Commit 56c1af46 authored by Wong Vee Khee's avatar Wong Vee Khee Committed by Bjorn Helgaas
Browse files

PCI: Add sysfs max_link_speed/width, current_link_speed/width, etc 



Expose PCIe bridges attributes such as secondary bus number, subordinate
bus number, max link speed and link width, current link speed and link
width via sysfs in /sys/bus/pci/devices/...

This information is available via lspci, but that requires root privilege.

Signed-off-by: default avatarWong Vee Khee <vee.khee.wong@ni.com>
Signed-off-by: default avatarHui Chun Ong <hui.chun.ong@ni.com>
[bhelgaas: changelog, return errors early to unindent usual case, return
errors with same style throughout]
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 99b3c58f

drivers/pci/pci-sysfs.c

+195 −4
Original line number Diff line number Diff line
@@ -154,6 +154,129 @@ static ssize_t resource_show(struct device *dev, struct device_attribute *attr, 
}

static DEVICE_ATTR_RO(resource);



static ssize_t max_link_speed_show(struct device *dev,

				   struct device_attribute *attr, char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u32 linkcap;

	int err;

	const char *speed;



	err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);

	if (err)

		return -EINVAL;



	switch (linkcap & PCI_EXP_LNKCAP_SLS) {

	case PCI_EXP_LNKCAP_SLS_8_0GB:

		speed = "8 GT/s";

		break;

	case PCI_EXP_LNKCAP_SLS_5_0GB:

		speed = "5 GT/s";

		break;

	case PCI_EXP_LNKCAP_SLS_2_5GB:

		speed = "2.5 GT/s";

		break;

	default:

		speed = "Unknown speed";

	}



	return sprintf(buf, "%s\n", speed);

}

static DEVICE_ATTR_RO(max_link_speed);



static ssize_t max_link_width_show(struct device *dev,

				   struct device_attribute *attr, char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u32 linkcap;

	int err;



	err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);

	if (err)

		return -EINVAL;



	return sprintf(buf, "%u\n", (linkcap & PCI_EXP_LNKCAP_MLW) >> 4);

}

static DEVICE_ATTR_RO(max_link_width);



static ssize_t current_link_speed_show(struct device *dev,

				       struct device_attribute *attr, char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u16 linkstat;

	int err;

	const char *speed;



	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);

	if (err)

		return -EINVAL;



	switch (linkstat & PCI_EXP_LNKSTA_CLS) {

	case PCI_EXP_LNKSTA_CLS_8_0GB:

		speed = "8 GT/s";

		break;

	case PCI_EXP_LNKSTA_CLS_5_0GB:

		speed = "5 GT/s";

		break;

	case PCI_EXP_LNKSTA_CLS_2_5GB:

		speed = "2.5 GT/s";

		break;

	default:

		speed = "Unknown speed";

	}



	return sprintf(buf, "%s\n", speed);

}

static DEVICE_ATTR_RO(current_link_speed);



static ssize_t current_link_width_show(struct device *dev,

				       struct device_attribute *attr, char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u16 linkstat;

	int err;



	err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);

	if (err)

		return -EINVAL;



	return sprintf(buf, "%u\n",

		(linkstat & PCI_EXP_LNKSTA_NLW) >> PCI_EXP_LNKSTA_NLW_SHIFT);

}

static DEVICE_ATTR_RO(current_link_width);



static ssize_t secondary_bus_number_show(struct device *dev,

					 struct device_attribute *attr,

					 char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u8 sec_bus;

	int err;



	err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);

	if (err)

		return -EINVAL;



	return sprintf(buf, "%u\n", sec_bus);

}

static DEVICE_ATTR_RO(secondary_bus_number);



static ssize_t subordinate_bus_number_show(struct device *dev,

					   struct device_attribute *attr,

					   char *buf)

{

	struct pci_dev *pci_dev = to_pci_dev(dev);

	u8 sub_bus;

	int err;



	err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);

	if (err)

		return -EINVAL;



	return sprintf(buf, "%u\n", sub_bus);

