This proposal aims to add a feature that outputs PCIe device power
consumption information to sysfs.
This feature can be implemented by adding support for PBEC (Power
Budgeting Extended Capability) output to the PCIe driver. PBEC is
defined in the PCIe specification(7.8.1) and is a standard method for
obtaining device power consumption information.
PCIe devices can significantly impact the overall power consumption of
a system. However, obtaining PCIe device power consumption information
has traditionally been difficult. This is because the 'lspci' command,
which is a standard tool for displaying information about PCI devices,
cannot access PBEC information. `lspci` is a standard tool for displaying
information about PCI devices.
The PBEC Data register changes depending on the value of the PBEC Data
Select register. To obtain all PBEC Data register values defined in the
device, obtain the value of the PBEC Data register while changing the
value of the PBEC Data Select register.
Signed-off-by: "Kobayashi,Daisuke" <kobayashi.da-06@xxxxxxxxxxx>
---
drivers/pci/pci-sysfs.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 2321fdfefd7d..b13d30da38a1 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -182,6 +182,33 @@ static ssize_t resource_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RO(resource);
+static ssize_t pbec_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct pci_dev *pci_dev = to_pci_dev(dev);
+ size_t len = 0;
+ int i, pos;
+ u32 data;
+
+ if (!pci_is_pcie(pci_dev))
+ return 0;
+
+ pos = pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_PWR);
+ if (!pos)
+ return 0;
+
+ for (i = 0; i < 0xff; i++) {
+ pci_write_config_byte(pci_dev, pos + PCI_PWR_DSR, (u8)i);
+ pci_read_config_dword(pci_dev, pos + PCI_PWR_DATA, &data);
+ if (!data)
+ break;
+ len += sysfs_emit_at(buf, len, "%04x\n", data);
+ }
+
+ return len;
+}
+static DEVICE_ATTR_RO(pbec);
+
static ssize_t max_link_speed_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -629,6 +656,7 @@ static struct attribute *pcie_dev_attrs[] = {
&dev_attr_current_link_width.attr,
&dev_attr_max_link_width.attr,
&dev_attr_max_link_speed.attr,
+ &dev_attr_pbec.attr,
NULL,
};
--
2.44.0
