Documentation/driver-api/rapidio/tsi721.rst

Source file repositories/reference/linux-study-clean/Documentation/driver-api/rapidio/tsi721.rst

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Documentation/driver-api/rapidio/tsi721.rst
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Support Tooling And Documentation: documentation
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=========================================================================
RapidIO subsystem mport driver for IDT Tsi721 PCI Express-to-SRIO bridge.
=========================================================================

1. Overview
===========

This driver implements all currently defined RapidIO mport callback functions.
It supports maintenance read and write operations, inbound and outbound RapidIO
doorbells, inbound maintenance port-writes and RapidIO messaging.

To generate SRIO maintenance transactions this driver uses one of Tsi721 DMA
channels. This mechanism provides access to larger range of hop counts and
destination IDs without need for changes in outbound window translation.

RapidIO messaging support uses dedicated messaging channels for each mailbox.
For inbound messages this driver uses destination ID matching to forward messages
into the corresponding message queue. Messaging callbacks are implemented to be
fully compatible with RIONET driver (Ethernet over RapidIO messaging services).

1. Module parameters:

- 'dbg_level'
      - This parameter allows to control amount of debug information
        generated by this device driver. This parameter is formed by set of
        This parameter can be changed bit masks that correspond to the specific
        functional block.
        For mask definitions see 'drivers/rapidio/devices/tsi721.h'
        This parameter can be changed dynamically.
        Use CONFIG_RAPIDIO_DEBUG=y to enable debug output at the top level.

- 'dma_desc_per_channel'
      - This parameter defines number of hardware buffer
        descriptors allocated for each registered Tsi721 DMA channel.
        Its default value is 128.

- 'dma_txqueue_sz'
      - DMA transactions queue size. Defines number of pending
        transaction requests that can be accepted by each DMA channel.
        Default value is 16.

- 'dma_sel'
      - DMA channel selection mask. Bitmask that defines which hardware
        DMA channels (0 ... 6) will be registered with DmaEngine core.
        If bit is set to 1, the corresponding DMA channel will be registered.
        DMA channels not selected by this mask will not be used by this device
        driver. Default value is 0x7f (use all channels).

- 'pcie_mrrs'
      - override value for PCIe Maximum Read Request Size (MRRS).
        This parameter gives an ability to override MRRS value set during PCIe
        configuration process. Tsi721 supports read request sizes up to 4096B.
        Value for this parameter must be set as defined by PCIe specification:
        0 = 128B, 1 = 256B, 2 = 512B, 3 = 1024B, 4 = 2048B and 5 = 4096B.
        Default value is '-1' (= keep platform setting).

- 'mbox_sel'
      - RIO messaging MBOX selection mask. This is a bitmask that defines
        messaging MBOXes are managed by this device driver. Mask bits 0 - 3
        correspond to MBOX0 - MBOX3. MBOX is under driver's control if the
        corresponding bit is set to '1'. Default value is 0x0f (= all).

2. Known problems
=================

  None.

3. DMA Engine Support
=====================

Annotation

Implementation Notes