u-boot/drivers/i2c/mvtwsi.c
Hans de Goede 2072e72629 mvtwsi: Remove unnecessary twsi_baud_rate and twsi_slave_address globals
These are used only once, so their is no need to have them global.

This also stops mvtwsi from using any bss vars making it easier to use
before dram init (to talk to the pmic to set the dram voltage).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
2014-05-14 12:59:12 +02:00

394 lines
11 KiB
C

/*
* Driver for the TWSI (i2c) controller found on the Marvell
* orion5x and kirkwood SoC families.
*
* Author: Albert Aribaud <albert.u.boot@aribaud.net>
* Copyright (c) 2010 Albert Aribaud.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <i2c.h>
#include <asm/errno.h>
#include <asm/io.h>
/*
* include a file that will provide CONFIG_I2C_MVTWSI_BASE
* and possibly other settings
*/
#if defined(CONFIG_ORION5X)
#include <asm/arch/orion5x.h>
#elif defined(CONFIG_KIRKWOOD)
#include <asm/arch/kirkwood.h>
#else
#error Driver mvtwsi not supported by SoC or board
#endif
/*
* TWSI register structure
*/
struct mvtwsi_registers {
u32 slave_address;
u32 data;
u32 control;
union {
u32 status; /* when reading */
u32 baudrate; /* when writing */
};
u32 xtnd_slave_addr;
u32 reserved[2];
u32 soft_reset;
};
/*
* Control register fields
*/
#define MVTWSI_CONTROL_ACK 0x00000004
#define MVTWSI_CONTROL_IFLG 0x00000008
#define MVTWSI_CONTROL_STOP 0x00000010
#define MVTWSI_CONTROL_START 0x00000020
#define MVTWSI_CONTROL_TWSIEN 0x00000040
#define MVTWSI_CONTROL_INTEN 0x00000080
/*
* Status register values -- only those expected in normal master
* operation on non-10-bit-address devices; whatever status we don't
* expect in nominal conditions (bus errors, arbitration losses,
* missing ACKs...) we just pass back to the caller as an error
* code.
*/
#define MVTWSI_STATUS_START 0x08
#define MVTWSI_STATUS_REPEATED_START 0x10
#define MVTWSI_STATUS_ADDR_W_ACK 0x18
#define MVTWSI_STATUS_DATA_W_ACK 0x28
#define MVTWSI_STATUS_ADDR_R_ACK 0x40
#define MVTWSI_STATUS_ADDR_R_NAK 0x48
#define MVTWSI_STATUS_DATA_R_ACK 0x50
#define MVTWSI_STATUS_DATA_R_NAK 0x58
#define MVTWSI_STATUS_IDLE 0xF8
/*
* The single instance of the controller we'll be dealing with
*/
static struct mvtwsi_registers *twsi =
(struct mvtwsi_registers *) CONFIG_I2C_MVTWSI_BASE;
/*
* Returned statuses are 0 for success and nonzero otherwise.
* Currently, cmd_i2c and cmd_eeprom do not interpret an error status.
* Thus to ease debugging, the return status contains some debug info:
* - bits 31..24 are error class: 1 is timeout, 2 is 'status mismatch'.
* - bits 23..16 are the last value of the control register.
* - bits 15..8 are the last value of the status register.
* - bits 7..0 are the expected value of the status register.
*/
#define MVTWSI_ERROR_WRONG_STATUS 0x01
#define MVTWSI_ERROR_TIMEOUT 0x02
#define MVTWSI_ERROR(ec, lc, ls, es) (((ec << 24) & 0xFF000000) | \
((lc << 16) & 0x00FF0000) | ((ls<<8) & 0x0000FF00) | (es & 0xFF))
/*
* Wait for IFLG to raise, or return 'timeout'; then if status is as expected,
* return 0 (ok) or return 'wrong status'.
*/
static int twsi_wait(int expected_status)
{
int control, status;
int timeout = 1000;
do {
control = readl(&twsi->control);
if (control & MVTWSI_CONTROL_IFLG) {
status = readl(&twsi->status);
if (status == expected_status)
return 0;
else
return MVTWSI_ERROR(
MVTWSI_ERROR_WRONG_STATUS,
control, status, expected_status);
}
udelay(10); /* one clock cycle at 100 kHz */
} while (timeout--);
status = readl(&twsi->status);
return MVTWSI_ERROR(
MVTWSI_ERROR_TIMEOUT, control, status, expected_status);
}
/*
* These flags are ORed to any write to the control register
* They allow global setting of TWSIEN and ACK.
* By default none are set.
* twsi_start() sets TWSIEN (in case the controller was disabled)
* twsi_recv() sets ACK or resets it depending on expected status.
