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CRIS v32: New version of I2C driver.
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- Add i2c_write and i2c_read as functions.
- Use spinlocks for critical regions.
- Add config item to set I2C data and clock port.
- Put unneeded testcode inside #if 0.
- Remove CVS id tag.
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Jesper Nilsson committed Feb 8, 2008
1 parent 0f22950 commit 201ca54
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Showing 2 changed files with 187 additions and 14 deletions.
199 changes: 185 additions & 14 deletions arch/cris/arch-v32/drivers/i2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,10 @@
*!
*! ---------------------------------------------------------------------------
*!
*! (C) Copyright 1999-2002 Axis Communications AB, LUND, SWEDEN
*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/
/* $Id: i2c.c,v 1.2 2005/05/09 15:29:49 starvik Exp $ */

/****************** INCLUDE FILES SECTION ***********************************/

#include <linux/module.h>
Expand Down Expand Up @@ -79,6 +79,8 @@ static const char i2c_name[] = "i2c";

#define i2c_delay(usecs) udelay(usecs)

static DEFINE_SPINLOCK(i2c_lock); /* Protect directions etc */

/****************** VARIABLE SECTION ************************************/

static struct crisv32_iopin cris_i2c_clk;
Expand Down Expand Up @@ -252,6 +254,7 @@ i2c_getack(void)
* generate ACK clock pulse
*/
i2c_clk(I2C_CLOCK_HIGH);
#if 0
/*
* Use PORT PB instead of I2C
* for input. (I2C not working)
Expand All @@ -264,18 +267,20 @@ i2c_getack(void)
i2c_data(1);
i2c_disable();
i2c_dir_in();
#endif

/*
* now wait for ack
*/
i2c_delay(CLOCK_HIGH_TIME/2);
/*
* check for ack
*/
if(i2c_getbit())
if (i2c_getbit())
ack = 0;
i2c_delay(CLOCK_HIGH_TIME/2);
if(!ack){
if(!i2c_getbit()) /* receiver pulled SDA low */
if (!ack) {
if (!i2c_getbit()) /* receiver pulld SDA low */
ack = 1;
i2c_delay(CLOCK_HIGH_TIME/2);
}
Expand All @@ -285,13 +290,15 @@ i2c_getack(void)
* before we enable our output. If we keep data high
* and enable output, we would generate a stop condition.
*/
#if 0
i2c_data(I2C_DATA_LOW);

/*
* end clock pulse
*/
i2c_enable();
i2c_dir_out();
#endif
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_HIGH_TIME/4);
/*
Expand Down Expand Up @@ -373,6 +380,137 @@ i2c_sendnack(void)
i2c_dir_in();
}

/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_write
*#
*# DESCRIPTION : Writes a value to an I2C device
*#
*#--------------------------------------------------------------------------*/
int
i2c_write(unsigned char theSlave, void *data, size_t nbytes)
{
int error, cntr = 3;
unsigned char bytes_wrote = 0;
unsigned char value;
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;
/*
* send data
*/
for (bytes_wrote = 0; bytes_wrote < nbytes; bytes_wrote++) {
memcpy(&value, data + bytes_wrote, sizeof value);
i2c_outbyte(value);
/*
* 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_read
*#
*# DESCRIPTION : Reads a value from an I2C device
*#
*#--------------------------------------------------------------------------*/
int
i2c_read(unsigned char theSlave, void *data, size_t nbytes)
{
unsigned char b = 0;
unsigned char bytes_read = 0;
int error, cntr = 3;
unsigned long flags;

spin_lock(&i2c_lock);

do {
error = 0;
memset(data, 0, nbytes);
/*
* we don't like to be interrupted
*/
local_irq_save(flags);
/*
* generate start condition
*/
i2c_start();
/*
* send slave address
*/
i2c_outbyte((theSlave | 0x01));
/*
* wait for ack
*/
if (!i2c_getack())
error = 1;
/*
* fetch data
*/
for (bytes_read = 0; bytes_read < nbytes; bytes_read++) {
b = i2c_inbyte();
memcpy(data + bytes_read, &b, sizeof b);

