[PATCH 4/7] gpio: of: Support some legacy Qualcomm HDMI bindings

[Linus Walleij <linus.walleij@linaro.org>]

Insteaf of the MSM DRM code going around and inspecting the
device tree nodes by itself to find "qcom,misc" GPIO phandles,
we add a quirk to the core so that if "qcom,misc-gpios" and
"qcom,misc-gpio" isn't found, we try to find just
"qcom,misc" as a last resort. Provide an explicit whitelist
for those GPIOs.

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
Rob/Sean: if the approach is overall OK I will merge this
one patch already for v5.3 so the rest can be queued for
v5.4 later.
---
 drivers/gpio/gpiolib-of.c | 43 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index aec7bd86ae7e..c927eaf6c88f 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -286,6 +286,45 @@ static struct gpio_desc *of_find_regulator_gpio(struct device *dev, const char *
 	return desc;
 }
 
+/*
+ * Some non-standard Qualcomm HDMI GPIOs need to be supported as they exist
+ * in random old device trees out there.
+ */
+static struct gpio_desc *of_find_hdmi_gpio(struct device *dev,
+					   const char *con_id,
+					   enum of_gpio_flags *of_flags)
+{
+	/*
+	 * These are the connection IDs we accept as legacy GPIO phandles.
+	 * If we get here, the same prefix ending with "-gpio" and "-gpios"
+	 * has already been tried so now we finally try with no suffix.
+	 */
+	const char *whitelist[] = {
+		"qcom,hdmi-tx-ddc-clk",
+		"qcom,hdmi-tx-ddc-data",
+		"qcom,hdmi-tx-hpd",
+		"qcom,hdmi-tx-mux-en",
+		"qcom,hdmi-tx-mux-sel",
+		"qcom,hdmi-tx-mux-lpm",
+	};
+	struct device_node *np = dev->of_node;
+	struct gpio_desc *desc;
+	int i;
+
+	if (!IS_ENABLED(CONFIG_DRM_MSM))
+		return ERR_PTR(-ENOENT);
+
+	if (!con_id)
+		return ERR_PTR(-ENOENT);
+
+	i = match_string(whitelist, ARRAY_SIZE(whitelist), con_id);
+	if (i < 0)
+		return ERR_PTR(-ENOENT);
+
+	desc = of_get_named_gpiod_flags(np, con_id, 0, of_flags);
+	return desc;
+}
+
 struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
 			       unsigned int idx, unsigned long *flags)
 {
@@ -330,6 +369,10 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
 	if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
 		desc = of_find_regulator_gpio(dev, con_id, &of_flags);
 
+	/* Special handling for HDMI GPIOs if used */
+	if (IS_ERR(desc) && PTR_ERR(desc) != -EPROBE_DEFER)
+		desc = of_find_hdmi_gpio(dev, con_id, &of_flags);
+
 	if (IS_ERR(desc))
 		return desc;
 
-- 
2.20.1