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author | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-05-23 00:03:29 +0200 |
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committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2009-06-01 12:48:49 +0200 |
commit | 0210b66dd88a2a1e451901b00378a2068b6ccb35 (patch) | |
tree | e1a308f0800a2a0950f1af4e259008af1a62babf /drivers/firewire/fw-device.c | |
parent | e5333db9285e088a98f4bad5147bfb0b4665fafb (diff) | |
download | kernel_samsung_smdk4412-0210b66dd88a2a1e451901b00378a2068b6ccb35.zip kernel_samsung_smdk4412-0210b66dd88a2a1e451901b00378a2068b6ccb35.tar.gz kernel_samsung_smdk4412-0210b66dd88a2a1e451901b00378a2068b6ccb35.tar.bz2 |
firewire: core: add sysfs attribute for easier udev rules
This adds the attribute /sys/bus/firewire/devices/fw[0-9]+/units. It
can be used in udev rules like the following ones:
# IIDC devices: industrial cameras and some webcams
SUBSYSTEM=="firewire", ATTR{units}=="*0x00a02d:0x00010?*", GROUP="video"
# AV/C devices: camcorders, set-top boxes, TV sets, audio devices, ...
SUBSYSTEM=="firewire", ATTR{units}=="*0x00a02d:0x010001*", GROUP="video"
Background:
firewire-core manages two device types:
- fw_device is a FireWire node. A character device file is associated
with it.
- fw_unit is a unit directory on a node. Each fw_device may have 0..n
children of type fw_unit. The units tell us what kinds of protocols
a node implements.
We want to set ownership or ACLs or permissions of the character device
file of an fw_device, or/and create symlinks to it, based on available
protocols. Until now udev rules had to look at the fw_unit devices and
then modify their parent's character device file accordingly. This is
problematic for two reasons: 1) It happens sometime after the creation
of the fw_device, 2) an access policy may require that information from
all children is evaluated before a decision about the parent is made.
Problem 1) can ultimately not be avoided since this is the nature of
FireWire nodes: They may add or remove unit directories at any point in
time.
However, we can still help userland a lot by providing the protocol type
information of all units in a summary sysfs attribute directly at the
fw_device. This way,
- the information is immediately available at the affected device
when userspace goes about to handle an ADD or CHANGE event of the
fw_device,
- with most policies, it won't be necessary anymore to dig through
child attributes.
The new attribute is called "units". It contains space-separated tuples
of specifier_id and version of each present unit. The delimiter within
tuples is a colon. Specifier_id and version are printed as 0x%06x.
Here is an example of a node which implements an IPv4 unit and an IPv6
unit: $ cat /sys/bus/firewire/devices/fw2/units
0x00005e:0x000001 0x00005e:0x000002
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire/fw-device.c')
-rw-r--r-- | drivers/firewire/fw-device.c | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c index 98ce084..5515883 100644 --- a/drivers/firewire/fw-device.c +++ b/drivers/firewire/fw-device.c @@ -355,9 +355,56 @@ static ssize_t guid_show(struct device *dev, return ret; } +static int units_sprintf(char *buf, u32 *directory) +{ + struct fw_csr_iterator ci; + int key, value; + int specifier_id = 0; + int version = 0; + + fw_csr_iterator_init(&ci, directory); + while (fw_csr_iterator_next(&ci, &key, &value)) { + switch (key) { + case CSR_SPECIFIER_ID: + specifier_id = value; + break; + case CSR_VERSION: + version = value; + break; + } + } + + return sprintf(buf, "0x%06x:0x%06x ", specifier_id, version); +} + +static ssize_t units_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct fw_device *device = fw_device(dev); + struct fw_csr_iterator ci; + int key, value, i = 0; + + down_read(&fw_device_rwsem); + fw_csr_iterator_init(&ci, &device->config_rom[5]); + while (fw_csr_iterator_next(&ci, &key, &value)) { + if (key != (CSR_UNIT | CSR_DIRECTORY)) + continue; + i += units_sprintf(&buf[i], ci.p + value - 1); + if (i >= PAGE_SIZE - (8 + 1 + 8 + 1)) + break; + } + up_read(&fw_device_rwsem); + + if (i) + buf[i - 1] = '\n'; + + return i; +} + static struct device_attribute fw_device_attributes[] = { __ATTR_RO(config_rom), __ATTR_RO(guid), + __ATTR_RO(units), __ATTR_NULL, }; @@ -1000,6 +1047,9 @@ static void fw_device_refresh(struct work_struct *work) create_units(device); + /* Userspace may want to re-read attributes. */ + kobject_uevent(&device->device.kobj, KOBJ_CHANGE); + if (atomic_cmpxchg(&device->state, FW_DEVICE_INITIALIZING, FW_DEVICE_RUNNING) == FW_DEVICE_GONE) |