Re: [PATCH v3] pinctrl: samsung: fix suspend/resume functionality

[Tomasz Figa <t.figa@samsung.com>]

Hi Doug,

On Thursday 16 of May 2013 21:33:18 Doug Anderson wrote:
> The GPIO states need to be restored after s2r and this is not currently
> supported in the pinctrl driver. This patch saves the gpio states before
> suspend and restores them after resume.
> 
> Saving and restoring is done very early using syscore_ops and must
> happen before pins are released from their powerdown state.
> 
> Patch originally from Prathyush K <prathyush.k@samsung.com> but
> rewritten by Doug Anderson <dianders@chromium.org>.
> 
> Signed-off-by: Prathyush K <prathyush.k@samsung.com>
> Signed-off-by: Doug Anderson <dianders@chromium.org>
> ---
> Changes in v3:
> - Skip save and restore for banks with no powerdown config.
> 
> Changes in v2:
> - Now uses sycore_ops to make sure we're early enough.
> - Try to handle two CON registers better.
> - Should handle s3c24xx better as per Heiko.
> - Simpler code; no longer tries to avoid glitching lines since
>   we _think_ all current SoCs should have pins in power down state
>   when the restore is called.
> - Dropped eint patch for now; Tomasz will post his version.
> 
>  drivers/pinctrl/pinctrl-samsung.c | 148
> ++++++++++++++++++++++++++++++++++++++ drivers/pinctrl/pinctrl-samsung.h | 
>  5 ++
>  2 files changed, 153 insertions(+)

On Exynos4210-based Trats board:

Tested-by: Tomasz Figa <t.figa@samsung.com>

Acked-by: Tomasz Figa <t.figa@samsung.com>

I will send several complementary patches in a while.

Best regards,
-- 
Tomasz Figa
Linux Kernel Developer
Samsung R&D Institute Poland
Samsung Electronics

