On Fri, 19 Nov 2021 16:02:39 -0800
Ben Widawsky <ben.widawsky@xxxxxxxxx> wrote:
> Endpoints have decoders too. It is useful to share the same
> infrastructure from cxl_core. Endpoints do not have dports (downstream
> targets), only the underlying physical medium. As a result, some special
> casing is needed.
>
> There is no functional change introduced yet as endpoints don't actually
> enumerate decoders yet.
>
> Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
I'm not a fan of special values like using 0 here to indicate endpoint
device. I'd rather see a base cxl_decode_alloc(..., bool ep)
and possibly wrappers for the non ep case and ep one.
Jonathan
> ---
> drivers/cxl/core/bus.c | 41 +++++++++++++++++++++++++++++++++--------
> 1 file changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c
> index 1ee12a60f3f4..16b15f54fb62 100644
> --- a/drivers/cxl/core/bus.c
> +++ b/drivers/cxl/core/bus.c
> @@ -187,6 +187,12 @@ static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = {
> NULL,
> };
>
> +static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = {
> + &cxl_decoder_base_attribute_group,
> + &cxl_base_attribute_group,
> + NULL,
> +};
> +
> static void cxl_decoder_release(struct device *dev)
> {
> struct cxl_decoder *cxld = to_cxl_decoder(dev);
> @@ -196,6 +202,12 @@ static void cxl_decoder_release(struct device *dev)
> kfree(cxld);
> }
>
> +static const struct device_type cxl_decoder_endpoint_type = {
> + .name = "cxl_decoder_endpoint",
> + .release = cxl_decoder_release,
> + .groups = cxl_decoder_endpoint_attribute_groups,
> +};
> +
> static const struct device_type cxl_decoder_switch_type = {
> .name = "cxl_decoder_switch",
> .release = cxl_decoder_release,
> @@ -208,6 +220,11 @@ static const struct device_type cxl_decoder_root_type = {
> .groups = cxl_decoder_root_attribute_groups,
> };
>
> +static bool is_endpoint_decoder(struct device *dev)
> +{
> + return dev->type == &cxl_decoder_endpoint_type;
> +}
> +
> bool is_root_decoder(struct device *dev)
> {
> return dev->type == &cxl_decoder_root_type;
> @@ -499,7 +516,9 @@ static int decoder_populate_targets(struct cxl_decoder *cxld,
> * cxl_decoder_alloc - Allocate a new CXL decoder
> * @port: owning port of this decoder
> * @nr_targets: downstream targets accessible by this decoder. All upstream
> - * ports and root ports must have at least 1 target.
> + * ports and root ports must have at least 1 target. Endpoint
> + * devices will have 0 targets. Callers wishing to register an
> + * endpoint device should specify 0.
> *
> * A port should contain one or more decoders. Each of those decoders enable
> * some address space for CXL.mem utilization. A decoder is expected to be
> @@ -516,7 +535,7 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
> struct device *dev;
> int rc = 0;
>
> - if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets == 0)
> + if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
> return ERR_PTR(-EINVAL);
>
> cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL);
> @@ -535,8 +554,11 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
> dev->parent = &port->dev;
> dev->bus = &cxl_bus_type;
>
> + /* Endpoints don't have a target list */
> + if (nr_targets == 0)
> + dev->type = &cxl_decoder_endpoint_type;
> /* root ports do not have a cxl_port_type parent */
> - if (port->dev.parent->type == &cxl_port_type)
> + else if (port->dev.parent->type == &cxl_port_type)
> dev->type = &cxl_decoder_switch_type;
> else
> dev->type = &cxl_decoder_root_type;
> @@ -579,12 +601,15 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map)
> if (cxld->interleave_ways < 1)
> return -EINVAL;
>
> - port = to_cxl_port(cxld->dev.parent);
> - rc = decoder_populate_targets(cxld, port, target_map);
> - if (rc)
> - return rc;
> -
> dev = &cxld->dev;
> +
> + port = to_cxl_port(cxld->dev.parent);
> + if (!is_endpoint_decoder(dev)) {
> + rc = decoder_populate_targets(cxld, port, target_map);
> + if (rc)
> + return rc;
> + }
> +
> rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
> if (rc)
> return rc;
