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(unknown [10.118.236.45]) by m3003.s.css.fujitsu.com (Postfix) with ESMTP id 7DE81200536D; Thu, 15 Aug 2024 09:53:35 +0900 (JST) From: "Kobayashi,Daisuke" To: linux-cxl@vger.kernel.org, dan.j.williams@intel.com Cc: y-goto@fujitsu.com, mj@ucw.cz, "Kobayashi,Daisuke" , Jonathan Cameron Subject: [PATCH v16 2/2] cxl/pci: Add sysfs attribute for CXL 1.1 device link status Date: Thu, 15 Aug 2024 09:55:11 +0900 Message-ID: <20240815005510.220835-4-kobayashi.da-06@fujitsu.com> X-Mailer: git-send-email 2.45.0 In-Reply-To: <20240815005510.220835-1-kobayashi.da-06@fujitsu.com> References: <20240815005510.220835-1-kobayashi.da-06@fujitsu.com> Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 Add sysfs attribute for CXL 1.1 device link status to the cxl pci device. In CXL1.1, the link status of the device is included in the RCRB mapped to the memory mapped register area. Critically, that arrangement makes the link status and control registers invisible to existing PCI user tooling. Export those registers via sysfs with the expectation that PCI user tooling will alternatively look for these sysfs files when attempting to access to these CXL 1.1 endpoints registers. Reviewed-by: Jonathan Cameron Signed-off-by: "Kobayashi,Daisuke" --- drivers/cxl/pci.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index 4eaf64d92541..4e51b6a0a97b 100644 --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -792,6 +792,83 @@ static int cxl_event_config(struct pci_host_bridge *host_bridge, return 0; } +static ssize_t rcd_pcie_cap_emit(struct device *dev, u16 offset, char *buf, size_t width) +{ + struct cxl_dev_state *cxlds = dev_get_drvdata(dev); + struct cxl_memdev *cxlmd = cxlds->cxlmd; + struct device *root_dev; + struct cxl_dport *dport; + struct cxl_port *root __free(put_cxl_root) = + cxl_mem_find_port(cxlmd, &dport); + + if (!root) + return -ENXIO; + + root_dev = root->uport_dev; + if (!root_dev) + return -ENXIO; + + guard(device)(root_dev); + if (!root_dev->driver) + return -ENXIO; + + switch (width) { + case 2: + return sysfs_emit(buf, "%#x\n", + readw(dport->regs.rcd_pcie_cap + offset)); + case 4: + return sysfs_emit(buf, "%#x\n", + readl(dport->regs.rcd_pcie_cap + offset)); + default: + return -EINVAL; + } +} + +static ssize_t rcd_link_cap_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return rcd_pcie_cap_emit(dev, PCI_EXP_LNKCAP, buf, sizeof(u32)); +} +static DEVICE_ATTR_RO(rcd_link_cap); + +static ssize_t rcd_link_ctrl_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return rcd_pcie_cap_emit(dev, PCI_EXP_LNKCTL, buf, sizeof(u16)); +} +static DEVICE_ATTR_RO(rcd_link_ctrl); + +static ssize_t rcd_link_status_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return rcd_pcie_cap_emit(dev, PCI_EXP_LNKSTA, buf, sizeof(u16)); +} +static DEVICE_ATTR_RO(rcd_link_status); + +static struct attribute *cxl_rcd_attrs[] = { + &dev_attr_rcd_link_cap.attr, + &dev_attr_rcd_link_ctrl.attr, + &dev_attr_rcd_link_status.attr, + NULL +}; + +static umode_t cxl_rcd_visible(struct kobject *kobj, struct attribute *a, int n) +{ + struct device *dev = kobj_to_dev(kobj); + struct pci_dev *pdev = to_pci_dev(dev); + + if (is_cxl_restricted(pdev)) + return a->mode; + + return 0; +} + +static struct attribute_group cxl_rcd_group = { + .attrs = cxl_rcd_attrs, + .is_visible = cxl_rcd_visible, +}; +__ATTRIBUTE_GROUPS(cxl_rcd); + static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) { struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus); @@ -975,6 +1052,7 @@ static struct pci_driver cxl_pci_driver = { .id_table = cxl_mem_pci_tbl, .probe = cxl_pci_probe, .err_handler = &cxl_error_handlers, + .dev_groups = cxl_rcd_groups, .driver = { .probe_type = PROBE_PREFER_ASYNCHRONOUS, },