linux-kernel - [PATCH v1 1/1] gpiolib: Use sysfs

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Date:   Tue, 18 May 2021 15:09:17 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH v1 1/1] gpiolib: Use sysfs_emit() in "show" functions

The sysfs_emit() function was introduced to make it less ambiguous
which function is preferred when writing to the output buffer in
a "show" callback [1].

Convert the GPIO library sysfs interface from sprintf() to sysfs_emit()
accordingly, as the latter is aware of the PAGE_SIZE buffer and correctly
returns the number of bytes written into the buffer.

No functional change intended.

[1] Documentation/filesystems/sysfs.rst

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/gpio/gpiolib-sysfs.c | 27 ++++++++++-----------------
 1 file changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 7c5afd999210..d836aba91d3c 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -66,9 +66,7 @@ static ssize_t direction_show(struct device *dev,
 	mutex_lock(&data->mutex);
 
 	gpiod_get_direction(desc);
-	status = sprintf(buf, "%s\n",
-			test_bit(FLAG_IS_OUT, &desc->flags)
-				? "out" : "in");
+	status = sysfs_emit(buf, "%s\n", test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in");
 
 	mutex_unlock(&data->mutex);
 
@@ -109,13 +107,9 @@ static ssize_t value_show(struct device *dev,
 	mutex_lock(&data->mutex);
 
 	status = gpiod_get_value_cansleep(desc);
-	if (status < 0)
-		goto err;
+	if (status >= 0)
+		status = sysfs_emit(buf, "%zd\n", status);
 
-	buf[0] = '0' + status;
-	buf[1] = '\n';
-	status = 2;
-err:
 	mutex_unlock(&data->mutex);
 
 	return status;
@@ -249,11 +243,11 @@ static ssize_t edge_show(struct device *dev,
 	mutex_lock(&data->mutex);
 
 	for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
-		if (data->irq_flags == trigger_types[i].flags) {
-			status = sprintf(buf, "%s\n", trigger_types[i].name);
+		if (data->irq_flags == trigger_types[i].flags)
 			break;
-		}
 	}
+	if (i < ARRAY_SIZE(trigger_types))
+		status = sysfs_emit(buf, "%s\n", trigger_types[i].name);
 
 	mutex_unlock(&data->mutex);
 
@@ -333,8 +327,7 @@ static ssize_t active_low_show(struct device *dev,
 
 	mutex_lock(&data->mutex);
 
-	status = sprintf(buf, "%d\n",
-				!!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
+	status = sysfs_emit(buf, "%d\n", !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
 
 	mutex_unlock(&data->mutex);
 
@@ -412,7 +405,7 @@ static ssize_t base_show(struct device *dev,
 {
 	const struct gpio_chip	*chip = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%d\n", chip->base);
+	return sysfs_emit(buf, "%d\n", chip->base);
 }
 static DEVICE_ATTR_RO(base);
 
@@ -421,7 +414,7 @@ static ssize_t label_show(struct device *dev,
 {
 	const struct gpio_chip	*chip = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%s\n", chip->label ? : "");
+	return sysfs_emit(buf, "%s\n", chip->label ?: "");
 }
 static DEVICE_ATTR_RO(label);
 
@@ -430,7 +423,7 @@ static ssize_t ngpio_show(struct device *dev,
 {
 	const struct gpio_chip	*chip = dev_get_drvdata(dev);
 
-	return sprintf(buf, "%u\n", chip->ngpio);
+	return sysfs_emit(buf, "%u\n", chip->ngpio);
 }
 static DEVICE_ATTR_RO(ngpio);
 
-- 
2.30.2