[RFC PATCH v1] EP93XX: Add ADC support

[H Hartley Sweeten]

On Monday, October 12, 2009 7:24 AM, Christian Gagneraud wrote:
> This patch add support for the ADC found in the EP93XX.
> 
> This work is based on S3C platform ADC, apart from hardware related
> stuff, the following modifications have been done:
> - Remove touchscreen support:
>   On S3C the TS is a "normal" ADC client, but it has priority over all
>   other clients. On EP93XX the TS controller is built-in and offer
>   advanced features.
> - Remove convert and select callbacks:
>   This was done for the shake of simplicity, it can be added easily.
> - Channel definition:
>   On S3c, channel is just an index (unsigned char). On EP93xx channel
>   is the analog switch configuration (unsigned long), it gives the
>   client full freedom on how to make the analog conversion (including
>   routing VRef+ and VRef-, activationg PU/PD resistors, connecting
>   pins to VDD/GND, ...)
> 
> 
> This is a first draft. Comments and criticism welcome.
> 
> Signed-off-by: Christian Gagneraud <cgagneraud at techworks.ie>
> ---

[snip]

> diff --git a/arch/arm/mach-ep93xx/adc.c b/arch/arm/mach-ep93xx/adc.c
> new file mode 100644
> index 0000000..78dc074
> --- /dev/null
> +++ b/arch/arm/mach-ep93xx/adc.c

[snip]

> +	adc->irq = platform_get_irq(pdev, 0);
> +	if (adc->irq <= 0) {
> +		dev_err(dev, "failed to get adc irq\n");
> +		ret = -ENOENT;
> +		goto err_alloc;
> +	}
> +
> +	ret = request_irq(adc->irq, ep93xx_adc_irq, IRQF_DISABLED,
> +			  dev_name(dev), adc);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to attach adc irq\n");
> +		goto err_alloc;
> +	}

The interrupt should be the last thing you request.  If an interrupt
occurs before the device is completely ready will crash the kernel.

Most of these dev_err messages are not needed.  The upper layers will
print the error code.  You can keep them around for early debugging
but they should be removed before the driver is finally merged.

Regards,
Hartley