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authorStefan Richter <stefanr@s5r6.in-berlin.de>2009-05-23 00:03:29 +0200
committerStefan Richter <stefanr@s5r6.in-berlin.de>2009-06-01 12:48:49 +0200
commit0210b66dd88a2a1e451901b00378a2068b6ccb35 (patch)
treee1a308f0800a2a0950f1af4e259008af1a62babf
parente5333db9285e088a98f4bad5147bfb0b4665fafb (diff)
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>
-rw-r--r--drivers/firewire/fw-device.c50
-rw-r--r--drivers/firewire/fw-device.h2
2 files changed, 51 insertions, 1 deletions
diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index 98ce0841f4c..55158834289 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)
diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 623cfee289b..892dd591627 100644
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -42,7 +42,7 @@ enum fw_device_state {
struct fw_attribute_group {
struct attribute_group *groups[2];
struct attribute_group group;
- struct attribute *attrs[11];
+ struct attribute *attrs[12];
};
struct fw_node;