d40860f8e2
Write some better documentation about what might be known about how the m920x I2C works, since a datasheet is lacking. The I2C xfer function should now handle more types of I2C transactions than it could before. Those it can't, will return error codes instead of being executed incorrectly. Multi-byte reads were not being done correctly, which should be fixed. Signed-off-by: Trent Piepho <xyzzy@speakeasy.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
68 lines
1.8 KiB
C
68 lines
1.8 KiB
C
#ifndef _DVB_USB_M920X_H_
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#define _DVB_USB_M920X_H_
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#define DVB_USB_LOG_PREFIX "m920x"
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#include "dvb-usb.h"
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#define deb_rc(args...) dprintk(dvb_usb_m920x_debug,0x01,args)
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#define M9206_CORE 0x22
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#define M9206_RC_STATE 0xff51
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#define M9206_RC_KEY 0xff52
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#define M9206_RC_INIT1 0xff54
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#define M9206_RC_INIT2 0xff55
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#define M9206_FW_GO 0xff69
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#define M9206_I2C 0x23
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#define M9206_FILTER 0x25
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#define M9206_FW 0x30
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#define M9206_MAX_FILTERS 8
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/*
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sequences found in logs:
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[index value]
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0x80 write addr
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(0x00 out byte)*
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0x40 out byte
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0x80 write addr
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(0x00 out byte)*
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0x80 read addr
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(0x21 in byte)*
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0x60 in byte
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this sequence works:
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0x80 read addr
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(0x21 in byte)*
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0x60 in byte
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Guess at API of the I2C function:
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I2C operation is done one byte at a time with USB control messages. The
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index the messages is sent to is made up of a set of flags that control
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the I2C bus state:
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0x80: Send START condition. After a START condition, one would normally
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always send the 7-bit slave I2C address as the 7 MSB, followed by
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the read/write bit as the LSB.
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0x40: Send STOP condition. This should be set on the last byte of an
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I2C transaction.
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0x20: Read a byte from the slave. As opposed to writing a byte to the
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slave. The slave will normally not produce any data unless you
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set the R/W bit to 1 when sending the slave's address after the
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START condition.
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0x01: Respond with ACK, as opposed to a NACK. For a multi-byte read,
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the master should send an ACK, that is pull SDA low during the 9th
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clock cycle, after every byte but the last. This flags only makes
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sense when bit 0x20 is set, indicating a read.
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What any other bits might mean, or how to get the slave's ACK/NACK
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response to a write, is unknown.
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*/
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struct m9206_state {
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u16 filters[M9206_MAX_FILTERS];
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int filtering_enabled;
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int rep_count;
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};
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#endif
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