linux-kernel - Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and trigger support

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Date:	Tue, 13 Aug 2013 18:05:00 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Zubair Lutfullah <zubair.lutfullah@...il.com>
Cc:	jic23@....ac.uk, dmitry.torokhov@...il.com, sameo@...ux.intel.com,
	linux-iio@...r.kernel.org, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, bigeasy@...utronix.de,
	gregkh@...uxfoundation.org, Russ.Dill@...com
Subject: Re: [PATCH 4/4] iio: ti_am335x_adc: Add continuous sampling and
 trigger support

On Tue, 13 Aug 2013, Zubair Lutfullah wrote:

> Previously the driver had only one-shot reading functionality.
> This patch adds triggered buffer support to the driver.
> A buffer of samples can now be read via /dev/iio.
> Any IIO trigger can be used to start acquisition.
> 
> Patil Rachna (TI) laid the ground work for ADC HW register access.
> Russ Dill (TI) fixed bugs in the driver relevant to FIFOs and IRQs.
> 
> I fixed channel scanning so multiple ADC channels can be read
> simultaneously and pushed to userspace. Restructured the driver
> to fit IIO ABI. And added trigger support.
> 
> Signed-off-by: Zubair Lutfullah <zubair.lutfullah@...il.com>
> Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Signed-off-by: Russ Dill <Russ.Dill@...com>
> ---
>  drivers/iio/adc/ti_am335x_adc.c      |  353 ++++++++++++++++++++++++++++------
>  include/linux/mfd/ti_am335x_tscadc.h |   13 +-
>  2 files changed, 303 insertions(+), 63 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c

<snip>

> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index e2db978..a1d22de 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -46,6 +46,9 @@
>  /* Step Enable */
>  #define STEPENB_MASK		(0x1FFFF << 0)
>  #define STEPENB(val)		((val) << 0)
> +#define ENB(val)			(1 << (val))
> +#define STPENB_STEPENB		STEPENB(0x1FFFF)
> +#define STPENB_STEPENB_TC	STEPENB(0x1FFF)
>  
>  /* IRQ enable */
>  #define IRQENB_HW_PEN		BIT(0)
> @@ -54,11 +57,14 @@
>  #define IRQENB_FIFO0UNDRFLW	BIT(4)
>  #define IRQENB_FIFO1THRES	BIT(5)
>  #define IRQENB_PENUP		BIT(9)
> +#define IRQENB_FIFO1OVRRUN	BIT(6)
> +#define IRQENB_FIFO1UNDRFLW	BIT(7)

Nit: Can we keep these in numerical order?

>  /* Step Configuration */
>  #define STEPCONFIG_MODE_MASK	(3 << 0)
>  #define STEPCONFIG_MODE(val)	((val) << 0)
>  #define STEPCONFIG_MODE_HWSYNC	STEPCONFIG_MODE(2)
> +#define STEPCONFIG_MODE_SWCNT	STEPCONFIG_MODE(1)
>  #define STEPCONFIG_AVG_MASK	(7 << 2)
>  #define STEPCONFIG_AVG(val)	((val) << 2)
>  #define STEPCONFIG_AVG_16	STEPCONFIG_AVG(4)
> @@ -126,7 +132,8 @@
>  #define	MAX_CLK_DIV		7
>  #define TOTAL_STEPS		16
>  #define TOTAL_CHANNELS		8
> -
> +#define FIFO1_THRESHOLD		19
> +#define FIFO_SIZE			64

Nit: Keep the line space between the defines and the multi-line comment.

>  /*
>  * ADC runs at 3MHz, and it takes
>  * 15 cycles to latch one data output.
> @@ -155,6 +162,10 @@ struct ti_tscadc_dev {
>  
>  	/* adc device */
>  	struct adc_device *adc;
> +
> +	/* Context save */
> +	unsigned int irqstat;
> +	unsigned int ctrl;
>  };
>  
>  static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p)

-- 
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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