diff options
Diffstat (limited to 'arch/cris/arch-v32/drivers/i2c.c')
| -rw-r--r-- | arch/cris/arch-v32/drivers/i2c.c | 611 |
1 files changed, 611 insertions, 0 deletions
diff --git a/arch/cris/arch-v32/drivers/i2c.c b/arch/cris/arch-v32/drivers/i2c.c new file mode 100644 index 000000000000..440c20a94963 --- /dev/null +++ b/arch/cris/arch-v32/drivers/i2c.c @@ -0,0 +1,611 @@ +/*!*************************************************************************** +*! +*! 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. +*| June 23 2003 Pieter Grimmerink Added 'i2c_sendnack'. i2c_readreg now +*| generates nack on last received byte, +*| instead of ack. +*| i2c_getack changed data level while clock +*| was high, causing DS75 to see a stop condition +*! +*! --------------------------------------------------------------------------- +*! +*! (C) Copyright 1999-2002 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> +#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 <linux/config.h> + +#include <asm/etraxi2c.h> + +#include <asm/system.h> +#include <asm/io.h> +#include <asm/delay.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 + +#define i2c_enable() +#define i2c_disable() + +/* enable or disable output-enable, to select output or input on the i2c bus */ + +#define i2c_dir_out() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_out) +#define i2c_dir_in() crisv32_io_set_dir(&cris_i2c_data, crisv32_io_dir_in) + +/* control the i2c clock and data signals */ + +#define i2c_clk(x) crisv32_io_set(&cris_i2c_clk, x) +#define i2c_data(x) crisv32_io_set(&cris_i2c_data, x) + +/* read a bit from the i2c interface */ + +#define i2c_getbit() crisv32_io_rd(&cris_i2c_data) + +#define i2c_delay(usecs) udelay(usecs) + +/****************** VARIABLE SECTION ************************************/ + +static struct crisv32_iopin cris_i2c_clk; +static struct crisv32_iopin cris_i2c_data; + +/****************** 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; + + 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); + + 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); + /* + * 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_sendnack(); + /* + * 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) +{ + int res; + + /* Setup and enable the Port B I2C interface */ + + crisv32_io_get_name(&cris_i2c_data, CONFIG_ETRAX_I2C_DATA_PORT); + crisv32_io_get_name(&cris_i2c_clk, CONFIG_ETRAX_I2C_CLK_PORT); + + /* register char device */ + + 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_init is called during boot */ + +module_init(i2c_init); + +/****************** END OF FILE i2c.c ********************************/ |