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/*
* i2c.c - driver for ADI TWI/I2C
*
* Copyright (c) 2006-2014 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#include <common.h>
#include <i2c.h>
#include <asm/clock.h>
#include <asm/twi.h>
#include <asm/io.h>
static struct twi_regs *i2c_get_base(struct i2c_adapter *adap);
/* Every register is 32bit aligned, but only 16bits in size */
#define ureg(name) u16 name; u16 __pad_##name;
struct twi_regs {
ureg(clkdiv);
ureg(control);
ureg(slave_ctl);
ureg(slave_stat);
ureg(slave_addr);
ureg(master_ctl);
ureg(master_stat);
ureg(master_addr);
ureg(int_stat);
ureg(int_mask);
ureg(fifo_ctl);
ureg(fifo_stat);
char __pad[0x50];
ureg(xmt_data8);
ureg(xmt_data16);
ureg(rcv_data8);
ureg(rcv_data16);
};
#undef ureg
#ifdef TWI_CLKDIV
#define TWI0_CLKDIV TWI_CLKDIV
# ifdef CONFIG_SYS_MAX_I2C_BUS
# undef CONFIG_SYS_MAX_I2C_BUS
# endif
#define CONFIG_SYS_MAX_I2C_BUS 1
#endif
/*
* The way speed is changed into duty often results in integer truncation
* with 50% duty, so we'll force rounding up to the next duty by adding 1
* to the max. In practice this will get us a speed of something like
* 385 KHz. The other limit is easy to handle as it is only 8 bits.
*/
#define I2C_SPEED_MAX 400000
#define I2C_SPEED_TO_DUTY(speed) (5000000 / (speed))
#define I2C_DUTY_MAX (I2C_SPEED_TO_DUTY(I2C_SPEED_MAX) + 1)
#define I2C_DUTY_MIN 0xff /* 8 bit limited */
#define SYS_I2C_DUTY I2C_SPEED_TO_DUTY(CONFIG_SYS_I2C_SPEED)
/* Note: duty is inverse of speed, so the comparisons below are correct */
#if SYS_I2C_DUTY < I2C_DUTY_MAX || SYS_I2C_DUTY > I2C_DUTY_MIN
# error "The I2C hardware can only operate 20KHz - 400KHz"
#endif
/* All transfers are described by this data structure */
struct i2c_msg {
u8 flags;
#define I2C_M_COMBO 0x4
#define I2C_M_STOP 0x2
#define I2C_M_READ 0x1
int len; /* msg length */
u8 *buf; /* pointer to msg data */
int alen; /* addr length */
u8 *abuf; /* addr buffer */
};
/* Allow msec timeout per ~byte transfer */
#define I2C_TIMEOUT 10
/**
* wait_for_completion - manage the actual i2c transfer
* @msg: the i2c msg
*/
static int wait_for_completion(struct twi_regs *twi, struct i2c_msg *msg)
{
u16 int_stat, ctl;
ulong timebase = get_timer(0);
do {
int_stat = readw(&twi->int_stat);
if (int_stat & XMTSERV) {
writew(XMTSERV, &twi->int_stat);
if (msg->alen) {
writew(*(msg->abuf++), &twi->xmt_data8);
--msg->alen;
} else if (!(msg->flags & I2C_M_COMBO) && msg->len) {
writew(*(msg->buf++), &twi->xmt_data8);
--msg->len;
} else {
ctl = readw(&twi->master_ctl);
if (msg->flags & I2C_M_COMBO)
writew(ctl | RSTART | MDIR,
&twi->master_ctl);
else
writew(ctl | STOP, &twi->master_ctl);
}
}
if (int_stat & RCVSERV) {
writew(RCVSERV, &twi->int_stat);
if (msg->len) {
*(msg->buf++) = readw(&twi->rcv_data8);
--msg->len;
} else if (msg->flags & I2C_M_STOP) {
ctl = readw(&twi->master_ctl);
writew(ctl | STOP, &twi->master_ctl);
}
}
if (int_stat & MERR) {
writew(MERR, &twi->int_stat);
return msg->len;
}
if (int_stat & MCOMP) {
writew(MCOMP, &twi->int_stat);
if (msg->flags & I2C_M_COMBO && msg->len) {
ctl = readw(&twi->master_ctl);
ctl = (ctl & ~RSTART) |
(min(msg->len, 0xff) << 6) | MEN | MDIR;
writew(ctl, &twi->master_ctl);
} else
break;
}
/* If we were able to do something, reset timeout */
if (int_stat)
timebase = get_timer(0);
} while (get_timer(timebase) < I2C_TIMEOUT);
return msg->len;
}
static int i2c_transfer(struct i2c_adapter *adap, uint8_t chip, uint addr,
int alen, uint8_t *buffer, int len, uint8_t flags)
{
struct twi_regs *twi = i2c_get_base(adap);
int ret;
