[PATCH 00/10] gpio: mockup: updates for 4.13

[PATCH 00/10] gpio: mockup: updates for 4.13

[Bartosz Golaszewski]

This series contains a couple bug fixes and other minor updates for
the GPIO testing module.

Bartosz Golaszewski (10):
  gpio: mockup: fix direction values
  gpio: mockup: add prefixes to the direction enum
  gpio: mockup: be quiet unless something goes wrong
  gpio: mockup: support irqmask and irqunmask
  gpio: mockup: improve the debugfs input sanitization
  gpio: mockup: refuse to accept an odd number of GPIO ranges
  gpio: mockup: improve readability
  gpio: mockup: don't return magic numbers from probe()
  gpio: mockup: improve the error message
  gpio: mockup: add myself as author

 drivers/gpio/gpio-mockup.c | 82 ++++++++++++++++++++++++++++++----------------
 1 file changed, 54 insertions(+), 28 deletions(-)

-- 
2.9.3

[PATCH 01/10] gpio: mockup: fix direction values

[Bartosz Golaszewski]

The comment in linux/gpio/driver.h says:

 @get_direction: returns direction for signal "offset", 0=out, 1=in

We got those switched at some point. Fix the values.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index c6dadac..c18d011 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -29,8 +29,8 @@
 #define	GPIO_MOCKUP_MAX_GC	10
 
 enum {
-	DIR_IN = 0,
-	DIR_OUT,
+	DIR_OUT = 0,
+	DIR_IN = 1,
 };
 
 /*
-- 
2.9.3

[PATCH 02/10] gpio: mockup: add prefixes to the direction enum

[Bartosz Golaszewski]

All internal symbols except for the direction enum follow the same
convention and use the gpio_mockup prefix. Add the prefix to the
DIR_IN and DIR_OUT definitions as well for consistency across the
file.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index c18d011..b1ee45c 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -29,8 +29,8 @@
 #define	GPIO_MOCKUP_MAX_GC	10
 
 enum {
-	DIR_OUT = 0,
-	DIR_IN = 1,
+	GPIO_MOCKUP_DIR_OUT = 0,
+	GPIO_MOCKUP_DIR_IN = 1,
 };
 
 /*
@@ -93,7 +93,7 @@ static int gpio_mockup_dirout(struct gpio_chip *gc, unsigned int offset,
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
 	gpio_mockup_set(gc, offset, value);
-	chip->lines[offset].dir = DIR_OUT;
+	chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
 
 	return 0;
 }
@@ -102,7 +102,7 @@ static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
 
-	chip->lines[offset].dir = DIR_IN;
+	chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
 
 	return 0;
 }
-- 
2.9.3

[PATCH 03/10] gpio: mockup: be quiet unless something goes wrong

[Bartosz Golaszewski]

When inserting and removing the module repeatedly (e.g. when running
the libgpiod test-suite) the kernel log gets clobbered with messages
reporting successful creation of dummy gpiochips.

Remove this message and only emit logs when something bad happens.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index b1ee45c..c17578e 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -364,9 +364,6 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 
 			return ret;
 		}
-
-		dev_info(dev, "gpio<%d..%d> add successful!",
-			 base, base + ngpio);
 	}
 
 	return 0;
-- 
2.9.3

[PATCH 04/10] gpio: mockup: support irqmask and irqunmask

[Bartosz Golaszewski]

Even though this is a testing module, be nice and actually implement
these functions.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index c17578e..ba8d62a 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -41,6 +41,7 @@ enum {
 struct gpio_mockup_line_status {
 	int dir;
 	bool value;
+	bool irq_enabled;
 };
 
 struct gpio_mockup_irq_context {
@@ -142,12 +143,21 @@ static int gpio_mockup_to_irq(struct gpio_chip *chip, unsigned int offset)
 	return chip->irq_base + offset;
 }
 
