RE: [spi-devel-general] [PATCH] drivers/misc: add driver for TexasInstruments DAC7512

[H Hartley Sweeten]

On Wednesday, October 07, 2009 1:01 PM, Daniel Mack wrote:
> This is actually too trivial to publish, but to export the function of
> that chip to the userspace, a module like this is needed.
> 
> Signed-off-by: Daniel Mack <daniel@xxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
> Cc: spi-devel-general@xxxxxxxxxxxxxxxxxxxxx
> ---

[snip]

> +static ssize_t dac7512_store_val(struct device *dev,
> +				 struct device_attribute *attr,
> +				 const char *buf, size_t count)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	unsigned char tmp[2];
> +	unsigned long val;
> +
> +	if (strict_strtoul(buf, 10, &val) < 0)
> +		return -EINVAL;
> +
> +	tmp[0] = val >> 8;
> +	tmp[1] = val & 0xff;
> +	spi_write(spi, tmp, sizeof(tmp));
> +	return count;
> +}
> +
> +static DEVICE_ATTR(value, S_IWUSR | S_IRUGO,
> +		   NULL, dac7512_store_val);

You have declared the "value" device attribute with mode S_IWUSR | S_IRUGO
but have not provided a show callback.

Regards,
Hartley
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