Scanning a lot of devices during boot requires a lot of time.
On other scenarios there is a need to bind a driver to a specific slot.
Binding devices to pci-stub driver does not work,
as it will not differentiate between devices of the
same type. Using some start scripts is error prone.
The solution leverages driver_override functionality introduced by
commit: 782a985d7af26db39e86070d28f987cad21313c0
Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
Date: Tue May 20 08:53:21 2014 -0600
PCI: Introduce new device binding path using pci_dev.driver_override
In order to bind PCI slot 0001:02:03.4 to pci-stub use:
driver[0001:02:03.4]=pci-stub
Signed-off-by: Marcel Apfelbaum <marcel.a@xxxxxxxxxx>
---
Notes:
- For the moment only 32 slots can be assigned specific driver.
- I have further ideas on top of this patch based on your reviews.
I thought of:
- Use wildcards to specify entire buses/devices, something like:
driver[0001:02:*.*]=pci-stub
- Use comma to separate several devices:
driver[0001:02:03.4,0001:02:04.0,...]=pci-stub
- Make domain optional:
driver[00:03.0]=pci-stub
Comments will be appreciated,
Thanks,
Marcel
Documentation/kernel-parameters.txt | 4 +++
drivers/pci/bus.c | 1 +
drivers/pci/pci.c | 61 +++++++++++++++++++++++++++++++++++++
drivers/pci/pci.h | 1 +
4 files changed, 67 insertions(+)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5ae8608..c1cbb4c 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2631,6 +2631,10 @@ 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.
+ driver Provide an override to the devid<->driver mapping
+ for a specific slot.
+ Bind PCI slot 0001:02:03.4 to pci-stub by:
+ driver[0001:02:03.4]=pci-stub
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 73aef51..7a7ed85 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -245,6 +245,7 @@ void pci_bus_add_device(struct pci_dev *dev)
* are not assigned yet for some devices.
*/
pci_fixup_device(pci_fixup_final, dev);
+ pci_device_setup_driver_override(dev);
pci_create_sysfs_dev_files(dev);
pci_proc_attach_device(dev);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index b7678be..0a3e07c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4426,6 +4426,65 @@ void __weak pci_fixup_cardbus(struct pci_bus *bus)
}
EXPORT_SYMBOL(pci_fixup_cardbus);
+#define DRIVER_OVERRIDE_NAME_LENGTH 64
+#define DRIVER_OVERRIDE_MAP_SIZE 32
+
+struct driver_override_entry {
+ unsigned int domain;
+ unsigned char bus;
+ unsigned int devfn;
+ char driver_name[DRIVER_OVERRIDE_NAME_LENGTH];
+};
+
+static struct driver_override_entry __initdata
+ driver_override_map[DRIVER_OVERRIDE_MAP_SIZE];
+static int driver_override_num_entries __initdata;
+
+void pci_device_setup_driver_override(struct pci_dev *dev)
+{
+ int i;
+
+ for (i = 0; i < driver_override_num_entries; i++) {
+ if (pci_domain_nr(dev->bus) != driver_override_map[i].domain ||
+ dev->bus->number != driver_override_map[i].bus ||
+ dev->devfn != driver_override_map[i].devfn)
+ continue;
+
+ dev->driver_override = kstrndup(driver_override_map[i].driver_name,
+ DRIVER_OVERRIDE_NAME_LENGTH,
+ GFP_KERNEL);
+ break;
+ }
+}
+
+static void __init pci_parse_driver_override(char *str)
+{
+ unsigned int domain, bus, dev, fn;
+ char driver_name[DRIVER_OVERRIDE_NAME_LENGTH];
+ int ret, next_entry;
+ char format[] = "[%4x:%2x:%2x.%2x]=%%%ds";
+
+ sprintf(format + 18, "%%%ds", DRIVER_OVERRIDE_NAME_LENGTH);
+ ret = sscanf(str, format, &domain, &bus, &dev, &fn, driver_name);
+
+ if (ret != 5) {
+ pr_err("PCI: Invalid command line: driver%s\n", str);
+ return;
+ }
+
+ if (driver_override_num_entries == DRIVER_OVERRIDE_MAP_SIZE) {
+ pr_err("PCI: Driver map overflow - ignoring driver%s\n", str);
+ return;
+ }
+
+ next_entry = driver_override_num_entries++;
+ driver_override_map[next_entry].domain = domain;
+ driver_override_map[next_entry].bus = bus && 0xff;
+ driver_override_map[next_entry].devfn = ((dev & 0x1f) << 3) | (fn & 0x7);
+ memcpy(driver_override_map[next_entry].driver_name,
+ driver_name, sizeof(driver_name));
+}
+
static int __init pci_setup(char *str)
{
while (str) {
@@ -4468,6 +4527,8 @@ static int __init pci_setup(char *str)
pcie_bus_config = PCIE_BUS_PEER2PEER;
} else if (!strncmp(str, "pcie_scan_all", 13)) {
pci_add_flags(PCI_SCAN_ALL_PCIE_DEVS);
+ } else if (!strncmp(str, "driver", 6)) {
+ pci_parse_driver_override(str + 6);
} else {
printk(KERN_ERR "PCI: Unknown option `%s'\n",
str);
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 0601890..023d78b 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -197,6 +197,7 @@ enum pci_bar_type {
bool pci_bus_read_dev_vendor_id(struct pci_bus *bus, int devfn, u32 *pl,
int crs_timeout);
int pci_setup_device(struct pci_dev *dev);
+void pci_device_setup_driver_override(struct pci_dev *dev);
int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
struct resource *res, unsigned int reg);
int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type);
--
1.8.3.1
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