host_node;
+
+ /*
+ * Get first endpoint child from device.
+ */
+ endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+ if (!endpoint)
+ return -ENODEV;
+
+ /*
+ * Follow the first endpoint to get the DSI host node.
+ */
+ dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+ if (!dsi_host_node)
+ goto error;
+
+ /*
+ * Get the DSI host from the DSI host node. If we get an error
+ * or the return is null assume we're not ready to probe just
+ * yet. Release the DSI host node since we're done with it.
+ */
+ *dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
+ of_node_put(dsi_host_node);
+ if (IS_ERR_OR_NULL(*dsi_host)) {
+ of_node_put(endpoint);
+ return -EPROBE_DEFER;
+ }
+
+ /*
+ * Set the node of the mipi_dsi_device_info to the correct node
+ * and then release the endpoint node since we're done with it.
+ */
+ info->node = of_graph_get_remote_port(endpoint);
+ if (IS_ERR_OR_NULL(info->node))
+ goto error;
+
+ of_node_put(endpoint);
+ return 0;
+
+error:
+ of_node_put(endpoint);
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(drm_of_get_dsi_bus);
diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index 10ab58c40746..a694ce71c3b2 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -15,6 +15,8 @@ struct drm_encoder;
struct drm_panel;
struct drm_bridge;
struct device_node;
+struct mipi_dsi_device_info;
+struct mipi_dsi_host;

/**
* enum drm_lvds_dual_link_pixels - Pixel order of an LVDS dual-link connection
@@ -56,6 +58,9 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
int port_reg, int reg,
const unsigned int min,
const unsigned int max);
+int drm_of_get_dsi_bus(struct device *dev,
+ struct mipi_dsi_host **dsi_host,
+ struct mipi_dsi_device_info *info);
#else
static inline uint32_t drm_of_crtc_port_mask(struct drm_device *dev,
struct device_node *port)
@@ -127,6 +132,12 @@ drm_of_get_data_lanes_count_ep(const struct device_node *port,
{
return -EINVAL;
}
+static int drm_of_get_dsi_bus(struct device *dev,
+ struct mipi_dsi_host **dsi_host,
+ struct mipi_dsi_device_info *info);
+{
+ return -EINVAL;
+}
#endif

/*