Re: [PATCH 06/17] gpio: mvebu: add suspend/resume support

[David Cohen <david.a.cohen@linux.intel.com>]

On Fri, Oct 24, 2014 at 01:59:19PM +0200, Thomas Petazzoni wrote:
> This commit adds the implementation of ->suspend() and ->resume()
> platform_driver hooks in order to save and restore the state of the
> GPIO configuration. In order to achieve that, additional fields are
> added to the mvebu_gpio_chip structure.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Alexandre Courbot <gnurou@gmail.com>
> Cc: linux-gpio@vger.kernel.org
> ---
>  drivers/gpio/gpio-mvebu.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 99 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
> index 418e386..dd5545c 100644
> --- a/drivers/gpio/gpio-mvebu.c
> +++ b/drivers/gpio/gpio-mvebu.c
> @@ -83,6 +83,14 @@ struct mvebu_gpio_chip {
>  	int		   irqbase;
>  	struct irq_domain *domain;
>  	int                soc_variant;
> +
> +	/* Used to preserve GPIO registers accross suspend/resume */
> +	u32                out_reg;
> +	u32                io_conf_reg;
> +	u32                blink_en_reg;
> +	u32                in_pol_reg;
> +	u32                edge_mask_regs[4];
> +	u32                level_mask_regs[4];
>  };
>  
>  /*
> @@ -554,6 +562,93 @@ static const struct of_device_id mvebu_gpio_of_match[] = {
>  };
>  MODULE_DEVICE_TABLE(of, mvebu_gpio_of_match);
>  
> +static int mvebu_gpio_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +	struct mvebu_gpio_chip *mvchip = platform_get_drvdata(pdev);
> +	int i;
> +
> +	mvchip->out_reg = readl(mvebu_gpioreg_out(mvchip));
> +	mvchip->io_conf_reg = readl(mvebu_gpioreg_io_conf(mvchip));
> +	mvchip->blink_en_reg = readl(mvebu_gpioreg_blink(mvchip));
> +	mvchip->in_pol_reg = readl(mvebu_gpioreg_in_pol(mvchip));
> +
> +	switch (mvchip->soc_variant) {
> +	case MVEBU_GPIO_SOC_VARIANT_ORION:
> +		mvchip->edge_mask_regs[0] =
> +			readl(mvchip->membase + GPIO_EDGE_MASK_OFF);
> +		mvchip->level_mask_regs[0] =
> +			readl(mvchip->membase + GPIO_LEVEL_MASK_OFF);
> +		break;
> +	case MVEBU_GPIO_SOC_VARIANT_MV78200:
> +		for (i = 0; i < 2; i++) {
> +			mvchip->edge_mask_regs[i] =
> +				readl(mvchip->membase +
> +				      GPIO_EDGE_MASK_MV78200_OFF(i));
> +			mvchip->level_mask_regs[i] =
> +				readl(mvchip->membase +
> +				      GPIO_LEVEL_MASK_MV78200_OFF(i));
> +		}
> +		break;
> +	case MVEBU_GPIO_SOC_VARIANT_ARMADAXP:
> +		for (i = 0; i < 4; i++) {
> +			mvchip->edge_mask_regs[i] =
> +				readl(mvchip->membase +
> +				      GPIO_EDGE_MASK_ARMADAXP_OFF(i));
> +			mvchip->level_mask_regs[i] =
> +				readl(mvchip->membase +
> +				      GPIO_LEVEL_MASK_ARMADAXP_OFF(i));
> +		}
> +		break;
> +	default:
> +		BUG();

Isn't it too severe? Is the platform going too unstable if driver
reaches this case?
I'd consider a WARN() instead.

> +	}
> +
> +	return 0;
> +}
> +
> +static int mvebu_gpio_resume(struct platform_device *pdev)
> +{
> +	struct mvebu_gpio_chip *mvchip = platform_get_drvdata(pdev);
> +	int i;
> +
> +	writel(mvchip->out_reg, mvebu_gpioreg_out(mvchip));
> +	writel(mvchip->io_conf_reg, mvebu_gpioreg_io_conf(mvchip));
> +	writel(mvchip->blink_en_reg, mvebu_gpioreg_blink(mvchip));
> +	writel(mvchip->in_pol_reg, mvebu_gpioreg_in_pol(mvchip));
> +
> +	switch (mvchip->soc_variant) {
> +	case MVEBU_GPIO_SOC_VARIANT_ORION:
> +		writel(mvchip->edge_mask_regs[0],
> +		       mvchip->membase + GPIO_EDGE_MASK_OFF);
> +		writel(mvchip->level_mask_regs[0],
> +		       mvchip->membase + GPIO_LEVEL_MASK_OFF);
> +		break;
> +	case MVEBU_GPIO_SOC_VARIANT_MV78200:
> +		for (i = 0; i < 2; i++) {
> +			writel(mvchip->edge_mask_regs[i],
> +			       mvchip->membase + GPIO_EDGE_MASK_MV78200_OFF(i));
> +			writel(mvchip->level_mask_regs[i],
> +			       mvchip->membase +
> +			       GPIO_LEVEL_MASK_MV78200_OFF(i));
> +		}
> +		break;
> +	case MVEBU_GPIO_SOC_VARIANT_ARMADAXP:
> +		for (i = 0; i < 4; i++) {
> +			writel(mvchip->edge_mask_regs[i],
> +			       mvchip->membase +
> +			       GPIO_EDGE_MASK_ARMADAXP_OFF(i));
> +			writel(mvchip->level_mask_regs[i],
> +			       mvchip->membase +
> +			       GPIO_LEVEL_MASK_ARMADAXP_OFF(i));
> +		}
> +		break;
> +	default:
> +		BUG();

Ditto.

Br, David Cohen

> +	}
> +
> +	return 0;
> +}
> +
>  static int mvebu_gpio_probe(struct platform_device *pdev)
>  {
>  	struct mvebu_gpio_chip *mvchip;
> @@ -577,6 +672,8 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
>  	if (!mvchip)
>  		return -ENOMEM;
>  
> +	platform_set_drvdata(pdev, mvchip);
> +
>  	if (of_property_read_u32(pdev->dev.of_node, "ngpios", &ngpios)) {
>  		dev_err(&pdev->dev, "Missing ngpios OF property\n");
>  		return -ENODEV;
> @@ -735,5 +832,7 @@ static struct platform_driver mvebu_gpio_driver = {
>  		.of_match_table = mvebu_gpio_of_match,
>  	},
>  	.probe		= mvebu_gpio_probe,
> +	.suspend        = mvebu_gpio_suspend,
> +	.resume         = mvebu_gpio_resume,
>  };
>  module_platform_driver(mvebu_gpio_driver);
> -- 
> 2.0.0
> 
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