powerpc/warp: switch to using gpiod API

This switches PIKA Warp away from legacy gpio API and to newer gpiod
API, so that we can eventually deprecate the former.

Because LEDs are normally driven by leds-gpio driver, but the
platform code also wants to access the LEDs during thermal shutdown,
and gpiod API does not allow locating GPIO without requesting it,
the platform code is now responsible for locating GPIOs through device
tree and requesting them. It then constructs platform data for
leds-gpio platform device and registers it. This allows platform
code to retain access to LED GPIO descriptors and use them when needed.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/YzKSLcrYmV5kjyeX@google.com

arch/powerpc/boot/dts/warp.dts

@@ -258,14 +258,12 @@ GPIO1: gpio@ef600c00 {
 			};
 
 			power-leds {
-				compatible = "gpio-leds";
+				compatible = "warp-power-leds";
 				green {
 					gpios = <&GPIO1 0 0>;
-					default-state = "keep";
 				};
 				red {
 					gpios = <&GPIO1 1 0>;
-					default-state = "keep";
 				};
 			};
 

arch/powerpc/platforms/44x/warp.c

@@ -5,15 +5,17 @@
  * Copyright (c) 2008-2009 PIKA Technologies
  *   Sean MacLennan <smaclennan@pikatech.com>
  */
+#include <linux/err.h>
 #include <linux/init.h>
 #include <linux/of_platform.h>
 #include <linux/kthread.h>
+#include <linux/leds.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
-#include <linux/of_gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/slab.h>
 #include <linux/export.h>
 
@@ -92,8 +94,6 @@ static int __init warp_post_info(void)
 
 static LIST_HEAD(dtm_shutdown_list);
 static void __iomem *dtm_fpga;
-static unsigned green_led, red_led;
-
 
 struct dtm_shutdown {
 	struct list_head list;
@@ -101,7 +101,6 @@ struct dtm_shutdown {
 	void *arg;
 };
 
-
 int pika_dtm_register_shutdown(void (*func)(void *arg), void *arg)
 {
 	struct dtm_shutdown *shutdown;
@@ -132,6 +131,35 @@ int pika_dtm_unregister_shutdown(void (*func)(void *arg), void *arg)
 	return -EINVAL;
 }
 
+#define WARP_GREEN_LED	0
+#define WARP_RED_LED	1
+
+static struct gpio_led warp_gpio_led_pins[] = {
+	[WARP_GREEN_LED] = {
+		.name		= "green",
+		.default_state	= LEDS_DEFSTATE_KEEP,
+		.gpiod		= NULL, /* to be filled by pika_setup_leds() */
+	},
+	[WARP_RED_LED] = {
+		.name		= "red",
+		.default_state	= LEDS_DEFSTATE_KEEP,
+		.gpiod		= NULL, /* to be filled by pika_setup_leds() */
+	},
+};
+
+static struct gpio_led_platform_data warp_gpio_led_data = {
+	.leds		= warp_gpio_led_pins,
+	.num_leds	= ARRAY_SIZE(warp_gpio_led_pins),
+};
+
+static struct platform_device warp_gpio_leds = {
+	.name	= "leds-gpio",
+	.id	= -1,
+	.dev	= {
+		.platform_data = &warp_gpio_led_data,
+	},
+};
+
 static irqreturn_t temp_isr(int irq, void *context)
 {
 	struct dtm_shutdown *shutdown;
@@ -139,7 +167,7 @@ static irqreturn_t temp_isr(int irq, void *context)
 
 	local_irq_disable();
 
-	gpio_set_value(green_led, 0);
+	gpiod_set_value(warp_gpio_led_pins[WARP_GREEN_LED].gpiod, 0);
 
 	/* Run through the shutdown list. */
 	list_for_each_entry(shutdown, &dtm_shutdown_list, list)
@@ -153,7 +181,7 @@ static irqreturn_t temp_isr(int irq, void *context)
 			out_be32(dtm_fpga + 0x14, reset);
 		}
 
-		gpio_set_value(red_led, value);
+		gpiod_set_value(warp_gpio_led_pins[WARP_RED_LED].gpiod, value);
 		value ^= 1;
 		mdelay(500);
 	}
@@ -162,25 +190,78 @@ static irqreturn_t temp_isr(int irq, void *context)
 	return IRQ_HANDLED;
 }
 
+/*
+ * Because green and red power LEDs are normally driven by leds-gpio driver,
+ * but in case of critical temperature shutdown we want to drive them
+ * ourselves, we acquire both and then create leds-gpio platform device
+ * ourselves, instead of doing it through device tree. This way we can still
+ * keep access to the gpios and use them when needed.
+ */
 static int pika_setup_leds(void)
 {
 	struct device_node *np, *child;
+	struct gpio_desc *gpio;
+	struct gpio_led *led;
+	int led_count = 0;
+	int error;
+	int i;
 
-	np = of_find_compatible_node(NULL, NULL, "gpio-leds");
+	np = of_find_compatible_node(NULL, NULL, "warp-power-leds");
 	if (!np) {
 		printk(KERN_ERR __FILE__ ": Unable to find leds\n");
 		return -ENOENT;
 	}
 
-	for_each_child_of_node(np, child)
-		if (of_node_name_eq(child, "green"))
-			green_led = of_get_gpio(child, 0);
-		else if (of_node_name_eq(child, "red"))
-			red_led = of_get_gpio(child, 0);
+	for_each_child_of_node(np, child) {
+		for (i = 0; i < ARRAY_SIZE(warp_gpio_led_pins); i++) {
+			led = &warp_gpio_led_pins[i];
+
+			if (!of_node_name_eq(child, led->name))
+				continue;
+
+			if (led->gpiod) {
+				printk(KERN_ERR __FILE__ ": %s led has already been defined\n",
+				       led->name);
+				continue;
+			}
+
+			gpio = fwnode_gpiod_get_index(of_fwnode_handle(child),
+						      NULL, 0, GPIOD_ASIS,
+						      led->name);
+			error = PTR_ERR_OR_ZERO(gpio);
+			if (error) {
+				printk(KERN_ERR __FILE__ ": Failed to get %s led gpio: %d\n",
+				       led->name, error);
+				of_node_put(child);
+				goto err_cleanup_pins;
+			}
+
+			led->gpiod = gpio;
+			led_count++;
+		}
+	}
 
 	of_node_put(np);
 
+	/* Skip device registration if no leds have been defined */
+	if (led_count) {
+		error = platform_device_register(&warp_gpio_leds);
+		if (error) {
+			printk(KERN_ERR __FILE__ ": Unable to add leds-gpio: %d\n",
+			       error);
+			goto err_cleanup_pins;
+		}
+	}
+
 	return 0;
+
+err_cleanup_pins:
+	for (i = 0; i < ARRAY_SIZE(warp_gpio_led_pins); i++) {
+		led = &warp_gpio_led_pins[i];
+		gpiod_put(led->gpiod);
+		led->gpiod = NULL;
+	}
+	return error;
 }
 
 static void pika_setup_critical_temp(struct device_node *np,