Re: [PATCH v5 13/20] pinctrl: samsung: Add filter selection support for alive banks

[William McVicker <willmcvicker@google.com>]

On 12/01/2023, Peter Griffin wrote:
> Newer Exynos SoCs have a filter selection register on alive bank pins.
> This allows the selection of a digital or delay filter for each pin. If
> the filter selection register is not available then the default filter
> (digital) is applied.
> 
> On suspend we apply the analog filter to all pins in the bank (as the
> digital filter relies on a clock). On resume the digital filter is
> reapplied to all pins in the bank. The digital filter is working via
> clock and has an adjustable filter delay register bitfield, whereas
> the analog filter uses a fixed delay.
> 
> The filter determines to what extent signal fluctuations received through
> the pad are considered glitches.
> 
> The code path can be exercised using
> echo mem > /sys/power/state
> And then wake the device using a eint gpio
> 
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>

Tested-by: Will McVicker <willmcvicker@google.com>

--

I verified boot and that the pinctrl driver is probing. When I tested

  echo mem > /sys/power/state

I wasn't able to re-wake the device (not sure how to send an eint gpio on
a phone form factor). I tried with no_console_suspend but that hits a SError
Interrupt (likely due to a PMU secure register access). Let me know if there's
anything else I should test out.

Thanks,
Will

> ---
>  drivers/pinctrl/samsung/pinctrl-exynos.c  | 89 ++++++++++++++++++++++-
>  drivers/pinctrl/samsung/pinctrl-exynos.h  |  7 ++
>  drivers/pinctrl/samsung/pinctrl-samsung.c |  2 +
>  drivers/pinctrl/samsung/pinctrl-samsung.h | 22 ++++++
>  4 files changed, 119 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/samsung/pinctrl-exynos.c b/drivers/pinctrl/samsung/pinctrl-exynos.c
> index 6b58ec84e34b..56fc11a1fe2f 100644
> --- a/drivers/pinctrl/samsung/pinctrl-exynos.c
> +++ b/drivers/pinctrl/samsung/pinctrl-exynos.c
> @@ -269,6 +269,71 @@ struct exynos_eint_gpio_save {
>  	u32 eint_mask;
>  };
>  
> +/*
> + * Set the desired filter (digital or analog delay) to every pin in
> + * the bank. Note the filter selection bitfield is only found on alive
> + * banks. The filter determines to what extent signal fluctuations
> + * received through the pad are considered glitches.
> + */
> +static void exynos_eint_flt_config(struct samsung_pinctrl_drv_data *d,
> +				   struct samsung_pin_bank *bank, int filter)
> +{
> +	unsigned int flt_reg, flt_con = 0;
> +	unsigned int val, shift;
> +	int i;
> +	int loop_cnt;
> +
> +	/*
> +	 * The FLTCON register has the following layout
> +	 *
> +	 * BitfieldName[PinNum][Bit:Bit]
> +	 * FLT_EN[3][31] FLT_SEL[3][30] FLT_WIDTH[3][29:24]
> +	 * FLT_EN[2][23] FLT_SEL[2][22] FLT_WIDTH[2][21:16]
> +	 * FLT_EN[1][15] FLT_SEL[1][14] FLT_WIDTH[1][13:8]
> +	 * FLT_EN[0][7]  FLT_SEL[0][6]  FLT_WIDTH[0][5:0]
> +	 *
> +	 * FLT_EN	0x0 = Disable, 0x1=Enable
> +	 * FLT_SEL	0x0 = Delay filter, 0x1 Digital filter
> +	 * FLT_WIDTH	Filtering width. Valid when FLT_SEL is 0x1
> +	 */
> +
> +	flt_con |= EXYNOS9_FLTCON_EN;
> +
> +	if (filter)
> +		flt_con |= EXYNOS9_FLTCON_DIGITAL;
> +
> +	flt_reg = EXYNOS_GPIO_EFLTCON_OFFSET + bank->fltcon_offset;
> +
> +	/*
> +	 * If nr_pins > 4, we should set FLTCON0 register fully.
> +	 * (pin0 ~ 3). So loop 4 times in case of FLTCON0.
> +	 */
> +	if (bank->nr_pins > EXYNOS9_FLTCON_NR_PIN)
> +		loop_cnt = EXYNOS9_FLTCON_NR_PIN;
> +	else
