diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/media/v4l-drivers/cx2341x.rst | 75 | ||||
| -rw-r--r-- | Documentation/video4linux/cx2341x/fw-calling.txt | 69 |
2 files changed, 75 insertions, 69 deletions
diff --git a/Documentation/media/v4l-drivers/cx2341x.rst b/Documentation/media/v4l-drivers/cx2341x.rst index 2677ac6fd649..cbfa14eccd76 100644 --- a/Documentation/media/v4l-drivers/cx2341x.rst +++ b/Documentation/media/v4l-drivers/cx2341x.rst @@ -1,6 +1,81 @@ The cx2341x driver ================== +How to call the firmware API +---------------------------- + +The preferred calling convention is known as the firmware mailbox. The +mailboxes are basically a fixed length array that serves as the call-stack. + +Firmware mailboxes can be located by searching the encoder and decoder memory +for a 16 byte signature. That signature will be located on a 256-byte boundary. + +Signature: + +.. code-block:: none + + 0x78, 0x56, 0x34, 0x12, 0x12, 0x78, 0x56, 0x34, + 0x34, 0x12, 0x78, 0x56, 0x56, 0x34, 0x12, 0x78 + +The firmware implements 20 mailboxes of 20 32-bit words. The first 10 are +reserved for API calls. The second 10 are used by the firmware for event +notification. + + ====== ================= + Index Name + ====== ================= + 0 Flags + 1 Command + 2 Return value + 3 Timeout + 4-19 Parameter/Result + ====== ================= + + +The flags are defined in the following table. The direction is from the +perspective of the firmware. + + ==== ========== ============================================ + Bit Direction Purpose + ==== ========== ============================================ + 2 O Firmware has processed the command. + 1 I Driver has finished setting the parameters. + 0 I Driver is using this mailbox. + ==== ========== ============================================ + +The command is a 32-bit enumerator. The API specifics may be found in this +chapter. + +The return value is a 32-bit enumerator. Only two values are currently defined: + +- 0=success +- -1=command undefined. + +There are 16 parameters/results 32-bit fields. The driver populates these fields +with values for all the parameters required by the call. The driver overwrites +these fields with result values returned by the call. + +The timeout value protects the card from a hung driver thread. If the driver +doesn't handle the completed call within the timeout specified, the firmware +will reset that mailbox. + +To make an API call, the driver iterates over each mailbox looking for the +first one available (bit 0 has been cleared). The driver sets that bit, fills +in the command enumerator, the timeout value and any required parameters. The +driver then sets the parameter ready bit (bit 1). The firmware scans the +mailboxes for pending commands, processes them, sets the result code, populates +the result value array with that call's return values and sets the call +complete bit (bit 2). Once bit 2 is set, the driver should retrieve the results +and clear all the flags. If the driver does not perform this task within the +time set in the timeout register, the firmware will reset that mailbox. + +Event notifications are sent from the firmware to the host. The host tells the +firmware which events it is interested in via an API call. That call tells the +firmware which notification mailbox to use. The firmware signals the host via +an interrupt. Only the 16 Results fields are used, the Flags, Command, Return +value and Timeout words are not used. + + Encoder firmware API description -------------------------------- diff --git a/Documentation/video4linux/cx2341x/fw-calling.txt b/Documentation/video4linux/cx2341x/fw-calling.txt deleted file mode 100644 index 8d21181de537..000000000000 --- a/Documentation/video4linux/cx2341x/fw-calling.txt +++ /dev/null @@ -1,69 +0,0 @@ -This page describes how to make calls to the firmware api. - -How to call -=========== - -The preferred calling convention is known as the firmware mailbox. The -mailboxes are basically a fixed length array that serves as the call-stack. - -Firmware mailboxes can be located by searching the encoder and decoder memory -for a 16 byte signature. That signature will be located on a 256-byte boundary. - -Signature: -0x78, 0x56, 0x34, 0x12, 0x12, 0x78, 0x56, 0x34, -0x34, 0x12, 0x78, 0x56, 0x56, 0x34, 0x12, 0x78 - -The firmware implements 20 mailboxes of 20 32-bit words. The first 10 are -reserved for API calls. The second 10 are used by the firmware for event -notification. - - Index Name - ----- ---- - 0 Flags - 1 Command - 2 Return value - 3 Timeout - 4-19 Parameter/Result - - -The flags are defined in the following table. The direction is from the -perspective of the firmware. - - Bit Direction Purpose - --- --------- ------- - 2 O Firmware has processed the command. - 1 I Driver has finished setting the parameters. - 0 I Driver is using this mailbox. - - -The command is a 32-bit enumerator. The API specifics may be found in the -fw-*-api.txt documents. - -The return value is a 32-bit enumerator. Only two values are currently defined: -0=success and -1=command undefined. - -There are 16 parameters/results 32-bit fields. The driver populates these fields -with values for all the parameters required by the call. The driver overwrites -these fields with result values returned by the call. The API specifics may be -found in the fw-*-api.txt documents. - -The timeout value protects the card from a hung driver thread. If the driver -doesn't handle the completed call within the timeout specified, the firmware -will reset that mailbox. - -To make an API call, the driver iterates over each mailbox looking for the -first one available (bit 0 has been cleared). The driver sets that bit, fills -in the command enumerator, the timeout value and any required parameters. The -driver then sets the parameter ready bit (bit 1). The firmware scans the -mailboxes for pending commands, processes them, sets the result code, populates -the result value array with that call's return values and sets the call -complete bit (bit 2). Once bit 2 is set, the driver should retrieve the results -and clear all the flags. If the driver does not perform this task within the -time set in the timeout register, the firmware will reset that mailbox. - -Event notifications are sent from the firmware to the host. The host tells the -firmware which events it is interested in via an API call. That call tells the -firmware which notification mailbox to use. The firmware signals the host via -an interrupt. Only the 16 Results fields are used, the Flags, Command, Return -value and Timeout words are not used. - |