linux-kernel - Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver support

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Date:	Thu, 11 Jun 2009 16:00:59 -0400
From:	Andres Salomon <dilinger@...labora.co.uk>
To:	Tobias_Mueller@...m.info
Cc:	akpm@...ux-foundation.org, Randy Dunlap <randy.dunlap@...cle.com>,
	deepak@...top.org, Takashi Iwai <tiwai@...e.de>,
	linux-kernel@...r.kernel.org, linux-geode@...ts.infradead.org,
	jordan@...micpenguin.net, cjb@...top.org
Subject: Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver  
 support

Awesome.  Comments below..


On Thu, 11 Jun 2009 20:52:52 +0200
Tobias Müller <Tobias_Mueller@...m.info> wrote:

> Here's the promised patch. :) I tried to solve all issues I had with
> Andres' patch.
> 
> 
> 
> From: Tobias Mueller <Tobias_Mueller@...m.info>
> 
> Added mask to enable/disable some GPIO pins.
> Added names for GPIO pins.
> Added code on GPIO initialisation to disable output/input aux
> functions.
> 
> Signed-off-by: Tobias Mueller <Tobias_Mueller@...m.info>
> ---
> diff --git a/drivers/gpio/cs5535-gpio.c b/drivers/gpio/cs5535-gpio.c
> index 5613889..8a0b290 100644
> --- a/drivers/gpio/cs5535-gpio.c
> +++ b/drivers/gpio/cs5535-gpio.c
> @@ -18,6 +18,11 @@
> 
>  #define DRV_NAME "cs5535-gpio"
>  #define GPIO_BAR 1
> +#define GPIO_DEFAULT_MASK 0x0B003C66

Where does this mask of available GPIOs originate from?


> +
> +static ulong mask = GPIO_DEFAULT_MASK;
> +module_param_named(mask, mask, ulong, 0444);
> +MODULE_PARM_DESC(mask, "GPIO channel mask.");
> 
>  static struct cs5535_gpio_chip {
>  	struct gpio_chip chip;
> @@ -102,6 +107,38 @@ EXPORT_SYMBOL_GPL(cs5535_gpio_isset);
>   * Generic gpio_chip API support.
>   */
> 
> +static int chip_gpio_request(struct gpio_chip *c, unsigned offset)
> +{
> +	struct cs5535_gpio_chip *chip = (struct cs5535_gpio_chip *)
> c;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&chip->lock, flags);
> +
> +	/* check if this pin is available */
> +	if ((mask & (1 << offset)) == 0) {
> +		printk(KERN_INFO DRV_NAME
> +		       ": pin %u is not available (check mask)\n",
> offset);
> +		return -EINVAL;

There's a locking error here; you really want to spin_unlock_irqrestore
before returning.


> +	}
> +
> +	/* disable output aux 1 & 2 on this pin */
> +	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX1);
> +	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_AUX2);
> +
> +	/* disable input aux 1 on this pin */
> +	__cs5535_gpio_clear(chip, offset, GPIO_INPUT_AUX1);
> +
> +	/* disable output */
> +	__cs5535_gpio_clear(chip, offset, GPIO_OUTPUT_ENABLE);
> +
> +	/* enable input */
> +	__cs5535_gpio_set(chip, offset, GPIO_INPUT_ENABLE);

I don't think this is the right place for all of this.  Your earlier
email mentioned disabling OUT_AUX{1,2} for outputs, and IN_AUX for
inputs.  I'm fine with doing that here, but I don't see why you're also
disabling output and enabling input by default.

> +
> +	spin_unlock_irqrestore(&chip->lock, flags);
> +
> +	return 0;
> +}
> +
>  static int chip_gpio_get(struct gpio_chip *chip, unsigned offset)
>  {
>  	return cs5535_gpio_isset(offset, GPIO_OUTPUT_VAL);
> @@ -145,19 +182,34 @@ static int chip_direction_output(struct
> gpio_chip *c, unsigned offset, int val)
>  	return 0;
>  }
> 
> +static char *cs5535_gpio_names[] = {
> +	"GPIO0", "GPIO1", "GPIO2", "GPIO3",
> +	"GPIO4", "GPIO5", "GPIO6", "GPIO7",
> +	"GPIO8", "GPIO9", "GPIO10", "GPIO11",
> +	"GPIO12", "GPIO13", "GPIO14", "GPIO15",
> +	"GPIO16", "GPIO17", "GPIO18", "GPIO19",
> +	"GPIO20", "GPIO21", "GPIO22", NULL,
> +	"GPIO24", "GPIO25", "GPIO26", "GPIO27",
> +	"GPIO28", NULL, NULL, NULL,
> +};
> +
>  static struct cs5535_gpio_chip cs5535_gpio_chip = {
>  	.chip = {
>  		.owner = THIS_MODULE,
>  		.label = DRV_NAME,
> 
>  		.base = 0,
> -		.ngpio = 28,
> +		.ngpio = 32,

Since GPIOs 29-31 aren't externally available, and 28 is
unavailable anyways, shouldn't we just set ngpio to 28?


> +		.names = cs5535_gpio_names,
> +
> +		.request = chip_gpio_request,
> 
>  		.get = chip_gpio_get,
>  		.set = chip_gpio_set,
> 
>  		.direction_input = chip_direction_input,
>  		.direction_output = chip_direction_output,
> +
>  	},
>  };
> 
> @@ -165,6 +217,7 @@ static int __init cs5535_gpio_probe(struct
> pci_dev *pdev, const struct pci_device_id *pci_id)
>  {
>  	int err;
> +	ulong mask_orig = mask;
> 
>  	/* There are two ways to get the GPIO base address; one is by
>  	 * fetching it from MSR_LBAR_GPIO, the other is by reading
> the @@ -193,6 +246,18 @@ static int __init cs5535_gpio_probe(struct
> pci_dev *pdev, dev_info(&pdev->dev, "allocated PCI BAR #%d: base
> 0x%llx\n", GPIO_BAR, (unsigned long long) cs5535_gpio_chip.base);
> 
> +	/* mask out reserved pins */
> +	mask &= 0x1F7FFFFF;
> +
> +	/* do not allow pin 28, Power Button, as there's special
> handling
> +	 * in the PMC needed. (note 12, p. 48) */
> +	mask &= ~(1 << 28);

Nice, even a pointer to the note. :)

> +
> +	if (mask_orig != mask)
> +		printk(KERN_INFO DRV_NAME
> +		       ": mask changed from 0x%08lX to 0x%08lX\n",
> +		       mask_orig, mask);
> +
>  	/* finally, register with the generic GPIO API */
>  	err = gpiochip_add(&cs5535_gpio_chip.chip);
>  	if (err) {
--
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