> +		loop_cnt = bank->nr_pins;
> +
> +	val = readl(d->virt_base + flt_reg);
> +	for (i = 0; i < loop_cnt; i++) {
> +		shift = i * EXYNOS9_FLTCON_LEN;
> +		val &= ~(EXYNOS9_FLTCON_MASK << shift);
> +		val |= (flt_con << shift);
> +	}
> +	writel(val, d->virt_base + flt_reg);
> +
> +	/* Loop for FLTCON1 pin 4 ~ 7 */
> +	if (bank->nr_pins > EXYNOS9_FLTCON_NR_PIN) {
> +		loop_cnt = (bank->nr_pins - EXYNOS9_FLTCON_NR_PIN);
> +		val = readl(d->virt_base + flt_reg + 0x4);
> +		for (i = 0; i < loop_cnt; i++) {
> +			shift = i * EXYNOS9_FLTCON_LEN;
> +			val &= ~(EXYNOS9_FLTCON_MASK << shift);
> +			val |= (flt_con << shift);
> +		}
> +		writel(val, d->virt_base + flt_reg + 0x4);
> +	}
> +}
> +
>  /*
>   * exynos_eint_gpio_init() - setup handling of external gpio interrupts.
>   * @d: driver data of samsung pinctrl driver.
> @@ -321,6 +386,10 @@ __init int exynos_eint_gpio_init(struct samsung_pinctrl_drv_data *d)
>  			goto err_domains;
>  		}
>  
> +		/* Set Delay Analog Filter */
> +		if (bank->fltcon_type != FLT_DEFAULT)
> +			exynos_eint_flt_config(d, bank,
> +					       EXYNOS9_FLTCON_DELAY);
>  	}
>  
>  	return 0;
> @@ -555,6 +624,11 @@ __init int exynos_eint_wkup_init(struct samsung_pinctrl_drv_data *d)
>  		if (bank->eint_type != EINT_TYPE_WKUP)
>  			continue;
>  
> +		/* Set Digital Filter */
> +		if (bank->fltcon_type != FLT_DEFAULT)
> +			exynos_eint_flt_config(d, bank,
> +					       EXYNOS9_FLTCON_DIGITAL);
> +
>  		bank->irq_chip = devm_kmemdup(dev, irq_chip, sizeof(*irq_chip),
>  					      GFP_KERNEL);
>  		if (!bank->irq_chip) {
> @@ -658,6 +732,7 @@ static void exynos_pinctrl_suspend_bank(
>  void exynos_pinctrl_suspend(struct samsung_pinctrl_drv_data *drvdata)
>  {
>  	struct samsung_pin_bank *bank = drvdata->pin_banks;
> +	struct samsung_pinctrl_drv_data *d = bank->drvdata;
>  	struct exynos_irq_chip *irq_chip = NULL;
>  	int i;
>  
> @@ -665,6 +740,10 @@ void exynos_pinctrl_suspend(struct samsung_pinctrl_drv_data *drvdata)
>  		if (bank->eint_type == EINT_TYPE_GPIO)
>  			exynos_pinctrl_suspend_bank(drvdata, bank);
>  		else if (bank->eint_type == EINT_TYPE_WKUP) {
> +			/* Setting Delay (Analog) Filter */
> +			if (bank->fltcon_type != FLT_DEFAULT)
> +				exynos_eint_flt_config(d, bank,
> +						       EXYNOS9_FLTCON_DELAY);
>  			if (!irq_chip) {
>  				irq_chip = bank->irq_chip;
>  				irq_chip->set_eint_wakeup_mask(drvdata,
> @@ -707,11 +786,19 @@ static void exynos_pinctrl_resume_bank(
>  void exynos_pinctrl_resume(struct samsung_pinctrl_drv_data *drvdata)
>  {
>  	struct samsung_pin_bank *bank = drvdata->pin_banks;
> +	struct samsung_pinctrl_drv_data *d = bank->drvdata;
>  	int i;
>  
>  	for (i = 0; i < drvdata->nr_banks; ++i, ++bank)
> -		if (bank->eint_type == EINT_TYPE_GPIO)
> +		if (bank->eint_type == EINT_TYPE_GPIO) {
>  			exynos_pinctrl_resume_bank(drvdata, bank);
> +		} else if (bank->eint_type == EINT_TYPE_WKUP ||
> +			   bank->eint_type == EINT_TYPE_WKUP_MUX) {
> +			/* Set Digital Filter */
> +			if (bank->fltcon_type != FLT_DEFAULT)
> +				exynos_eint_flt_config(d, bank,
> +						       EXYNOS9_FLTCON_DIGITAL);
> +		}
>  }
>  
>  static void exynos_retention_enable(struct samsung_pinctrl_drv_data *drvdata)
> diff --git a/drivers/pinctrl/samsung/pinctrl-exynos.h b/drivers/pinctrl/samsung/pinctrl-exynos.h
> index 3ac52c2cf998..e2799ff1b5e9 100644
> --- a/drivers/pinctrl/samsung/pinctrl-exynos.h
> +++ b/drivers/pinctrl/samsung/pinctrl-exynos.h
> @@ -50,6 +50,13 @@
>  
>  #define EXYNOS_EINT_MAX_PER_BANK	8
