Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754127AbaDEBkY (ORCPT ); Fri, 4 Apr 2014 21:40:24 -0400 Received: from va3ehsobe003.messaging.microsoft.com ([216.32.180.13]:57965 "EHLO va3outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753034AbaDEBkU (ORCPT ); Fri, 4 Apr 2014 21:40:20 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -3 X-BigFish: VS-3(z579ehz13e6Kzz1f42h2148h1ee6h1de0h1fdah2073h2146h1202h1e76h2189h1d1ah1d2ah21bch1fc6h208chzz1de098h17326ah8275bh8275dh1de097h186068hz2dh2a8h839h944hd24he5bhf0ah1220h1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh2222h224fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h2218h2216h226dh22d0h24afh2327h2336h2438h2461h2487h24ach24d7h2516h2545h255eh25cch25f6h2605h268bh26d3h1155h) Date: Fri, 4 Apr 2014 20:35:12 -0500 From: Kim Phillips To: Alex Williamson CC: Kim Phillips , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [RFC PATCH] PCI: Introduce new device binding path using pci_dev.driver_override Message-ID: <20140404203512.5b5ac8a134a71065518712c3@freescale.com> In-Reply-To: <1396479728.476.410.camel@ul30vt.home> References: <20140401161851.18815.31108.stgit@bling.home> <20140401185212.7229f2c114c7e95089f00e90@linaro.org> <20140402002324.GA2662@kroah.com> <20140402170638.51745f5c231a7632422e4cc5@linaro.org> <1396479728.476.410.camel@ul30vt.home> Organization: Freescale Semiconductor, Inc. X-Mailer: Sylpheed 3.2.0 (GTK+ 2.24.13; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% X-FOPE-CONNECTOR: Id%0$Dn%FREESCALE.MAIL.ONMICROSOFT.COM$RO%1$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Needed by platform device drivers, such as the vfio-platform driver [1], in order to bypass the existing OF, ACPI, id_table and name string matches, and successfully be able to be bound to any device, like so: echo vfio-platform > /sys/bus/platform/devices/fff51000.ethernet/driver_override echo fff51000.ethernet > /sys/bus/platform/devices/fff51000.ethernet/driver/unbind echo fff51000.ethernet > /sys/bus/platform/drivers_probe This mimics "PCI: Introduce new device binding path using pci_dev.driver_override" [2], which is an interface enhancement for more deterministic PCI device binding, e.g., when in the presence of hotplug. [1] http://lkml.iu.edu/hypermail/linux/kernel/1402.1/00177.html [2] http://thread.gmane.org/gmane.linux.kernel.iommu/4605 Signed-off-by: Kim Phillips --- if this looks ok, should it be included in the next version of the vfio-platform submission series, like last time ([1] above)? Documentation/ABI/testing/sysfs-bus-platform | 17 ++++++++++ drivers/base/platform.c | 46 ++++++++++++++++++++++++++++ include/linux/platform_device.h | 1 + 3 files changed, 64 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-platform diff --git a/Documentation/ABI/testing/sysfs-bus-platform b/Documentation/ABI/testing/sysfs-bus-platform new file mode 100644 index 0000000..6b14a6a --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-platform @@ -0,0 +1,17 @@ +What: /sys/bus/platform/devices/.../driver_override +Date: April 2014 +Contact: Kim Phillips +Description: + This file allows the driver for a device to be specified + which will override standard OF, ACPI, ID table, and name + matching. When specified, only a driver with a name matching + the value written to driver_override will have an opportunity + to bind to the device. The override may be cleared by + writing an empty string (ex. echo > driver_override), returning + the device to standard matching rules binding. Writing to + driver_override does not automatically unbind the device from + its current driver or make any attempt to automatically load + the specified driver name. If no driver with a matching name + is currently loaded in the kernel, no match will be found. + This also allows devices to opt-out of driver binding using + a driver_override name such as "none". diff --git a/drivers/base/platform.c b/drivers/base/platform.c index e714709..ded1db1 100644 --- a/drivers/base/platform.c +++ b/drivers/base/platform.c @@ -22,6 +22,7 @@ #include #include #include +#include #include "base.h" #include "power/power.h" @@ -690,8 +691,49 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a, } static DEVICE_ATTR_RO(modalias); +static ssize_t driver_override_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct platform_device *pdev = to_platform_device(dev); + char *driver_override, *old = pdev->driver_override; + + if (count > PATH_MAX) + return -EINVAL; + + driver_override = kstrndup(buf, count, GFP_KERNEL); + if (!driver_override) + return -ENOMEM; + + while (strlen(driver_override) && + driver_override[strlen(driver_override) - 1] == '\n') + driver_override[strlen(driver_override) - 1] = '\0'; + + if (strlen(driver_override)) { + pdev->driver_override = driver_override; + } else { + kfree(driver_override); + pdev->driver_override = NULL; + } + + kfree(old); + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct platform_device *pdev = to_platform_device(dev); + + return sprintf(buf, "%s\n", pdev->driver_override); +} +static DEVICE_ATTR_RW(driver_override); + + static struct attribute *platform_dev_attrs[] = { &dev_attr_modalias.attr, + &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(platform_dev); @@ -747,6 +789,10 @@ static int platform_match(struct device *dev, struct device_driver *drv) struct platform_device *pdev = to_platform_device(dev); struct platform_driver *pdrv = to_platform_driver(drv); + /* When driver_override is set, only bind to the matching driver */ + if (pdev->driver_override) + return !strcmp(pdev->driver_override, drv->name); + /* Attempt an OF style match first */ if (of_driver_match_device(dev, drv)) return 1; diff --git a/include/linux/platform_device.h b/include/linux/platform_device.h index 16f6654..153d303 100644 --- a/include/linux/platform_device.h +++ b/include/linux/platform_device.h @@ -28,6 +28,7 @@ struct platform_device { struct resource *resource; const struct platform_device_id *id_entry; + char *driver_override; /* Driver name to force a match */ /* MFD cell pointer */ struct mfd_cell *mfd_cell; -- 1.9.1 -- 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/