how to use device_get_binding()

[zhouhaifang]

device_get_binding() this function has many parameters ,very Incomprehensible to use, in the nordic samples i use debug step by step to find what port what pin to be used ,but cannot find

[Heidi-Irene Harvey Sollie]

Hi! 

I'm not sure what you mean because device_get_binding() only has one parameter:

const struct device *device_get_binding(const char *name).

The parameter is the device name you want to get the binding for. 

However, there are multiple macros that will return the device name, for instance DT_LABEL(node_id), DT_PROP(node_id prop). 

There are also a lot of macros that return the node identifier. DT_NODELABEL(label) takes the node label as a parameter to return the node_id. DT_ALIAS(alias) uses the alias, DT_PATH(...) uses the node path, and DT_INST(inst, compact) returns the node identified for an instance of a compatible. 

Is this what you were looking for?

Best regards,

Heidi

[paul_tanner]

Hi,

I hope you won't think this off-topic:

Ideally when you get a binding it would be good to be able to pass this into procedures that use it (to avoid repeating this everywhere).

However, this throws errors: 

struct device *source = device_get_binding(DEVICE_LABEL);

void get_device_data(struct device *source) {

  // use the device

}

get_device_data(*source);

It seems that device_get_binding() insists on a const struct.  If not you get 

error: invalid storage class for function

But if you make that const struct device *source you get a different error

error: incompatible type for argument 1

So I'm wondering if there's any way to pass a binding into a procedure, preferably a global one?

[Heidi-Irene Harvey Sollie]

Hi!

I'm not sure why you're getting that error, but there are multiple samples that do what you're describing.

See the ADXL362 sample L37, L47, L63, L69, etc.

Try replicating this and let me know how it goes.

Best regards,

Heidi

[paul_tanner]

Thx Heidi,

There's a reference to this https://github.com/nrfconnect/sdk-zephyr/commit/e18fcbba5a4e63b54116f40ae5f0323d5237d329 which could explain it if I understood it.

Basically it's telling the compiler to allow dev to be global without declaring it globally?

I'll try that.