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wvk86bjorn-helgaas
wvk86
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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: Wong Vee Khee <[email protected]> Signed-off-by: Hui Chun Ong <[email protected]> [bhelgaas: changelog, return errors early to unindent usual case, return errors with same style throughout] Signed-off-by: Bjorn Helgaas <[email protected]>
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2 files changed

+196
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‎drivers/pci/pci-sysfs.c‎

Lines changed: 195 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -154,6 +154,129 @@ static ssize_t resource_show(struct device *dev, struct device_attribute *attr,
154154
}
155155
static DEVICE_ATTR_RO(resource);
156156

157+
static ssize_t max_link_speed_show(struct device *dev,
158+
struct device_attribute *attr, char *buf)
159+
{
160+
struct pci_dev *pci_dev = to_pci_dev(dev);
161+
u32 linkcap;
162+
int err;
163+
const char *speed;
164+
165+
err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);
166+
if (err)
167+
return -EINVAL;
168+
169+
switch (linkcap & PCI_EXP_LNKCAP_SLS) {
170+
case PCI_EXP_LNKCAP_SLS_8_0GB:
171+
speed = "8 GT/s";
172+
break;
173+
case PCI_EXP_LNKCAP_SLS_5_0GB:
174+
speed = "5 GT/s";
175+
break;
176+
case PCI_EXP_LNKCAP_SLS_2_5GB:
177+
speed = "2.5 GT/s";
178+
break;
179+
default:
180+
speed = "Unknown speed";
181+
}
182+
183+
return sprintf(buf, "%s\n", speed);
184+
}
185+
static DEVICE_ATTR_RO(max_link_speed);
186+
187+
static ssize_t max_link_width_show(struct device *dev,
188+
struct device_attribute *attr, char *buf)
189+
{
190+
struct pci_dev *pci_dev = to_pci_dev(dev);
191+
u32 linkcap;
192+
int err;
193+
194+
err = pcie_capability_read_dword(pci_dev, PCI_EXP_LNKCAP, &linkcap);
195+
if (err)
196+
return -EINVAL;
197+
198+
return sprintf(buf, "%u\n", (linkcap & PCI_EXP_LNKCAP_MLW) >> 4);
199+
}
200+
static DEVICE_ATTR_RO(max_link_width);
201+
202+
static ssize_t current_link_speed_show(struct device *dev,
203+
struct device_attribute *attr, char *buf)
204+
{
205+
struct pci_dev *pci_dev = to_pci_dev(dev);
206+
u16 linkstat;
207+
int err;
208+
const char *speed;
209+
210+
err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
211+
if (err)
212+
return -EINVAL;
213+
214+
switch (linkstat & PCI_EXP_LNKSTA_CLS) {
215+
case PCI_EXP_LNKSTA_CLS_8_0GB:
216+
speed = "8 GT/s";
217+
break;
218+
case PCI_EXP_LNKSTA_CLS_5_0GB:
219+
speed = "5 GT/s";
220+
break;
221+
case PCI_EXP_LNKSTA_CLS_2_5GB:
222+
speed = "2.5 GT/s";
223+
break;
224+
default:
225+
speed = "Unknown speed";
226+
}
227+
228+
return sprintf(buf, "%s\n", speed);
229+
}
230+
static DEVICE_ATTR_RO(current_link_speed);
231+
232+
static ssize_t current_link_width_show(struct device *dev,
233+
struct device_attribute *attr, char *buf)
234+
{
235+
struct pci_dev *pci_dev = to_pci_dev(dev);
236+
u16 linkstat;
237+
int err;
238+
239+
err = pcie_capability_read_word(pci_dev, PCI_EXP_LNKSTA, &linkstat);
240+
if (err)
241+
return -EINVAL;
242+
243+
return sprintf(buf, "%u\n",
244+
(linkstat & PCI_EXP_LNKSTA_NLW) >> PCI_EXP_LNKSTA_NLW_SHIFT);
245+
}
246+
static DEVICE_ATTR_RO(current_link_width);
247+
248+
static ssize_t secondary_bus_number_show(struct device *dev,
249+
struct device_attribute *attr,
250+
char *buf)
251+
{
252+
struct pci_dev *pci_dev = to_pci_dev(dev);
253+
u8 sec_bus;
254+
int err;
255+
256+
err = pci_read_config_byte(pci_dev, PCI_SECONDARY_BUS, &sec_bus);
257+
if (err)
258+
return -EINVAL;
259+
260+
return sprintf(buf, "%u\n", sec_bus);
261+
}
262+
static DEVICE_ATTR_RO(secondary_bus_number);
263+
264+
static ssize_t subordinate_bus_number_show(struct device *dev,
265+
struct device_attribute *attr,
266+
char *buf)
267+
{
268+
struct pci_dev *pci_dev = to_pci_dev(dev);
269+
u8 sub_bus;
270+
int err;
271+
272+
err = pci_read_config_byte(pci_dev, PCI_SUBORDINATE_BUS, &sub_bus);
273+
if (err)
274+
return -EINVAL;
275+
276+
return sprintf(buf, "%u\n", sub_bus);
277+
}
278+
static DEVICE_ATTR_RO(subordinate_bus_number);
279+
157280
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
158281
char *buf)
159282
{
@@ -629,12 +752,17 @@ static struct attribute *pci_dev_attrs[] = {
629752
NULL,
630753
};
631754

