Re: [RFC PATCH 3/6] i2c: add device config helpers

Vlad Dogaru <vlad.dogaru@...>

On Mon, Apr 25, 2016 at 01:10:49PM +0200, Tomasz Bursztyka wrote:
Hi Vlad,

Add some macros that drivers and applications can use in describing I2C

Change-Id: Ic7af97804e88ed3b9d4f68f9ac358a425f4cc17c
Signed-off-by: Vlad Dogaru <vlad.dogaru(a)>
include/i2c.h | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/include/i2c.h b/include/i2c.h
index d1c699c..87cb071 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -266,6 +266,23 @@ static inline int i2c_resume(struct device *dev)
return api->resume(dev);
+struct i2c_client_config {
+ //struct device *i2c_master;
+ char *i2c_master;
+ uint16_t i2c_addr;
+#define DECLARE_I2C_CLIENT_CONFIG struct i2c_client_config i2c_client
+#define I2C_CLIENT(master, addr) \
I don't know if their is a rule for macro's parameter naming.
My personal - and thus subjective - opinion is to separate those to
actual C code, and
I tend to enclose these with '_', so it would be _master_, _addr_
Or prefixing with '__' works as well.
Sure thing.

+ .i2c_client = { \
So it means we cannot use anything else but "i2c_client" as a name
in our device's configuration structure?
Would be easier that way:
{ \
.i2c_master = (master), \
.i2c_addr = (addr) \

Thus usage would be:

my_dev_config.i2c_info = I2C_CLIENT(foo, bar)
The configuration tool needs to generate config structures (see
devices.c in patch 6/6). These structures are device specific, but the
tool should be as generic as possible. Hard coding the struct member
name to "i2c_client" helps achieve that.

Thus, assuming the macros are correctly used, the config tool needs only
information such as "this device is connected to master I2C0, address
0x76", to generate "I2C_CLIENT(I2C0, 0x76)". Allowing the name to
change would be an extra variable.

+ .i2c_master = (master), \
+ .i2c_addr = (addr), \
+ }
+#define GET_I2C_MASTER(conf) ((conf)->i2c_client.i2c_master)
+#define GET_I2C_ADDR(conf) ((conf)->i2c_client.i2c_addr)
I2C_ prefixed

And names are not relevant enough. What's the form of master's
information? What address?
I2C_GET_CLIENT_ADDR() (or _ADDRESS() actually)
Hopefully these will be better once I add some comments. There is an
example in patch 6/6, I hope that will clear these up.

And finally, document the struct and the macros.

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