firewire: cdev: ABI documentation enhancements
Add overview documentation in Documentation/ABI/stable/firewire-cdev.
Improve the inline reference documentation in firewire-cdev.h:
- Add /* available since kernel... */ comments to event numbers
consistent with the comments on ioctl numbers.
- Shorten some documentation on an event and an ioctl that are
less interesting to current programming because there are newer
preferable variants.
- Spell Configuration ROM (name of an IEEE 1212 register) in
upper case.
- Move the dummy FW_CDEV_VERSION out of the reader's field of
vision. We should remove it from the header next year or so.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
diff --git a/include/linux/firewire-cdev.h b/include/linux/firewire-cdev.h
index 55814aa..357dbfc 100644
--- a/include/linux/firewire-cdev.h
+++ b/include/linux/firewire-cdev.h
@@ -30,10 +30,13 @@
#include <linux/types.h>
#include <linux/firewire-constants.h>
+/* available since kernel version 2.6.22 */
#define FW_CDEV_EVENT_BUS_RESET 0x00
#define FW_CDEV_EVENT_RESPONSE 0x01
#define FW_CDEV_EVENT_REQUEST 0x02
#define FW_CDEV_EVENT_ISO_INTERRUPT 0x03
+
+/* available since kernel version 2.6.30 */
#define FW_CDEV_EVENT_ISO_RESOURCE_ALLOCATED 0x04
#define FW_CDEV_EVENT_ISO_RESOURCE_DEALLOCATED 0x05
@@ -120,24 +123,11 @@
/**
* struct fw_cdev_event_request - Old version of &fw_cdev_event_request2
- * @closure: See &fw_cdev_event_common; set by %FW_CDEV_IOC_ALLOCATE ioctl
* @type: See &fw_cdev_event_common; always %FW_CDEV_EVENT_REQUEST
- * @tcode: See &fw_cdev_event_request2
- * @offset: See &fw_cdev_event_request2
- * @handle: See &fw_cdev_event_request2
- * @length: See &fw_cdev_event_request2
- * @data: See &fw_cdev_event_request2
*
* This event is sent instead of &fw_cdev_event_request2 if the kernel or
- * the client implements ABI version <= 3.
- *
- * Unlike &fw_cdev_event_request2, the sender identity cannot be established,
- * broadcast write requests cannot be distinguished from unicast writes, and
- * @tcode of lock requests is %TCODE_LOCK_REQUEST.
- *
- * Requests to the FCP_REQUEST or FCP_RESPONSE register are responded to as
- * with &fw_cdev_event_request2, except in kernel 2.6.32 and older which send
- * the response packet of the client's %FW_CDEV_IOC_SEND_RESPONSE ioctl.
+ * the client implements ABI version <= 3. &fw_cdev_event_request lacks
+ * essential information; use &fw_cdev_event_request2 instead.
*/
struct fw_cdev_event_request {
__u64 closure;
@@ -452,30 +442,29 @@
* %FW_CDEV_ISO_CONTEXT_RECEIVE_MULTICHANNEL, and
* %FW_CDEV_IOC_SET_ISO_CHANNELS
*/
-#define FW_CDEV_VERSION 3 /* Meaningless; don't use this macro. */
/**
* struct fw_cdev_get_info - General purpose information ioctl
* @version: The version field is just a running serial number. Both an
* input parameter (ABI version implemented by the client) and
* output parameter (ABI version implemented by the kernel).
- * A client must not fill in an %FW_CDEV_VERSION defined from an
- * included kernel header file but the actual version for which
- * the client was implemented. This is necessary for forward
- * compatibility. We never break backwards compatibility, but
- * may add more structs, events, and ioctls in later revisions.
- * @rom_length: If @rom is non-zero, at most rom_length bytes of configuration
+ * A client shall fill in the ABI @version for which the client
+ * was implemented. This is necessary for forward compatibility.
+ * @rom_length: If @rom is non-zero, up to @rom_length bytes of Configuration
* ROM will be copied into that user space address. In either
* case, @rom_length is updated with the actual length of the
- * configuration ROM.
+ * Configuration ROM.
* @rom: If non-zero, address of a buffer to be filled by a copy of the
- * device's configuration ROM
+ * device's Configuration ROM
* @bus_reset: If non-zero, address of a buffer to be filled by a
* &struct fw_cdev_event_bus_reset with the current state
* of the bus. This does not cause a bus reset to happen.
