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bh=C34aAuYsQC5hMZs65e/nt69Wo2kbH1VyCWSIIhYy5rI=; b=f2M/6o+PetbiZj7fhUj0FGmyZoh4Wr9nMVLoqgUZS/lMMQIXx3VvMJFU3Ax6JkPc70gz1t5Rzf5NZvmOizsV3wgrRAlzjkfyRLqdcYyUvMSAZH3az/fQuBDBYoIKl4Se3JrasWU/mYQhg9siFd9jFxFmeRUV5ICvQ4mU8Gnvsqs= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=zohomail.com; spf=pass smtp.mailfrom=ming.li@zohomail.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1785926479; s=zm2022; d=zohomail.com; i=ming.li@zohomail.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:To:To:Cc:Cc:From:From:In-Reply-To:Content-Type:Content-Transfer-Encoding:Feedback-ID:Message-Id:Reply-To; bh=C34aAuYsQC5hMZs65e/nt69Wo2kbH1VyCWSIIhYy5rI=; b=f3WcU5kXjAqqsSFtis0H6QhzULiuX6Kg0gZSgg/4VJckrhBdTJqpdjI+Cn4B5Shk o0tujNMYQsE6M8lFrrrhTE3BN6dafPpjb+8bajaefCFEgQ3mhQbjKu4Ve0ZCmhq2UMD /T0nwDaut70h4zFPRaHuWLZOtYerF6HWuDeQpM5E= Received: by mx.zohomail.com with SMTPS id 1785926475831411.3137122566767; Wed, 5 Aug 2026 03:41:15 -0700 (PDT) Message-ID: Date: Wed, 5 Aug 2026 18:41:11 +0800 Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 1/8] cxl: Add BI register probing and port initialization To: Davidlohr Bueso Cc: jic23@kernel.org, alison.schofield@intel.com, icheng@nvidia.com, benjamin.cheatham@amd.com, alucerop@amd.com, dongjoo.seo1@samsung.com, linux-cxl@vger.kernel.org, dave.jiang@intel.com References: <20260728144136.709882-1-dave@stgolabs.net> <20260728144136.709882-2-dave@stgolabs.net> From: Li Ming In-Reply-To: <20260728144136.709882-2-dave@stgolabs.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Feedback-ID: zu08011227bf045e66db49ba5a883e18560000d5ce15227106f2a6ae9742690204b076d4a8c5222c49c02518:ZohoMail X-Zoho-CM-AccountID: abd763e7b9fa23acf4f42a44f9876d2d993e05abdb9290f9ccb1008c977bf7f0 X-ZohoMailClient: External On 7/28/2026 10:41 PM, Davidlohr Bueso wrote: > Add register probing for BI Route Table and BI Decoder capability > structures in cxl_probe_component_regs(), and helpers to map them. > > cxl_dport_map_bi() maps the BI Decoder of a downstream port (root > port or switch DSP) at dport-creation time via cxl_port_add_dport(); > cxl_port_map_bi() maps a port's own BI capability during port probe > when the upstream link is in 256B Flit operation -- BI Decoder for > an endpoint, BI RT for a switch USP. > > Signed-off-by: Davidlohr Bueso Reviewed-by: Li Ming Just a minor suggestion below. > --- > drivers/cxl/core/core.h | 1 + > drivers/cxl/core/pci.c | 38 ++++++++++++++++++++++++++++++++++ > drivers/cxl/core/port.c | 4 +++- > drivers/cxl/core/regs.c | 14 +++++++++++++ > drivers/cxl/cxl.h | 7 +++++++ > drivers/cxl/port.c | 45 +++++++++++++++++++++++++++++++++++++++++ > include/cxl/cxl.h | 6 ++++++ > 7 files changed, 114 insertions(+), 1 deletion(-) > > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h > index 07555ae63859..e36b55fd63bd 100644 > --- a/drivers/cxl/core/core.h > +++ b/drivers/cxl/core/core.h > @@ -209,6 +209,7 @@ static inline void devm_cxl_dport_ras_setup(struct cxl_dport *dport) { } > #endif /* CONFIG_CXL_RAS */ > > int cxl_gpf_port_setup(struct cxl_dport *dport); > +void devm_cxl_dport_bi_setup(struct cxl_dport *dport); > > struct cxl_hdm; > int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index e4338fd7e01b..f82559d8a8c5 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -926,3 +926,41 @@ int cxl_port_get_possible_dports(struct cxl_port *port) > > return