From f2991d30ff590bf932483a6dfc16c7ebe2f83341 Mon Sep 17 00:00:00 2001 From: Laurentiu Tudor Date: Fri, 13 Apr 2018 12:42:40 +0300 Subject: [PATCH] bus: fsl-mc: add device binding path 'driver_override' This patch is required for vfio-fsl-mc meta driver to successfully bind layerscape container devices for device passthrough. This patch adds a mechanism to allow a layerscape device to specify a driver rather than a layerscape driver provide a device match. This patch is based on following proposed patches for PCI and platform devices - https://lkml.org/lkml/2014/4/8/571 :- For Platform devices - http://lists-archives.com/linux-kernel/28030441-pci-introduce-new-device-binding-path-using-pci_dev-driver_override.html :- For PCI devices Example to allow a device (dprc.1) to specifically bind with driver (vfio-fsl-mc):- - echo vfio-fsl-mc > /sys/bus/fsl-mc/devices/dprc.1/driver_override - echo dprc.1 > /sys/bus/fsl-mc/drivers/fsl_mc_dprc/unbind - echo dprc.1 > /sys/bus/fsl-mc/drivers/vfio-fsl-mc/bind Signed-off-by: Bharat Bhushan Signed-off-by: Laurentiu Tudor --- drivers/bus/fsl-mc/fsl-mc-bus.c | 53 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) --- a/drivers/bus/fsl-mc/fsl-mc-bus.c +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c @@ -83,6 +83,12 @@ static int fsl_mc_bus_match(struct devic struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(drv); bool found = false; + /* When driver_override is set, only bind to the matching driver */ + if (mc_dev->driver_override) { + found = !strcmp(mc_dev->driver_override, mc_drv->driver.name); + goto out; + } + if (!mc_drv->match_id_table) goto out; @@ -147,8 +153,52 @@ static ssize_t modalias_show(struct devi } 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 fsl_mc_device *mc_dev = to_fsl_mc_device(dev); + const char *driver_override, *old = mc_dev->driver_override; + char *cp; + + if (WARN_ON(dev->bus != &fsl_mc_bus_type)) + return -EINVAL; + + if (count >= (PAGE_SIZE - 1)) + return -EINVAL; + + driver_override = kstrndup(buf, count, GFP_KERNEL); + if (!driver_override) + return -ENOMEM; + + cp = strchr(driver_override, '\n'); + if (cp) + *cp = '\0'; + + if (strlen(driver_override)) { + mc_dev->driver_override = driver_override; + } else { + kfree(driver_override); + mc_dev->driver_override = NULL; + } + + kfree(old); + + return count; +} + +static ssize_t driver_override_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev); + + return snprintf(buf, PAGE_SIZE, "%s\n", mc_dev->driver_override); +} +static DEVICE_ATTR_RW(driver_override); + static struct attribute *fsl_mc_dev_attrs[] = { &dev_attr_modalias.attr, + &dev_attr_driver_override.attr, NULL, }; @@ -749,6 +799,9 @@ EXPORT_SYMBOL_GPL(fsl_mc_device_add); */ void fsl_mc_device_remove(struct fsl_mc_device *mc_dev) { + kfree(mc_dev->driver_override); + mc_dev->driver_override = NULL; + /* * The device-specific remove callback will get invoked by device_del() */