By using the static enumeration kcmdline, a user can override secondary
and subordinate bus numbers assigned to child bridges. This includes
adding padding to subordinate bus numbers, to accommodate dynamic PCI
device discovery.
Signed-off-by: Jason Tang <jason.tang2@xxxxxxx>
---
Documentation/kernel-parameters.txt | 9 ++
drivers/pci/pci.h | 4 +
drivers/pci/pci_static_enum.c | 173 +++++++++++++++++++++++++++++++++++
drivers/pci/probe.c | 8 +-
4 files changed, 193 insertions(+), 1 deletion(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4d68ec8..af2ce92 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2765,6 +2765,15 @@ 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:
+ <device>@<option>[<option2>...]
+ Where <device> is <domain>:<bus>:<slot>.<func>
+ and <option> is any combination of:
+ B<secondary>-<subordinate> -
+ force secondary and subordinate bus numbers
+ All values are in hexadecimal.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 3282b51..7a051f5 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -323,6 +323,8 @@ static inline int pci_dev_specific_reset(struct pci_dev *dev, int probe)
#ifdef CONFIG_PCI_STATIC_ENUMERATION
void pci_static_enum_set_opt(const char *str);
+int pci_static_enum_exists(void);
+void pci_static_enum_bus_nums(struct pci_bus *bus);
/**
* pci_bus_subordinate() - return the subordinate bus number assigned
* to @dev by the static enumeration profile, or 0 if not set
@@ -333,6 +335,8 @@ static inline unsigned char pci_bus_subordinate(struct pci_bus *bus)
}
#else
static inline void pci_static_enum_set_opt(const char *str) { return; }
+static inline int pci_static_enum_exists(void) { return 0; }
+static inline void pci_static_enum_bus_nums(struct pci_bus *bus) { return; }
static inline unsigned char pci_bus_subordinate(struct pci_bus *bus)
{
return 0;
diff --git a/drivers/pci/pci_static_enum.c b/drivers/pci/pci_static_enum.c
index a28bd33..dda9055 100644
--- a/drivers/pci/pci_static_enum.c
+++ b/drivers/pci/pci_static_enum.c
@@ -11,6 +11,7 @@
#include <linux/init.h>
#include <linux/list.h>
+#include <linux/pci.h>
#include <linux/spinlock.h>
#include <linux/string.h>
@@ -20,6 +21,18 @@
static DEFINE_SPINLOCK(static_enum_lock);
+struct pci_static_enum_setting {
+ struct list_head list;
+ int seg;
+ int bus;
+ int devfn;
+ unsigned char secondary_bus;
+ unsigned char subordinate_bus;
+};
+
+LIST_HEAD(settings_list);
+static int options_parsed;
+
#define PCI_STATIC_ENUM_PARAM_SIZE COMMAND_LINE_SIZE
static char pci_static_enum_param[PCI_STATIC_ENUM_PARAM_SIZE] = { 0 };
@@ -52,3 +65,163 @@ void __init pci_static_enum_set_opt(const char *str)
strncat(pci_static_enum_param + cur, str, len);
spin_unlock(&static_enum_lock);
}
+
+/**
+ * pci_static_enum_parse_options() - parse the static enumeration
+ * options string, creating the linked list of settings
+ * Return: 0 on success, negative on error or if static enumeration is
+ * disabled.
