linux-kernel - Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

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Message-ID: <20130827084245.GA7669@lee--X1>
Date:	Tue, 27 Aug 2013 09:42:45 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Zubair Lutfullah <zubair.lutfullah@...il.com>
Cc:	jic23@....ac.uk, bigeasy@...utronix.de, linux-iio@...r.kernel.org,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	gregkh@...uxfoundation.org
Subject: Re: [PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling support

On Sun, 25 Aug 2013, Zubair Lutfullah wrote:

> Previously the driver had only one-shot reading functionality.
> This patch adds triggered buffer support to the driver.
> 
> Continuous sampling starts when buffer is enabled.
> And samples are pushed to userpace by the trigger which
> triggers automatically at every hardware interrupt
> of FIFO1 filling with samples upto threshold value.
> 
> Userspace responsibility to stop sampling by writing zero
> in the buffer enable file.
> 
> 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      |  254 +++++++++++++++++++++++++++++++---
>  include/linux/mfd/ti_am335x_tscadc.h |   13 ++
>  2 files changed, 246 insertions(+), 21 deletions(-)

MFD stuff looks okay to me.

Acked-by: Lee Jones <lee.jones@...aro.org>

<snip>

> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index db1791b..a372ebf 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -46,17 +46,25 @@
>  /* 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)
>  #define IRQENB_FIFO0THRES	BIT(2)
> +#define IRQENB_FIFO0OVRRUN	BIT(3)
> +#define IRQENB_FIFO0UNDRFLW	BIT(4)
>  #define IRQENB_FIFO1THRES	BIT(5)
> +#define IRQENB_FIFO1OVRRUN	BIT(6)
> +#define IRQENB_FIFO1UNDRFLW	BIT(7)
>  #define IRQENB_PENUP		BIT(9)
>  
>  /* 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)
> @@ -124,6 +132,7 @@
>  #define	MAX_CLK_DIV		7
>  #define TOTAL_STEPS		16
>  #define TOTAL_CHANNELS		8
> +#define FIFO1_THRESHOLD		19
>  
>  /*
>  * ADC runs at 3MHz, and it takes
> @@ -153,6 +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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