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6e84650e2f
Bitbang I2C could do with delay after last stop before next back-back transaction Signed-off-by: Andy Green <andy@openmoko.com>
103 lines
2.7 KiB
C
103 lines
2.7 KiB
C
/*
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* (C) Copyright 2007 OpenMoko, Inc.
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* Author: Andy Green <andy@openmoko.com>
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*
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* Generic i2c bitbang state machine
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*
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*/
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/* controls symbol sequencing on i2c */
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enum i2c_bitbang_control {
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IBCONTROL_DO_START = -1,
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IBCONTROL_DO_STOP = -2,
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IBCONTROL_DO_READ = -3,
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IBCONTROL_COMPLETE = -4
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};
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/* control intra-bit and byte states */
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enum i2c_bitbang_states {
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IBS_INIT,
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IBS_START1,
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IBS_START2,
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IBS_ADS_TX_S,
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IBS_ADS_TX_H,
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IBS_ADS_TX_L,
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IBS_ADS_TX_ACK_H,
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IBS_ADS_TX_ACK_L,
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IBS_DATA_RX_S,
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IBS_DATA_RX_H,
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IBS_DATA_RX_L,
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IBS_DATA_RX_ACK_H,
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IBS_DATA_RX_ACK_L,
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IBS_STOP1,
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IBS_STOP2,
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IBS_STOP3,
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IBS_STOP4
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};
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/* context for bitbang GPIO pins and transaction */
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struct i2c_bitbang {
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enum i2c_bitbang_states state;
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int count;
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unsigned int data[8]; /* read result found here */
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int index;
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int index_read;
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char (*read_sda)(void);
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/* data = 0 = op low, 1 == inp */
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void (*set)(char clock, char data);
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/* delay > 1 half-bit time, used by i2c_complete_synchronously() */
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void (*spin)(void);
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void (*close)(void);
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};
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/* synchronous read and write functions spin until completed or failed
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* i2c_read_sync returns -1 for fail or byte result from device
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*/
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extern int i2c_read_sync(struct i2c_bitbang * bb, unsigned char ads7,
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unsigned char reg);
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extern void i2c_write_sync(struct i2c_bitbang * bb, unsigned char ads7,
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unsigned char reg, unsigned char data);
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/*
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* set up an asynchronous read or write transaction
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*/
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extern void i2c_read(struct i2c_bitbang * bb, unsigned char ads7,
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unsigned char reg);
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extern void i2c_write(struct i2c_bitbang * bb, unsigned char ads7,
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unsigned char reg, unsigned char data);
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/*
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* after setting up a read or write transaction above, you loop calling this
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* with >= 1.25us (400kHz) or >= 5us (100kHz) delay between calls. You don't
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* have to spin but can do something useful if you know it will take more than
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* an i2c bit-time, hiding the time for the i2c transaction completely.
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*/
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extern int i2c_next_state(struct i2c_bitbang * bb); /* return !=0 = completed */
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