>  #define EXYNOS_EINT_NR_WKUP_EINT
> +/* EINT filter configuration */
> +#define EXYNOS9_FLTCON_EN		BIT(7)
> +#define EXYNOS9_FLTCON_DIGITAL		BIT(6)
> +#define EXYNOS9_FLTCON_DELAY		(0 << 6)
> +#define EXYNOS9_FLTCON_MASK		0xff
> +#define EXYNOS9_FLTCON_LEN		8
> +#define EXYNOS9_FLTCON_NR_PIN		4
>  
>  #define EXYNOS_PIN_BANK_EINTN(pins, reg, id)		\
>  	{						\
> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.c b/drivers/pinctrl/samsung/pinctrl-samsung.c
> index 79babbb39ced..50c360b4753a 100644
> --- a/drivers/pinctrl/samsung/pinctrl-samsung.c
> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.c
> @@ -1105,6 +1105,8 @@ samsung_pinctrl_get_soc_data(struct samsung_pinctrl_drv_data *d,
>  		bank->eint_func = bdata->eint_func;
>  		bank->eint_type = bdata->eint_type;
>  		bank->eint_mask = bdata->eint_mask;
> +		bank->fltcon_type = bdata->fltcon_type;
> +		bank->fltcon_offset = bdata->fltcon_offset;
>  		bank->eint_offset = bdata->eint_offset;
>  		bank->name = bdata->name;
>  
> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.h b/drivers/pinctrl/samsung/pinctrl-samsung.h
> index 9b3db50adef3..5fab3885a7d7 100644
> --- a/drivers/pinctrl/samsung/pinctrl-samsung.h
> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.h
> @@ -82,6 +82,20 @@ enum eint_type {
>  	EINT_TYPE_WKUP_MUX,
>  };
>  
> +/**
> + * enum fltcon_type - filter selection
> + * @FLT_DEFAULT: filter not selectable, default digital filter
> + * @FLT_SELECT: filter selectable (digital or delay)
> + *
> + * Some banks on newer Exynos based SoCs have a selectable filter on alive
> + * banks of 'analog/delay' or 'digital'. If the filter selection register is
> + * not available then the default filter is used (digital).
> + */
> +enum fltcon_type {
> +	FLT_DEFAULT,
> +	FLT_SELECTABLE,
> +};
> +
>  /* maximum length of a pin in pin descriptor (example: "gpa0-0") */
>  #define PIN_NAME_LENGTH	10
>  
> @@ -122,6 +136,8 @@ struct samsung_pin_bank_type {
>   * @eint_type: type of the external interrupt supported by the bank.
>   * @eint_mask: bit mask of pins which support EINT function.
>   * @eint_offset: SoC-specific EINT register or interrupt offset of bank.
> + * @fltcon_type: whether the filter (delay/digital) is selectable
> + * @fltcon_offset: SoC-specific EINT filter control register offset of bank.
>   * @name: name to be prefixed for each pin in this pin bank.
>   */
>  struct samsung_pin_bank_data {
> @@ -133,6 +149,8 @@ struct samsung_pin_bank_data {
>  	enum eint_type	eint_type;
>  	u32		eint_mask;
>  	u32		eint_offset;
> +	enum fltcon_type fltcon_type;
> +	u32		fltcon_offset;
>  	const char	*name;
>  };
>  
> @@ -147,6 +165,8 @@ struct samsung_pin_bank_data {
>   * @eint_type: type of the external interrupt supported by the bank.
>   * @eint_mask: bit mask of pins which support EINT function.
>   * @eint_offset: SoC-specific EINT register or interrupt offset of bank.
> + * @fltcon_type: whether the filter (delay/digital) is selectable
> + * @fltcon_offset: SoC-specific EINT filter control register offset of bank.
>   * @name: name to be prefixed for each pin in this pin bank.
>   * @id: id of the bank, propagated to the pin range.
>   * @pin_base: starting pin number of the bank.
> @@ -170,6 +190,8 @@ struct samsung_pin_bank {
>  	enum eint_type	eint_type;
>  	u32		eint_mask;
>  	u32		eint_offset;
> +	enum fltcon_type fltcon_type;
> +	u32		fltcon_offset;
>  	const char	*name;
>  	u32		id;
>  
> -- 
> 2.43.0.rc2.451.g8631bc7472-goog
>