i2c: mux: arb-gpio: Rewrite to use GPIO descriptors

Instead of complex code picking GPIOs out of the device tree
and keeping track of polarity for each GPIO line, use descriptors
and pull polarity handling into the gpiolib.

We look for "our-claim" and "their-claim" since the gpiolib
code will try e.g. "our-claim-gpios" and "our-claim-gpio" in
turn to locate these GPIO lines from the device tree.

Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Doug Anderson <dianders@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Peter Rosin <peda@axentia.se>

drivers/i2c/muxes/i2c-arb-gpio-challenge.c

@@ -15,12 +15,11 @@
  */
 
 #include <linux/delay.h>
-#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
 #include <linux/module.h>
-#include <linux/of_gpio.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
@@ -28,22 +27,16 @@
 /**
  * struct i2c_arbitrator_data - Driver data for I2C arbitrator
  *
- * @our_gpio: GPIO we'll use to claim.
- * @our_gpio_release: 0 if active high; 1 if active low; AKA if the GPIO ==
- *   this then consider it released.
- * @their_gpio: GPIO that the other side will use to claim.
- * @their_gpio_release: 0 if active high; 1 if active low; AKA if the GPIO ==
- *   this then consider it released.
+ * @our_gpio: GPIO descriptor we'll use to claim.
+ * @their_gpio: GPIO descriptor that the other side will use to claim.
  * @slew_delay_us: microseconds to wait for a GPIO to go high.
  * @wait_retry_us: we'll attempt another claim after this many microseconds.
  * @wait_free_us: we'll give up after this many microseconds.
  */
 
 struct i2c_arbitrator_data {
-	int our_gpio;
-	int our_gpio_release;
-	int their_gpio;
-	int their_gpio_release;
+	struct gpio_desc *our_gpio;
+	struct gpio_desc *their_gpio;
 	unsigned int slew_delay_us;
 	unsigned int wait_retry_us;
 	unsigned int wait_free_us;
@@ -64,15 +57,15 @@ static int i2c_arbitrator_select(struct i2c_mux_core *muxc, u32 chan)
 	stop_time = jiffies + usecs_to_jiffies(arb->wait_free_us) + 1;
 	do {
 		/* Indicate that we want to claim the bus */
-		gpio_set_value(arb->our_gpio, !arb->our_gpio_release);
+		gpiod_set_value(arb->our_gpio, 1);
 		udelay(arb->slew_delay_us);
 
 		/* Wait for the other master to release it */
 		stop_retry = jiffies + usecs_to_jiffies(arb->wait_retry_us) + 1;
 		while (time_before(jiffies, stop_retry)) {
-			int gpio_val = !!gpio_get_value(arb->their_gpio);
+			int gpio_val = gpiod_get_value(arb->their_gpio);
 
-			if (gpio_val == arb->their_gpio_release) {
+			if (!gpio_val) {
 				/* We got it, so return */
 				return 0;
 			}
@@ -81,13 +74,13 @@ static int i2c_arbitrator_select(struct i2c_mux_core *muxc, u32 chan)
 		}
 
 		/* It didn't release, so give up, wait, and try again */
-		gpio_set_value(arb->our_gpio, arb->our_gpio_release);
+		gpiod_set_value(arb->our_gpio, 0);
 
 		usleep_range(arb->wait_retry_us, arb->wait_retry_us * 2);
 	} while (time_before(jiffies, stop_time));
 
 	/* Give up, release our claim */
-	gpio_set_value(arb->our_gpio, arb->our_gpio_release);
+	gpiod_set_value(arb->our_gpio, 0);
 	udelay(arb->slew_delay_us);
 	dev_err(muxc->dev, "Could not claim bus, timeout\n");
 	return -EBUSY;
@@ -103,7 +96,7 @@ static int i2c_arbitrator_deselect(struct i2c_mux_core *muxc, u32 chan)
 	const struct i2c_arbitrator_data *arb = i2c_mux_priv(muxc);
 
 	/* Release the bus and wait for the other master to notice */
-	gpio_set_value(arb->our_gpio, arb->our_gpio_release);
+	gpiod_set_value(arb->our_gpio, 0);
 	udelay(arb->slew_delay_us);
 
 	return 0;
@@ -116,8 +109,7 @@ static int i2c_arbitrator_probe(struct platform_device *pdev)
 	struct device_node *parent_np;
 	struct i2c_mux_core *muxc;
 	struct i2c_arbitrator_data *arb;
-	enum of_gpio_flags gpio_flags;
-	unsigned long out_init;
+	struct gpio_desc *dummy;
 	int ret;
 
 	/* We only support probing from device tree; no platform_data */
@@ -138,45 +130,28 @@ static int i2c_arbitrator_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, muxc);
 
-	/* Request GPIOs */
-	ret = of_get_named_gpio_flags(np, "our-claim-gpio", 0, &gpio_flags);
-	if (!gpio_is_valid(ret)) {
-		if (ret != -EPROBE_DEFER)
-			dev_err(dev, "Error getting our-claim-gpio\n");
-		return ret;
-	}
-	arb->our_gpio = ret;
-	arb->our_gpio_release = !!(gpio_flags & OF_GPIO_ACTIVE_LOW);
-	out_init = (gpio_flags & OF_GPIO_ACTIVE_LOW) ?
-		GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
-	ret = devm_gpio_request_one(dev, arb->our_gpio, out_init,
-				    "our-claim-gpio");
-	if (ret) {
-		if (ret != -EPROBE_DEFER)
-			dev_err(dev, "Error requesting our-claim-gpio\n");
-		return ret;
+	/* Request GPIOs, our GPIO as unclaimed to begin with */
+	arb->our_gpio = devm_gpiod_get(dev, "our-claim", GPIOD_OUT_LOW);
+	if (IS_ERR(arb->our_gpio)) {
+		dev_err(dev, "could not get \"our-claim\" GPIO (%ld)\n",
+			PTR_ERR(arb->our_gpio));
+		return PTR_ERR(arb->our_gpio);
 	}
 
-	ret = of_get_named_gpio_flags(np, "their-claim-gpios", 0, &gpio_flags);
-	if (!gpio_is_valid(ret)) {
-		if (ret != -EPROBE_DEFER)
-			dev_err(dev, "Error getting their-claim-gpio\n");
-		return ret;
-	}
-	arb->their_gpio = ret;
-	arb->their_gpio_release = !!(gpio_flags & OF_GPIO_ACTIVE_LOW);
-	ret = devm_gpio_request_one(dev, arb->their_gpio, GPIOF_IN,
-				    "their-claim-gpio");
-	if (ret) {
-		if (ret != -EPROBE_DEFER)
-			dev_err(dev, "Error requesting their-claim-gpio\n");
-		return ret;
+	arb->their_gpio = devm_gpiod_get(dev, "their-claim", GPIOD_IN);
+	if (IS_ERR(arb->their_gpio)) {
+		dev_err(dev, "could not get \"their-claim\" GPIO (%ld)\n",
+			PTR_ERR(arb->their_gpio));
+		return PTR_ERR(arb->their_gpio);
 	}
 
 	/* At the moment we only support a single two master (us + 1 other) */
-	if (gpio_is_valid(of_get_named_gpio(np, "their-claim-gpios", 1))) {
+	dummy = devm_gpiod_get_index(dev, "their-claim", 1, GPIOD_IN);
+	if (!IS_ERR(dummy)) {
 		dev_err(dev, "Only one other master is supported\n");
 		return -EINVAL;
+	} else if (PTR_ERR(dummy) == -EPROBE_DEFER) {
+		return -EPROBE_DEFER;
 	}
 
 	/* Arbitration parameters */