ctx.count; > } > + > +static void cxl_dport_map_bi(struct cxl_dport *dport) > +{ > + struct cxl_register_map *map = &dport->reg_map; > + struct device *dev = dport->dport_dev; > + > + if (!map->component_map.bi_decoder.valid) { > + dev_dbg(dev, "BI Decoder registers not found\n"); > + return; > + } > + > + if (cxl_map_component_regs(map, &dport->regs.component, > + BIT(CXL_CM_CAP_CAP_ID_BI_DECODER))) > + dev_dbg(dev, "Failed to map BI Decoder capability\n"); > +} > + > +/** > + * devm_cxl_dport_bi_setup - Map BI Decoder registers on a CXL dport > + * @dport: the cxl_dport that needs to be initialized > + * > + * Must be called while the dport's devres group is open so iomap > + * allocations are released on dport removal. > + */ > +void devm_cxl_dport_bi_setup(struct cxl_dport *dport) > +{ > + if (!dev_is_pci(dport->dport_dev)) > + return; > + > + switch (pci_pcie_type(to_pci_dev(dport->dport_dev))) { > + case PCI_EXP_TYPE_ROOT_PORT: > + case PCI_EXP_TYPE_DOWNSTREAM: > + dport->reg_map.host = dport_to_host(dport); > + cxl_dport_map_bi(dport); > + break; > + default: > + break; > + } > +} > diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c > index 1215ee4f4035..b2f8fb9547d3 100644 > --- a/drivers/cxl/core/port.c > +++ b/drivers/cxl/core/port.c > @@ -1242,8 +1242,10 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev, > > cxl_debugfs_create_dport_dir(dport); > > - if (!dport->rch) > + if (!dport->rch) { > devm_cxl_dport_ras_setup(dport); > + devm_cxl_dport_bi_setup(dport); > + } > > /* keep the group, and mark the end of devm actions */ > cxl_dport_close_dr_group(dport, no_free_ptr(dport_dr_group)); > diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c > index 93710cf4f0a6..a6caa793e7a4 100644 > --- a/drivers/cxl/core/regs.c > +++ b/drivers/cxl/core/regs.c > @@ -92,6 +92,18 @@ void cxl_probe_component_regs(struct device *dev, void __iomem *base, > length = CXL_RAS_CAPABILITY_LENGTH; > rmap = &map->ras; > break; > + case CXL_CM_CAP_CAP_ID_BI_RT: > + dev_dbg(dev, "found BI RT capability (0x%x)\n", > + offset); > + length = CXL_BI_RT_CAPABILITY_LENGTH; > + rmap = &map->bi_rt; > + break; > + case CXL_CM_CAP_CAP_ID_BI_DECODER: > + dev_dbg(dev, "found BI Decoder capability (0x%x)\n", > + offset); > + length = CXL_BI_DECODER_CAPABILITY_LENGTH; > + rmap = &map->bi_decoder; > + break; > default: > dev_dbg(dev, "Unknown CM cap ID: %d (0x%x)\n", cap_id, > offset); > @@ -211,6 +223,8 @@ int cxl_map_component_regs(const struct cxl_register_map *map, > } mapinfo[] = { > { &map->component_map.hdm_decoder, ®s->hdm_decoder }, > { &map->component_map.ras, ®s->ras }, > + { &map->component_map.bi_rt, ®s->bi_rt }, > + { &map->component_map.bi_decoder, ®s->bi_decoder }, > }; > int i; > > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index c0e5308e4d1b..f9fcb6387fc8 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -39,9 +39,16 @@ extern const struct nvdimm_security_ops *cxl_security_ops; > #define CXL_CM_CAP_HDR_ARRAY_SIZE_MASK GENMASK(31, 24) > #define CXL_CM_CAP_PTR_MASK GENMASK(31, 20) > > +/* CXL 4.0 8.2.4 Table 8-74 */ > #define CXL_CM_CAP_CAP_ID_RAS 0x2 > #define CXL_CM_CAP_CAP_ID_HDM 0x5 > #define CXL_CM_CAP_CAP_HDM_VERSION 1 > +#define CXL_CM_CAP_CAP_ID_BI_RT 0xB > +#define CXL_CM_CAP_CAP_ID_BI_DECODER 0xC > + > +/* CXL 4.0 8.2.4.26 / 8.2.4.27 BI Capability Structures */ > +#define CXL_BI_RT_CAPABILITY_LENGTH 0xC > +#define