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bus/fsl-mc: add support for 'driver_override' in the mc-bus 

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.

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

Reviewed-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Acked-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
Link: https://lore.kernel.org/r/20200929085441.17448-4-diana.craciun@oss.nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bharat Bhushan 2020-09-29 11:54:31 +03:00 committed by Greg Kroah-Hartman
parent 35df88208c
commit 1f86a00c11
2 changed files with 56 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

54
drivers/bus/fsl-mc/fsl-mc-bus.c
View File

@ -3,6 +3,7 @@
* Freescale Management Complex (MC) bus driver
*
* Copyright (C) 2014-2016 Freescale Semiconductor, Inc.
* Copyright 2019-2020 NXP
* Author: German Rivera <German.Rivera@freescale.com>
*
*/
@ -78,6 +79,12 @@ static int fsl_mc_bus_match(struct device *dev, struct device_driver *drv)
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 +154,52 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
}
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);
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,
};
@ -748,6 +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()
*/

2
include/linux/fsl/mc.h
View File

@ -161,6 +161,7 @@ struct fsl_mc_obj_desc {
* @regions: pointer to array of MMIO region entries
* @irqs: pointer to array of pointers to interrupts allocated to this device
* @resource: generic resource associated with this MC object device, if any.
* @driver_override: driver name to force a match
*
* Generic device object for MC object devices that are "attached" to a
* MC bus.
@ -194,6 +195,7 @@ struct fsl_mc_device {
struct fsl_mc_device_irq **irqs;
struct fsl_mc_resource *resource;
struct device_link *consumer_link;
char *driver_override;
};
#define to_fsl_mc_device(_dev) \