[PATCH 1/2] iio: Add IIO_STATIC_CONST_DEVICE_ATTR

[Matti Vaittinen]

Add IIO_STATIC_CONST_DEVICE_ATTR macro for creating an read-only
iio_dev_attr which returns constant value. This macro is intended to be
used when replacing the IIO_CONST_ATTR - attributes for triggered
buffers because the triggered buffer attributes must be of type
iio_dev_attr.

Signed-off-by: Matti Vaittinen <mazziesaccount at gmail.com>
---
I am not thrilled about how keyword 'static' is handled here but in my
calendar this day seems to be called the day of the developer without
working ideas. Feel free to suggest something if you guys have more
luck with ideas. :) And I still think this macro is better than adding
the summy 'show' callback in each individual driver :/

 include/linux/iio/sysfs.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/iio/sysfs.h b/include/linux/iio/sysfs.h
index e51fba66de4b..de5bb125815c 100644
--- a/include/linux/iio/sysfs.h
+++ b/include/linux/iio/sysfs.h
@@ -97,6 +97,17 @@ struct iio_const_attr {
 	= { .string = _string,						\
 	    .dev_attr = __ATTR(_name, S_IRUGO, iio_read_const_attr, NULL)}
 
+#define IIO_STATIC_CONST_DEVICE_ATTR(_name, _string)				\
+	static ssize_t iio_const_dev_attr_show_##_name(			\
+					struct device *dev,		\
+					struct device_attribute *attr,	\
+					char *buf)			\
+	{								\
+		return sysfs_emit(buf, "%s\n", _string);		\
+	}								\
+	static IIO_DEVICE_ATTR(_name, 0444,				\
+			       iio_const_dev_attr_show_##_name, NULL, 0)
+
 /* Generic attributes of onetype or another */
 
 /**
-- 
2.37.3


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =] 
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