-/*
- * While we should generally support irqmask and irqunmask, this driver is
- * for testing purposes only so we don't care.
- */
-static void gpio_mockup_irqmask(struct irq_data *d) { }
-static void gpio_mockup_irqunmask(struct irq_data *d) { }
+static void gpio_mockup_irqmask(struct irq_data *data)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+
+	chip->lines[data->irq - gc->irq_base].irq_enabled = false;
+}
+
+static void gpio_mockup_irqunmask(struct irq_data *data)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
+
+	chip->lines[data->irq - gc->irq_base].irq_enabled = true;
+}
 
 static struct irq_chip gpio_mockup_irqchip = {
 	.name		= GPIO_MOCKUP_NAME,
@@ -178,6 +188,7 @@ static int gpio_mockup_irqchip_setup(struct device *dev,
 
 	for (i = 0; i < gc->ngpio; i++) {
 		irq_set_chip(irq_base + i, gc->irqchip);
+		irq_set_chip_data(irq_base + i, gc);
 		irq_set_handler(irq_base + i, &handle_simple_irq);
 		irq_modify_status(irq_base + i,
 				  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
@@ -206,6 +217,9 @@ static ssize_t gpio_mockup_event_write(struct file *file,
 	chip = priv->chip;
 	gc = &chip->gc;
 
+	if (!chip->lines[priv->offset].irq_enabled)
+		return size;
+
 	if (copy_from_user(&buf, usr_buf, 1))
 		return -EFAULT;
 
-- 
2.9.3

[PATCH 05/10] gpio: mockup: improve the debugfs input sanitization

[Bartosz Golaszewski]

We're currently only checking the first character of the input to the
debugfs event files, so a string like '0sdfdsf' is valid and indicates
a falling edge event.

Be more strict and only allow '0', '1', '0\n' & '1\n'.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index ba8d62a..b197b93 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -208,8 +208,8 @@ static ssize_t gpio_mockup_event_write(struct file *file,
 	struct seq_file *sfile;
 	struct gpio_desc *desc;
 	struct gpio_chip *gc;
+	char buf[2];
 	int val;
-	char buf;
 
 	sfile = file->private_data;
 	priv = sfile->private;
@@ -220,12 +220,18 @@ static ssize_t gpio_mockup_event_write(struct file *file,
 	if (!chip->lines[priv->offset].irq_enabled)
 		return size;
 
-	if (copy_from_user(&buf, usr_buf, 1))
+	if (size > 2)
+		return -EINVAL;
+
+	if (copy_from_user(&buf, usr_buf, 2))
 		return -EFAULT;
 
-	if (buf == '0')
+	if (size == 2 && buf[1] != '\n')
+		return -EINVAL;
+
+	if (buf[0] == '0')
 		val = 0;
-	else if (buf == '1')
+	else if (buf[0] == '1')
 		val = 1;
 	else
 		return -EINVAL;
-- 
2.9.3

[PATCH 06/10] gpio: mockup: refuse to accept an odd number of GPIO ranges

[Bartosz Golaszewski]

Currently we ignore the last odd range value, since each chip is
described by two values. Be more strict and require the user to
pass an even number of ranges.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index b197b93..d771112 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -346,7 +346,7 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 	int ret, i, base, ngpio;
 	char *chip_name;
 
-	if (gpio_mockup_params_nr < 2)
+	if (gpio_mockup_params_nr < 2 || (gpio_mockup_params_nr % 2))
 		return -EINVAL;
 
 	chips = devm_kzalloc(dev,
-- 
2.9.3

[PATCH 07/10] gpio: mockup: improve readability

[Bartosz Golaszewski]

We currently shift bits here and there without actually explaining
what we're doing. Add some helper variables with names indicating
their purpose to improve the code readability.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index d771112..f6efa97 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -27,6 +27,11 @@
 
 #define GPIO_MOCKUP_NAME	"gpio-mockup"
 #define	GPIO_MOCKUP_MAX_GC	10
+/*
+ * We're storing two values per chip: the GPIO base and the number
+ * of GPIO lines.
+ */
+#define GPIO_MOCKUP_MAX_RANGES	(GPIO_MOCKUP_MAX_GC * 2)
 
 enum {
 	GPIO_MOCKUP_DIR_OUT = 0,
@@ -62,7 +67,7 @@ struct gpio_mockup_dbgfs_private {
 	int offset;
 };
 
-static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_GC << 1];
+static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
 static int gpio_mockup_params_nr;
 module_param_array(gpio_mockup_ranges, int, &gpio_mockup_params_nr, 0400);
 
@@ -341,23 +346,24 @@ static int gpio_mockup_add(struct device *dev,
 
 static int gpio_mockup_probe(struct platform_device *pdev)
 {
-	struct gpio_mockup_chip *chips;
+	int ret, i, base, ngpio, num_chips;
 	struct device *dev = &pdev->dev;
-	int ret, i, base, ngpio;
+	struct gpio_mockup_chip *chips;
 	char *chip_name;
 
 	if (gpio_mockup_params_nr < 2 || (gpio_mockup_params_nr % 2))
 		return -EINVAL;
 
-	chips = devm_kzalloc(dev,
-			     sizeof(*chips) * (gpio_mockup_params_nr >> 1),
-			     GFP_KERNEL);
+	/* Each chip is described by two values. */
+	num_chips = gpio_mockup_params_nr / 2;
+
+	chips = devm_kzalloc(dev, sizeof(*chips) * num_chips, GFP_KERNEL);
 	if (!chips)
 		return -ENOMEM;
 
 	platform_set_drvdata(pdev, chips);
 
-	for (i = 0; i < gpio_mockup_params_nr >> 1; i++) {
+	for (i = 0; i < num_chips; i++) {
 		base = gpio_mockup_ranges[i * 2];
 
 		if (base == -1)
-- 
2.9.3

[PATCH 08/10] gpio: mockup: don't return magic numbers from probe()

[Bartosz Golaszewski]

When the requested number of GPIO lines is 0, return -EINVAL, not
-1 which is -EPERM.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index f6efa97..3ffc3ce 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -381,7 +381,7 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 			ret = gpio_mockup_add(dev, &chips[i],
 					      chip_name, base, ngpio);
 		} else {
-			ret = -1;
+			ret = -EINVAL;
 		}
 
 		if (ret) {
-- 
2.9.3

[PATCH 09/10] gpio: mockup: improve the error message

[Bartosz Golaszewski]

Indicate the error number and make the message a bit more elaborate.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 3ffc3ce..96a6c6e 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -385,8 +385,9 @@ static int gpio_mockup_probe(struct platform_device *pdev)
 		}
 
 		if (ret) {
-			dev_err(dev, "gpio<%d..%d> add failed\n",
-				base, base < 0 ? ngpio : base + ngpio);
+			dev_err(dev,
+				"adding gpiochip failed: %d (base: %d, ngpio: %d)\n",
+				ret, base, base < 0 ? ngpio : base + ngpio);
 
 			return ret;
 		}
-- 
2.9.3

[PATCH 10/10] gpio: mockup: add myself as author

[Bartosz Golaszewski]

Just taking credit for the recent changes and new features. :)

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
 drivers/gpio/gpio-mockup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 96a6c6e..d870597 100644
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2014  Kamlakant Patel <kamlakant.patel@broadcom.com>
  * Copyright (C) 2015-2016  Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
+ * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
  *
  * This program is free software; you can redistribute  it and/or modify it
  * under  the terms of  the GNU General  Public License as published by the
@@ -444,5 +445,6 @@ module_exit(mock_device_exit);
 
 MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
 MODULE_AUTHOR("Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>");
+MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
 MODULE_DESCRIPTION("GPIO Testing driver");
 MODULE_LICENSE("GPL v2");
-- 
2.9.3

Re: [PATCH 01/10] gpio: mockup: fix direction values

[Andy Shevchenko]

On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> The comment in linux/gpio/driver.h says:
>
>  @get_direction: returns direction for signal "offset", 0=out, 1=in
>
> We got those switched at some point. Fix the values.

Shouldn't it have a Fixes tag?


>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> ---
>  drivers/gpio/gpio-mockup.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> index c6dadac..c18d011 100644
> --- a/drivers/gpio/gpio-mockup.c
> +++ b/drivers/gpio/gpio-mockup.c
> @@ -29,8 +29,8 @@
>  #define        GPIO_MOCKUP_MAX_GC      10
>
>  enum {
> -       DIR_IN = 0,
> -       DIR_OUT,
> +       DIR_OUT = 0,
> +       DIR_IN = 1,
>  };
>
>  /*
> --
> 2.9.3
>



-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 05/10] gpio: mockup: improve the debugfs input sanitization

[Andy Shevchenko]

On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> We're currently only checking the first character of the input to the
> debugfs event files, so a string like '0sdfdsf' is valid and indicates
> a falling edge event.
>
> Be more strict and only allow '0', '1', '0\n' & '1\n'.

Why not to be so strict and use

kstrtobool_from_user();

instead?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 05/10] gpio: mockup: improve the debugfs input sanitization

[Andy Shevchenko]

On Sat, May 27, 2017 at 7:45 PM, Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>> We're currently only checking the first character of the input to the
>> debugfs event files, so a string like '0sdfdsf' is valid and indicates
>> a falling edge event.
>>
>> Be more strict and only allow '0', '1', '0\n' & '1\n'.
>
> Why not to be so strict and use
>
> kstrtobool_from_user();
>
> instead?

