led: driver for LEDs on PCEngines ALIX.2 and ALIX.3 boards

From: Constantin Baranov <[email protected]>

Driver for LEDs on PCEngines ALIX.2 and ALIX.3 system boards.

Signed-off-by Constantin Baranov <[email protected]>

---
 drivers/leds/Kconfig     |    6 +
 drivers/leds/Makefile    |    1 
 drivers/leds/leds-alix.c |  146 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 153 insertions(+)

diff -uprN linux-2.6.27-rc3/drivers/leds/Kconfig linux-2.6.27-rc3-alix/drivers/leds/Kconfig

drivers/leds/Kconfig +6 -0

@@ -77,6 +77,12 @@ config LEDS_WRAP
 	help
 	  This option enables support for the PCEngines WRAP programmable LEDs.
 
+config LEDS_ALIX
+	tristate "LED support for ALIX series"
+	depends on LEDS_CLASS && X86
+	help
+	  This option enables support for the PCEngines ALIX.2 and ALIX.3 LEDs.
+
 config LEDS_H1940
 	tristate "LED Support for iPAQ H1940 device"
 	depends on LEDS_CLASS && ARCH_H1940

diff -uprN linux-2.6.27-rc3/drivers/leds/leds-alix.c linux-2.6.27-rc3-alix/drivers/leds/leds-alix.c

drivers/leds/leds-alix.c +78 -0

+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/platform_device.h>
+
+struct alix_led {
+	struct led_classdev cdev;
+	unsigned short port;
+	unsigned int on_value;
+	unsigned int off_value;
+};
+
+static void alix_led_set(struct led_classdev *led_cdev,
+			 enum led_brightness brightness)
+{
+	struct alix_led *led_dev =
+		container_of(led_cdev, struct alix_led, cdev);
+	if (brightness)
+		outl(led_dev->on_value, led_dev->port);
+	else
+		outl(led_dev->off_value, led_dev->port);
+}
+
+static struct alix_led alix_leds[] = {
+	{
+		.cdev = {
+			.name = "alix:1",
+			.brightness_set = alix_led_set,
+		},
+		.port = 0x6100,
+		.on_value = 1 << 22,
+		.off_value = 1 << 6,
+	},
+	{
+		.cdev = {
+			.name = "alix:2",
+			.brightness_set = alix_led_set,
+		},
+		.port = 0x6180,
+		.on_value = 1 << 25,
+		.off_value = 1 << 9,
+	},
+	{
+		.cdev = {
+			.name = "alix:3",
+			.brightness_set = alix_led_set,
+		},
+		.port = 0x6180,
+		.on_value = 1 << 27,
+		.off_value = 1 << 11,
+	},
+};
+
+#ifdef CONFIG_PM
+
+static int alix_led_suspend(struct platform_device *dev, pm_message_t state)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
+		led_classdev_suspend(&alix_leds[i].cdev);
+	return 0;
+}
+
+static int alix_led_resume(struct platform_device *dev)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
+		led_classdev_resume(&alix_leds[i].cdev);
+	return 0;
+}
+
+#else
+
+#define alix_led_suspend NULL
+#define alix_led_resume NULL
+
+#endif
+

drivers/leds/leds-alix.c +37 -0

+static struct platform_driver alix_led_driver = {
+	.remove = alix_led_remove,
+	.suspend = alix_led_suspend,
+	.resume = alix_led_resume,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static struct platform_device *pdev;
+
+static int __init alix_led_init(void)
+{
+	int ret;
+	pdev = platform_device_register_simple(KBUILD_MODNAME, -1, NULL, 0);
+	if (!IS_ERR(pdev)) {
+		ret = platform_driver_probe(&alix_led_driver, alix_led_probe);
+		if (ret)
+			platform_device_unregister(pdev);
+	} else
+		ret = PTR_ERR(pdev);
+	return ret;
+}
+
+static void __exit alix_led_exit(void)
+{
+	platform_device_unregister(pdev);
+	platform_driver_unregister(&alix_led_driver);
+}
+
+module_init(alix_led_init);
+module_exit(alix_led_exit);
+
+MODULE_AUTHOR("Constantin Baranov <[email protected]>");
+MODULE_DESCRIPTION("PCEngines ALIX LED driver");
+MODULE_LICENSE("GPL");

diff -uprN linux-2.6.27-rc3/drivers/leds/Makefile linux-2.6.27-rc3-alix/drivers/leds/Makefile

Review

Quoted 10 lines · On Tue, 19 Aug 2008 22:23:41 +0500 Constantin Baranov <[email protected]>…

(quoted diff) +10 -0

+static int __init alix_led_probe(struct platform_device *pdev)
+{
+	int i;
+	int ret = 0;
+	
+	for (i = 0; i < ARRAY_SIZE(alix_leds) && ret >= 0; i++)
+		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
+
+	if (ret < 0) {
+		for (i = i - 2; i >= 0; i--)

this is off-by-one, surely.

If we get here with i==1, we'll loop 4 billion times.

How's this look?

