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u-boot-brain/drivers/i2c/soft_i2c.c
Tom Rini 83d290c56f SPDX: Convert all of our single license tags to Linux Kernel style 
When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-07 09:34:12 -04:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2009
* Heiko Schocher, DENX Software Engineering, hs@denx.de.
* Changes for multibus/multiadapter I2C support.
*
* (C) Copyright 2001, 2002
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* This has been changed substantially by Gerald Van Baren, Custom IDEAS,
* vanbaren@cideas.com. It was heavily influenced by LiMon, written by
* Neil Russell.
*
* NOTE: This driver should be converted to driver model before June 2017.
* Please see doc/driver-model/i2c-howto.txt for instructions.
*/
#include <common.h>
#if defined(CONFIG_AT91FAMILY)
#include <asm/io.h>
#include <asm/arch/hardware.h>
#include <asm/arch/at91_pio.h>
#ifdef CONFIG_ATMEL_LEGACY
#include <asm/arch/gpio.h>
#endif
#endif
#include <i2c.h>
#if defined(CONFIG_SOFT_I2C_GPIO_SCL)
# include <asm/gpio.h>
# ifndef I2C_GPIO_SYNC
# define I2C_GPIO_SYNC
# endif
# ifndef I2C_INIT
# define I2C_INIT \
do { \
gpio_request(CONFIG_SOFT_I2C_GPIO_SCL, "soft_i2c"); \
gpio_request(CONFIG_SOFT_I2C_GPIO_SDA, "soft_i2c"); \
} while (0)
# endif
# ifndef I2C_ACTIVE
# define I2C_ACTIVE do { } while (0)
# endif
# ifndef I2C_TRISTATE
# define I2C_TRISTATE do { } while (0)
# endif
# ifndef I2C_READ
# define I2C_READ gpio_get_value(CONFIG_SOFT_I2C_GPIO_SDA)
# endif
# ifndef I2C_SDA
# define I2C_SDA(bit) \
do { \
if (bit) \
gpio_direction_input(CONFIG_SOFT_I2C_GPIO_SDA); \
else \
gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SDA, 0); \
I2C_GPIO_SYNC; \
} while (0)
# endif
# ifndef I2C_SCL
# define I2C_SCL(bit) \
do { \
gpio_direction_output(CONFIG_SOFT_I2C_GPIO_SCL, bit); \
I2C_GPIO_SYNC; \
} while (0)
# endif
# ifndef I2C_DELAY
# define I2C_DELAY udelay(5) /* 1/4 I2C clock duration */
# endif
#endif
/* #define DEBUG_I2C */
DECLARE_GLOBAL_DATA_PTR;
#ifndef I2C_SOFT_DECLARATIONS
# define I2C_SOFT_DECLARATIONS
#endif
#if !defined(CONFIG_SYS_I2C_SOFT_SPEED)
#define CONFIG_SYS_I2C_SOFT_SPEED CONFIG_SYS_I2C_SPEED
#endif
#if !defined(CONFIG_SYS_I2C_SOFT_SLAVE)
#define CONFIG_SYS_I2C_SOFT_SLAVE CONFIG_SYS_I2C_SLAVE
#endif
/*-----------------------------------------------------------------------
* Definitions
*/
#define RETRIES 0
#define I2C_ACK 0 /* PD_SDA level to ack a byte */
#define I2C_NOACK 1 /* PD_SDA level to noack a byte */
#ifdef DEBUG_I2C
#define PRINTD(fmt,args...) do { \
printf (fmt ,##args); \
} while (0)
#else
#define PRINTD(fmt,args...)
#endif
/*-----------------------------------------------------------------------
* Local functions
*/
#if !defined(CONFIG_SYS_I2C_INIT_BOARD)
static void send_reset (void);
#endif
static void send_start (void);
static void send_stop (void);
static void send_ack (int);
static int write_byte (uchar byte);
static uchar read_byte (int);
#if !defined(CONFIG_SYS_I2C_INIT_BOARD)
/*-----------------------------------------------------------------------
* Send a reset sequence consisting of 9 clocks with the data signal high
* to clock any confused device back into an idle state. Also send a
* <stop> at the end of the sequence for belts & suspenders.