Or if you still wish to be strict,
ret = kstrtou8_from_user();
if (ret)
 return ret;

if (val > 1)
 return -ERANGE;

or alike.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 06/10] gpio: mockup: refuse to accept an odd number of GPIO ranges

[Andy Shevchenko]

On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> Currently we ignore the last odd range value, since each chip is
> described by two values. Be more strict and require the user to
> pass an even number of ranges.

> -       if (gpio_mockup_params_nr < 2)
> +       if (gpio_mockup_params_nr < 2 || (gpio_mockup_params_nr % 2))

     if (((gpio_mockup_params_nr + 1) & ~3) < 3)

3 might have a suffix regarding to the type of variable.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 06/10] gpio: mockup: refuse to accept an odd number of GPIO ranges

[Andy Shevchenko]

On Sat, May 27, 2017 at 8:29 PM, Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
> On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>> Currently we ignore the last odd range value, since each chip is
>> described by two values. Be more strict and require the user to
>> pass an even number of ranges.
>
>> -       if (gpio_mockup_params_nr < 2)
>> +       if (gpio_mockup_params_nr < 2 || (gpio_mockup_params_nr % 2))
>
>      if (((gpio_mockup_params_nr + 1) & ~3) < 3)
>
> 3 might have a suffix regarding to the type of variable.

Oh, ignore that, sorry, for a noise.


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 05/10] gpio: mockup: improve the debugfs input sanitization

[Bartosz Golaszewski]

2017-05-27 18:47 GMT+02:00 Andy Shevchenko <andy.shevchenko@gmail.com>:
> On Sat, May 27, 2017 at 7:45 PM, Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
>> On Thu, May 25, 2017 at 11:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>>> We're currently only checking the first character of the input to the
>>> debugfs event files, so a string like '0sdfdsf' is valid and indicates
>>> a falling edge event.
>>>
>>> Be more strict and only allow '0', '1', '0\n' & '1\n'.
>>
>> Why not to be so strict and use
>>
>> kstrtobool_from_user();
>>
>> instead?
>

Because it doesn't really make sense here - we're indicating a RISING
or FALLING edge event. This doesn't really correspond well with
boolean values IMO.

> Or if you still wish to be strict,
> ret = kstrtou8_from_user();
> if (ret)
>  return ret;
>
> if (val > 1)
>  return -ERANGE;
>
> or alike.

This one looks good, I'll include it in v2.

Thanks,
Bartosz

Re: [PATCH 01/10] gpio: mockup: fix direction values

[Linus Walleij]

On Thu, May 25, 2017 at 10:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> The comment in linux/gpio/driver.h says:
>
>  @get_direction: returns direction for signal "offset", 0=out, 1=in
>
> We got those switched at some point. Fix the values.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Patch applied.

Yours,
Linus Walleij

Re: [PATCH 02/10] gpio: mockup: add prefixes to the direction enum

[Linus Walleij]

On Thu, May 25, 2017 at 10:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> All internal symbols except for the direction enum follow the same
> convention and use the gpio_mockup prefix. Add the prefix to the
> DIR_IN and DIR_OUT definitions as well for consistency across the
> file.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Patch applied.

Yours,
Linus Walleij

Re: [PATCH 03/10] gpio: mockup: be quiet unless something goes wrong

[Linus Walleij]

On Thu, May 25, 2017 at 10:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> When inserting and removing the module repeatedly (e.g. when running
> the libgpiod test-suite) the kernel log gets clobbered with messages
> reporting successful creation of dummy gpiochips.
>
> Remove this message and only emit logs when something bad happens.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Patch applied.

Yours,
Linus Walleij

Re: [PATCH 04/10] gpio: mockup: support irqmask and irqunmask

[Linus Walleij]

On Thu, May 25, 2017 at 10:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> Even though this is a testing module, be nice and actually implement
> these functions.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Patch applied.

Yours,
Linus Walleij

Re: [PATCH 05/10] gpio: mockup: improve the debugfs input sanitization

[Linus Walleij]

On Thu, May 25, 2017 at 10:33 AM, Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> We're currently only checking the first character of the input to the
> debugfs event files, so a string like '0sdfdsf' is valid and indicates
> a falling edge event.
>
> Be more strict and only allow '0', '1', '0\n' & '1\n'.
>
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

Since I applied patches 1-4 you only need to resend from this point
when posting v2.

Yours,
Linus Walleij