[alsa-devel] SSM2518 Device Tree support ?

[Ricard Wanderlof]

Bringing up an old thread becuase i have a similar issue with the 
adau1761-i2c.c driver which should be configurable in the same way - it 
links into the I2C driver framework too. I know my ssm2518.c patch was 
recently applied, but using this driver (prior to the patch) as an 
example as Lars-Peter mentioned that it should be able to work this way.

On Thu, 13 Aug 2015, Lars-Peter Clausen wrote:

> [ ... device tree support in ssm2518.c ... ]
> What's not in the driver is a explicit of match table. It will work without
> since the I2C subsystem supports matching based on the I2C ID table.

How does this actually work? I've tried to figure it out but haven't 
gotten anywhere.

From:

http://wiki.analog.com/resources/tools-software/linux-drivers/sound/ssm2518 :


i2s: i2c at 41600000 {
	compatible = "...;
	...

	#size-cells = <0>;
	#address-cells = <1>;
            
	ssm2518: ssm2518 at 34 {
		compatible = "adi,ssm2518";
		reg = <0x34>;
		gpios = <&gpio 5 0>;
	};
};


In codecs/ssm2518.c:


static const struct i2c_device_id ssm2518_i2c_ids[] = {
        { "ssm2518", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, ssm2518_i2c_ids);

static struct i2c_driver ssm2518_driver = {
        .driver = {
                .name = "ssm2518",
                .owner = THIS_MODULE,
        },
        .probe = ssm2518_i2c_probe,
        .remove = ssm2518_i2c_remove,
        .id_table = ssm2518_i2c_ids,
};
module_i2c_driver(ssm2518_driver);


So how does the i2c framework ultimately get the ssm2518 probe function to 
be called? The only real ID here are the strings "ssm2518" but they don't 
show up in the DT entry, except as part of the ssm2518 compatible string.

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30