From 332ed63ee9ec0b899cf6d03eecd85bebe1b8e943 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Fri, 21 Sep 2012 14:29:00 +0100
Subject: staging:iio:ad7780: Make powerdown GPIO optional

Some designs hardwire the PDRST pin to always on. In this case there is no GPIO
to control the mode of the device, so make the GPIO optional. Since now all of
the the platform data fields are optional now, make the platform data as a whole
optional as well.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/staging/iio/adc/ad7780.c b/drivers/staging/iio/adc/ad7780.c
index 5f807ce..1dd7cdb 100644
--- a/drivers/staging/iio/adc/ad7780.c
+++ b/drivers/staging/iio/adc/ad7780.c
@@ -73,7 +73,8 @@ static int ad7780_set_mode(struct ad_sigma_delta *sigma_delta,
 		break;
 	}
 
-	gpio_set_value(st->powerdown_gpio, val);
+	if (gpio_is_valid(st->powerdown_gpio))
+		gpio_set_value(st->powerdown_gpio, val);
 
 	return 0;
 }
@@ -148,11 +149,6 @@ static int __devinit ad7780_probe(struct spi_device *spi)
 	struct iio_dev *indio_dev;
 	int ret, voltage_uv = 0;
 
-	if (!pdata) {
-		dev_dbg(&spi->dev, "no platform data?\n");
-		return -ENODEV;
-	}
-
 	indio_dev = iio_device_alloc(sizeof(*st));
 	if (indio_dev == NULL)
 		return -ENOMEM;
@@ -174,8 +170,6 @@ static int __devinit ad7780_probe(struct spi_device *spi)
 	st->chip_info =
 		&ad7780_chip_info_tbl[spi_get_device_id(spi)->driver_data];
 
-	st->powerdown_gpio = pdata->gpio_pdrst;
-
 	if (pdata && pdata->vref_mv)
 		st->int_vref_mv = pdata->vref_mv;
 	else if (voltage_uv)
@@ -192,11 +186,17 @@ static int __devinit ad7780_probe(struct spi_device *spi)
 	indio_dev->num_channels = 1;
 	indio_dev->info = &ad7780_info;
 
-	ret = gpio_request_one(pdata->gpio_pdrst, GPIOF_OUT_INIT_LOW,
+	if (pdata && gpio_is_valid(pdata->gpio_pdrst)) {
+
+		ret = gpio_request_one(pdata->gpio_pdrst, GPIOF_OUT_INIT_LOW,
 			       "AD7780 /PDRST");
-	if (ret) {
-		dev_err(&spi->dev, "failed to request GPIO PDRST\n");
-		goto error_disable_reg;
+		if (ret) {
+			dev_err(&spi->dev, "failed to request GPIO PDRST\n");
+			goto error_disable_reg;
+		}
+		st->powerdown_gpio = pdata->gpio_pdrst;
+	} else {
+		st->powerdown_gpio = -1;
 	}
 
 	ret = ad_sd_setup_buffer_and_trigger(indio_dev);
@@ -212,7 +212,8 @@ static int __devinit ad7780_probe(struct spi_device *spi)
 error_cleanup_buffer_and_trigger:
 	ad_sd_cleanup_buffer_and_trigger(indio_dev);
 error_free_gpio:
-	gpio_free(pdata->gpio_pdrst);
+	if (pdata && gpio_is_valid(pdata->gpio_pdrst))
+		gpio_free(pdata->gpio_pdrst);
 error_disable_reg:
 	if (!IS_ERR(st->reg))
 		regulator_disable(st->reg);
@@ -233,7 +234,9 @@ static int __devexit ad7780_remove(struct spi_device *spi)
 	iio_device_unregister(indio_dev);
 	ad_sd_cleanup_buffer_and_trigger(indio_dev);
 
-	gpio_free(st->powerdown_gpio);
+	if (gpio_is_valid(st->powerdown_gpio))
+		gpio_free(st->powerdown_gpio);
+
 	if (!IS_ERR(st->reg)) {
 		regulator_disable(st->reg);
 		regulator_put(st->reg);
-- 
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