Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753303AbaJTOFk (ORCPT ); Mon, 20 Oct 2014 10:05:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60819 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753217AbaJTOFh (ORCPT ); Mon, 20 Oct 2014 10:05:37 -0400 From: Marcel Apfelbaum To: linux-pci@vger.kernel.org, bhelgaas@google.com Cc: linux-kernel@vger.kernel.org, marcel@redhat.com, mst@redhat.com, alex.williamson@redhat.com Subject: [PATCH v4] PCI: add kernel parameter to override devid<->driver mapping. Date: Mon, 20 Oct 2014 17:04:42 +0300 Message-Id: <1413813882-27047-1-git-send-email-marcel.a@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 slots to specific drivers use: pci=driver[xxxx:xx:xx.x]=foo,driver[xxxx:xx:xx.x]=bar,... Signed-off-by: Marcel Apfelbaum --- v3 -> v4: - Addressed Alex Williamson's comments: - Modified the type of driver_override_entry's fields - Used PCI_DEVFN when appropriated - Removed redundant checks - Replaced BUG_ON with pr_err messages - Simpler command line parsing - Addressed Michael S. Tsirkin comments - removed DRIVER_OVERRIDE_NAME_LENGTH limitation v2 -> v3: - Corrected subject line v1 -> v2: - Addressed Michael S. Tsirkin comments - Removed 32 slots limitation - Better handling of memory allocation failures (preferred BUG_ON over error messages) - Addressed Alex Williamson's comments: - Modified commit message to show parameter usage more clear. - I preferred to re-use parse_args instead of manually using strstr in order to better comply with command line parsing rules. - I didn't use any locking when parsing the command line args (see parse_done usage) assuming that first call will be early in system boot and no race can occur. Please correct me if I am wrong. Notes: - 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 | 111 ++++++++++++++++++++++++++++++++++++ drivers/pci/pci.c | 2 + 3 files changed, 117 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..b49f5cc 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -15,6 +15,8 @@ #include #include +#include + #include "pci.h" void pci_add_resource_offset(struct list_head *resources, struct resource *res, @@ -230,6 +232,114 @@ EXPORT_SYMBOL(pci_bus_alloc_resource); void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { } +struct driver_override_entry { + u16 domain; + u8 bus; + u8 devfn; + char *driver_name; + struct list_head list; +}; + +static LIST_HEAD(driver_override_entries); + +static int pci_device_parse_driver_override(char *param, char *val, + const char *unused) +{ + unsigned int domain, bus, dev, fn; + char *buf; + struct driver_override_entry *entry; + int ret; + + buf = kmalloc(COMMAND_LINE_SIZE, GFP_KERNEL); + if (!buf) + goto err_buf; + + while (val) { + char *k = strchr(val, ','); + + if (k) + *k++ = 0; + + if (strncmp(val, "driver", 6)) { + val = k; + continue; + } + + memset(buf, 0, COMMAND_LINE_SIZE); + ret = sscanf(val + 6, "[%4x:%2x:%2x.%2x]=%s", + &domain, &bus, &dev, &fn, buf); + if (ret != 5) { + pr_warn("PCI: Invalid command line: %s\n", val); + val = k; + continue; + } + + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + goto err_entry; + + INIT_LIST_HEAD(&entry->list); + entry->domain = domain; + entry->bus = bus; + entry->devfn = PCI_DEVFN(dev, fn); + entry->driver_name = kstrdup(buf, GFP_KERNEL); + if (!entry->driver_name) + goto err_driver_name; + + list_add_tail(&entry->list, &driver_override_entries); + val = k; + } + + kfree(buf); + return 0; + +err_driver_name: + kfree(entry); + +err_entry: + kfree(buf); + +err_buf: + pr_err("PCI: Out of memory while parsing command line: %s\n", val); + return -ENOMEM; +} + +static void pci_device_setup_driver_override(struct pci_dev *dev) +{ + static int parse_done; + struct driver_override_entry *entry; + + if (!parse_done) { + char *cmdline = kstrdup(saved_command_line, GFP_KERNEL); + + if (!cmdline) + goto err_out_of_mem; + + parse_args("pci", cmdline, NULL, + 0, 0, 0, &pci_device_parse_driver_override); + kfree(cmdline); + parse_done = 1; + } + + list_for_each_entry(entry, &driver_override_entries, list) { + if (pci_domain_nr(dev->bus) != entry->domain || + dev->bus->number != entry->bus || + dev->devfn != entry->devfn) + continue; + + dev->driver_override = kstrdup(entry->driver_name, GFP_KERNEL); + if (!dev->driver_override) + goto err_out_of_mem; + + break; + } + + return; + +err_out_of_mem: + pr_err("PCI: Out of memory while setting up driver override\n"); +} + /** * pci_bus_add_device - start driver for a single device * @dev: device to add @@ -245,6 +355,7 @@ 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 625a4ac..37809d4 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4508,6 +4508,8 @@ 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)) { + /* lazy evaluation by the pci subsystem */ } else { printk(KERN_ERR "PCI: Unknown option `%s'\n", str); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/