> diff --git a/drivers/pinctrl/pinctrl-samsung.c
> b/drivers/pinctrl/pinctrl-samsung.c index 9763668..d45e36f 100644
> --- a/drivers/pinctrl/pinctrl-samsung.c
> +++ b/drivers/pinctrl/pinctrl-samsung.c
> @@ -28,6 +28,7 @@
>  #include <linux/gpio.h>
>  #include <linux/irqdomain.h>
>  #include <linux/spinlock.h>
> +#include <linux/syscore_ops.h>
> 
>  #include "core.h"
>  #include "pinctrl-samsung.h"
> @@ -48,6 +49,9 @@ static struct pin_config {
>  	{ "samsung,pin-pud-pdn", PINCFG_TYPE_PUD_PDN },
>  };
> 
> +/* Global list of devices (struct samsung_pinctrl_drv_data) */
> +LIST_HEAD(drvdata_list);
> +
>  static unsigned int pin_base;
> 
>  static inline struct samsung_pin_bank *gc_to_pin_bank(struct gpio_chip *gc)
> @@ -961,9 +965,145 @@ static int samsung_pinctrl_probe(struct
> platform_device *pdev) ctrl->eint_wkup_init(drvdata);
> 
>  	platform_set_drvdata(pdev, drvdata);
> +
> +	/* Add to the global list */
> +	list_add_tail(&drvdata->node, &drvdata_list);
> +
>  	return 0;
>  }
> 
> +#ifdef CONFIG_PM
> +
> +/**
> + * samsung_pinctrl_suspend_dev - save pinctrl state for suspend for a
> device + *
> + * Save data for all banks handled by this device.
> + */
> +static void samsung_pinctrl_suspend_dev(
> +	struct samsung_pinctrl_drv_data *drvdata)
> +{
> +	struct samsung_pin_ctrl *ctrl = drvdata->ctrl;
> +	void __iomem *virt_base = drvdata->virt_base;
> +	int i;
> +
> +	for (i = 0; i < ctrl->nr_banks; i++) {
> +		struct samsung_pin_bank *bank = &ctrl->pin_banks[i];
> +		void __iomem *reg = virt_base + bank->pctl_offset;
> +
> +		u8 *offs = bank->type->reg_offset;
> +		u8 *widths = bank->type->fld_width;
> +		enum pincfg_type type;
> +
> +		/* Registers without a powerdown config aren't lost */
> +		if (!widths[PINCFG_TYPE_CON_PDN])
> +			continue;
> +
> +		for (type = 0; type < PINCFG_TYPE_NUM; type++)
> +			if (widths[type])
> +				bank->pm_save[type] = readl(reg + offs[type]);
> +
> +		if (widths[PINCFG_TYPE_FUNC] * bank->nr_pins > 32) {
> +			/* Some banks have two config registers */
> +			bank->pm_save[PINCFG_TYPE_NUM] =
> +				readl(reg + offs[PINCFG_TYPE_FUNC] + 4);
> +			pr_debug("Save %s @ %p (con %#010x %08x)\n",
> +				 bank->name, reg,
> +				 bank->pm_save[PINCFG_TYPE_FUNC],
> +				 bank->pm_save[PINCFG_TYPE_NUM]);
> +		} else {
> +			pr_debug("Save %s @ %p (con %#010x)\n", bank->name,
> +				 reg, bank->pm_save[PINCFG_TYPE_FUNC]);
> +		}
> +	}
> +}
> +
> +/**
> + * samsung_pinctrl_resume_dev - restore pinctrl state from suspend for a
> device + *
> + * Restore one of the banks that was saved during suspend.
> + *
> + * We don't bother doing anything complicated to avoid glitching lines
> since + * we're called before pad retention is turned off.
> + */
> +static void samsung_pinctrl_resume_dev(struct samsung_pinctrl_drv_data
> *drvdata) +{
> +	struct samsung_pin_ctrl *ctrl = drvdata->ctrl;
> +	void __iomem *virt_base = drvdata->virt_base;
> +	int i;
> +
> +	for (i = 0; i < ctrl->nr_banks; i++) {
> +		struct samsung_pin_bank *bank = &ctrl->pin_banks[i];
> +		void __iomem *reg = virt_base + bank->pctl_offset;
> +
> +		u8 *offs = bank->type->reg_offset;
> +		u8 *widths = bank->type->fld_width;
> +		enum pincfg_type type;
> +
> +		/* Registers without a powerdown config aren't lost */
> +		if (!widths[PINCFG_TYPE_CON_PDN])
> +			continue;
> +
> +		if (widths[PINCFG_TYPE_FUNC] * bank->nr_pins > 32) {
> +			/* Some banks have two config registers */
> +			pr_debug("%s @ %p (con %#010x %08x => %#010x %08x)\n",
> +				 bank->name, reg,
> +				 readl(reg + offs[PINCFG_TYPE_FUNC]),
> +				 readl(reg + offs[PINCFG_TYPE_FUNC] + 4),
> +				 bank->pm_save[PINCFG_TYPE_FUNC],
> +				 bank->pm_save[PINCFG_TYPE_NUM]);
> +			writel(bank->pm_save[PINCFG_TYPE_NUM],
> +			       reg + offs[PINCFG_TYPE_FUNC] + 4);
> +		} else {
> +			pr_debug("%s @ %p (con %#010x => %#010x)\n", bank->name,
> +				 reg, readl(reg + offs[PINCFG_TYPE_FUNC]),
> +				 bank->pm_save[PINCFG_TYPE_FUNC]);
> +		}
> +		for (type = 0; type < PINCFG_TYPE_NUM; type++)
> +			if (widths[type])
> +				writel(bank->pm_save[type], reg + offs[type]);
> +	}
> +}
> +
> +/**
> + * samsung_pinctrl_suspend - save pinctrl state for suspend
> + *
> + * Save data for all banks across all devices.
> + */
> +static int samsung_pinctrl_suspend(void)
> +{
> +	struct samsung_pinctrl_drv_data *drvdata;
> +
> +	list_for_each_entry(drvdata, &drvdata_list, node) {
> +		samsung_pinctrl_suspend_dev(drvdata);
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * samsung_pinctrl_resume - restore pinctrl state for suspend
> + *
> + * Restore data for all banks across all devices.
> + */
> +static void samsung_pinctrl_resume(void)
> +{
> +	struct samsung_pinctrl_drv_data *drvdata;
> +
> +	list_for_each_entry_reverse(drvdata, &drvdata_list, node) {
> +		samsung_pinctrl_resume_dev(drvdata);
> +	}
> +}
> +
> +#else
> +#define samsung_pinctrl_suspend		NULL
> +#define samsung_pinctrl_resume		NULL
> +#endif
> +
> +static struct syscore_ops samsung_pinctrl_syscore_ops = {
> +	.suspend	= samsung_pinctrl_suspend,
> +	.resume		= samsung_pinctrl_resume,
> +};
> +
>  static const struct of_device_id samsung_pinctrl_dt_match[] = {
>  #ifdef CONFIG_PINCTRL_EXYNOS
>  	{ .compatible = "samsung,exynos4210-pinctrl",
> @@ -992,6 +1132,14 @@ static struct platform_driver samsung_pinctrl_driver =
> {
> 
>  static int __init samsung_pinctrl_drv_register(void)
>  {
> +	/*
> +	 * Register syscore ops for save/restore of registers across suspend.
> +	 * It's important to ensure that this driver is running at an earlier
> +	 * initcall level than any arch-specific init calls that install syscore
> +	 * ops that turn off pad retention (like exynos_pm_resume).
> +	 */
> +	register_syscore_ops(&samsung_pinctrl_syscore_ops);
> +
>  	return platform_driver_register(&samsung_pinctrl_driver);
>  }
>  postcore_initcall(samsung_pinctrl_drv_register);
> diff --git a/drivers/pinctrl/pinctrl-samsung.h
> b/drivers/pinctrl/pinctrl-samsung.h index 7c7f9eb..9f5cc81 100644
> --- a/drivers/pinctrl/pinctrl-samsung.h
> +++ b/drivers/pinctrl/pinctrl-samsung.h
> @@ -127,6 +127,7 @@ struct samsung_pin_bank_type {
>   * @gpio_chip: GPIO chip of the bank.
>   * @grange: linux gpio pin range supported by this bank.
>   * @slock: spinlock protecting bank registers
> + * @pm_save: saved register values during suspend
>   */
>  struct samsung_pin_bank {
>  	struct samsung_pin_bank_type *type;
> @@ -144,6 +145,8 @@ struct samsung_pin_bank {
>  	struct gpio_chip gpio_chip;
>  	struct pinctrl_gpio_range grange;
>  	spinlock_t slock;
> +
> +	u32 pm_save[PINCFG_TYPE_NUM + 1]; /* +1 to handle double CON registers*/
>  };
> 
>  /**
> @@ -189,6 +192,7 @@ struct samsung_pin_ctrl {
> 
>  /**
>   * struct samsung_pinctrl_drv_data: wrapper for holding driver data
> together. + * @node: global list node
>   * @virt_base: register base address of the controller.
>   * @dev: device instance representing the controller.
>   * @irq: interrpt number used by the controller to notify gpio interrupts.
> @@ -201,6 +205,7 @@ struct samsung_pin_ctrl {
>   * @nr_function: number of such pin functions.
>   */
>  struct samsung_pinctrl_drv_data {
> +	struct list_head		node;
>  	void __iomem			*virt_base;
>  	struct device			*dev;
>  	int				irq;