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cxl/port: Record dport in endpoint references
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Recall that the primary role of the cxl_mem driver is to probe if the
given endpoint is connected to a CXL port topology. In that process it
walks its device ancestry to its PCI root port. If that root port is
also a CXL root port then the probe process adds cxl_port object
instances at switch in the path between to the root and the endpoint. As
those cxl_port instances are added, or if a previous enumeration
attempt already created the port, a 'struct cxl_ep' instance is
registered with that port to track the endpoints interested in that
port.

At the time the cxl_ep is registered the downstream egress path from the
port to the endpoint is known. Take the opportunity to record that
information as it will be needed for dynamic programming of decoder
targets during region provisioning.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/165784329944.1758207.15203961796832072116.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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Dan Williams committed Jul 22, 2022
1 parent cf88042 commit de516b4
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Showing 2 changed files with 37 additions and 17 deletions.
52 changes: 35 additions & 17 deletions drivers/cxl/core/port.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -882,8 +882,9 @@ static struct cxl_ep *find_ep(struct cxl_port *port, struct device *ep_dev)
return NULL;
}

static int add_ep(struct cxl_port *port, struct cxl_ep *new)
static int add_ep(struct cxl_ep *new)
{
struct cxl_port *port = new->dport->port;
struct cxl_ep *dup;

device_lock(&port->dev);
Expand All @@ -901,14 +902,14 @@ static int add_ep(struct cxl_port *port, struct cxl_ep *new)

/**
* cxl_add_ep - register an endpoint's interest in a port
* @port: a port in the endpoint's topology ancestry
* @dport: the dport that routes to @ep_dev
* @ep_dev: device representing the endpoint
*
* Intermediate CXL ports are scanned based on the arrival of endpoints.
* When those endpoints depart the port can be destroyed once all
* endpoints that care about that port have been removed.
*/
static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)
static int cxl_add_ep(struct cxl_dport *dport, struct device *ep_dev)
{
struct cxl_ep *ep;
int rc;
Expand All @@ -919,8 +920,9 @@ static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)

INIT_LIST_HEAD(&ep->list);
ep->ep = get_device(ep_dev);
ep->dport = dport;

rc = add_ep(port, ep);
rc = add_ep(ep);
if (rc)
cxl_ep_release(ep);
return rc;
Expand All @@ -929,11 +931,13 @@ static int cxl_add_ep(struct cxl_port *port, struct device *ep_dev)
struct cxl_find_port_ctx {
const struct device *dport_dev;
const struct cxl_port *parent_port;
struct cxl_dport **dport;
};

static int match_port_by_dport(struct device *dev, const void *data)
{
const struct cxl_find_port_ctx *ctx = data;
struct cxl_dport *dport;
struct cxl_port *port;

if (!is_cxl_port(dev))
Expand All @@ -942,7 +946,10 @@ static int match_port_by_dport(struct device *dev, const void *data)
return 0;

port = to_cxl_port(dev);
return cxl_find_dport_by_dev(port, ctx->dport_dev) != NULL;
dport = cxl_find_dport_by_dev(port, ctx->dport_dev);
if (ctx->dport)
*ctx->dport = dport;
return dport != NULL;
}

static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
Expand All @@ -958,24 +965,32 @@ static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
return NULL;
}

static struct cxl_port *find_cxl_port(struct device *dport_dev)
static struct cxl_port *find_cxl_port(struct device *dport_dev,
struct cxl_dport **dport)
{
struct cxl_find_port_ctx ctx = {
.dport_dev = dport_dev,
.dport = dport,
};
struct cxl_port *port;

return __find_cxl_port(&ctx);
port = __find_cxl_port(&ctx);
return port;
}

static struct cxl_port *find_cxl_port_at(struct cxl_port *parent_port,
struct device *dport_dev)
struct device *dport_dev,
struct cxl_dport **dport)
{
struct cxl_find_port_ctx ctx = {
.dport_dev = dport_dev,
.parent_port = parent_port,
.dport = dport,
};
struct cxl_port *port;

return __find_cxl_port(&ctx);
port = __find_cxl_port(&ctx);
return port;
}

/*
Expand Down Expand Up @@ -1060,7 +1075,7 @@ static void cxl_detach_ep(void *data)
if (!dport_dev)
break;

port = find_cxl_port(dport_dev);
port = find_cxl_port(dport_dev, NULL);
if (!port)
continue;

Expand Down Expand Up @@ -1135,6 +1150,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
struct device *dparent = grandparent(dport_dev);
struct cxl_port *port, *parent_port = NULL;
resource_size_t component_reg_phys;
struct cxl_dport *dport;
int rc;

if (!dparent) {
Expand All @@ -1148,7 +1164,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
return -ENXIO;
}

parent_port = find_cxl_port(dparent);
parent_port = find_cxl_port(dparent, NULL);
if (!parent_port) {
/* iterate to create this parent_port */
return -EAGAIN;
Expand All @@ -1163,13 +1179,14 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
goto out;
}

port = find_cxl_port_at(parent_port, dport_dev);
port = find_cxl_port_at(parent_port, dport_dev, &dport);
if (!port) {
component_reg_phys = find_component_registers(uport_dev);
port = devm_cxl_add_port(&parent_port->dev, uport_dev,
component_reg_phys, parent_port);
/* retry find to pick up the new dport information */
if (!IS_ERR(port))
get_device(&port->dev);
port = find_cxl_port_at(parent_port, dport_dev, &dport);
}
out:
device_unlock(&parent_port->dev);
Expand All @@ -1179,7 +1196,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
else {
dev_dbg(&cxlmd->dev, "add to new port %s:%s\n",
dev_name(&port->dev), dev_name(port->uport));
rc = cxl_add_ep(port, &cxlmd->dev);
rc = cxl_add_ep(dport, &cxlmd->dev);
if (rc == -EEXIST) {
/*
* "can't" happen, but this error code means
Expand Down Expand Up @@ -1213,6 +1230,7 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
for (iter = dev; iter; iter = grandparent(iter)) {
struct device *dport_dev = grandparent(iter);
struct device *uport_dev;
struct cxl_dport *dport;
struct cxl_port *port;

if (!dport_dev)
Expand All @@ -1228,12 +1246,12 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
dev_dbg(dev, "scan: iter: %s dport_dev: %s parent: %s\n",
dev_name(iter), dev_name(dport_dev),
dev_name(uport_dev));
port = find_cxl_port(dport_dev);
port = find_cxl_port(dport_dev, &dport);
if (port) {
dev_dbg(&cxlmd->dev,
"found already registered port %s:%s\n",
dev_name(&port->dev), dev_name(port->uport));
rc = cxl_add_ep(port, &cxlmd->dev);
rc = cxl_add_ep(dport, &cxlmd->dev);

/*
* If the endpoint already exists in the port's list,
Expand Down Expand Up @@ -1274,7 +1292,7 @@ EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_ports, CXL);

struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd)
{
return find_cxl_port(grandparent(&cxlmd->dev));
return find_cxl_port(grandparent(&cxlmd->dev), NULL);
}
EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, CXL);

Expand Down
2 changes: 2 additions & 0 deletions drivers/cxl/cxl.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -378,10 +378,12 @@ struct cxl_dport {
/**
* struct cxl_ep - track an endpoint's interest in a port
* @ep: device that hosts a generic CXL endpoint (expander or accelerator)
* @dport: which dport routes to this endpoint on @port
* @list: node on port->endpoints list
*/
struct cxl_ep {
struct device *ep;
struct cxl_dport *dport;
struct list_head list;
};

Expand Down

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