From cf0681ca4cc5c9faa85a2df4c063b926fc09c977 Mon Sep 17 00:00:00 2001 From: Tomasz Figa Date: Thu, 8 Jan 2015 07:52:38 +0100 Subject: ARM: 8262/1: l2c: Add support for overriding prefetch settings Firmware on certain boards (e.g. ODROID-U3) can leave incorrect L2C prefetch settings configured in registers leading to crashes if L2C is enabled without overriding them. This patch introduces bindings to enable prefetch settings to be specified from DT and necessary support in the driver. [mszyprow: rebased onto v3.18-rc1, added error message when prefetch related dt property has been provided without any value] Signed-off-by: Tomasz Figa Signed-off-by: Marek Szyprowski Tested-by: Nishanth Menon Acked-by: Nishanth Menon Acked-by: Tony Lindgren Signed-off-by: Russell King --- Documentation/devicetree/bindings/arm/l2cc.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'Documentation') diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt index 292ef7ca3058..0dbabe9a6b0a 100644 --- a/Documentation/devicetree/bindings/arm/l2cc.txt +++ b/Documentation/devicetree/bindings/arm/l2cc.txt @@ -57,6 +57,16 @@ Optional properties: - cache-id-part: cache id part number to be used if it is not present on hardware - wt-override: If present then L2 is forced to Write through mode +- arm,double-linefill : Override double linefill enable setting. Enable if + non-zero, disable if zero. +- arm,double-linefill-incr : Override double linefill on INCR read. Enable + if non-zero, disable if zero. +- arm,double-linefill-wrap : Override double linefill on WRAP read. Enable + if non-zero, disable if zero. +- arm,prefetch-drop : Override prefetch drop enable setting. Enable if non-zero, + disable if zero. +- arm,prefetch-offset : Override prefetch offset value. Valid values are + 0-7, 15, 23, and 31. Example: -- cgit v1.2.3-59-g8ed1b From 3cf385713460eb2bb4cb7ceb8ed89833b00b594b Mon Sep 17 00:00:00 2001 From: Antonios Motakis Date: Tue, 6 Jan 2015 11:15:11 +0100 Subject: ARM: 8256/1: driver coamba: add device binding path 'driver_override' As already demonstrated with PCI [1] and the platform bus [2], a driver_override property in sysfs can be used to bypass the id matching of a device to a AMBA driver. This can be used by VFIO to bind to any AMBA device requested by the user. [1] http://lists-archives.com/linux-kernel/28030441-pci-introduce-new-device-binding-path-using-pci_dev-driver_override.html [2] https://www.redhat.com/archives/libvir-list/2014-April/msg00382.html Signed-off-by: Antonios Motakis Reviewed-by: Kim Phillips Signed-off-by: Russell King --- Documentation/ABI/testing/sysfs-bus-amba | 20 ++++++++++++++ drivers/amba/bus.c | 47 ++++++++++++++++++++++++++++++++ include/linux/amba/bus.h | 1 + 3 files changed, 68 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-amba (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-bus-amba b/Documentation/ABI/testing/sysfs-bus-amba new file mode 100644 index 000000000000..e7b54677cfbe --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-amba @@ -0,0 +1,20 @@ +What: /sys/bus/amba/devices/.../driver_override +Date: September 2014 +Contact: Antonios Motakis +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 is specified by writing a string to the + driver_override file (echo vfio-amba > driver_override) and may + be cleared with an empty string (echo > driver_override). + This returns 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. If no driver with a + matching name is currently loaded in the kernel, the device will + not bind to any driver. This also allows devices to opt-out of + driver binding using a driver_override name such as "none". + Only a single driver may be specified in the override, there is + no support for parsing delimiters. diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 52ddd9fbb55e..f0099360039e 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -18,6 +18,7 @@ #include #include #include +#include #include @@ -43,6 +44,10 @@ static int amba_match(struct device *dev, struct device_driver *drv) struct amba_device *pcdev = to_amba_device(dev); struct amba_driver *pcdrv = to_amba_driver(drv); + /* When driver_override is set, only bind to the matching driver */ + if (pcdev->driver_override) + return !strcmp(pcdev->driver_override, drv->name); + return amba_lookup(pcdrv->id_table, pcdev) != NULL; } @@ -59,6 +64,47 @@ static int amba_uevent(struct device *dev, struct kobj_uevent_env *env) return retval; } +static ssize_t driver_override_show(struct device *_dev, + struct device_attribute *attr, char *buf) +{ + struct amba_device *dev = to_amba_device(_dev); + + if (!dev->driver_override) + return 0; + + return sprintf(buf, "%s\n", dev->driver_override); +} + +static ssize_t driver_override_store(struct device *_dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct amba_device *dev = to_amba_device(_dev); + char *driver_override, *old = dev->driver_override, *cp; + + if (count > PATH_MAX) + 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)) { + dev->driver_override = driver_override; + } else { + kfree(driver_override); + dev->driver_override = NULL; + } + + kfree(old); + + return count; +} + #define amba_attr_func(name,fmt,arg...) \ static ssize_t name##_show(struct device *_dev, \ struct device_attribute *attr, char *buf) \ @@ -81,6 +127,7 @@ amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n", static struct device_attribute amba_dev_attrs[] = { __ATTR_RO(id), __ATTR_RO(resource), + __ATTR_RW(driver_override), __ATTR_NULL, }; diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h index 0ab5f8e0dea2..50fc66868402 100644 --- a/include/linux/amba/bus.h +++ b/include/linux/amba/bus.h @@ -33,6 +33,7 @@ struct amba_device { struct clk *pclk; unsigned int periphid; unsigned int irq[AMBA_NR_IRQS]; + char *driver_override; }; struct amba_driver { -- cgit v1.2.3-59-g8ed1b