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linux/arch/cris/arch-v10/drivers/i2c.c
Arjan van de Ven 5dfe4c964a [PATCH] mark struct file_operations const 2 
Many struct file_operations in the kernel can be "const".  Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data.  In addition it'll catch accidental writes at compile time to
these shared resources.

[akpm@osdl.org: sparc64 fix]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-12 09:48:44 -08:00

778 lines
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/*!***************************************************************************
*!
*! FILE NAME : i2c.c
*!
*! DESCRIPTION: implements an interface for IIC/I2C, both directly from other
*! kernel modules (i2c_writereg/readreg) and from userspace using
*! ioctl()'s
*!
*! Nov 30 1998 Torbjorn Eliasson Initial version.
*! Bjorn Wesen Elinux kernel version.
*! Jan 14 2000 Johan Adolfsson Fixed PB shadow register stuff -
*! don't use PB_I2C if DS1302 uses same bits,
*! use PB.
*! $Log: i2c.c,v $
*! Revision 1.13 2005/03/07 13:13:07 starvik
*! Added spinlocks to protect states etc
*!
*! Revision 1.12 2005/01/05 06:11:22 starvik
*! No need to do local_irq_disable after local_irq_save.
*!
*! Revision 1.11 2004/12/13 12:21:52 starvik
*! Added I/O and DMA allocators from Linux 2.4
*!
*! Revision 1.9 2004/08/24 06:49:14 starvik
*! Whitespace cleanup
*!
*! Revision 1.8 2004/06/08 08:48:26 starvik
*! Removed unused code
*!
*! Revision 1.7 2004/05/28 09:26:59 starvik
*! Modified I2C initialization to work in 2.6.
*!
*! Revision 1.6 2004/05/14 07:58:03 starvik
*! Merge of changes from 2.4
*!
*! Revision 1.4 2002/12/11 13:13:57 starvik
*! Added arch/ to v10 specific includes
*! Added fix from Linux 2.4 in serial.c (flush_to_flip_buffer)
*!
*! Revision 1.3 2002/11/20 11:56:11 starvik
*! Merge of Linux 2.5.48
*!
*! Revision 1.2 2002/11/18 13:16:06 starvik
*! Linux 2.5 port of latest 2.4 drivers
*!
*! Revision 1.9 2002/10/31 15:32:26 starvik
*! Update Port B register and shadow even when running with hardware support
*! to avoid glitches when reading bits
*! Never set direction to out in i2c_inbyte
*! Removed incorrect clock toggling at end of i2c_inbyte
*!
*! Revision 1.8 2002/08/13 06:31:53 starvik
*! Made SDA and SCL line configurable
*! Modified i2c_inbyte to work with PCF8563
*!
*! Revision 1.7 2001/04/04 13:11:36 markusl
*! Updated according to review remarks
*!
*! Revision 1.6 2001/03/19 12:43:00 markusl
*! Made some symbols unstatic (used by the eeprom driver)
*!
*! Revision 1.5 2001/02/27 13:52:48 bjornw
*! malloc.h -> slab.h
*!
*! Revision 1.4 2001/02/15 07:17:40 starvik
*! Corrected usage if port_pb_i2c_shadow
*!
*! Revision 1.3 2001/01/26 17:55:13 bjornw
*! * Made I2C_USES_PB_NOT_PB_I2C a CONFIG option instead of assigning it
*! magically. Config.in needs to set it for the options that need it, like
*! Dallas 1302 support. Actually, it should be default since it screws up
*! the PB bits even if you don't use I2C..
*! * Include linux/config.h to get the above
*!
*! Revision 1.2 2001/01/18 15:49:30 bjornw
*! 2.4 port of I2C including some cleanups (untested of course)
*!
*! Revision 1.1 2001/01/18 15:35:25 bjornw
*! Verbatim copy of the Etrax i2c driver, 2.0 elinux version
*!
