[PATCH v6 5/6] drm: sun4i: Add support for enabling DDC I2C bus to sun8i_dw_hdmi glue

[megous]

From: Ondrej Jirman <meg...@megous.com>

Orange Pi 3 board requires enabling a voltage shifting circuit via GPIO
for the DDC bus to be usable.

Add support for hdmi-connector node's optional ddc-en-gpios property to
support this use case.

Signed-off-by: Ondrej Jirman <meg...@megous.com>
---
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c | 55 +++++++++++++++++++++++++--
 drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h |  3 ++
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c 
b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
index 39d8509d96a0..59b81ba02d96 100644
--- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
+++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c
@@ -98,6 +98,30 @@ static u32 sun8i_dw_hdmi_find_possible_crtcs(struct 
drm_device *drm,
        return crtcs;
 }
 
+static int sun8i_dw_hdmi_find_connector_pdev(struct device *dev,
+                                            struct platform_device **pdev_out)
+{
+       struct platform_device *pdev;
+       struct device_node *remote;
+
+       remote = of_graph_get_remote_node(dev->of_node, 1, -1);
+       if (!remote)
+               return -ENODEV;
+
+       if (!of_device_is_compatible(remote, "hdmi-connector")) {
+               of_node_put(remote);
+               return -ENODEV;
+       }
+
+       pdev = of_find_device_by_node(remote);
+       of_node_put(remote);
+       if (!pdev)
+               return -ENODEV;
+
+       *pdev_out = pdev;
+       return 0;
+}
+
 static int sun8i_dw_hdmi_bind(struct device *dev, struct device *master,
                              void *data)
 {
@@ -151,16 +175,29 @@ static int sun8i_dw_hdmi_bind(struct device *dev, struct 
device *master,
                return PTR_ERR(hdmi->regulator);
        }
 
+       ret = sun8i_dw_hdmi_find_connector_pdev(dev, &hdmi->connector_pdev);
+       if (!ret) {
+               hdmi->ddc_en = gpiod_get_optional(&hdmi->connector_pdev->dev,
+                                                 "ddc-en", GPIOD_OUT_HIGH);
+               if (IS_ERR(hdmi->ddc_en)) {
+                       platform_device_put(hdmi->connector_pdev);
+                       dev_err(dev, "Couldn't get ddc-en gpio\n");
+                       return PTR_ERR(hdmi->ddc_en);
+               }
+       }
+
        ret = regulator_enable(hdmi->regulator);
        if (ret) {
                dev_err(dev, "Failed to enable regulator\n");
-               return ret;
+               goto err_unref_ddc_en;
        }
 
+       gpiod_set_value(hdmi->ddc_en, 1);
+
        ret = reset_control_deassert(hdmi->rst_ctrl);
        if (ret) {
                dev_err(dev, "Could not deassert ctrl reset control\n");
-               goto err_disable_regulator;
+               goto err_disable_ddc_en;
        }
 
        ret = clk_prepare_enable(hdmi->clk_tmds);
@@ -213,8 +250,14 @@ static int sun8i_dw_hdmi_bind(struct device *dev, struct 
device *master,
        clk_disable_unprepare(hdmi->clk_tmds);
 err_assert_ctrl_reset:
        reset_control_assert(hdmi->rst_ctrl);
-err_disable_regulator:
+err_disable_ddc_en:
+       gpiod_set_value(hdmi->ddc_en, 0);
        regulator_disable(hdmi->regulator);
+err_unref_ddc_en:
+       if (hdmi->ddc_en)
+               gpiod_put(hdmi->ddc_en);
+
+       platform_device_put(hdmi->connector_pdev);
 
        return ret;
 }
@@ -228,7 +271,13 @@ static void sun8i_dw_hdmi_unbind(struct device *dev, 
struct device *master,
        sun8i_hdmi_phy_remove(hdmi);
        clk_disable_unprepare(hdmi->clk_tmds);
        reset_control_assert(hdmi->rst_ctrl);
+       gpiod_set_value(hdmi->ddc_en, 0);
        regulator_disable(hdmi->regulator);
+
+       if (hdmi->ddc_en)
+               gpiod_put(hdmi->ddc_en);
+
+       platform_device_put(hdmi->connector_pdev);
 }
 
 static const struct component_ops sun8i_dw_hdmi_ops = {
diff --git a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h 
b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h
index 720c5aa8adc1..dad66b8301c2 100644
--- a/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h
+++ b/drivers/gpu/drm/sun4i/sun8i_dw_hdmi.h
@@ -9,6 +9,7 @@
 #include <drm/bridge/dw_hdmi.h>
 #include <drm/drm_encoder.h>
 #include <linux/clk.h>
+#include <linux/gpio/consumer.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/reset.h>
@@ -190,6 +191,8 @@ struct sun8i_dw_hdmi {
        struct regulator                *regulator;
        const struct sun8i_dw_hdmi_quirks *quirks;
        struct reset_control            *rst_ctrl;
+       struct platform_device          *connector_pdev;
+       struct gpio_desc                *ddc_en;
 };
 
 static inline struct sun8i_dw_hdmi *
-- 
2.21.0