A DPI color encoder, as a simple display bridge, converts input DPI color
coding to output DPI color coding, like Adafruit Kippah DPI hat[1] which
converts input 18-bit pixel data to 24-bit pixel data(with 2 low padding
bits in every color component though). Add the DPI color encoder support
in the simple bridge driver.

[1] https://learn.adafruit.com/adafruit-dpi-display-kippah-ttl-tft/downloads

Signed-off-by: Liu Ying <victor....@nxp.com>
---
 drivers/gpu/drm/bridge/simple-bridge.c | 104 ++++++++++++++++++++++++-
 1 file changed, 102 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/simple-bridge.c 
b/drivers/gpu/drm/bridge/simple-bridge.c
index ab0b0e36e97a..c0445bd20e07 100644
--- a/drivers/gpu/drm/bridge/simple-bridge.c
+++ b/drivers/gpu/drm/bridge/simple-bridge.c
@@ -7,6 +7,7 @@
  */
 
 #include <linux/gpio/consumer.h>
+#include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_graph.h>
@@ -17,12 +18,14 @@
 #include <drm/drm_bridge.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_of.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
 
 struct simple_bridge_info {
        const struct drm_bridge_timings *timings;
        unsigned int connector_type;
+       const struct drm_bridge_funcs *bridge_funcs;
 };
 
 struct simple_bridge {
@@ -34,6 +37,9 @@ struct simple_bridge {
        struct drm_bridge       *next_bridge;
        struct regulator        *vdd;
        struct gpio_desc        *enable;
+
+       int                     dpi_color_coding_input;
+       int                     dpi_color_coding_output;
 };
 
 static inline struct simple_bridge *
@@ -156,16 +162,93 @@ static void simple_bridge_disable(struct drm_bridge 
*bridge)
                regulator_disable(sbridge->vdd);
 }
 
-static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
+static const struct drm_bridge_funcs default_simple_bridge_bridge_funcs = {
        .attach         = simple_bridge_attach,
        .enable         = simple_bridge_enable,
        .disable        = simple_bridge_disable,
 };
 
+static u32 *
+dpi_color_encoder_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+                                           struct drm_bridge_state 
*bridge_state,
+                                           struct drm_crtc_state *crtc_state,
+                                           struct drm_connector_state 
*conn_state,
+                                           u32 output_fmt,
+                                           unsigned int *num_input_fmts)
+{
+       struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
+       u32 *input_fmts;
+
+       *num_input_fmts = 0;
+
+       if (sbridge->dpi_color_coding_output != output_fmt)
+               return NULL;
+
+       input_fmts = kzalloc(sizeof(*input_fmts), GFP_KERNEL);
+       if (!input_fmts)
+               return NULL;
+
+       *num_input_fmts = 1;
+       input_fmts[0] = sbridge->dpi_color_coding_input;
+       return input_fmts;
+}
+
+static const struct drm_bridge_funcs dpi_color_encoder_bridge_funcs = {
+       .attach                         = simple_bridge_attach,
+       .enable                         = simple_bridge_enable,
+       .disable                        = simple_bridge_disable,
+       .atomic_reset                   = drm_atomic_helper_bridge_reset,
+       .atomic_duplicate_state         = 
drm_atomic_helper_bridge_duplicate_state,
+       .atomic_destroy_state           = 
drm_atomic_helper_bridge_destroy_state,
+       .atomic_get_input_bus_fmts      = 
dpi_color_encoder_atomic_get_input_bus_fmts,
+};
+
+static int simple_bridge_get_dpi_color_coding(struct simple_bridge *sbridge,
+                                             struct device *dev)
+{
+       struct device_node *ep0, *ep1 = NULL;
+       int ret = 0;
+
+       ep0 = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
+       if (!ep0) {
+               dev_err(dev, "failed to get port@0 endpoint\n");
+               ret = -ENODEV;
+               goto out;
+       }
+
+       ep1 = of_graph_get_endpoint_by_regs(dev->of_node, 1, 0);
+       if (!ep1) {
+               dev_err(dev, "failed to get port@1 endpoint\n");
+               ret = -ENODEV;
+               goto out;
+       }
+
+       sbridge->dpi_color_coding_input = drm_of_dpi_get_color_coding(ep0);
+       if (sbridge->dpi_color_coding_input < 0) {
+               dev_err(dev, "failed to get DPI input media bus format\n");
+               ret = sbridge->dpi_color_coding_input;
+               goto out;
+       }
+
+       sbridge->dpi_color_coding_output = drm_of_dpi_get_color_coding(ep1);
+       if (sbridge->dpi_color_coding_output < 0) {
+               dev_err(dev, "failed to get DPI output media bus format\n");
+               ret = sbridge->dpi_color_coding_output;
+               goto out;
+       }
+
+out:
+       of_node_put(ep1);
+       of_node_put(ep0);
+
+       return ret;
+}
+
 static int simple_bridge_probe(struct platform_device *pdev)
 {
        struct simple_bridge *sbridge;
        struct device_node *remote;
+       int ret;
 
        sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
        if (!sbridge)
@@ -202,8 +285,14 @@ static int simple_bridge_probe(struct platform_device 
*pdev)
                return dev_err_probe(&pdev->dev, PTR_ERR(sbridge->enable),
                                     "Unable to retrieve enable GPIO\n");
 
+       if (of_device_is_compatible(pdev->dev.of_node, "dpi-color-encoder")) {
+               ret = simple_bridge_get_dpi_color_coding(sbridge, &pdev->dev);
+               if (ret)
+                       return ret;
+       }
+
        /* Register the bridge. */
-       sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
+       sbridge->bridge.funcs = sbridge->info->bridge_funcs;
        sbridge->bridge.of_node = pdev->dev.of_node;
        sbridge->bridge.timings = sbridge->info->timings;
 
@@ -253,29 +342,40 @@ static const struct of_device_id simple_bridge_match[] = {
                .compatible = "dumb-vga-dac",
                .data = &(const struct simple_bridge_info) {
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
+                       .bridge_funcs = &default_simple_bridge_bridge_funcs,
                },
        }, {
                .compatible = "adi,adv7123",
                .data = &(const struct simple_bridge_info) {
                        .timings = &default_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
+                       .bridge_funcs = &default_simple_bridge_bridge_funcs,
+               },
+       }, {
+               .compatible = "dpi-color-encoder",
+               .data = &(const struct simple_bridge_info) {
+                       .connector_type = DRM_MODE_CONNECTOR_DPI,
+                       .bridge_funcs = &dpi_color_encoder_bridge_funcs,
                },
        }, {
                .compatible = "ti,opa362",
                .data = &(const struct simple_bridge_info) {
                        .connector_type = DRM_MODE_CONNECTOR_Composite,
+                       .bridge_funcs = &default_simple_bridge_bridge_funcs,
                },
        }, {
                .compatible = "ti,ths8135",
                .data = &(const struct simple_bridge_info) {
                        .timings = &ti_ths8135_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
+                       .bridge_funcs = &default_simple_bridge_bridge_funcs,
                },
        }, {
                .compatible = "ti,ths8134",
                .data = &(const struct simple_bridge_info) {
                        .timings = &ti_ths8134_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
+                       .bridge_funcs = &default_simple_bridge_bridge_funcs,
                },
        },
        {},
-- 
2.34.1

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