This proposal aims to add a feature that outputs PCIe device power
consumption information to sysfs.
Add support for PBEC (Power Budgeting Extended Capability) output
to the PCIe driver. PBEC is defined in the
PCIe specification(PCIe r6.0, sec 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.
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..468c929a9347 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 power_budget_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;
+
+ pos = pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_PWR);
+ if (!pos)
+ return -EINVAL;
+
+ 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) {
+ if (len == 0)
+ return -EINVAL;
+ break;
+ }
+ len += sysfs_emit_at(buf, len, "%04x\n", data);
+ }
+
+ return len;
+}
+static DEVICE_ATTR_RO(power_budget);
+
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_power_budget.attr,
NULL,
};
--
2.45.0
