On Mon, Jan 31, 2022 at 8:20 AM Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> wrote: > > On Wed, 26 Jan 2022 15:59:07 -0800 > Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > > > In preparation for switch port enumeration while also preserving the > > potential for multi-domain / multi-root CXL topologies. Introduce a > > 'struct device' generic mechanism for retrieving a root CXL port, if one > > is registered. Note that the only know multi-domain CXL configurations > > are running the cxl_test unit test on a system that also publishes an > > ACPI0017 device. > > > > With this in hand the nvdimm-bridge lookup can be with > > device_find_child() instead of bus_find_device() + custom mocked lookup > > infrastructure in cxl_test. > > > > The mechanism looks for a 2nd level port since the root level topology > > is platform-firmware specific and the 2nd level down follows standard > > PCIe topology expectations. The cxl_acpi 2nd level is associated with a > > PCIe Root Port. > > > > Reported-by: Ben Widawsky <ben.widawsky@xxxxxxxxx> > > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> > A question inline. > > Thanks, > > Jonathan > > > --- > > Changes since v4: > > - reset @iter each loop otherwise only the first dport can be scanned. > > > > drivers/cxl/core/pmem.c | 14 ++++++++--- > > drivers/cxl/core/port.c | 50 +++++++++++++++++++++++++++++++++++++++++ > > drivers/cxl/cxl.h | 1 + > > tools/testing/cxl/Kbuild | 2 -- > > tools/testing/cxl/mock_pmem.c | 24 -------------------- > > 5 files changed, 61 insertions(+), 30 deletions(-) > > delete mode 100644 tools/testing/cxl/mock_pmem.c > > > > diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c > > index 40b3f5030496..8de240c4d96b 100644 > > --- a/drivers/cxl/core/pmem.c > > +++ b/drivers/cxl/core/pmem.c > > @@ -57,24 +57,30 @@ bool is_cxl_nvdimm_bridge(struct device *dev) > > } > > EXPORT_SYMBOL_NS_GPL(is_cxl_nvdimm_bridge, CXL); > > > > -__mock int match_nvdimm_bridge(struct device *dev, const void *data) > > +static int match_nvdimm_bridge(struct device *dev, void *data) > > { > > return is_cxl_nvdimm_bridge(dev); > > } > > > > struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_nvdimm *cxl_nvd) > > { > > + struct cxl_port *port = find_cxl_root(&cxl_nvd->dev); > > struct device *dev; > > > > - dev = bus_find_device(&cxl_bus_type, NULL, cxl_nvd, match_nvdimm_bridge); > > + if (!port) > > + return NULL; > > + > > + dev = device_find_child(&port->dev, NULL, match_nvdimm_bridge); > > + put_device(&port->dev); > > + > > if (!dev) > > return NULL; > > + > > return to_cxl_nvdimm_bridge(dev); > > } > > EXPORT_SYMBOL_NS_GPL(cxl_find_nvdimm_bridge, CXL); > > > > -static struct cxl_nvdimm_bridge * > > -cxl_nvdimm_bridge_alloc(struct cxl_port *port) > > +static struct cxl_nvdimm_bridge *cxl_nvdimm_bridge_alloc(struct cxl_port *port) > > { > > struct cxl_nvdimm_bridge *cxl_nvb; > > struct device *dev; > > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > > index 4c921c49f967..6447f12ef71d 100644 > > --- a/drivers/cxl/core/port.c > > +++ b/drivers/cxl/core/port.c > > @@ -457,6 +457,56 @@ int devm_cxl_register_pci_bus(struct device *host, struct device *uport, > > } > > EXPORT_SYMBOL_NS_GPL(devm_cxl_register_pci_bus, CXL); > > > > +/* Find a 2nd level CXL port that has a dport that is an ancestor of @match */ > > +static int match_cxl_root_child(struct device *dev, const void *match) > > +{ > > + const struct device *iter = NULL; > > + struct cxl_port *port, *parent; > > + struct cxl_dport *dport; > > + > > + if (!is_cxl_port(dev)) > > + return 0; > > + > > + port = to_cxl_port(dev); > > + if (is_cxl_root(port)) > > + return 0; > > + > > + parent = to_cxl_port(port->dev.parent); > > + if (!is_cxl_root(parent)) > > + return 0; > > + > > + cxl_device_lock(&port->dev); > > + list_for_each_entry(dport, &port->dports, list) { > > + iter = match; > > This confuses me. In the call below to bus_find_device() > data == NULL, which ends up as match here. I think you misread, @start is NULL @data becomes @match as the starting point for the search. > > So how does that ever find a match? > > > + while (iter) { > > + if (iter == dport->dport) > > + goto out; > > + iter = iter->parent; > > + } > > + } > > +out: > > + cxl_device_unlock(&port->dev); > > + > > + return !!iter; > > return iter; should be sufficient as docs just say non zero for a match > in bus_find_device() match functions. drivers/cxl/core/port.c:488:16: error: returning ‘const struct device *’ from a function with return type ‘int’ makes integer from pointer without a cast [-Werror=int-conversion] > > > +} > > + > > +struct cxl_port *find_cxl_root(struct device *dev) > > +{ > > + struct device *port_dev; > > + struct cxl_port *root; > > + > > + port_dev = > > + bus_find_device(&cxl_bus_type, NULL, dev, match_cxl_root_child); > > Line breaking is rather ugly to my eye. Perhaps break > parameter list up instead? This is what clang-format picked, but yes it's a tag ugly. I'll go ahead and s/match_cxl_root_child/match_root_child/ since there are no public symbol namespace issues with this static helper.