From 52409fae3e4b8d16b68b61902fc09075cd97b75d Mon Sep 17 00:00:00 2001 From: Dominik Sliwa Date: Sun, 2 Jul 2017 16:41:37 +0200 Subject: Backports generated from 4.11 kernel Initial commit. Signed-off-by: Dominik Sliwa --- drivers/bcma/README | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 drivers/bcma/README (limited to 'drivers/bcma/README') diff --git a/drivers/bcma/README b/drivers/bcma/README new file mode 100644 index 0000000..f7e7ce4 --- /dev/null +++ b/drivers/bcma/README @@ -0,0 +1,19 @@ +Broadcom introduced new bus as replacement for older SSB. It is based on AMBA, +however from programming point of view there is nothing AMBA specific we use. + +Standard AMBA drivers are platform specific, have hardcoded addresses and use +AMBA standard fields like CID and PID. + +In case of Broadcom's cards every device consists of: +1) Broadcom specific AMBA device. It is put on AMBA bus, but can not be treated + as standard AMBA device. Reading it's CID or PID can cause machine lockup. +2) AMBA standard devices called ports or wrappers. They have CIDs (AMBA_CID) + and PIDs (0x103BB369), but we do not use that info for anything. One of that + devices is used for managing Broadcom specific core. + +Addresses of AMBA devices are not hardcoded in driver and have to be read from +EPROM. + +In this situation we decided to introduce separated bus. It can contain up to +16 devices identified by Broadcom specific fields: manufacturer, id, revision +and class. -- cgit v1.2.3