if (bytes_read < (nbytes - 1))
i2c_sendack();
}
/*
* last received byte needs to be nacked
* instead of acked
*/
i2c_sendnack();
/*
* end sequence
*/
i2c_stop();
/*
* enable interrupt again
*/
local_irq_restore(flags);
} while (error && cntr--);

spin_unlock(&i2c_lock);

return -error;
}

/*#---------------------------------------------------------------------------
*#
*# FUNCTION NAME: i2c_writereg
Expand All @@ -387,6 +525,8 @@ i2c_writereg(unsigned char theSlave, unsigned char theReg,
int error, cntr = 3;
unsigned long flags;

spin_lock(&i2c_lock);

do {
error = 0;
/*
Expand Down Expand Up @@ -431,11 +571,12 @@ i2c_writereg(unsigned char theSlave, unsigned char theReg,
* enable interrupt again
*/
local_irq_restore(flags);

} while(error && cntr--);

i2c_delay(CLOCK_LOW_TIME);

spin_unlock(&i2c_lock);

return -error;
}

Expand All @@ -453,6 +594,8 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)
int error, cntr = 3;
unsigned long flags;

spin_lock(&i2c_lock);

do {
error = 0;
/*
Expand Down Expand Up @@ -482,7 +625,7 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)
* now it's time to wait for ack
*/
if(!i2c_getack())
error = 1;
error |= 2;
/*
* repeat start condition
*/
Expand All @@ -496,7 +639,7 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)
* wait for ack
*/
if(!i2c_getack())
error = 1;
error |= 4;
/*
* fetch register
*/
Expand All @@ -517,6 +660,8 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)

} while(error && cntr--);

spin_unlock(&i2c_lock);

return b;
}

Expand Down Expand Up @@ -583,12 +728,37 @@ static const struct file_operations i2c_fops = {
int __init
i2c_init(void)
{
int res;
static int res;
static int first = 1;

/* Setup and enable the Port B I2C interface */
if (!first)
return res;

first = 0;

/* Setup and enable the DATA and CLK pins */

res = crisv32_io_get_name(&cris_i2c_data,
CONFIG_ETRAX_V32_I2C_DATA_PORT);
if (res < 0)
return res;

res = crisv32_io_get_name(&cris_i2c_clk, CONFIG_ETRAX_V32_I2C_CLK_PORT);
crisv32_io_set_dir(&cris_i2c_clk, crisv32_io_dir_out);

return res;
}

crisv32_io_get_name(&cris_i2c_data, CONFIG_ETRAX_I2C_DATA_PORT);
crisv32_io_get_name(&cris_i2c_clk, CONFIG_ETRAX_I2C_CLK_PORT);

int __init
i2c_register(void)
{

int res;

res = i2c_init();
if (res < 0)
return res;

/* register char device */

Expand All @@ -598,13 +768,14 @@ i2c_init(void)
return res;
}

printk(KERN_INFO "I2C driver v2.2, (c) 1999-2001 Axis Communications AB\n");
printk(KERN_INFO
"I2C driver v2.2, (c) 1999-2007 Axis Communications AB\n");

return 0;
}

/* this makes sure that i2c_init is called during boot */

module_init(i2c_init);
module_init(i2c_register);

/****************** END OF FILE i2c.c ********************************/
2 changes: 2 additions & 0 deletions arch/cris/arch-v32/drivers/i2c.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@

/* High level I2C actions */
int __init i2c_init(void);
int i2c_write(unsigned char theSlave, void *data, size_t nbytes);
int i2c_read(unsigned char theSlave, void *data, size_t nbytes);
int i2c_writereg(unsigned char theSlave, unsigned char theReg, unsigned char theValue);
unsigned char i2c_readreg(unsigned char theSlave, unsigned char theReg);

Expand Down

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