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999-2002 Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/
/* $Id: i2c.c,v 1.13 2005/03/07 13:13:07 starvik Exp $ */
/****************** INCLUDE FILES SECTION ***********************************/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/init.h>
#include <asm/etraxi2c.h>
#include <asm/system.h>
#include <asm/arch/svinto.h>
#include <asm/io.h>
#include <asm/delay.h>
#include <asm/arch/io_interface_mux.h>
#include "i2c.h"
/****************** I2C DEFINITION SECTION *************************/
#define D(x)
#define I2C_MAJOR 123 /* LOCAL/EXPERIMENTAL */
static const char i2c_name[] = "i2c";
#define CLOCK_LOW_TIME 8
#define CLOCK_HIGH_TIME 8
#define START_CONDITION_HOLD_TIME 8
#define STOP_CONDITION_HOLD_TIME 8
#define ENABLE_OUTPUT 0x01
#define ENABLE_INPUT 0x00
#define I2C_CLOCK_HIGH 1
#define I2C_CLOCK_LOW 0
#define I2C_DATA_HIGH 1
#define I2C_DATA_LOW 0
#ifdef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
/* Use PB and not PB_I2C */
#ifndef CONFIG_ETRAX_I2C_DATA_PORT
#define CONFIG_ETRAX_I2C_DATA_PORT 0
#endif
#ifndef CONFIG_ETRAX_I2C_CLK_PORT
#define CONFIG_ETRAX_I2C_CLK_PORT 1
#endif
#define SDABIT CONFIG_ETRAX_I2C_DATA_PORT
#define SCLBIT CONFIG_ETRAX_I2C_CLK_PORT
#define i2c_enable()
#define i2c_disable()
/* enable or disable output-enable, to select output or input on the i2c bus */
#define i2c_dir_out() \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 1)
#define i2c_dir_in() \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, SDABIT, 0)
/* control the i2c clock and data signals */
#define i2c_clk(x) \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SCLBIT, x)
#define i2c_data(x) \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, SDABIT, x)
/* read a bit from the i2c interface */
#define i2c_getbit() (((*R_PORT_PB_READ & (1 << SDABIT))) >> SDABIT)
#else
/* enable or disable the i2c interface */
#define i2c_enable() *R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_en))
#define i2c_disable() *R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_en))
/* enable or disable output-enable, to select output or input on the i2c bus */
#define i2c_dir_out() \
*R_PORT_PB_I2C = (port_pb_i2c_shadow &= ~IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 1);
#define i2c_dir_in() \
*R_PORT_PB_I2C = (port_pb_i2c_shadow |= IO_MASK(R_PORT_PB_I2C, i2c_oe_)); \
REG_SHADOW_SET(R_PORT_PB_DIR, port_pb_dir_shadow, 0, 0);
/* control the i2c clock and data signals */
#define i2c_clk(x) \
*R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
~IO_MASK(R_PORT_PB_I2C, i2c_clk)) | IO_FIELD(R_PORT_PB_I2C, i2c_clk, (x))); \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 1, x);
#define i2c_data(x) \
*R_PORT_PB_I2C = (port_pb_i2c_shadow = (port_pb_i2c_shadow & \
~IO_MASK(R_PORT_PB_I2C, i2c_d)) | IO_FIELD(R_PORT_PB_I2C, i2c_d, (x))); \
REG_SHADOW_SET(R_PORT_PB_DATA, port_pb_data_shadow, 0, x);
/* read a bit from the i2c interface */
#define i2c_getbit() (*R_PORT_PB_READ & 0x1)
#endif
/* use the kernels delay routine */
#define i2c_delay(usecs) udelay(usecs)
static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */
/****************** FUNCTION DEFINITION SECTION *************************/
/* generate i2c start condition */
void
i2c_start(void)
{
/*
* SCL=1 SDA=1
*/
i2c_dir_out();
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_data(I2C_DATA_HIGH);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
/*
* SCL=1 SDA=0
*/
i2c_data(I2C_DATA_LOW);
i2c_delay(START_CONDITION_HOLD_TIME);
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
}
/* generate i2c stop condition */
void
i2c_stop(void)
{
i2c_dir_out();
/*
* SCL=0 SDA=0
*/
i2c_clk(I2C_CLOCK_LOW);
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME*2);
/*
* SCL=1 SDA=0
*/
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME*2);
/*
* SCL=1 SDA=1
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(STOP_CONDITION_HOLD_TIME);
i2c_dir_in();
}
/* write a byte to the i2c interface */
void
i2c_outbyte(unsigned char x)
{
int i;
i2c_dir_out();
for (i = 0; i < 8; i++) {
if (x & 0x80) {
i2c_data(I2C_DATA_HIGH);
} else {
i2c_data(I2C_DATA_LOW);
}
i2c_delay(CLOCK_LOW_TIME/2);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
x <<= 1;
}
i2c_data(I2C_DATA_LOW);
i2c_delay(CLOCK_LOW_TIME/2);
/*
* enable input
*/
i2c_dir_in();
}
/* read a byte from the i2c interface */
unsigned char
i2c_inbyte(void)
{
unsigned char aBitByte = 0;
int i;
/* Switch off I2C to get bit */
i2c_disable();
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/2);
/* Get bit */
aBitByte |= i2c_getbit();
/* Enable I2C */
i2c_enable();
i2c_delay(CLOCK_LOW_TIME/2);
for (i = 1; i < 8; i++) {
aBitByte <<= 1;
/* Clock pulse */
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
/* Switch off I2C to get bit */
i2c_disable();
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/2);
/* Get bit */
aBitByte |= i2c_getbit();
/* Enable I2C */
i2c_enable();
i2c_delay(CLOCK_LOW_TIME/2);
}
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
/*
* we leave the clock low, getbyte is usually followed
* by sendack/nack, they assume the clock to be low
*/
i2c_clk(I2C_CLOCK_LOW);
return aBitByte;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_getack
*#
*# DESCRIPTION : checks if ack was received from ic2
*#
*#--------------------------------------------------------------------------*/
int
i2c_getack(void)
{
int ack = 1;
/*
* enable output
*/
i2c_dir_out();
/*
* Release data bus by setting
* data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* enable input
*/
i2c_dir_in();
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* generate ACK clock pulse
*/
i2c_clk(I2C_CLOCK_HIGH);
/*
* Use PORT PB instead of I2C
* for input. (I2C not working)
*/
i2c_clk(1);
i2c_data(1);
/*
* switch off I2C
*/
i2c_data(1);
i2c_disable();
i2c_dir_in();
/*
* now wait for ack
*/
i2c_delay(CLOCK_HIGH_TIME/2);
/*
* check for ack
*/
if(i2c_getbit())
ack = 0;
i2c_delay(CLOCK_HIGH_TIME/2);
if(!ack){
if(!i2c_getbit()) /* receiver pulld SDA low */
ack = 1;
i2c_delay(CLOCK_HIGH_TIME/2);
}
/*
* our clock is high now, make sure data is low
* before we enable our output. If we keep data high
* and enable output, we would generate a stop condition.
