cregit-Linux how code gets into the kernel

Release 4.14 arch/cris/arch-v10/drivers/i2c.c

// SPDX-License-Identifier: GPL-2.0
/*!***************************************************************************
*!
*! 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
*!
*! (C) Copyright 1999-2007 Axis Communications AB, LUND, SWEDEN
*!
*!***************************************************************************/

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

#include <linux/module.h>
#include <linux/sched.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 <arch/svinto.h>
#include <asm/io.h>
#include <asm/delay.h>
#include <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); }

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/* 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(); }

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/* 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(); }

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Linus Torvalds9696.00%266.67%
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/* 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; }

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Linus Torvalds8763.04%133.33%
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Andrew Morton64.35%133.33%
Total138100.00%3100.00%

/*#--------------------------------------------------------------------------- *# *# 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; }

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Linus Torvalds15196.18%266.67%
Andrew Morton63.82%133.33%
Total157100.00%3100.00%

/*#--------------------------------------------------------------------------- *# *# 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(); }

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/*#--------------------------------------------------------------------------- *# *# 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(); }

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/*#--------------------------------------------------------------------------- *# *# 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; }

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Linus Torvalds12387.23%250.00%
Mikael Starvik1812.77%250.00%
Total141100.00%4100.00%

/*#--------------------------------------------------------------------------- *# *# 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_sendnack(); /* * end sequence */ i2c_stop(); /* * enable interrupt again */ local_irq_restore(flags); } while(error && cntr--); spin_unlock(&i2c_lock); return b; }

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Linus Torvalds14087.50%233.33%
Mikael Starvik1811.25%233.33%
Andrew Morton10.62%116.67%
Jesper Nilsson10.62%116.67%
Total160100.00%6100.00%


static int i2c_open(struct inode *inode, struct file *filp) { return 0; }

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static int i2c_release(struct inode *inode, struct file *filp) { return 0; }

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Linus Torvalds19100.00%1100.00%
Total19100.00%1100.00%

/* Main device API. ioctl's to write or read to/from i2c registers. */
static long i2c_ioctl(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(KERN_DEBUG "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(KERN_DEBUG "i2cr %d %d ", I2C_ARGSLAVE(arg), I2C_ARGREG(arg))); val = i2c_readreg(I2C_ARGSLAVE(arg), I2C_ARGREG(arg)); D(printk(KERN_DEBUG "= %d\n", val)); return val; } default: return -EINVAL; } return 0; }

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Linus Torvalds15196.79%266.67%
Jesper Nilsson53.21%133.33%
Total156100.00%3100.00%

static const struct file_operations i2c_fops = { .owner = THIS_MODULE, .unlocked_ioctl = i2c_ioctl, .open = i2c_open, .release = i2c_release, .llseek = noop_llseek, };
int __init i2c_init(void) { static int res = 0; static int first = 1; if (!first) { return res; } first = 0; /* 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; }

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Mikael Starvik11652.73%125.00%
Linus Torvalds9744.09%125.00%
Jesper Nilsson41.82%125.00%
Andrew Morton31.36%125.00%
Total220100.00%4100.00%


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; }

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Linus Torvalds3757.81%250.00%
Andrew Morton1523.44%125.00%
Mikael Starvik1218.75%125.00%
Total64100.00%4100.00%

/* this makes sure that i2c_register is called during boot */ module_init(i2c_register); /****************** END OF FILE i2c.c ********************************/

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Linus Torvalds132978.36%215.38%
Mikael Starvik25114.80%215.38%
Andrew Morton875.13%17.69%
Jesper Nilsson140.83%430.77%
Art Haas80.47%17.69%
Arnd Bergmann50.29%17.69%
Arjan van de Ven10.06%17.69%
Greg Kroah-Hartman10.06%17.69%
Total1696100.00%13100.00%
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