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i2c: New macro to initialize i2c address lists on the fly

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For video4linux we sometimes need to probe for a single i2c address.
Normally you would do it like this:

static const unsigned short addrs[] = {
	addr, I2C_CLIENT_END
};

client = i2c_new_probed_device(adapter, &info, addrs);

This is a bit awkward and I came up with this macro:

#define V4L2_I2C_ADDRS(addr, addrs...) \
	((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })

This can construct a list of one or more i2c addresses on the fly. But
this is something that really belongs in i2c.h, renamed to I2C_ADDRS.

With this macro we can just do:

client = i2c_new_probed_device(adapter, &info, I2C_ADDRS(addr));

Note that this can also be used to initialize an array:

static const unsigned short addrs[] = I2C_ADDRS(0x2a, 0x2c);

Whether you want to is another matter, but it works. This functionality is 
also available in the oldest supported gcc (3.2).

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Hans Verkuil 2009-06-19 16:58:21 +02:00 committed by Jean Delvare
parent 23af840057
commit c70366732f
1 changed files with 4 additions and 0 deletions
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4
include/linux/i2c.h
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@ -393,6 +393,10 @@ struct i2c_client_address_data {
/* The numbers to use to set I2C bus address */
#define ANY_I2C_BUS 0xffff
/* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
#define I2C_ADDRS(addr, addrs...) \
((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })
/* ----- functions exported by i2c.o */