*/
static void send_reset(void)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
int j;
I2C_SCL(1);
I2C_SDA(1);
#ifdef I2C_INIT
I2C_INIT;
#endif
I2C_TRISTATE;
for(j = 0; j < 9; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
}
send_stop();
I2C_TRISTATE;
}
#endif
/*-----------------------------------------------------------------------
* START: High -> Low on SDA while SCL is High
*/
static void send_start(void)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
I2C_DELAY;
I2C_SDA(1);
I2C_ACTIVE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_SDA(0);
I2C_DELAY;
}
/*-----------------------------------------------------------------------
* STOP: Low -> High on SDA while SCL is High
*/
static void send_stop(void)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(0);
I2C_ACTIVE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_SDA(1);
I2C_DELAY;
I2C_TRISTATE;
}
/*-----------------------------------------------------------------------
* ack should be I2C_ACK or I2C_NOACK
*/
static void send_ack(int ack)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
I2C_SCL(0);
I2C_DELAY;
I2C_ACTIVE;
I2C_SDA(ack);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
I2C_SCL(0);
I2C_DELAY;
}
/*-----------------------------------------------------------------------
* Send 8 bits and look for an acknowledgement.
*/
static int write_byte(uchar data)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
int j;
int nack;
I2C_ACTIVE;
for(j = 0; j < 8; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(data & 0x80);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
data <<= 1;
}
/*
* Look for an <ACK>(negative logic) and return it.
*/
I2C_SCL(0);
I2C_DELAY;
I2C_SDA(1);
I2C_TRISTATE;
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
I2C_DELAY;
nack = I2C_READ;
I2C_SCL(0);
I2C_DELAY;
I2C_ACTIVE;
return(nack); /* not a nack is an ack */
}
/*-----------------------------------------------------------------------
* if ack == I2C_ACK, ACK the byte so can continue reading, else
* send I2C_NOACK to end the read.
*/
static uchar read_byte(int ack)
{
I2C_SOFT_DECLARATIONS /* intentional without ';' */
int data;
int j;
/*
* Read 8 bits, MSB first.
*/
I2C_TRISTATE;
I2C_SDA(1);
data = 0;
for(j = 0; j < 8; j++) {
I2C_SCL(0);
I2C_DELAY;
I2C_SCL(1);
I2C_DELAY;
data <<= 1;
data |= I2C_READ;
I2C_DELAY;
}
send_ack(ack);
return(data);
}
/*-----------------------------------------------------------------------
* Initialization
*/
static void soft_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
{
#if defined(CONFIG_SYS_I2C_INIT_BOARD)
/* call board specific i2c bus reset routine before accessing the */
/* environment, which might be in a chip on that bus. For details */
/* about this problem see doc/I2C_Edge_Conditions. */
i2c_init_board();
#else
/*
* WARNING: Do NOT save speed in a static variable: if the
* I2C routines are called before RAM is initialized (to read
* the DIMM SPD, for instance), RAM won't be usable and your
* system will crash.
*/
send_reset ();
#endif
}
/*-----------------------------------------------------------------------
* Probe to see if a chip is present. Also good for checking for the
* completion of EEPROM writes since the chip stops responding until
* the write completes (typically 10mSec).
*/
static int soft_i2c_probe(struct i2c_adapter *adap, uint8_t addr)
{
int rc;
/*
* perform 1 byte write transaction with just address byte
* (fake write)
*/
send_start();
rc = write_byte ((addr << 1) | 0);
send_stop();
return (rc ? 1 : 0);
}
/*-----------------------------------------------------------------------
* Read bytes
*/
static int soft_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
int alen, uchar *buffer, int len)
{
int shift;
PRINTD("i2c_read: chip %02X addr %02X alen %d buffer %p len %d\n",
chip, addr, alen, buffer, len);
#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
/*
* EEPROM chips that implement "address overflow" are ones
* like Catalyst 24WC04/08/16 which has 9/10/11 bits of
* address and the extra bits end up in the "chip address"
* bit slots. This makes a 24WC08 (1Kbyte) chip look like
* four 256 byte chips.
*
* Note that we consider the length of the address field to
* still be one byte because the extra address bits are
* hidden in the chip address.
*/
chip |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
PRINTD("i2c_read: fix addr_overflow: chip %02X addr %02X\n",
chip, addr);
#endif
/*
* Do the addressing portion of a write cycle to set the
* chip's address pointer. If the address length is zero,
* don't do the normal write cycle to set the address pointer,
* there is no address pointer in this chip.