632-
static const struct attribute_group pci_dev_group = {
633-
.attrs = pci_dev_attrs,
755+
static struct attribute *pci_bridge_attrs[] = {
756+
&dev_attr_subordinate_bus_number.attr,
757+
&dev_attr_secondary_bus_number.attr,
758+
NULL,
634759
};
635760

636-
const struct attribute_group *pci_dev_groups[] = {
637-
&pci_dev_group,
761+
static struct attribute *pcie_dev_attrs[] = {
762+
&dev_attr_current_link_speed.attr,
763+
&dev_attr_current_link_width.attr,
764+
&dev_attr_max_link_width.attr,
765+
&dev_attr_max_link_speed.attr,
638766
NULL,
639767
};
640768

@@ -1557,6 +1685,57 @@ static umode_t pci_dev_hp_attrs_are_visible(struct kobject *kobj,
15571685
return a->mode;
15581686
}
15591687

1688+
static umode_t pci_bridge_attrs_are_visible(struct kobject *kobj,
1689+
struct attribute *a, int n)
1690+
{
1691+
struct device *dev = kobj_to_dev(kobj);
1692+
struct pci_dev *pdev = to_pci_dev(dev);
1693+
1694+
if (pci_is_bridge(pdev))
1695+
return a->mode;
1696+
1697+
return 0;
1698+
}
1699+
1700+
static umode_t pcie_dev_attrs_are_visible(struct kobject *kobj,
1701+
struct attribute *a, int n)
1702+
{
1703+
struct device *dev = kobj_to_dev(kobj);
1704+
struct pci_dev *pdev = to_pci_dev(dev);
1705+
1706+
if (pci_is_pcie(pdev))
1707+
return a->mode;
1708+
1709+
return 0;
1710+
}
1711+
1712+
static const struct attribute_group pci_dev_group = {
1713+
.attrs = pci_dev_attrs,
1714+
};
1715+
1716+
const struct attribute_group *pci_dev_groups[] = {
1717+
&pci_dev_group,
1718+
NULL,
1719+
};
1720+
1721+
static const struct attribute_group pci_bridge_group = {
1722+
.attrs = pci_bridge_attrs,
1723+
};
1724+
1725+
const struct attribute_group *pci_bridge_groups[] = {
1726+
&pci_bridge_group,
1727+
NULL,
1728+
};
1729+
1730+
static const struct attribute_group pcie_dev_group = {
1731+
.attrs = pcie_dev_attrs,
1732+
};
1733+
1734+
const struct attribute_group *pcie_dev_groups[] = {
1735+
&pcie_dev_group,
1736+
NULL,
1737+
};
1738+
15601739
static struct attribute_group pci_dev_hp_attr_group = {
15611740
.attrs = pci_dev_hp_attrs,
15621741
.is_visible = pci_dev_hp_attrs_are_visible,
@@ -1592,12 +1771,24 @@ static struct attribute_group pci_dev_attr_group = {
15921771
.is_visible = pci_dev_attrs_are_visible,
15931772
};
15941773

1774+
static struct attribute_group pci_bridge_attr_group = {
1775+
.attrs = pci_bridge_attrs,
1776+
.is_visible = pci_bridge_attrs_are_visible,
1777+
};
1778+
1779+
static struct attribute_group pcie_dev_attr_group = {
1780+
.attrs = pcie_dev_attrs,
1781+
.is_visible = pcie_dev_attrs_are_visible,
1782+
};
1783+
15951784
static const struct attribute_group *pci_dev_attr_groups[] = {
15961785
&pci_dev_attr_group,
15971786
&pci_dev_hp_attr_group,
15981787
#ifdef CONFIG_PCI_IOV
15991788
&sriov_dev_attr_group,
16001789
#endif
1790+
&pci_bridge_attr_group,
1791+
&pcie_dev_attr_group,
16011792
NULL,
16021793
};
16031794

‎include/uapi/linux/pci_regs.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -517,6 +517,7 @@
517517
#define PCI_EXP_LNKCAP_SLS 0x0000000f /* Supported Link Speeds */
518518
#define PCI_EXP_LNKCAP_SLS_2_5GB 0x00000001 /* LNKCAP2 SLS Vector bit 0 */
519519
#define PCI_EXP_LNKCAP_SLS_5_0GB 0x00000002 /* LNKCAP2 SLS Vector bit 1 */
520+
#define PCI_EXP_LNKCAP_SLS_8_0GB 0x00000003 /* LNKCAP2 SLS Vector bit 2 */
520521
#define PCI_EXP_LNKCAP_MLW 0x000003f0 /* Maximum Link Width */
521522
#define PCI_EXP_LNKCAP_ASPMS 0x00000c00 /* ASPM Support */
522523
#define PCI_EXP_LNKCAP_L0SEL 0x00007000 /* L0s Exit Latency */

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