+ */
+static int pci_static_enum_parse_options(void)
+{
+ const char *p = pci_static_enum_param;
+
+ pr_debug(PREFIX "Set options are: %s\n", pci_static_enum_param);
+ options_parsed = 1;
+ while (*p) {
+ struct pci_static_enum_setting *setting, *tmp;
+ int seg, bus, slot, func;
+ unsigned int secondary_bus, subordinate_bus;
+ int count = 0, entry_found = 0;
+
+ if (strncmp(p, "off", 3) == 0) {
+ /* delete existing profile, if any */
+ list_for_each_entry_safe(setting, tmp, &settings_list,
+ list) {
+ kfree(setting);
+ }
+ INIT_LIST_HEAD(&settings_list);
+ return -1;
+ }
+
+ 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 parameter: `%s'\n", p);
+ return -1;
+ }
+ p += count;
+
+ /* check if an entry already created; if not, make one
+ and add it to the list */
+ list_for_each_entry(setting, &settings_list, list) {
+ if (setting->seg == seg && setting->bus == bus
+ && setting->devfn == PCI_DEVFN(slot, func)) {
+ entry_found = 1;
+ break;
+ }
+ }
+
+ if (!entry_found) {
+ setting = kzalloc(sizeof(*setting), GFP_KERNEL);
+ if (!setting) {
+ pr_err(PREFIX "Out of memory\n");
+ return -1;
+ }
+ setting->seg = seg;
+ setting->bus = bus;
+ setting->devfn = PCI_DEVFN(slot, func);
+ list_add(&setting->list, &settings_list);
+ }
+
+ while (*p && *p != ';') {
+ count = 0;
+ if (sscanf
+ (p, "B%x-%x%n", &secondary_bus, &subordinate_bus,
+ &count) == 2 && count > 0) {
+ p += count;
+ setting->secondary_bus = secondary_bus;
+ setting->subordinate_bus = subordinate_bus;
+ } else {
+ pr_err(PREFIX "Invalid enum option: `%s'\n", p);
+ return -1;
+ }
+ }
+
+ /* increment to next field, if any */
+ if (*p == ';')
+ p++;
+ }
+
+ return 0;
+}
+
+/**
+ * pci_static_enum_find_setting() - look for the requested PCI
+ * device's setting within the static enumeration settings
+ * @domain: target domain to find
+ * @bus: target bus to find
+ * @devfn: target device and function to find
+ * Return: pointer to found static enumeration settings, or NULL if
+ * not found or on error
+ */
+static struct pci_static_enum_setting *pci_static_enum_find_setting(int domain, unsigned
+ char
+ bus,
+ unsigned int
+ devfn)
+{
+ struct pci_static_enum_setting *setting = NULL;
+
+ spin_lock(&static_enum_lock);
+ if (!options_parsed && pci_static_enum_parse_options() < 0)
+ goto out;
+
+ list_for_each_entry(setting, &settings_list, list) {
+ if (setting->seg == domain && setting->bus == bus
+ && setting->devfn == devfn)
+ goto out;
+ }
+
+ /* no static enumeration profile for the requested device */
+ setting = NULL;
+out:
+ spin_unlock(&static_enum_lock);
+ return setting;
+}
+
+/**
+ * pci_static_enum_exists() - returns non-zero if a static enumeration
+ * mapping exists, 0 otherwise
+ */
+int pci_static_enum_exists(void)
+{
+ int retval;
+
+ spin_lock(&static_enum_lock);
+ retval = pci_static_enum_param[0];
+ spin_unlock(&static_enum_lock);
+ return retval;
+}
+
+/**
+ * pci_static_enum_bus_nums() - statically enumerate the secondary and
+ * subordinate bus numbers for the given bus, according to its static
+ * enumeration profile
+ * @bus: bus to reenumerate
+ */
+void pci_static_enum_bus_nums(struct pci_bus *bus)
+{
+ struct pci_static_enum_setting *setting;
+
+ if (pci_is_root_bus(bus)) {
+ /* cannot reenumerate the root complex */
+ return;
+ }
+ setting =
+ pci_static_enum_find_setting(pci_domain_nr(bus),
+ bus->parent->number, bus->self->devfn);
+ if (!setting)
+ return;
+ if (setting->secondary_bus == 0) {
+ /* no bus settings specified for this device */
+ return;
+ }
+ pr_info(PREFIX "Overriding %x:%x:%x.%x to bus numbers %x-%x\n",
+ pci_domain_nr(bus), bus->parent->number,
+ PCI_SLOT(bus->self->devfn), PCI_FUNC(bus->self->devfn),
+ setting->secondary_bus, setting->subordinate_bus);
+ bus->number = bus->busn_res.start = setting->secondary_bus;
+ bus->subordinate = setting->subordinate_bus;
+}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 9c3a9b2..a7bf7c5 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -704,6 +704,10 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
child->bridge = get_device(&bridge->dev);
child->dev.parent = child->bridge;
+ /* if the child bus has a static enumeration profile, override
+ its bus numbers here */
+ pci_static_enum_bus_nums(child);
+
dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child),
child->number);
@@ -805,6 +809,7 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
pci_enable_crs(dev);
if ((secondary || subordinate) && !pcibios_assign_all_busses() &&
+ !pci_static_enum_exists() &&
!is_cardbus && !broken) {
unsigned int cmax;
/*
@@ -843,7 +848,8 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)
* do in the second pass.
*/
if (!pass) {
- if (pcibios_assign_all_busses() || broken || is_cardbus)
+ if (pcibios_assign_all_busses() || broken ||
+ is_cardbus || pci_static_enum_exists())
/* Temporarily disable forwarding of the
configuration cycles on all bridges in
this bus segment to avoid possible
--
1.7.9.5
--
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