feat: use the gpio descriptor interface

this updates the interactions with gpio pins to use the newer gpio
descriptor API in the kernel rather than the deprecated gpio-by-int
interface

this means that the gpio pins can be configured as part of the device
tree rather than during compile time

drm_iface.c

@@ -6,7 +6,7 @@
  */
 
 #include <linux/delay.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/module.h>
 #include <linux/property.h>
 #include <linux/sched/clock.h>
@@ -61,6 +61,10 @@ struct sharp_memory_panel {
 	unsigned char *trailer_buf;
 
 	char indicators[MAX_INDICATORS];
+
+	struct gpio_desc *gpio_scs;
+	struct gpio_desc *gpio_disp;
+	struct gpio_desc *gpio_vcom;
 };
 
 static struct sharp_memory_panel* g_panel = NULL;
@@ -78,7 +82,7 @@ static void vcom_timer_callback(struct timer_list *t)
 
 	// Toggle the GPIO pin
 	vcom_setting = (vcom_setting) ? 0 : 1;
-	gpio_set_value(GPIO_VCOM, vcom_setting);
+	gpiod_set_value(panel->gpio_vcom, 1);
 
 	// Reschedule the timer
 	mod_timer(&panel->vcom_timer, jiffies + msecs_to_jiffies(1000));
@@ -98,9 +102,18 @@ static int sharp_memory_spi_clear_screen(struct sharp_memory_panel *panel)
 
 	// Write clear screen command
 	ndelay(80);
-	gpio_set_value(GPIO_SCS, 1);
+
+	if (panel->gpio_scs)
+	{
+		gpiod_set_value(panel->gpio_scs, 1);
+	}
+
 	rc = spi_sync_transfer(panel->spi, panel->spi_3_xfers, 2);
-	gpio_set_value(GPIO_SCS, 0);
+
+	if (panel->gpio_scs)
+	{
+		gpiod_set_value(panel->gpio_scs, 0);
+	}
 
 	return rc;
 }
@@ -133,9 +146,18 @@ static int sharp_memory_spi_write_tagged_lines(struct sharp_memory_panel *panel,
 	panel->spi_3_xfers[2].len = 1;
 
 	ndelay(80);
-	gpio_set_value(GPIO_SCS, 1);
+
+	if (panel->gpio_scs)
+	{
+		gpiod_set_value(panel->gpio_scs, 1);
+	}
+
 	rc = spi_sync_transfer(panel->spi, panel->spi_3_xfers, 3);
-	gpio_set_value(GPIO_SCS, 0);
+
+	if (panel->gpio_scs)
+	{
+		gpiod_set_value(panel->gpio_scs, 0);
+	}
 
 	return rc;
 }
@@ -331,9 +353,12 @@ static void power_off(struct sharp_memory_panel *panel)
 	printk(KERN_INFO "sharp_memory: powering off\n");
 
 	/* Turn off power and all signals */
-	gpio_set_value(GPIO_SCS, 0);
+	if (panel->gpio_scs)
-	gpio_set_value(GPIO_DISP, 0);
+	{
-	gpio_set_value(GPIO_VCOM, 0);
+		gpiod_set_value(panel->gpio_scs, 0);
+	}
+	gpiod_set_value(panel->gpio_disp, 0);
+	gpiod_set_value(panel->gpio_vcom, 0);
 }
 
 static void sharp_memory_pipe_enable(struct drm_simple_display_pipe *pipe,
@@ -355,14 +380,17 @@ static void sharp_memory_pipe_enable(struct drm_simple_display_pipe *pipe,
 	}
 
 	// Power up sequence
-	gpio_set_value(GPIO_SCS, 0);
+	if (panel->gpio_scs)
-	gpio_set_value(GPIO_DISP, 1);
+	{
-	gpio_set_value(GPIO_VCOM, 0);
+		gpiod_set_value(panel->gpio_scs, 0);
+	}
+	gpiod_set_value(panel->gpio_disp, 1);
+	gpiod_set_value(panel->gpio_vcom, 0);
 	usleep_range(5000, 10000);
 
 	// Clear display
 	if (sharp_memory_spi_clear_screen(panel)) {
-		gpio_set_value(GPIO_DISP, 0); // Power down display, VCOM is not running
+		gpiod_set_value(panel->gpio_disp, 0); // Power down display, VCOM is not running
 		goto out_exit;
 	}
 
@@ -499,6 +527,19 @@ int drm_probe(struct spi_device *spi)
 		}
 	}
 
+	// Initialize GPIO
+    panel->gpio_scs = devm_gpiod_get_optional(dev, "scs", GPIOD_OUT_LOW);
+	if (IS_ERR(panel->gpio_scs))
+		return dev_err_probe(dev, PTR_ERR(panel->gpio_scs), "Failed to get GPIO 'scs'\n");
+
+    panel->gpio_disp = devm_gpiod_get(dev, "disp", GPIOD_OUT_HIGH);
+    if (IS_ERR(panel->gpio_disp))
+		return dev_err_probe(dev, PTR_ERR(panel->gpio_disp), "Failed to get GPIO 'disp'\n");
+
+    panel->gpio_vcom = devm_gpiod_get(dev, "vcom", GPIOD_OUT_LOW);
+    if (IS_ERR(panel->gpio_vcom))
+		return dev_err_probe(dev, PTR_ERR(panel->gpio_vcom), "Failed to get GPIO 'vcom'\n");
+
 	// Allocate panel storage
 	panel = devm_drm_dev_alloc(dev, &sharp_memory_driver,
 		struct sharp_memory_panel, drm);
@@ -577,6 +618,8 @@ int drm_probe(struct spi_device *spi)
 void drm_remove(struct spi_device *spi)
 {
 	struct drm_device *drm;
+	struct device *dev;
+	struct sharp_memory_panel *panel;
 
 	printk(KERN_INFO "sharp_memory: drm_remove\n");
 
@@ -586,6 +629,18 @@ void drm_remove(struct spi_device *spi)
 	// Get DRM and panel device from SPI
 	drm = spi_get_drvdata(spi);
 
+	// Clean up the GPIO descriptors
+	dev = &spi->dev;
+	panel = drm_to_panel(drm)
+
+	if (panel->gpio_scs)
+	{
+		devm_gpiod_put(dev, panel->gpio_scs)
+	}
+	devm_gpiod_put(dev, panel->gpio_disp)
+	devm_gpiod_put(dev, panel->gpio_vcom)
+
+
 	drm_dev_unplug(drm);
 	drm_atomic_helper_shutdown(drm);
 }

drm_iface.h

@@ -2,7 +2,7 @@
 #define DRM_IFACE_H_
 
 #include <linux/delay.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/module.h>
 #include <linux/property.h>
 #include <linux/sched/clock.h>

sharp.dts

@@ -48,6 +48,11 @@
 				reg = <0>;
 				pinctrl-names = "default";
 				pinctrl-0 = <&sharp_pins>;
+
+				vcom-gpios = <&gpio 23 0>;
+				disp-gpios = <&gpio 22 0>;
+				scs-gpios = <&gpio 8 0>;
+
 				spi-cs-high = <1>;
 				spi-max-frequency = <8000000>;
 				buswidth = <8>;