xref: /OK3568_Linux_fs/kernel/drivers/bcma/README (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593SmuzhiyunBroadcom introduced new bus as replacement for older SSB. It is based on AMBA,
2*4882a593Smuzhiyunhowever from programming point of view there is nothing AMBA specific we use.
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4*4882a593SmuzhiyunStandard AMBA drivers are platform specific, have hardcoded addresses and use
5*4882a593SmuzhiyunAMBA standard fields like CID and PID.
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7*4882a593SmuzhiyunIn case of Broadcom's cards every device consists of:
8*4882a593Smuzhiyun1) Broadcom specific AMBA device. It is put on AMBA bus, but can not be treated
9*4882a593Smuzhiyun   as standard AMBA device. Reading it's CID or PID can cause machine lockup.
10*4882a593Smuzhiyun2) AMBA standard devices called ports or wrappers. They have CIDs (AMBA_CID)
11*4882a593Smuzhiyun   and PIDs (0x103BB369), but we do not use that info for anything. One of that
12*4882a593Smuzhiyun   devices is used for managing Broadcom specific core.
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14*4882a593SmuzhiyunAddresses of AMBA devices are not hardcoded in driver and have to be read from
15*4882a593SmuzhiyunEPROM.
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17*4882a593SmuzhiyunIn this situation we decided to introduce separated bus. It can contain up to
18*4882a593Smuzhiyun16 devices identified by Broadcom specific fields: manufacturer, id, revision
19*4882a593Smuzhiyunand class.
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