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-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.
-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
- 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.