CXL_BI_DECODER_CAPABILITY_LENGTH 0xC > > /* HDM decoders CXL 2.0 8.2.5.12 CXL HDM Decoder Capability Structure */ > #define CXL_HDM_DECODER_CAP_OFFSET 0x0 > diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c > index 99cf77b6b699..a527dd13fb68 100644 > --- a/drivers/cxl/port.c > +++ b/drivers/cxl/port.c > @@ -58,6 +58,47 @@ static int discover_region(struct device *dev, void *unused) > return 0; > } > > +static void cxl_port_map_bi(struct cxl_port *port) > +{ > + struct cxl_register_map *map = &port->reg_map; > + struct cxl_dport *parent_dport = port->parent_dport; > + struct device *udev; > + int cap_id; > + > + /* no upstream BI registers above host bridges or the cxl_root */ > + if (!parent_dport || is_cxl_root(parent_dport->port)) > + return; > + > + udev = is_cxl_endpoint(port) ? > + port->uport_dev->parent : port->uport_dev; > + if (!dev_is_pci(udev)) > + return; > + > + /* BI requires 256B Flit on the upstream link */ > + if (!cxl_pci_flit_256(to_pci_dev(udev))) > + return; > + > + /* map this port's own BI capability */ > + if (is_cxl_endpoint(port)) { > + if (!map->component_map.bi_decoder.valid) { > + dev_dbg(&port->dev, "BI Decoder registers not found\n"); > + return; > + } > + cap_id = CXL_CM_CAP_CAP_ID_BI_DECODER; > + } else { > + if (!map->component_map.bi_rt.valid) { > + dev_dbg(&port->dev, "BI RT registers not found\n"); > + return; > + } > + cap_id = CXL_CM_CAP_CAP_ID_BI_RT; > + } > + > + map->host = &port->dev; > + if (cxl_map_component_regs(map, &port->regs, BIT(cap_id))) > + dev_dbg(&port->dev, "Failed to map BI capability 0x%x\n", > + cap_id); > +} > + > static int cxl_switch_port_probe(struct cxl_port *port) > { > /* Reset nr_dports for rebind of driver */ > @@ -128,6 +169,8 @@ static int cxl_endpoint_port_probe(struct cxl_port *port) > read_cdat_data(port); > cxl_endpoint_parse_cdat(port); > > + cxl_port_map_bi(port); > + > get_device(&cxlmd->dev); > rc = devm_add_action_or_reset(&port->dev, schedule_detach, cxlmd); > if (rc) > @@ -252,6 +295,8 @@ static struct cxl_dport *cxl_port_add_dport(struct cxl_port *port, > * on failure, or the device does not implement RAS registers. > */ > devm_cxl_port_ras_setup(port); > + > + cxl_port_map_bi(port); How about adding a devm_cxl_port_bi_setup()? like what you have done for cxl_dport_map_bi(). It can align with devm_cxl_port_ras_setup(). > } > > dport = devm_cxl_add_dport_by_dev(port, dport_dev); > diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h > index 016c74fb747c..2816954680b3 100644 > --- a/include/cxl/cxl.h > +++ b/include/cxl/cxl.h > @@ -34,10 +34,14 @@ struct cxl_regs { > * Common set of CXL Component register block base pointers > * @hdm_decoder: CXL 2.0 8.2.5.12 CXL HDM Decoder Capability Structure > * @ras: CXL 2.0 8.2.5.9 CXL RAS Capability Structure > + * @bi_rt: CXL 4.0 8.2.4.26 CXL BI Route Table Capability Structure > + * @bi_decoder: CXL 4.0 8.2.4.27 CXL BI Decoder Capability Structure > */ > struct_group_tagged(cxl_component_regs, component, > void __iomem *hdm_decoder; > void __iomem *ras; > + void __iomem *bi_rt; > + void __iomem *bi_decoder; > ); > /* > * Common set of CXL Device register block base pointers > @@ -80,6 +84,8 @@ struct cxl_reg_map { > struct cxl_component_reg_map { > struct cxl_reg_map hdm_decoder; > struct cxl_reg_map ras; > + struct cxl_reg_map bi_rt; > + struct cxl_reg_map bi_decoder; > }; > > struct cxl_device_reg_map {