linux-kernel - Re: [PATCH v2 2/3] iio: adc: exynos-adc: Add support for ADC FSD-HW controller

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Date:   Sun, 22 May 2022 12:25:55 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Tamseel Shams <m.shams@...sung.com>
Cc:     lars@...afoo.de, robh+dt@...nel.org, krzk+dt@...nel.org,
        geert@...ux-m68k.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, alim.akhtar@...sung.com,
        paul@...pouillou.net, linux-fsd@...la.com
Subject: Re: [PATCH v2 2/3] iio: adc: exynos-adc: Add support for ADC FSD-HW
 controller

On Fri, 20 May 2022 20:28:19 +0530
Tamseel Shams <m.shams@...sung.com> wrote:

> From: Alim Akhtar <alim.akhtar@...sung.com>
> 
> Exynos's ADC-FSD-HW has some difference in registers set, number of
> programmable channels (16 channel) etc. This patch adds support for
> ADC-FSD-HW controller version.
> 
> Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
> Signed-off-by: Tamseel Shams <m.shams@...sung.com>

Hi,

One suggestion inline, otherwise LGTM. Plenty of time to tidy this up as
this won't make the upcoming merge window - I'll be queuing it up for 5.20

Thanks,

Jonathan

> ---
> - Changes since v1
> * Addressed Jonathan's comment by using already provided isr handle
> 
>  drivers/iio/adc/exynos_adc.c | 55 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
> 
> diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
> index cff1ba57fb16..183ae591327a 100644
> --- a/drivers/iio/adc/exynos_adc.c
> +++ b/drivers/iio/adc/exynos_adc.c
> @@ -55,6 +55,11 @@
>  #define ADC_V2_INT_ST(x)	((x) + 0x14)
>  #define ADC_V2_VER(x)		((x) + 0x20)
>  
> +/* ADC_FSD_HW register definitions */
> +#define ADC_FSD_DAT(x)			((x) + 0x08)

I mention this below, but these different register sets
should be in the struct exynos_adc_data to avoid the need
for an if "compatible" == check on each use of them.


> +#define ADC_FSD_DAT_SUM(x)		((x) + 0x0C)
> +#define ADC_FSD_DBG_DATA(x)		((x) + 0x1C)
> +
>  /* Bit definitions for ADC_V1 */
>  #define ADC_V1_CON_RES		(1u << 16)
>  #define ADC_V1_CON_PRSCEN	(1u << 14)
> @@ -92,6 +97,7 @@
>  
>  /* Bit definitions for ADC_V2 */
>  #define ADC_V2_CON1_SOFT_RESET	(1u << 2)
> +#define ADC_V2_CON1_SOFT_NON_RESET	(1u << 1)
>  
>  #define ADC_V2_CON2_OSEL	(1u << 10)
>  #define ADC_V2_CON2_ESEL	(1u << 9)
> @@ -100,6 +106,7 @@
>  #define ADC_V2_CON2_ACH_SEL(x)	(((x) & 0xF) << 0)
>  #define ADC_V2_CON2_ACH_MASK	0xF
>  
> +#define MAX_ADC_FSD_CHANNELS		16
>  #define MAX_ADC_V2_CHANNELS		10
>  #define MAX_ADC_V1_CHANNELS		8
>  #define MAX_EXYNOS3250_ADC_CHANNELS	2
> @@ -484,6 +491,43 @@ static const struct exynos_adc_data exynos7_adc_data = {
>  	.start_conv	= exynos_adc_v2_start_conv,
>  };
>  
> +static void exynos_adc_fsd_init_hw(struct exynos_adc *info)
> +{
> +	u32 con2;
> +
> +	writel(ADC_V2_CON1_SOFT_RESET, ADC_V2_CON1(info->regs));
> +
> +	writel(ADC_V2_CON1_SOFT_NON_RESET, ADC_V2_CON1(info->regs));
> +
> +	con2 = ADC_V2_CON2_C_TIME(6);
> +	writel(con2, ADC_V2_CON2(info->regs));
> +
> +	/* Enable interrupts */
> +	writel(1, ADC_V2_INT_EN(info->regs));
> +}
> +
> +static void exynos_adc_fsd_exit_hw(struct exynos_adc *info)
> +{
> +	u32 con2;
> +
> +	con2 = readl(ADC_V2_CON2(info->regs));
> +	con2 &= ~ADC_V2_CON2_C_TIME(7);
> +	writel(con2, ADC_V2_CON2(info->regs));
> +
> +	/* Disable interrupts */
> +	writel(0, ADC_V2_INT_EN(info->regs));
> +}
> +
> +static const struct exynos_adc_data fsd_hw_adc_data = {
> +	.num_channels	= MAX_ADC_FSD_CHANNELS,
> +	.mask		= ADC_DATX_MASK, /* 12 bit ADC resolution */
> +
> +	.init_hw	= exynos_adc_fsd_init_hw,
> +	.exit_hw	= exynos_adc_fsd_exit_hw,
> +	.clear_irq	= exynos_adc_v2_clear_irq,
> +	.start_conv	= exynos_adc_v2_start_conv,
> +};
> +
>  static const struct of_device_id exynos_adc_match[] = {
>  	{
>  		.compatible = "samsung,s3c2410-adc",
> @@ -518,6 +562,9 @@ static const struct of_device_id exynos_adc_match[] = {
>  	}, {
>  		.compatible = "samsung,exynos7-adc",
>  		.data = &exynos7_adc_data,
> +	}, {
> +		.compatible = "samsung,exynos-adc-fsd-hw",
> +		.data = &fsd_hw_adc_data,
>  	},
>  	{},
>  };
> @@ -626,6 +673,8 @@ static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
>  		info->ts_x = readl(ADC_V1_DATX(info->regs));
>  		info->ts_y = readl(ADC_V1_DATY(info->regs));
>  		writel(ADC_TSC_WAIT4INT | ADC_S3C2443_TSC_UD_SEN, ADC_V1_TSC(info->regs));
> +	} else if (of_device_is_compatible(info->dev->of_node, "samsung,exynos-adc-fsd-hw")) {

Rather than a fairly expensive look up into a device tree node, why not add
the information to the struct exynos_adc_adc in some fashion?  Maybe as an offset
for the register block?

 
> +		info->value = readl(ADC_FSD_DAT(info->regs)) & mask;
>  	} else {
>  		info->value = readl(ADC_V1_DATX(info->regs)) & mask;
>  	}
> @@ -719,6 +768,12 @@ static const struct iio_chan_spec exynos_adc_iio_channels[] = {
>  	ADC_CHANNEL(7, "adc7"),
>  	ADC_CHANNEL(8, "adc8"),
>  	ADC_CHANNEL(9, "adc9"),
> +	ADC_CHANNEL(10, "adc10"),
> +	ADC_CHANNEL(11, "adc11"),
> +	ADC_CHANNEL(12, "adc12"),
> +	ADC_CHANNEL(13, "adc13"),
> +	ADC_CHANNEL(14, "adc14"),
> +	ADC_CHANNEL(15, "adc15"),
>  };
>  
>  static int exynos_adc_remove_devices(struct device *dev, void *c)