@@ -2828,6 +2828,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
pcie_scan_all Scan all possible PCIe devices. Otherwise we
only look for one device below a PCIe downstream
port.
+ enum= Enable static enumeration, overriding any
+ BIOS/firmware settings. If "off" then disable
+ all static enumeration. Otherwise, format is:
+ <bridge>[;<bridge2>...]
+ where <bridge> is <domain>:<bus>:<slot>.<func>.
+ All values are in hexadecimal.
+ Bridges will be marked as hotpluggable, and thus
+ use hpmemsize and hpbuses options to further
+ statically configure them.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
@@ -337,8 +337,10 @@ struct pci_host_bridge *pci_find_host_bridge(struct pci_bus *bus);
#ifdef CONFIG_PCI_STATIC_ENUMERATION
void pci_static_enum_set_opt(const char *str);
+void pci_static_enum_bridge(struct pci_bus *bus);
#else
static inline void pci_static_enum_set_opt(const char *str) { return; }
+static inline void pci_static_enum_bridge(struct pci_bus *bus) { };
#endif
#endif /* DRIVERS_PCI_H */
@@ -10,6 +10,7 @@
*/
#include <linux/init.h>
+#include <linux/pci.h>
#include <linux/string.h>
#include <asm/setup.h>
@@ -19,6 +20,12 @@
#define PCI_STATIC_ENUM_PARAM_SIZE COMMAND_LINE_SIZE
static char pci_static_enum_param[PCI_STATIC_ENUM_PARAM_SIZE] = { 0 };
+struct pci_static_enum_setting {
+ int seg;
+ int bus;
+ int devfn;
+};
+
/**
* pci_static_enum_set_opt() - set PCI static enumeration options as
* given by kernel command line
@@ -29,3 +36,76 @@ void __init pci_static_enum_set_opt(const char *str)
strncpy(pci_static_enum_param, str, sizeof(pci_static_enum_param));
pci_static_enum_param[sizeof(pci_static_enum_param) - 1] = '\0';
}
+
+/**
+ * pci_static_enum_find_setting() - find requested bridge within options
+ * @bus: bridge to find
+ * @setting: found static enumeration settings
+ * Return: %true if @bus has a static enumeration setting, %false otherwise
+ */
+static bool pci_static_enum_find_setting(struct pci_bus *bus, struct pci_static_enum_setting
+ *setting)
+{
+ const char *p = pci_static_enum_param;
+ int target_seg = pci_domain_nr(bus);
+ int target_bus = bus->parent->number;
+ int target_devfn = bus->self->devfn;
+
+ pr_debug(PREFIX "Options are: `%s'\n", p);
+ pr_debug(PREFIX "Looking for seg %x bus %x devfn %x\n", target_seg,
+ target_bus, target_devfn);
+
+ while (*p) {
+ int seg, bus, slot, func;
+ int count = 0;
+
+ if (strncmp(p, "off", 3) == 0)
+ return false;
+
+ if (sscanf(p, "%x:%x:%x.%x%n",
+ &seg, &bus, &slot, &func, &count) != 4
+ || count == 0) {
+ /* invalid format */
+ pr_err(PREFIX "Can't parse enum parameters: `%s'\n", p);
+ return false;
+ }
+ p += count;
+
+ setting->seg = seg;
+ setting->bus = bus;
+ setting->devfn = PCI_DEVFN(slot, func);
+
+ if (target_seg == setting->seg &&
+ target_bus == setting->bus &&
+ target_devfn == setting->devfn)
+ return true;
+
+ /* increment to next field, if any */
+ if (*p == ';')
+ p++;
+ }
+
+ return false;
+}
+
+/**
+ * pci_static_enum_bridge() - mark this bridge as hotpluggable if its
+ * location is specified by kernel command line
+ */
+void pci_static_enum_bridge(struct pci_bus *bus)
+{
+ bool setting_found;
+ struct pci_static_enum_setting setting;
+
+ if (pci_is_root_bus(bus)) {
+ /* cannot reenumerate the root complex */
+ return;
+ }
+ setting_found = pci_static_enum_find_setting(bus, &setting);
+ if (!setting_found)
+ return;
+ pr_info(PREFIX "Overriding %x:%x:%x.%x\n",
+ setting.seg, setting.bus, PCI_SLOT(setting.devfn),
+ PCI_FUNC(setting.devfn));
+ bus->self->is_hotplug_bridge = 1;
+}
@@ -703,6 +703,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
child->self = bridge;
child->bridge = get_device(&bridge->dev);
child->dev.parent = child->bridge;
+ pci_static_enum_bridge(child);
pci_set_bus_of_node(child);
pci_set_bus_speed(child);
With the "enum" kcmdline, the user can mark specific PCI bridges as hotpluggable, even if those devices do not normally have that capability. The user can then use the "hpbuses" kcmdline to reserve bus numbers for those bridges, to accommodate dynamic PCI device discovery, including hot-added bridges. Signed-off-by: Jason Tang <jason.tang2@ngc.com> --- Documentation/kernel-parameters.txt | 9 +++++ drivers/pci/pci.h | 2 + drivers/pci/pci_static_enum.c | 80 +++++++++++++++++++++++++++++++++++++ drivers/pci/probe.c | 1 + 4 files changed, 92 insertions(+)