* @bus_reset_closure: Value of &closure in this and subsequent bus reset events
* @card: The index of the card this device belongs to
*
+ * The %FW_CDEV_IOC_GET_INFO ioctl is usually the very first one which a client
+ * performs right after it opened a /dev/fw* file.
+ *
* As a side effect, reception of %FW_CDEV_EVENT_BUS_RESET events to be read(2)
* is started by this ioctl.
*/
@@ -615,7 +604,7 @@
* @handle: Handle to the descriptor, written by the kernel
*
* Add a descriptor block and optionally a preceding immediate key to the local
- * node's configuration ROM.
+ * node's Configuration ROM.
*
* The @key field specifies the upper 8 bits of the descriptor root directory
* pointer and the @data and @length fields specify the contents. The @key
@@ -630,9 +619,9 @@
* If successful, the kernel adds the descriptor and writes back a @handle to
* the kernel-side object to be used for later removal of the descriptor block
* and immediate key. The kernel will also generate a bus reset to signal the
- * change of the configuration ROM to other nodes.
+ * change of the Configuration ROM to other nodes.
*
- * This ioctl affects the configuration ROMs of all local nodes.
+ * This ioctl affects the Configuration ROMs of all local nodes.
* The ioctl only succeeds on device files which represent a local node.
*/
struct fw_cdev_add_descriptor {
@@ -644,13 +633,13 @@
};
/**
- * struct fw_cdev_remove_descriptor - Remove contents from the configuration ROM
+ * struct fw_cdev_remove_descriptor - Remove contents from the Configuration ROM
* @handle: Handle to the descriptor, as returned by the kernel when the
* descriptor was added
*
* Remove a descriptor block and accompanying immediate key from the local
- * nodes' configuration ROMs. The kernel will also generate a bus reset to
- * signal the change of the configuration ROM to other nodes.
+ * nodes' Configuration ROMs. The kernel will also generate a bus reset to
+ * signal the change of the Configuration ROM to other nodes.
*/
struct fw_cdev_remove_descriptor {
__u32 handle;
@@ -866,13 +855,8 @@
* @local_time: system time, in microseconds since the Epoch
* @cycle_timer: Cycle Time register contents
*
- * The %FW_CDEV_IOC_GET_CYCLE_TIMER ioctl reads the isochronous cycle timer
- * and also the system clock (%CLOCK_REALTIME). This allows to express the
- * receive time of an isochronous packet as a system time.
- *
- * @cycle_timer consists of 7 bits cycleSeconds, 13 bits cycleCount, and
- * 12 bits cycleOffset, in host byte order. Cf. the Cycle Time register
- * per IEEE 1394 or Isochronous Cycle Timer register per OHCI-1394.
+ * Same as %FW_CDEV_IOC_GET_CYCLE_TIMER2, but fixed to use %CLOCK_REALTIME
+ * and only with microseconds resolution.
*
* In version 1 and 2 of the ABI, this ioctl returned unreliable (non-
* monotonic) @cycle_timer values on certain controllers.
@@ -889,10 +873,17 @@
* @clk_id: input parameter, clock from which to get the system time
* @cycle_timer: Cycle Time register contents
*
- * The %FW_CDEV_IOC_GET_CYCLE_TIMER2 works like
- * %FW_CDEV_IOC_GET_CYCLE_TIMER but lets you choose a clock like with POSIX'
- * clock_gettime function. Supported @clk_id values are POSIX' %CLOCK_REALTIME
- * and %CLOCK_MONOTONIC and Linux' %CLOCK_MONOTONIC_RAW.
+ * The %FW_CDEV_IOC_GET_CYCLE_TIMER2 ioctl reads the isochronous cycle timer
+ * and also the system clock. This allows to correlate reception time of
+ * isochronous packets with system time.
+ *
+ * @clk_id lets you choose a clock like with POSIX' clock_gettime function.
+ * Supported @clk_id values are POSIX' %CLOCK_REALTIME and %CLOCK_MONOTONIC
+ * and Linux' %CLOCK_MONOTONIC_RAW.
+ *
+ * @cycle_timer consists of 7 bits cycleSeconds, 13 bits cycleCount, and
+ * 12 bits cycleOffset, in host byte order. Cf. the Cycle Time register
+ * per IEEE 1394 or Isochronous Cycle Timer register per OHCI-1394.
*/
struct fw_cdev_get_cycle_timer2 {
__s64 tv_sec;
@@ -1014,4 +1005,6 @@
__u64 closure;
};
+#define FW_CDEV_VERSION 3 /* Meaningless legacy macro; don't use it. */
+
#endif /* _LINUX_FIREWIRE_CDEV_H */