*/
send_start();
if(alen > 0) {
if(write_byte(chip << 1)) { /* write cycle */
send_stop();
PRINTD("i2c_read, no chip responded %02X\n", chip);
return(1);
}
shift = (alen-1) * 8;
while(alen-- > 0) {
if(write_byte(addr >> shift)) {
PRINTD("i2c_read, address not <ACK>ed\n");
return(1);
}
shift -= 8;
}
/* Some I2C chips need a stop/start sequence here,
* other chips don't work with a full stop and need
* only a start. Default behaviour is to send the
* stop/start sequence.
*/
#ifdef CONFIG_SOFT_I2C_READ_REPEATED_START
send_start();
#else
send_stop();
send_start();
#endif
}
/*
* Send the chip address again, this time for a read cycle.
* Then read the data. On the last byte, we do a NACK instead
* of an ACK(len == 0) to terminate the read.
*/
write_byte((chip << 1) | 1); /* read cycle */
while(len-- > 0) {
*buffer++ = read_byte(len == 0);
}
send_stop();
return(0);
}
/*-----------------------------------------------------------------------
* Write bytes
*/
static int soft_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
int alen, uchar *buffer, int len)
{
int shift, failures = 0;
PRINTD("i2c_write: chip %02X addr %02X alen %d buffer %p len %d\n",
chip, addr, alen, buffer, len);
send_start();
if(write_byte(chip << 1)) { /* write cycle */
send_stop();
PRINTD("i2c_write, no chip responded %02X\n", chip);
return(1);
}
shift = (alen-1) * 8;
while(alen-- > 0) {
if(write_byte(addr >> shift)) {
PRINTD("i2c_write, address not <ACK>ed\n");
return(1);
}
shift -= 8;
}
while(len-- > 0) {
if(write_byte(*buffer++)) {
failures++;
}
}
send_stop();
return(failures);
}
/*
* Register soft i2c adapters
*/
U_BOOT_I2C_ADAP_COMPLETE(soft00, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED, CONFIG_SYS_I2C_SOFT_SLAVE,
0)
#if defined(I2C_SOFT_DECLARATIONS2)
U_BOOT_I2C_ADAP_COMPLETE(soft01, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_2,
CONFIG_SYS_I2C_SOFT_SLAVE_2,
1)
#endif
#if defined(I2C_SOFT_DECLARATIONS3)
U_BOOT_I2C_ADAP_COMPLETE(soft02, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_3,
CONFIG_SYS_I2C_SOFT_SLAVE_3,
2)
#endif
#if defined(I2C_SOFT_DECLARATIONS4)
U_BOOT_I2C_ADAP_COMPLETE(soft03, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_4,
CONFIG_SYS_I2C_SOFT_SLAVE_4,
3)
#endif
#if defined(I2C_SOFT_DECLARATIONS5)
U_BOOT_I2C_ADAP_COMPLETE(soft04, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_5,
CONFIG_SYS_I2C_SOFT_SLAVE_5,
4)
#endif
#if defined(I2C_SOFT_DECLARATIONS6)
U_BOOT_I2C_ADAP_COMPLETE(soft05, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_6,
CONFIG_SYS_I2C_SOFT_SLAVE_6,
5)
#endif
#if defined(I2C_SOFT_DECLARATIONS7)
U_BOOT_I2C_ADAP_COMPLETE(soft06, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_7,
CONFIG_SYS_I2C_SOFT_SLAVE_7,
6)
#endif
#if defined(I2C_SOFT_DECLARATIONS8)
U_BOOT_I2C_ADAP_COMPLETE(soft07, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_8,
CONFIG_SYS_I2C_SOFT_SLAVE_8,
7)
#endif
#if defined(I2C_SOFT_DECLARATIONS9)
U_BOOT_I2C_ADAP_COMPLETE(soft08, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_9,
CONFIG_SYS_I2C_SOFT_SLAVE_9,
8)
#endif
#if defined(I2C_SOFT_DECLARATIONS10)
U_BOOT_I2C_ADAP_COMPLETE(soft09, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_10,
CONFIG_SYS_I2C_SOFT_SLAVE_10,
9)
#endif
#if defined(I2C_SOFT_DECLARATIONS11)
U_BOOT_I2C_ADAP_COMPLETE(soft10, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_11,
CONFIG_SYS_I2C_SOFT_SLAVE_11,
10)
#endif
#if defined(I2C_SOFT_DECLARATIONS12)
U_BOOT_I2C_ADAP_COMPLETE(soft11, soft_i2c_init, soft_i2c_probe,
soft_i2c_read, soft_i2c_write, NULL,
CONFIG_SYS_I2C_SOFT_SPEED_12,
CONFIG_SYS_I2C_SOFT_SLAVE_12,
11)
#endif
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