From 2fd18abad179b11cbd881f2bd271b193ababfb65 Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Mon, 18 Oct 2010 09:22:38 -0700
Subject: [PATCH] Input: ad7877 - use attribute group to control visibility of
 attributes

Instead of manually creating one set of attributes or another set up
is_visible method in attribute group structure to control whether
aux3 or gpio3 attribute is presented to userspace.

Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
---
 drivers/input/touchscreen/ad7877.c | 49 ++++++++++++++++++------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/drivers/input/touchscreen/ad7877.c b/drivers/input/touchscreen/ad7877.c
index b7de78e82737..326d7336a372 100644
--- a/drivers/input/touchscreen/ad7877.c
+++ b/drivers/input/touchscreen/ad7877.c
@@ -206,8 +206,8 @@ struct ad7877 {
 	u16 conversion_data[AD7877_NR_SENSE] ____cacheline_aligned;
 };
 
-static int gpio3;
-module_param(gpio3, int, 0);
+static bool gpio3;
+module_param(gpio3, bool, 0);
 MODULE_PARM_DESC(gpio3, "If gpio3 is set to 1 AUX3 acts as GPIO3");
 
 /*
@@ -471,7 +471,7 @@ static void ad7877_enable(struct ad7877 *ts)
 #define SHOW(name) static ssize_t \
 name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
 { \
-	struct ad7877	*ts = dev_get_drvdata(dev); \
+	struct ad7877 *ts = dev_get_drvdata(dev); \
 	ssize_t v = ad7877_read_adc(ts->spi, \
 			AD7877_READ_CHAN(name)); \
 	if (v < 0) \
@@ -491,7 +491,7 @@ SHOW(temp2)
 static ssize_t ad7877_disable_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	struct ad7877	*ts = dev_get_drvdata(dev);
+	struct ad7877 *ts = dev_get_drvdata(dev);
 
 	return sprintf(buf, "%u\n", ts->disabled);
 }
@@ -521,7 +521,7 @@ static DEVICE_ATTR(disable, 0664, ad7877_disable_show, ad7877_disable_store);
 static ssize_t ad7877_dac_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	struct ad7877	*ts = dev_get_drvdata(dev);
+	struct ad7877 *ts = dev_get_drvdata(dev);
 
 	return sprintf(buf, "%u\n", ts->dac);
 }
@@ -551,7 +551,7 @@ static DEVICE_ATTR(dac, 0664, ad7877_dac_show, ad7877_dac_store);
 static ssize_t ad7877_gpio3_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	struct ad7877	*ts = dev_get_drvdata(dev);
+	struct ad7877 *ts = dev_get_drvdata(dev);
 
 	return sprintf(buf, "%u\n", ts->gpio3);
 }
@@ -582,7 +582,7 @@ static DEVICE_ATTR(gpio3, 0664, ad7877_gpio3_show, ad7877_gpio3_store);
 static ssize_t ad7877_gpio4_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	struct ad7877	*ts = dev_get_drvdata(dev);
+	struct ad7877 *ts = dev_get_drvdata(dev);
 
 	return sprintf(buf, "%u\n", ts->gpio4);
 }
@@ -615,16 +615,35 @@ static struct attribute *ad7877_attributes[] = {
 	&dev_attr_temp2.attr,
 	&dev_attr_aux1.attr,
 	&dev_attr_aux2.attr,
+	&dev_attr_aux3.attr,
 	&dev_attr_bat1.attr,
 	&dev_attr_bat2.attr,
 	&dev_attr_disable.attr,
 	&dev_attr_dac.attr,
+	&dev_attr_gpio3.attr,
 	&dev_attr_gpio4.attr,
 	NULL
 };
 
+static mode_t ad7877_attr_is_visible(struct kobject *kobj,
+				     struct attribute *attr, int n)
+{
+	mode_t mode = attr->mode;
+
+	if (attr == &dev_attr_aux3.attr) {
+		if (gpio3)
+			mode = 0;
+	} else if (attr == &dev_attr_gpio3.attr) {
+		if (!gpio3)
+			mode = 0;
+	}
+
+	return mode;
+}
+
 static const struct attribute_group ad7877_attr_group = {
-	.attrs = ad7877_attributes,
+	.is_visible	= ad7877_attr_is_visible,
+	.attrs		= ad7877_attributes,
 };
 
 static void ad7877_setup_ts_def_msg(struct spi_device *spi, struct ad7877 *ts)
@@ -787,20 +806,12 @@ static int __devinit ad7877_probe(struct spi_device *spi)
 	if (err)
 		goto err_free_irq;
 
-	err = device_create_file(&spi->dev,
-				 gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
-	if (err)
-		goto err_remove_attr_group;
-
 	err = input_register_device(input_dev);
 	if (err)
-		goto err_remove_attr;
+		goto err_remove_attr_group;
 
 	return 0;
 
-err_remove_attr:
-	device_remove_file(&spi->dev,
-			   gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
 err_remove_attr_group:
 	sysfs_remove_group(&spi->dev.kobj, &ad7877_attr_group);
 err_free_irq:
@@ -814,11 +825,9 @@ err_free_mem:
 
 static int __devexit ad7877_remove(struct spi_device *spi)
 {
-	struct ad7877		*ts = dev_get_drvdata(&spi->dev);
+	struct ad7877 *ts = dev_get_drvdata(&spi->dev);
 
 	sysfs_remove_group(&spi->dev.kobj, &ad7877_attr_group);
-	device_remove_file(&spi->dev,
-			   gpio3 ? &dev_attr_gpio3 : &dev_attr_aux3);
 
 	ad7877_disable(ts);
 	free_irq(ts->spi->irq, ts);
-- 
2.34.1