*/
i2c_data(I2C_DATA_LOW);
/*
* end clock pulse
*/
i2c_enable();
i2c_dir_out();
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_HIGH_TIME/4);
/*
* enable output
*/
i2c_dir_out();
/*
* remove ACK clock pulse
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME/2);
return ack;
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: I2C::sendAck
*#
*# DESCRIPTION : Send ACK on received data
*#
*#--------------------------------------------------------------------------*/
void
i2c_sendack(void)
{
/*
* enable output
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_out();
/*
* set ack pulse high
*/
i2c_data(I2C_DATA_LOW);
/*
* generate clock pulse
*/
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME/6);
/*
* reset data out
*/
i2c_data(I2C_DATA_HIGH);
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_in();
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_sendnack
*#
*# DESCRIPTION : Sends NACK on received data
*#
*#--------------------------------------------------------------------------*/
void
i2c_sendnack(void)
{
/*
* enable output
*/
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_out();
/*
* set data high
*/
i2c_data(I2C_DATA_HIGH);
/*
* generate clock pulse
*/
i2c_delay(CLOCK_HIGH_TIME/6);
i2c_clk(I2C_CLOCK_HIGH);
i2c_delay(CLOCK_HIGH_TIME);
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_LOW_TIME);
i2c_dir_in();
}
/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_writereg
*#
*# DESCRIPTION : Writes a value to an I2C device
*#
*#--------------------------------------------------------------------------*/
int
i2c_writereg(unsigned char theSlave, unsigned char theReg,
unsigned char theValue)
{
int error, cntr = 3;
unsigned long flags;
spin_lock(&i2c_lock);
do {
error = 0;
/*
* we don't like to be interrupted
*/
local_irq_save(flags);
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 |= 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);
spin_unlock(&i2c_lock);
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;
spin_lock(&i2c_lock);
do {
error = 0;
/*
* we don't like to be interrupted
*/
local_irq_save(flags);
/*
* 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--);
spin_unlock(&i2c_lock);
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 const struct file_operations i2c_fops = {
.owner = THIS_MODULE,
.ioctl = i2c_ioctl,
.open = i2c_open,
.release = i2c_release,
};
int __init
i2c_init(void)
{
static int res = 0;
static int first = 1;
if (!first) {
return res;
}
/* Setup and enable the Port B I2C interface */
#ifndef CONFIG_ETRAX_I2C_USES_PB_NOT_PB_I2C
if ((res = cris_request_io_interface(if_i2c, "I2C"))) {
printk(KERN_CRIT "i2c_init: Failed to get IO interface\n");
return res;
}
*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);
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));
#else
if ((res = cris_io_interface_allocate_pins(if_i2c,
'b',
CONFIG_ETRAX_I2C_DATA_PORT,
CONFIG_ETRAX_I2C_DATA_PORT))) {
printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C data port\n");
return res;
} else if ((res = cris_io_interface_allocate_pins(if_i2c,
'b',
CONFIG_ETRAX_I2C_CLK_PORT,
CONFIG_ETRAX_I2C_CLK_PORT))) {
cris_io_interface_free_pins(if_i2c,
'b',
CONFIG_ETRAX_I2C_DATA_PORT,
CONFIG_ETRAX_I2C_DATA_PORT);
printk(KERN_WARNING "i2c_init: Failed to get IO pin for I2C clk port\n");
}
#endif
return res;
}
static int __init
i2c_register(void)
{
int res;
res = i2c_init();
if (res < 0)
return res;
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) 1999-2004 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 ********************************/
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