drm/exynos: dp: support hotplug detection via GPIO

Certain bridge chips use a GPIO to indicate the cable status instead
of the I_DP_HPD pin.  This adds an optional device-tree property,
"samsung,hpd-gpio", to the exynos-dp controller which indicates that
the specified GPIO should be used for hotplug detection.
The GPIO is then set up as an edge-triggered interrupt where the
rising edge indicates hotplug-in and the falling edge indicates hotplug-out.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Acked-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

diff --git a/Documentation/devicetree/bindings/video/exynos_dp.txt b/Documentation/devicetree/bindings/video/exynos_dp.txt
index 57ccdde..53dbccf 100644 (file)
--- a/Documentation/devicetree/bindings/video/exynos_dp.txt
+++ b/Documentation/devicetree/bindings/video/exynos_dp.txt
@@ -62,6 +62,10 @@ Optional properties for dp-controller:
        -hsync-active-high:
                HSYNC polarity configuration.
                        High if defined, Low if not defined
+       -samsung,hpd-gpio:
+               Hotplug detect GPIO.
+                       Indicates which GPIO should be used for hotplug
+                       detection
 
 Example:
 

diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.c b/drivers/gpu/drm/exynos/exynos_dp_core.c
index 1f8914b..2b30c55 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_dp_core.c
+++ b/drivers/gpu/drm/exynos/exynos_dp_core.c
@@ -18,6 +18,8 @@
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/gpio.h>
 #include <linux/component.h>
 #include <linux/phy/phy.h>
 #include <video/of_display_timing.h>
@@ -1217,6 +1219,7 @@ static int exynos_dp_bind(struct device *dev, struct device *master, void *data)
        struct drm_device *drm_dev = data;
        struct resource *res;
        struct exynos_dp_device *dp;
+       unsigned int irq_flags;
 
        int ret = 0;
 
@@ -1254,7 +1257,30 @@ static int exynos_dp_bind(struct device *dev, struct device *master, void *data)
        if (IS_ERR(dp->reg_base))
                return PTR_ERR(dp->reg_base);
 
-       dp->irq = platform_get_irq(pdev, 0);
+       dp->hpd_gpio = of_get_named_gpio(dev->of_node, "samsung,hpd-gpio", 0);
+
+       if (gpio_is_valid(dp->hpd_gpio)) {
+               /*
+                * Set up the hotplug GPIO from the device tree as an interrupt.
+                * Simply specifying a different interrupt in the device tree
+                * doesn't work since we handle hotplug rather differently when
+                * using a GPIO.  We also need the actual GPIO specifier so
+                * that we can get the current state of the GPIO.
+                */
+               ret = devm_gpio_request_one(&pdev->dev, dp->hpd_gpio, GPIOF_IN,
+                                           "hpd_gpio");
+               if (ret) {
+                       dev_err(&pdev->dev, "failed to get hpd gpio\n");
+                       return ret;
+               }
+               dp->irq = gpio_to_irq(dp->hpd_gpio);
+               irq_flags = IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING;
+       } else {
+               dp->hpd_gpio = -ENODEV;
+               dp->irq = platform_get_irq(pdev, 0);
+               irq_flags = 0;
+       }
+
        if (dp->irq == -ENXIO) {
                dev_err(&pdev->dev, "failed to get irq\n");
                return -ENODEV;
@@ -1266,8 +1292,8 @@ static int exynos_dp_bind(struct device *dev, struct device *master, void *data)
 
        exynos_dp_init_dp(dp);
 