From: Andrew Morton <[email protected]>

- cleanups

- fix off-by-one on error path

Cc Constantin Baranov <[email protected]>

Cc Richard Purdie <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

---

 drivers/leds/leds-alix.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff -puN drivers/leds/leds-alix.c~led-driver-for-leds-on-pcengines-alix2-and-alix3-boards-fix drivers/leds/leds-alix.c

drivers/leds/leds-alix.c renamed from drivers/leds/leds-alix.c~led-driver-for-leds-on-pcengines-alix2-and-alix3-boards-fix +4 -1

@@ -4,7 +4,7 @@
  * Copyright (C) 2008 Constantin Baranov <[email protected]>
  */
 
-#include <asm/io.h>
+#include <linux/io.h>
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/leds.h>

@@ -22,6 +22,7 @@ static void alix_led_set(struct led_clas
 {
 	struct alix_led *led_dev =
 		container_of(led_cdev, struct alix_led, cdev);
+
 	if (brightness)
 		outl(led_dev->on_value, led_dev->port);
 	else

@@ -63,6 +64,7 @@ static struct alix_led alix_leds[] = {
 static int alix_led_suspend(struct platform_device *dev, pm_message_t state)
 {
 	int i;
+
 	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
 		led_classdev_suspend(&alix_leds[i].cdev);
 	return 0;

@@ -71,6 +73,7 @@ static int alix_led_suspend(struct platf
 static int alix_led_resume(struct platform_device *dev)
 {
 	int i;
+
 	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
 		led_classdev_resume(&alix_leds[i].cdev);
 	return 0;

drivers/leds/leds-alix.c renamed from drivers/leds/leds-alix.c~led-driver-for-leds-on-pcengines-alix2-and-alix3-boards-fix +2 -0

@@ -102,6 +105,7 @@ static int __init alix_led_probe(struct 
 static int alix_led_remove(struct platform_device *pdev)
 {
 	int i;
+
 	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
 		led_classdev_unregister(&alix_leds[i].cdev);
 	return 0;

@@ -122,6 +126,7 @@ static struct platform_device *pdev;
 static int __init alix_led_init(void)
 {
 	int ret;
+
 	pdev = platform_device_register_simple(KBUILD_MODNAME, -1, NULL, 0);
 	if (!IS_ERR(pdev)) {
 		ret = platform_driver_probe(&alix_led_driver, alix_led_probe);

_

Quoted 10 lines

static int alix_led_resume(struct platform_device *dev) {

(quoted diff) +1 -0

 	int i;
+
 	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
 		led_classdev_resume(&alix_leds[i].cdev);
 	return 0;

@@ -92,7 +95,7 @@ static int __init alix_led_probe(struct 
 		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
 

Review static int __init alix_led_probe(struct · line 100

Quoted 5 lines

(quoted diff) +1 -1

 	if (ret < 0) {
-		for (i = i - 2; i >= 0; i--)
+		while (--i >= 0)
 			led_classdev_unregister(&alix_leds[i].cdev);
 	}

At the first iteration this while-loop will attempt to unregister device that has failed and thus is not registered.
My for-loop starts from device immediately before failed one.

Note that probe routine originates from leds-ams-delta.c.

Quoted 10 lines · On Sat, 23 Aug 2008 02:08:15 +0500 Constantin Baranov <[email protected]>…

Quoted 10 lines

static int alix_led_resume(struct platform_device *dev) {

(quoted diff) +1 -0

 	int i;
+
 	for (i = 0; i < ARRAY_SIZE(alix_leds); i++)
 		led_classdev_resume(&alix_leds[i].cdev);
 	return 0;

@@ -92,7 +95,7 @@ static int __init alix_led_probe(struct 
 		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
 

Quoted 8 lines

Review static int __init alix_led_probe(struct · line 100

Quoted 5 lines

(quoted diff) +1 -1

 	if (ret < 0) {
-		for (i = i - 2; i >= 0; i--)
+		while (--i >= 0)
 			led_classdev_unregister(&alix_leds[i].cdev);
 	}

At the first iteration this while-loop will attempt to unregister device that has failed and thus is not registered.
My for-loop starts from device immediately before failed one.

ug, OK, the complex expression in that for-loop is to blame.

For maintinability we should aim for code which is as simple and as straightfroward as possible and which adheres to oft-used and well-understood kernel idioms.

For example, this?

static int __init alix_led_probe(struct platform_device *pdev)

{
	int i;
	int ret;

	for (i = 0; i < ARRAY_SIZE(alix_leds); i++) {
		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
		if (ret < 0)
			goto fail;
	}
	return 0;

fail:

	while (--i >= 0)
		led_classdev_unregister(&alix_leds[i].cdev);
	return ret;
}

(note there's no longer a need for a fake initalisation of `ret')

Quoted 1 line

Note that probe routine originates from leds-ams-delta.c.

That's what you get for copying stuff :(

Quoted 20 lines

For example, this?

static int __init alix_led_probe(struct platform_device *pdev)

{
	int i;
	int ret;

	for (i = 0; i < ARRAY_SIZE(alix_leds); i++) {
		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
		if (ret < 0)
			goto fail;
	}
	return 0;

fail:

	while (--i >= 0)
		led_classdev_unregister(&alix_leds[i].cdev);
	return ret;
}

Quoted 5 lines

(note there's no longer a need for a fake initalisation of `ret')

Quoted 1 line

Note that probe routine originates from leds-ams-delta.c.

That's what you get for copying stuff :(

Well, this variant looks better and correct and still works. Should I post again patch or fix-patch?

Quoted 2 lines · On Tue, 19 Aug 2008 22:23:41 +0500 Constantin Baranov <[email protected]>…

drivers/leds/leds-alix.c +0 -0

drivers/leds/leds-alix.c

Quoted 10 lines

drivers/leds/leds-alix.c +10 -0

+static int __init alix_led_probe(struct platform_device *pdev)
+{
+	int i;
+	int ret = 0;
+	
+	for (i = 0; i < ARRAY_SIZE(alix_leds) && ret >= 0; i++)
+		ret = led_classdev_register(&pdev->dev, &alix_leds[i].cdev);
+
+	if (ret < 0) {
+		for (i = i - 2; i >= 0; i--)

this is off-by-one, surely.

If we get here with i==1, we'll loop 4 billion times.

Quoted 5 lines

drivers/leds/leds-alix.c +5 -0

+			led_classdev_unregister(&alix_leds[i].cdev);
+	}
+
+	return ret;
+}

How's this look?