u16 ctl;
uchar addr_buffer[] = {
(addr >> 0),
(addr >> 8),
(addr >> 16),
};
struct i2c_msg msg = {
.flags = flags | (len >= 0xff ? I2C_M_STOP : 0),
.buf = buffer,
.len = len,
.abuf = addr_buffer,
.alen = alen,
};
/* wait for things to settle */
while (readw(&twi->master_stat) & BUSBUSY)
if (ctrlc())
return 1;
/* Set Transmit device address */
writew(chip, &twi->master_addr);
/* Clear the FIFO before starting things */
writew(XMTFLUSH | RCVFLUSH, &twi->fifo_ctl);
writew(0, &twi->fifo_ctl);
/* prime the pump */
if (msg.alen) {
len = (msg.flags & I2C_M_COMBO) ? msg.alen : msg.alen + len;
writew(*(msg.abuf++), &twi->xmt_data8);
--msg.alen;
} else if (!(msg.flags & I2C_M_READ) && msg.len) {
writew(*(msg.buf++), &twi->xmt_data8);
--msg.len;
}
/* clear int stat */
writew(-1, &twi->master_stat);
writew(-1, &twi->int_stat);
writew(0, &twi->int_mask);
/* Master enable */
ctl = readw(&twi->master_ctl);
ctl = (ctl & FAST) | (min(len, 0xff) << 6) | MEN |
((msg.flags & I2C_M_READ) ? MDIR : 0);
writew(ctl, &twi->master_ctl);
/* process the rest */
ret = wait_for_completion(twi, &msg);
if (ret) {
ctl = readw(&twi->master_ctl) & ~MEN;
writew(ctl, &twi->master_ctl);
ctl = readw(&twi->control) & ~TWI_ENA;
writew(ctl, &twi->control);
ctl = readw(&twi->control) | TWI_ENA;
writew(ctl, &twi->control);
}
return ret;
}
static uint adi_i2c_setspeed(struct i2c_adapter *adap, uint speed)
{
struct twi_regs *twi = i2c_get_base(adap);
u16 clkdiv = I2C_SPEED_TO_DUTY(speed);
/* Set TWI interface clock */
if (clkdiv < I2C_DUTY_MAX || clkdiv > I2C_DUTY_MIN)
return -1;
clkdiv = (clkdiv << 8) | (clkdiv & 0xff);
writew(clkdiv, &twi->clkdiv);
/* Don't turn it on */
writew(speed > 100000 ? FAST : 0, &twi->master_ctl);
return 0;
}
static void adi_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
{
struct twi_regs *twi = i2c_get_base(adap);
u16 prescale = ((get_i2c_clk() / 1000 / 1000 + 5) / 10) & 0x7F;
/* Set TWI internal clock as 10MHz */
writew(prescale, &twi->control);
/* Set TWI interface clock as specified */
i2c_set_bus_speed(speed);
/* Enable it */
writew(TWI_ENA | prescale, &twi->control);
}
static int adi_i2c_read(struct i2c_adapter *adap, uint8_t chip,
uint addr, int alen, uint8_t *buffer, int len)
{
return i2c_transfer(adap, chip, addr, alen, buffer,
len, alen ? I2C_M_COMBO : I2C_M_READ);
}
static int adi_i2c_write(struct i2c_adapter *adap, uint8_t chip,
uint addr, int alen, uint8_t *buffer, int len)
{
return i2c_transfer(adap, chip, addr, alen, buffer, len, 0);
}
static int adi_i2c_probe(struct i2c_adapter *adap, uint8_t chip)
{
u8 byte;
return adi_i2c_read(adap, chip, 0, 0, &byte, 1);
}
static struct twi_regs *i2c_get_base(struct i2c_adapter *adap)
{
switch (adap->hwadapnr) {
#if CONFIG_SYS_MAX_I2C_BUS > 2
case 2:
return (struct twi_regs *)TWI2_CLKDIV;
#endif
#if CONFIG_SYS_MAX_I2C_BUS > 1
case 1:
return (struct twi_regs *)TWI1_CLKDIV;
#endif
case 0:
return (struct twi_regs *)TWI0_CLKDIV;
default:
printf("wrong hwadapnr: %d\n", adap->hwadapnr);
}
return NULL;
}
U_BOOT_I2C_ADAP_COMPLETE(adi_i2c0, adi_i2c_init, adi_i2c_probe,
adi_i2c_read, adi_i2c_write,
adi_i2c_setspeed,
CONFIG_SYS_I2C_SPEED,
0,
0)
#if CONFIG_SYS_MAX_I2C_BUS > 1
U_BOOT_I2C_ADAP_COMPLETE(adi_i2c1, adi_i2c_init, adi_i2c_probe,
adi_i2c_read, adi_i2c_write,
adi_i2c_setspeed,
CONFIG_SYS_I2C_SPEED,
0,
1)
#endif
#if CONFIG_SYS_MAX_I2C_BUS > 2
U_BOOT_I2C_ADAP_COMPLETE(adi_i2c2, adi_i2c_init, adi_i2c_probe,
adi_i2c_read, adi_i2c_write,
adi_i2c_setspeed,
CONFIG_SYS_I2C_SPEED,
0,
2)
#endif
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