From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H Hartley Sweeten" Subject: Re: [PATCH] drivers/misc: add driver for TexasInstruments DAC7512 Date: Mon, 12 Oct 2009 12:31:46 -0400 Message-ID: References: <1254945665-28053-1-git-send-email-daniel@caiaq.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Andrew Morton , David Brownell To: "Daniel Mack" , Return-path: Content-class: urn:content-classes:message In-Reply-To: <1254945665-28053-1-git-send-email-daniel-rDUAYElUppE@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org 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 > Cc: Andrew Morton > Cc: David Brownell > Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > --- [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 ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference