1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
730 lines
15 KiB
C
730 lines
15 KiB
C
/*!***************************************************************************
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*!
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*! FILE NAME : i2c.c
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*!
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*! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
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*! kernel modules (i2c_writereg/readreg) and from userspace using
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*! ioctl()'s
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*!
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*! Nov 30 1998 Torbjorn Eliasson Initial version.
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*! Bjorn Wesen Elinux kernel version.
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*! Jan 14 2000 Johan Adolfsson Fixed PB shadow register stuff -
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*! don't use PB_I2C if DS1302 uses same bits,
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*! use PB.
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*! $Log: i2c.c,v $
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*! Revision 1.9 2004/08/24 06:49:14 starvik
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*! Whitespace cleanup
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*!
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*! Revision 1.8 2004/06/08 08:48:26 starvik
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*! Removed unused code
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*!
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*! Revision 1.7 2004/05/28 09:26:59 starvik
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*! Modified I2C initialization to work in 2.6.
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*!
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*! Revision 1.6 2004/05/14 07:58:03 starvik
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*! Merge of changes from 2.4
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*!
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*! Revision 1.4 2002/12/11 13:13:57 starvik
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*! Added arch/ to v10 specific includes
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*! Added fix from Linux 2.4 in serial.c (flush_to_flip_buffer)
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*!
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*! Revision 1.3 2002/11/20 11:56:11 starvik
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*! Merge of Linux 2.5.48
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*!
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*! Revision 1.2 2002/11/18 13:16:06 starvik
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*! Linux 2.5 port of latest 2.4 drivers
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*!
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*! Revision 1.9 2002/10/31 15:32:26 starvik
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*! Update Port B register and shadow even when running with hardware support
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*! to avoid glitches when reading bits
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*! Never set direction to out in i2c_inbyte
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*! Removed incorrect clock togling at end of i2c_inbyte
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*!
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*! Revision 1.8 2002/08/13 06:31:53 starvik
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*! Made SDA and SCL line configurable
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*! Modified i2c_inbyte to work with PCF8563
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*!
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*! Revision 1.7 2001/04/04 13:11:36 markusl
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*! Updated according to review remarks
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*!
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*! Revision 1.6 2001/03/19 12:43:00 markusl
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*! Made some symbols unstatic (used by the eeprom driver)
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*!
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*! Revision 1.5 2001/02/27 13:52:48 bjornw
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*! malloc.h -> slab.h
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*!
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*! Revision 1.4 2001/02/15 07:17:40 starvik
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*! Corrected usage if port_pb_i2c_shadow
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*!
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*! Revision 1.3 2001/01/26 17:55:13 bjornw
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*! * Made I2C_USES_PB_NOT_PB_I2C a CONFIG option instead of assigning it
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*! magically. Config.in needs to set it for the options that need it, like
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*! Dallas 1302 support. Actually, it should be default since it screws up
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*! the PB bits even if you don't use I2C..
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*! * Include linux/config.h to get the above
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*!
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*! Revision 1.2 2001/01/18 15:49:30 bjornw
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*! 2.4 port of I2C including some cleanups (untested of course)
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*!
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*! Revision 1.1 2001/01/18 15:35:25 bjornw
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*! Verbatim copy of the Etrax i2c driver, 2.0 elinux version
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*!
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*!
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*! ---------------------------------------------------------------------------
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*!
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*! (C) Copyright 1999-2002 Axis Communications AB, LUND, SWEDEN
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*!
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*!***************************************************************************/
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/* $Id: i2c.c,v 1.9 2004/08/24 06:49:14 starvik Exp $ */
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/****************** INCLUDE FILES SECTION ***********************************/
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/config.h>
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#include <asm/etraxi2c.h>
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#include <asm/system.h>
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#include <asm/arch/svinto.h>
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#include <asm/io.h>
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#include <asm/delay.h>
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#include "i2c.h"
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/****************** I2C DEFINITION SECTION *************************/
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#define D(x)
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#define I2C_MAJOR 123 /* LOCAL/EXPERIMENTAL */
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static const char i2c_name[] = "i2c";
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#define CLOCK_LOW_TIME 8
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#define CLOCK_HIGH_TIME 8
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#define START_CONDITION_HOLD_TIME 8
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#define STOP_CONDITION_HOLD_TIME 8
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#define ENABLE_OUTPUT 0x01
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#define ENABLE_INPUT 0x00
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#define I2C_CLOCK_HIGH 1
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#define I2C_CLOCK_LOW 0
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#define I2C_DATA_HIGH 1
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#define I2C_DATA_LOW 0
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#ifdef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
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/* Use PB and not PB_I2C */
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#ifndef CONFIG_ETRAX_I2C_DATA_PORT
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#define CONFIG_ETRAX_I2C_DATA_PORT 0
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#endif
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#ifndef CONFIG_ETRAX_I2C_CLK_PORT
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#define CONFIG_ETRAX_I2C_CLK_PORT 1
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#endif
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#define SDABIT CONFIG_ETRAX_I2C_DATA_PORT
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#define SCLBIT CONFIG_ETRAX_I2C_CLK_PORT
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#define i2c_enable()
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#define i2c_disable()
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/* enable or disable output-enable, to select output or input on the i2c bus */
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#define i2c_dir_out() \
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REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 1)
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#define i2c_dir_in() \
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REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 0)
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/* control the i2c clock and data signals */
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#define i2c_clk(x) \
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REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SCLBIT, x)
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#define i2c_data(x) \
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REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SDABIT, x)
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/* read a bit from the i2c interface */
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#define i2c_getbit() (((*R_PORT_PB_READ & (1 << SDABIT))) >> SDABIT)
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#else
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/* enable or disable the i2c interface */
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#define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
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#define i2c_disable() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_en))
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/* enable or disable output-enable, to select output or input on the i2c bus */
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#define i2c_dir_out() \
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*R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
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REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 1);
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#define i2c_dir_in() \
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*R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
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REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 0);
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/* control the i2c clock and data signals */
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#define i2c_clk(x) \
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*R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
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~IO_MASK(R_PORT_PB_I2C, i2c_clk)) | IO_FIELD(R_PORT_PB_I2C, i2c_clk, (x))); \
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REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 1, x);
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#define i2c_data(x) \
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*R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
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~IO_MASK(R_PORT_PB_I2C, i2c_d)) | IO_FIELD(R_PORT_PB_I2C, i2c_d, (x))); \
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REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 0, x);
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/* read a bit from the i2c interface */
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#define i2c_getbit() (*R_PORT_PB_READ & 0x1)
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#endif
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/* use the kernels delay routine */
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#define i2c_delay(usecs) udelay(usecs)
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/****************** FUNCTION DEFINITION SECTION *************************/
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/* generate i2c start condition */
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void
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i2c_start(void)
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{
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/*
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* SCL=1 SDA=1
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*/
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i2c_dir_out();
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i2c_delay(CLOCK_HIGH_TIME/6);
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i2c_data(I2C_DATA_HIGH);
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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/*
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* SCL=1 SDA=0
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*/
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i2c_data(I2C_DATA_LOW);
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i2c_delay(START_CONDITION_HOLD_TIME);
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/*
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* SCL=0 SDA=0
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*/
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_LOW_TIME);
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}
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/* generate i2c stop condition */
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void
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i2c_stop(void)
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{
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i2c_dir_out();
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/*
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* SCL=0 SDA=0
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*/
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i2c_clk(I2C_CLOCK_LOW);
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i2c_data(I2C_DATA_LOW);
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i2c_delay(CLOCK_LOW_TIME*2);
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/*
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* SCL=1 SDA=0
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*/
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME*2);
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/*
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* SCL=1 SDA=1
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*/
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i2c_data(I2C_DATA_HIGH);
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i2c_delay(STOP_CONDITION_HOLD_TIME);
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i2c_dir_in();
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}
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/* write a byte to the i2c interface */
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void
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i2c_outbyte(unsigned char x)
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{
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int i;
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i2c_dir_out();
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for (i = 0; i < 8; i++) {
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if (x & 0x80) {
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i2c_data(I2C_DATA_HIGH);
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} else {
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i2c_data(I2C_DATA_LOW);
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}
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i2c_delay(CLOCK_LOW_TIME/2);
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_LOW_TIME/2);
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x <<= 1;
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}
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i2c_data(I2C_DATA_LOW);
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i2c_delay(CLOCK_LOW_TIME/2);
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/*
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* enable input
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*/
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i2c_dir_in();
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}
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/* read a byte from the i2c interface */
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unsigned char
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i2c_inbyte(void)
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{
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unsigned char aBitByte = 0;
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int i;
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/* Switch off I2C to get bit */
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i2c_disable();
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i2c_dir_in();
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i2c_delay(CLOCK_HIGH_TIME/2);
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/* Get bit */
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aBitByte |= i2c_getbit();
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/* Enable I2C */
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i2c_enable();
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i2c_delay(CLOCK_LOW_TIME/2);
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for (i = 1; i < 8; i++) {
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aBitByte <<= 1;
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/* Clock pulse */
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_LOW_TIME);
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/* Switch off I2C to get bit */
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i2c_disable();
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i2c_dir_in();
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i2c_delay(CLOCK_HIGH_TIME/2);
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/* Get bit */
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aBitByte |= i2c_getbit();
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/* Enable I2C */
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i2c_enable();
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i2c_delay(CLOCK_LOW_TIME/2);
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}
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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/*
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* we leave the clock low, getbyte is usually followed
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* by sendack/nack, they assume the clock to be low
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*/
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i2c_clk(I2C_CLOCK_LOW);
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return aBitByte;
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}
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/*#---------------------------------------------------------------------------
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*#
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*# FUNCTION NAME: i2c_getack
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*#
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*# DESCRIPTION : checks if ack was received from ic2
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*#
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*#--------------------------------------------------------------------------*/
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int
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i2c_getack(void)
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{
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int ack = 1;
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/*
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* enable output
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*/
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i2c_dir_out();
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/*
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* Release data bus by setting
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* data high
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*/
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i2c_data(I2C_DATA_HIGH);
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/*
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* enable input
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*/
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i2c_dir_in();
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i2c_delay(CLOCK_HIGH_TIME/4);
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/*
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* generate ACK clock pulse
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*/
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i2c_clk(I2C_CLOCK_HIGH);
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/*
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* Use PORT PB instead of I2C
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* for input. (I2C not working)
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*/
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i2c_clk(1);
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i2c_data(1);
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/*
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* switch off I2C
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*/
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i2c_data(1);
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i2c_disable();
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i2c_dir_in();
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/*
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* now wait for ack
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*/
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i2c_delay(CLOCK_HIGH_TIME/2);
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/*
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* check for ack
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*/
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if(i2c_getbit())
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ack = 0;
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i2c_delay(CLOCK_HIGH_TIME/2);
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if(!ack){
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if(!i2c_getbit()) /* receiver pulld SDA low */
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ack = 1;
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i2c_delay(CLOCK_HIGH_TIME/2);
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}
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/*
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* our clock is high now, make sure data is low
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* before we enable our output. If we keep data high
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* and enable output, we would generate a stop condition.
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*/
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i2c_data(I2C_DATA_LOW);
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/*
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* end clock pulse
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*/
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i2c_enable();
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i2c_dir_out();
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_HIGH_TIME/4);
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/*
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* enable output
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*/
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i2c_dir_out();
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/*
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* remove ACK clock pulse
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*/
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i2c_data(I2C_DATA_HIGH);
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i2c_delay(CLOCK_LOW_TIME/2);
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return ack;
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}
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/*#---------------------------------------------------------------------------
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*#
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*# FUNCTION NAME: I2C::sendAck
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*#
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*# DESCRIPTION : Send ACK on received data
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*#
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*#--------------------------------------------------------------------------*/
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void
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i2c_sendack(void)
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{
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/*
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* enable output
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*/
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i2c_delay(CLOCK_LOW_TIME);
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i2c_dir_out();
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/*
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* set ack pulse high
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*/
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i2c_data(I2C_DATA_LOW);
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/*
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* generate clock pulse
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*/
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i2c_delay(CLOCK_HIGH_TIME/6);
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_LOW_TIME/6);
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/*
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* reset data out
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*/
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i2c_data(I2C_DATA_HIGH);
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i2c_delay(CLOCK_LOW_TIME);
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i2c_dir_in();
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}
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/*#---------------------------------------------------------------------------
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*#
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*# FUNCTION NAME: i2c_sendnack
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*#
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*# DESCRIPTION : Sends NACK on received data
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*#
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*#--------------------------------------------------------------------------*/
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void
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i2c_sendnack(void)
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{
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/*
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* enable output
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*/
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i2c_delay(CLOCK_LOW_TIME);
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i2c_dir_out();
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/*
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* set data high
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*/
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i2c_data(I2C_DATA_HIGH);
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/*
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* generate clock pulse
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*/
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i2c_delay(CLOCK_HIGH_TIME/6);
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i2c_clk(I2C_CLOCK_HIGH);
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i2c_delay(CLOCK_HIGH_TIME);
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i2c_clk(I2C_CLOCK_LOW);
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i2c_delay(CLOCK_LOW_TIME);
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i2c_dir_in();
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}
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/*#---------------------------------------------------------------------------
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*#
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*# FUNCTION NAME: i2c_writereg
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*#
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*# DESCRIPTION : Writes a value to an I2C device
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*#
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*#--------------------------------------------------------------------------*/
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int
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i2c_writereg(unsigned char theSlave, unsigned char theReg,
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unsigned char theValue)
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{
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int error, cntr = 3;
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unsigned long flags;
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do {
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error = 0;
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/*
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* we don't like to be interrupted
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*/
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local_irq_save(flags);
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local_irq_disable();
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i2c_start();
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/*
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* send slave address
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*/
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i2c_outbyte((theSlave & 0xfe));
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/*
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* wait for ack
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*/
|
|
if(!i2c_getack())
|
|
error = 1;
|
|
/*
|
|
* now select register
|
|
*/
|
|
i2c_dir_out();
|
|
i2c_outbyte(theReg);
|
|
/*
|
|
* now it's time to wait for ack
|
|
*/
|
|
if(!i2c_getack())
|
|
error |= 2;
|
|
/*
|
|
* send register register data
|
|
*/
|
|
i2c_outbyte(theValue);
|
|
/*
|
|
* now it's time to wait for ack
|
|
*/
|
|
if(!i2c_getack())
|
|
error |= 4;
|
|
/*
|
|
* end byte stream
|
|
*/
|
|
i2c_stop();
|
|
/*
|
|
* enable interrupt again
|
|
*/
|
|
local_irq_restore(flags);
|
|
|
|
} while(error && cntr--);
|
|
|
|
i2c_delay(CLOCK_LOW_TIME);
|
|
|
|
return -error;
|
|
}
|
|
|
|
/*#---------------------------------------------------------------------------
|
|
*#
|
|
*# FUNCTION NAME: i2c_readreg
|
|
*#
|
|
*# DESCRIPTION : Reads a value from the decoder registers.
|
|
*#
|
|
*#--------------------------------------------------------------------------*/
|
|
unsigned char
|
|
i2c_readreg(unsigned char theSlave, unsigned char theReg)
|
|
{
|
|
unsigned char b = 0;
|
|
int error, cntr = 3;
|
|
unsigned long flags;
|
|
|
|
do {
|
|
error = 0;
|
|
/*
|
|
* we don't like to be interrupted
|
|
*/
|
|
local_irq_save(flags);
|
|
local_irq_disable();
|
|
/*
|
|
* generate start condition
|
|
*/
|
|
i2c_start();
|
|
|
|
/*
|
|
* send slave address
|
|
*/
|
|
i2c_outbyte((theSlave & 0xfe));
|
|
/*
|
|
* wait for ack
|
|
*/
|
|
if(!i2c_getack())
|
|
error = 1;
|
|
/*
|
|
* now select register
|
|
*/
|
|
i2c_dir_out();
|
|
i2c_outbyte(theReg);
|
|
/*
|
|
* now it's time to wait for ack
|
|
*/
|
|
if(!i2c_getack())
|
|
error = 1;
|
|
/*
|
|
* repeat start condition
|
|
*/
|
|
i2c_delay(CLOCK_LOW_TIME);
|
|
i2c_start();
|
|
/*
|
|
* send slave address
|
|
*/
|
|
i2c_outbyte(theSlave | 0x01);
|
|
/*
|
|
* wait for ack
|
|
*/
|
|
if(!i2c_getack())
|
|
error = 1;
|
|
/*
|
|
* fetch register
|
|
*/
|
|
b = i2c_inbyte();
|
|
/*
|
|
* last received byte needs to be nacked
|
|
* instead of acked
|
|
*/
|
|
i2c_sendack();
|
|
/*
|
|
* end sequence
|
|
*/
|
|
i2c_stop();
|
|
/*
|
|
* enable interrupt again
|
|
*/
|
|
local_irq_restore(flags);
|
|
|
|
} while(error && cntr--);
|
|
|
|
return b;
|
|
}
|
|
|
|
static int
|
|
i2c_open(struct inode *inode, struct file *filp)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
i2c_release(struct inode *inode, struct file *filp)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
/* Main device API. ioctl's to write or read to/from i2c registers.
|
|
*/
|
|
|
|
static int
|
|
i2c_ioctl(struct inode *inode, struct file *file,
|
|
unsigned int cmd, unsigned long arg)
|
|
{
|
|
if(_IOC_TYPE(cmd) != ETRAXI2C_IOCTYPE) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
switch (_IOC_NR(cmd)) {
|
|
case I2C_WRITEREG:
|
|
/* write to an i2c slave */
|
|
D(printk("i2cw %d %d %d\n",
|
|
I2C_ARGSLAVE(arg),
|
|
I2C_ARGREG(arg),
|
|
I2C_ARGVALUE(arg)));
|
|
|
|
return i2c_writereg(I2C_ARGSLAVE(arg),
|
|
I2C_ARGREG(arg),
|
|
I2C_ARGVALUE(arg));
|
|
case I2C_READREG:
|
|
{
|
|
unsigned char val;
|
|
/* read from an i2c slave */
|
|
D(printk("i2cr %d %d ",
|
|
I2C_ARGSLAVE(arg),
|
|
I2C_ARGREG(arg)));
|
|
val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg));
|
|
D(printk("= %d\n", val));
|
|
return val;
|
|
}
|
|
default:
|
|
return -EINVAL;
|
|
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct file_operations i2c_fops = {
|
|
.owner = THIS_MODULE,
|
|
.ioctl = i2c_ioctl,
|
|
.open = i2c_open,
|
|
.release = i2c_release,
|
|
};
|
|
|
|
int __init
|
|
i2c_init(void)
|
|
{
|
|
/* Setup and enable the Port B I2C interface */
|
|
|
|
#ifndef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
|
|
*R_PORT_PB_I2C = port_pb_i2c_shadow |=
|
|
IO_STATE(R_PORT_PB_I2C, i2c_en, on) |
|
|
IO_FIELD(R_PORT_PB_I2C, i2c_d, 1) |
|
|
IO_FIELD(R_PORT_PB_I2C, i2c_clk, 1) |
|
|
IO_STATE(R_PORT_PB_I2C, i2c_oe_, enable);
|
|
#endif
|
|
|
|
port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir0);
|
|
port_pb_dir_shadow &= ~IO_MASK(R_PORT_PB_DIR, dir1);
|
|
|
|
*R_PORT_PB_DIR = (port_pb_dir_shadow |=
|
|
IO_STATE(R_PORT_PB_DIR, dir0, input) |
|
|
IO_STATE(R_PORT_PB_DIR, dir1, output));
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __init
|
|
i2c_register(void)
|
|
{
|
|
int res;
|
|
|
|
i2c_init();
|
|
res = register_chrdev(I2C_MAJOR, i2c_name, &i2c_fops);
|
|
if(res < 0) {
|
|
printk(KERN_ERR "i2c: couldn't get a major number.\n");
|
|
return res;
|
|
}
|
|
|
|
printk(KERN_INFO "I2C driver v2.2, (c) 1999-2001 Axis Communications AB\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* this makes sure that i2c_register is called during boot */
|
|
|
|
module_init(i2c_register);
|
|
|
|
/****************** END OF FILE i2c.c ********************************/
|