[PATCH 21/47] New version of CRISv32 I2C driver.

Jesper Nilsson
2007-12-06T12:48:37Z

- 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.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
---
arch/cris/arch-v32/drivers/i2c.c | 199 +++++++++++++++++++++++++++++++++++---
arch/cris/arch-v32/drivers/i2c.h | 2 +
2 files changed, 187 insertions(+), 14 deletions(-)

diff --git a/arch/cris/arch-v32/drivers/i2c.c b/arch/cris/arch-v32/drivers/i2c.c
index f1edd2e..4eda323 100644
--- a/arch/cris/arch-v32/drivers/i2c.c
+++ b/arch/cris/arch-v32/drivers/i2c.c
@@ -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>
@@ -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;
@@ -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)
@@ -264,6 +267,8 @@ i2c_getack(void)
i2c_data(1);
i2c_disable();
i2c_dir_in();
+#endif
+
/*
* now wait for ack
*/
@@ -271,11 +276,11 @@ i2c_getack(void)
/*
* 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);
}
@@ -285,6 +290,7 @@ 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);

/*
@@ -292,6 +298,7 @@ i2c_getack(void)
*/
i2c_enable();
i2c_dir_out();
+#endif
i2c_clk(I2C_CLOCK_LOW);
i2c_delay(CLOCK_HIGH_TIME/4);
/*
@@ -375,6 +382,137 @@ i2c_sendnack(void)

/*#---------------------------------------------------------------------------
*#
+*# 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
*#
*# DESCRIPTION : Writes a value to an I2C device
@@ -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;
/*
@@ -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;
}

@@ -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;
/*
@@ -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
*/
@@ -496,7 +639,7 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)
* wait for ack
*/
if(!i2c_getack())
- error = 1;
+ error |= 4;
/*
* fetch register
*/
@@ -517,6 +660,8 @@ i2c_readreg(unsigned char theSlave, unsigned char theReg)

} while(error && cntr--);

+ spin_unlock(&i2c_lock);
+
return b;
}

@@ -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 */

@@ -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 ********************************/
diff --git a/arch/cris/arch-v32/drivers/i2c.h b/arch/cris/arch-v32/drivers/i2c.h
index bfe1a13..c073cf4 100644
--- a/arch/cris/arch-v32/drivers/i2c.h
+++ b/arch/cris/arch-v32/drivers/i2c.h
@@ -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);

--
1.5.3.6.970.gd25430