-       ret = devm_request_irq(&pdev->dev, dp->irq, exynos_dp_irq_handler, 0,
-                               "exynos-dp", dp);
+       ret = devm_request_irq(&pdev->dev, dp->irq, exynos_dp_irq_handler,
+                       irq_flags, "exynos-dp", dp);
        if (ret) {
                dev_err(&pdev->dev, "failed to request irq\n");
                return ret;

diff --git a/drivers/gpu/drm/exynos/exynos_dp_core.h b/drivers/gpu/drm/exynos/exynos_dp_core.h
index d6a900d..56fa43e 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_dp_core.h
+++ b/drivers/gpu/drm/exynos/exynos_dp_core.h
@@ -159,6 +159,7 @@ struct exynos_dp_device {
        struct work_struct      hotplug_work;
        struct phy              *phy;
        int                     dpms_mode;
+       int                     hpd_gpio;
 
        struct exynos_drm_panel_info panel;
 };

diff --git a/drivers/gpu/drm/exynos/exynos_dp_reg.c b/drivers/gpu/drm/exynos/exynos_dp_reg.c
index b70da50..79291a2 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_dp_reg.c
+++ b/drivers/gpu/drm/exynos/exynos_dp_reg.c
@@ -13,6 +13,7 @@
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/delay.h>
+#include <linux/gpio.h>
 
 #include "exynos_dp_core.h"
 #include "exynos_dp_reg.h"
@@ -326,6 +327,9 @@ void exynos_dp_clear_hotplug_interrupts(struct exynos_dp_device *dp)
 {
        u32 reg;
 
+       if (gpio_is_valid(dp->hpd_gpio))
+               return;
+
        reg = HOTPLUG_CHG | HPD_LOST | PLUG;
        writel(reg, dp->reg_base + EXYNOS_DP_COMMON_INT_STA_4);
 
@@ -337,6 +341,9 @@ void exynos_dp_init_hpd(struct exynos_dp_device *dp)
 {
        u32 reg;
 
+       if (gpio_is_valid(dp->hpd_gpio))
+               return;
+
        exynos_dp_clear_hotplug_interrupts(dp);
 
        reg = readl(dp->reg_base + EXYNOS_DP_SYS_CTL_3);
@@ -348,19 +355,27 @@ enum dp_irq_type exynos_dp_get_irq_type(struct exynos_dp_device *dp)
 {
        u32 reg;
 
-       /* Parse hotplug interrupt status register */
-       reg = readl(dp->reg_base + EXYNOS_DP_COMMON_INT_STA_4);
+       if (gpio_is_valid(dp->hpd_gpio)) {
+               reg = gpio_get_value(dp->hpd_gpio);
+               if (reg)
+                       return DP_IRQ_TYPE_HP_CABLE_IN;
+               else
+                       return DP_IRQ_TYPE_HP_CABLE_OUT;
+       } else {
+               /* Parse hotplug interrupt status register */
+               reg = readl(dp->reg_base + EXYNOS_DP_COMMON_INT_STA_4);
 
-       if (reg & PLUG)
-               return DP_IRQ_TYPE_HP_CABLE_IN;
+               if (reg & PLUG)
+                       return DP_IRQ_TYPE_HP_CABLE_IN;
 
-       if (reg & HPD_LOST)
-               return DP_IRQ_TYPE_HP_CABLE_OUT;
+               if (reg & HPD_LOST)
+                       return DP_IRQ_TYPE_HP_CABLE_OUT;
 
-       if (reg & HOTPLUG_CHG)
-               return DP_IRQ_TYPE_HP_CHANGE;
+               if (reg & HOTPLUG_CHG)
+                       return DP_IRQ_TYPE_HP_CHANGE;
 
-       return DP_IRQ_TYPE_UNKNOWN;
+               return DP_IRQ_TYPE_UNKNOWN;
+       }
 }
 
 void exynos_dp_reset_aux(struct exynos_dp_device *dp)
@@ -402,9 +417,14 @@ int exynos_dp_get_plug_in_status(struct exynos_dp_device *dp)
 {
        u32 reg;
 
-       reg = readl(dp->reg_base + EXYNOS_DP_SYS_CTL_3);
-       if (reg & HPD_STATUS)
-               return 0;
+       if (gpio_is_valid(dp->hpd_gpio)) {
+               if (gpio_get_value(dp->hpd_gpio))
+                       return 0;
+       } else {
+               reg = readl(dp->reg_base + EXYNOS_DP_SYS_CTL_3);
+               if (reg & HPD_STATUS)
+                       return 0;
+       }
 
        return -EINVAL;
 }