157 lines
5.2 KiB
Plaintext
157 lines
5.2 KiB
Plaintext
all multibyte words are little-endian
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--
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USB interface is a vendor interface, with an in and an out endpoint
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--
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module:
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cmd value index len
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kernel:
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request reqtype(fix) value index dmalen
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i2c_msg:
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cmd? type? flags addr len
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CMD_SET_DELAY:
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delayv 0 0
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CMD_GET_STATUS: data=[status retval]
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0 0 1
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i2c_msg:
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type: byte
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cmd: byte
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flags: ushort
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addr: ushort
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len: ushort
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data: byte[len]
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commands:
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CMD_ECHO = 0
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CMD_GET_FUNC = 1
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CMD_SET_DELAY = 2
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CMD_GET_STATUS = 3
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CMD_I2C_IO = 4
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CMD_I2C_IO_W_BEGIN = 5 = CMD_I2C_IO | CMD_I2C_IO_BEGIN
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CMD_I2C_IO_W_END = 6 = CMD_I2C_IO | CMD_I2C_IO_END
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CMD_I2C_IO_W_BEGINEND = 7 = CMD_I2C_IO | CMD_I2C_IO_BEGIN | CMD_I2C_IO_END
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CMD_I2C_IO_BEGIN = 1<<0 // the beginning of the I2C transaction: do a start cond
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CMD_I2C_IO_END = 1<<1 // the end of the I2C transaction: do an end cond
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// if none of the above two: repeated start condition anyway?
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statuses:
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STATUS_IDLE = 0
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STATUS_ADDRESS_ACK = 1
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STATUS_DDRESS_NAK = 2
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flags: (literally just from the kernel)
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I2C_M_RD 0x0001 /* guaranteed to be 0x0001! */
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I2C_M_TEN 0x0010 /* use only if I2C_FUNC_10BIT_ADDR */
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I2C_M_DMA_SAFE 0x0200 /* use only in kernel space */
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I2C_M_RECV_LEN 0x0400 /* use only if I2C_FUNC_SMBUS_READ_BLOCK_DATA */
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I2C_M_NO_RD_ACK 0x0800 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
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I2C_M_IGNORE_NAK 0x1000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
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I2C_M_REV_DIR_ADDR 0x2000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
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I2C_M_NOSTART 0x4000 /* use only if I2C_FUNC_NOSTART */
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I2C_M_STOP 0x8000 /* use only if I2C_FUNC_PROTOCOL_MANGLING */
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funcs:
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* I2C_FUNC_I2C 0x00000001
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I2C_FUNC_10BIT_ADDR 0x00000002 /* required for I2C_M_TEN */
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I2C_FUNC_PROTOCOL_MANGLING 0x00000004 /* required for I2C_M_IGNORE_NAK etc. */
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I2C_FUNC_SMBUS_PEC 0x00000008
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I2C_FUNC_NOSTART 0x00000010 /* required for I2C_M_NOSTART */
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I2C_FUNC_SLAVE 0x00000020
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I2C_FUNC_SMBUS_BLOCK_PROC_CALL 0x00008000 /* SMBus 2.0 or later */
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* I2C_FUNC_SMBUS_QUICK 0x00010000
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* I2C_FUNC_SMBUS_READ_BYTE 0x00020000
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* I2C_FUNC_SMBUS_WRITE_BYTE 0x00040000
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* I2C_FUNC_SMBUS_READ_BYTE_DATA 0x00080000
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* I2C_FUNC_SMBUS_WRITE_BYTE_DATA 0x00100000
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* I2C_FUNC_SMBUS_READ_WORD_DATA 0x00200000
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* I2C_FUNC_SMBUS_WRITE_WORD_DATA 0x00400000
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* I2C_FUNC_SMBUS_PROC_CALL 0x00800000
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I2C_FUNC_SMBUS_READ_BLOCK_DATA 0x01000000 /* required for I2C_M_RECV_LEN */
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* I2C_FUNC_SMBUS_WRITE_BLOCK_DATA 0x02000000
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* I2C_FUNC_SMBUS_READ_I2C_BLOCK 0x04000000 /* I2C-like block xfer */
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* I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
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I2C_FUNC_SMBUS_READ_I2C_BLOCK_2 0x10000000 /* I2C-like block xfer */
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I2C_FUNC_SMBUS_WRITE_I2C_BLOCK_2 0x20000000 /* w/ 2-byte reg. addr. */
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* I2C_FUNC_SMBUS_READ_BLOCK_DATA_PEC 0x40000000 /* SMBus 2.0 or later */
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* I2C_FUNC_SMBUS_WRITE_BLOCK_DATA_PEC 0x80000000 /* SMBus 2.0 or later */
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* I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | I2C_FUNC_SMBUS_WRITE_BYTE)
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* I2C_FUNC_SMBUS_BYTE_DATA (I2C_FUNC_SMBUS_READ_BYTE_DATA | I2C_FUNC_SMBUS_WRITE_BYTE_DATA)
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* I2C_FUNC_SMBUS_WORD_DATA (I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA)
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I2C_FUNC_SMBUS_BLOCK_DATA (I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)
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* I2C_FUNC_SMBUS_I2C_BLOCK (I2C_FUNC_SMBUS_READ_I2C_BLOCK | I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)
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* I2C_FUNC_SMBUS_EMUL (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \
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I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \
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I2C_FUNC_SMBUS_PROC_CALL | I2C_FUNC_SMBUS_WRITE_BLOCK_DATA | \
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I2C_FUNC_SMBUS_I2C_BLOCK | I2C_FUNC_SMBUS_PEC)
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/* if I2C_M_RECV_LEN is also supported */
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I2C_FUNC_SMBUS_EMUL_ALL (I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA | \
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I2C_FUNC_SMBUS_BLOCK_PROC_CALL)
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USB vendor setup:
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state machine: 3 8-bit registers: status, cmd, len
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status is STATUS_ADDRESS_IDLE at reset
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cmd, len are reset to 0
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ECHO command:
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send back flags bytes
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GET_FUNC command:
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send back supported functions: 4-byte little-endian of the above flags
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SET_DELAY command:
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sets clock period, in flags, unit is microseconds
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GET_STATUS command:
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return the status register (1 byte)
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I2C_IO command: I2C xfers:
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actual CMD_I2C_IO stuff:
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do start cond
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send (device addr << 1) | (I2C_M_RD?1:0) (aka set device address and read/write mode)
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if ack bit received from previous step
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status = STATUS_ADDRESS_ACK
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save cmd and len in state regs
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if CMD_I2C_IO_END set in cmd AND len is 0:
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do end cond
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else
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status = STATUS_ADDRESS_NAK
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do end cond
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USB vendor read:
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if status == STATUS_ADDRESS_ACK:
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if number of bytes in this block larger than bytes expected:
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clamp this length, only use the number of expected bytes in the block
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read bytes, decrease len reg by number of bytes read
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(if last byte read, set NAK in I2C xfer, else ACK)
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if CMD_I2C_IO_END set in cmd reg AND len reg is 0:
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do end cond
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return bytes read over USB
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else:
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do nothing, return zeros
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USB vendor write:
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if status == STATUS_ADDRESS_ACK:
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if number of bytes in this block larger than bytes expected:
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clamp this length, only use the number of expected bytes in the block
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write bytes, decrease len reg by number of bytes written
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(if no ack bit returned, maybe set an error state??)
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if CMD_I2C_IO_END set in cmd reg AND len reg is 0:
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do end cond
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echo back bytes written
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else:
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do nothing, return zeros
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