}

static DEVICE_ATTR_RO(subordinate_bus_number);



static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,

			     char *buf)

{
@@ -629,12 +752,17 @@ static struct attribute *pci_dev_attrs[] = { 
	NULL,

};



static const struct attribute_group pci_dev_group = {

	.attrs = pci_dev_attrs,

static struct attribute *pci_bridge_attrs[] = {

	&dev_attr_subordinate_bus_number.attr,

	&dev_attr_secondary_bus_number.attr,

	NULL,

};



const struct attribute_group *pci_dev_groups[] = {

	&pci_dev_group,

static struct attribute *pcie_dev_attrs[] = {

	&dev_attr_current_link_speed.attr,

	&dev_attr_current_link_width.attr,

	&dev_attr_max_link_width.attr,

	&dev_attr_max_link_speed.attr,

	NULL,

};
@@ -1557,6 +1685,57 @@ static umode_t pci_dev_hp_attrs_are_visible(struct kobject *kobj, 
	return a->mode;

}



static umode_t pci_bridge_attrs_are_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 (pci_is_bridge(pdev))

		return a->mode;



	return 0;

}



static umode_t pcie_dev_attrs_are_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 (pci_is_pcie(pdev))

		return a->mode;



	return 0;

}



static const struct attribute_group pci_dev_group = {

	.attrs = pci_dev_attrs,

};



const struct attribute_group *pci_dev_groups[] = {

	&pci_dev_group,

	NULL,

};



static const struct attribute_group pci_bridge_group = {

	.attrs = pci_bridge_attrs,

};



const struct attribute_group *pci_bridge_groups[] = {

	&pci_bridge_group,

	NULL,

};



static const struct attribute_group pcie_dev_group = {

	.attrs = pcie_dev_attrs,

};



const struct attribute_group *pcie_dev_groups[] = {

	&pcie_dev_group,

	NULL,

};



static struct attribute_group pci_dev_hp_attr_group = {

	.attrs = pci_dev_hp_attrs,

	.is_visible = pci_dev_hp_attrs_are_visible,
@@ -1592,12 +1771,24 @@ static struct attribute_group pci_dev_attr_group = { 
	.is_visible = pci_dev_attrs_are_visible,

};



static struct attribute_group pci_bridge_attr_group = {

	.attrs = pci_bridge_attrs,

	.is_visible = pci_bridge_attrs_are_visible,

};



static struct attribute_group pcie_dev_attr_group = {

	.attrs = pcie_dev_attrs,

	.is_visible = pcie_dev_attrs_are_visible,

};



static const struct attribute_group *pci_dev_attr_groups[] = {

	&pci_dev_attr_group,

	&pci_dev_hp_attr_group,

#ifdef CONFIG_PCI_IOV

	&sriov_dev_attr_group,

#endif

	&pci_bridge_attr_group,

	&pcie_dev_attr_group,

	NULL,

};

include/uapi/linux/pci_regs.h

+1 −0
Original line number Diff line number Diff line
@@ -517,6 +517,7 @@ 
#define  PCI_EXP_LNKCAP_SLS	0x0000000f /* Supported Link Speeds */

#define  PCI_EXP_LNKCAP_SLS_2_5GB 0x00000001 /* LNKCAP2 SLS Vector bit 0 */

#define  PCI_EXP_LNKCAP_SLS_5_0GB 0x00000002 /* LNKCAP2 SLS Vector bit 1 */

#define  PCI_EXP_LNKCAP_SLS_8_0GB 0x00000003 /* LNKCAP2 SLS Vector bit 2 */

#define  PCI_EXP_LNKCAP_MLW	0x000003f0 /* Maximum Link Width */

#define  PCI_EXP_LNKCAP_ASPMS	0x00000c00 /* ASPM Support */

#define  PCI_EXP_LNKCAP_L0SEL	0x00007000 /* L0s Exit Latency */

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