On 26/06/25 12:19PM, Alison Schofield wrote:
>On Tue, Jun 17, 2025 at 06:09:39PM +0530, Neeraj Kumar wrote:
>> Add cxl_find_root_decoder to find root decoder on cxl bus. It is used to
>> find root decoder during region creation
>
>Does the existing to_cxl_root_decoder() provide what you need here?
>

Hi Alison,

Actually, my need is to find decoder0.0 from port1, with which endpoint device is connected.
Here i am already using to_cxl_root_decoder() inside cxl_find_root_decoder().
In cxl_find_root_decoder(), First i am finding dev which is required by to_cxl_root_decoder()

	struct cxl_root_decoder *cxl_find_root_decoder(struct cxl_port *port)
	{
		struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
		struct device *dev = device_find_child(&cxl_root->port.dev, NULL, match_root_decoder);
		return to_cxl_root_decoder(dev);
	}


Thanks,
Neeraj

>>
>> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>
>> ---
>>  drivers/cxl/core/port.c | 26 ++++++++++++++++++++++++++
>>  drivers/cxl/cxl.h       |  1 +
>>  2 files changed, 27 insertions(+)
>>
>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>> index 2452f7c15b2d..94d9322b8e38 100644
>> --- a/drivers/cxl/core/port.c
>> +++ b/drivers/cxl/core/port.c
>> @@ -513,6 +513,32 @@ struct cxl_switch_decoder *to_cxl_switch_decoder(struct device *dev)
>>  }
>>  EXPORT_SYMBOL_NS_GPL(to_cxl_switch_decoder, "CXL");
>>
>> +static int match_root_decoder(struct device *dev, void *data)
>> +{
>> +	return is_root_decoder(dev);
>> +}
>> +
>> +/**
>> + * cxl_find_root_decoder() - find a cxl root decoder on cxl bus
>> + * @port: any descendant port in root-cxl-port topology
>> + */
>> +struct cxl_root_decoder *cxl_find_root_decoder(struct cxl_port *port)
>> +{
>> +	struct cxl_root *cxl_root __free(put_cxl_root) = find_cxl_root(port);
>> +	struct device *dev;
>> +
>> +	if (!cxl_root)
>> +		return NULL;
>> +
>> +	dev = device_find_child(&cxl_root->port.dev, NULL, match_root_decoder);
>> +
>> +	if (!dev)
>> +		return NULL;
>> +
>> +	return to_cxl_root_decoder(dev);
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_find_root_decoder, "CXL");
>> +
>>  static void cxl_ep_release(struct cxl_ep *ep)
>>  {
>>  	put_device(ep->ep);
>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>> index 30c80e04cb27..2c6a782d0941 100644
>> --- a/drivers/cxl/cxl.h
>> +++ b/drivers/cxl/cxl.h
>> @@ -871,6 +871,7 @@ bool is_cxl_nvdimm_bridge(struct device *dev);
>>  int devm_cxl_add_nvdimm(struct cxl_port *parent_port, struct cxl_memdev *cxlmd);
>>  struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_port *port);
>>  void cxl_region_discovery(struct cxl_port *port);
>> +struct cxl_root_decoder *cxl_find_root_decoder(struct cxl_port *port);
>>
>>  #ifdef CONFIG_CXL_REGION
>>  bool is_cxl_pmem_region(struct device *dev);
>> --
>> 2.34.1
>>
>>