*/
static u8 twsi_control_flags = MVTWSI_CONTROL_TWSIEN;
/*
* Assert the START condition, either in a single I2C transaction
* or inside back-to-back ones (repeated starts).
*/
static int twsi_start(int expected_status)
{
/* globally set TWSIEN in case it was not */
twsi_control_flags |= MVTWSI_CONTROL_TWSIEN;
/* assert START */
writel(twsi_control_flags | MVTWSI_CONTROL_START, &twsi->control);
/* wait for controller to process START */
return twsi_wait(expected_status);
}
/*
* Send a byte (i2c address or data).
*/
static int twsi_send(u8 byte, int expected_status)
{
/* put byte in data register for sending */
writel(byte, &twsi->data);
/* clear any pending interrupt -- that'll cause sending */
writel(twsi_control_flags, &twsi->control);
/* wait for controller to receive byte and check ACK */
return twsi_wait(expected_status);
}
/*
* Receive a byte.
* Global mvtwsi_control_flags variable says if we should ack or nak.
*/
static int twsi_recv(u8 *byte)
{
int expected_status, status;
/* compute expected status based on ACK bit in global control flags */
if (twsi_control_flags & MVTWSI_CONTROL_ACK)
expected_status = MVTWSI_STATUS_DATA_R_ACK;
else
expected_status = MVTWSI_STATUS_DATA_R_NAK;
/* acknowledge *previous state* and launch receive */
writel(twsi_control_flags, &twsi->control);
/* wait for controller to receive byte and assert ACK or NAK */
status = twsi_wait(expected_status);
/* if we did receive expected byte then store it */
if (status == 0)
*byte = readl(&twsi->data);
/* return status */
return status;
}
/*
* Assert the STOP condition.
* This is also used to force the bus back in idle (SDA=SCL=1).
*/
static int twsi_stop(int status)
{
int control, stop_status;
int timeout = 1000;
/* assert STOP */
control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
writel(control, &twsi->control);
/* wait for IDLE; IFLG won't rise so twsi_wait() is no use. */
do {
stop_status = readl(&twsi->status);
if (stop_status == MVTWSI_STATUS_IDLE)
break;
udelay(10); /* one clock cycle at 100 kHz */
} while (timeout--);
control = readl(&twsi->control);
if (stop_status != MVTWSI_STATUS_IDLE)
if (status == 0)
status = MVTWSI_ERROR(
MVTWSI_ERROR_TIMEOUT,
control, status, MVTWSI_STATUS_IDLE);
return status;
}
/*
* Ugly formula to convert m and n values to a frequency comes from
* TWSI specifications
*/
#define TWSI_FREQUENCY(m, n) \
(CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n)))
/*
* Reset controller.
* Called at end of i2c_init unsuccessful i2c transactions.
* Controller reset also resets the baud rate and slave address, so
* re-establish them.
*/
static void twsi_reset(u8 baud_rate, u8 slave_address)
{
/* ensure controller will be enabled by any twsi*() function */
twsi_control_flags = MVTWSI_CONTROL_TWSIEN;
/* reset controller */
writel(0, &twsi->soft_reset);
/* wait 2 ms -- this is what the Marvell LSP does */
udelay(20000);
/* set baud rate */
writel(baud_rate, &twsi->baudrate);
/* set slave address even though we don't use it */
writel(slave_address, &twsi->slave_address);
writel(0, &twsi->xtnd_slave_addr);
/* assert STOP but don't care for the result */
(void) twsi_stop(0);
}
/*
* I2C init called by cmd_i2c when doing 'i2c reset'.
* Sets baud to the highest possible value not exceeding requested one.
*/
void i2c_init(int requested_speed, int slaveadd)
{
int tmp_speed, highest_speed, n, m;
int baud = 0x44; /* baudrate at controller reset */
/* use actual speed to collect progressively higher values */
highest_speed = 0;
/* compute m, n setting for highest speed not above requested speed */
for (n = 0; n < 8; n++) {
for (m = 0; m < 16; m++) {
tmp_speed = TWSI_FREQUENCY(m, n);
if ((tmp_speed <= requested_speed)
&& (tmp_speed > highest_speed)) {
highest_speed = tmp_speed;
baud = (m << 3) | n;
}
}
}
/* reset controller */
twsi_reset(baud, slaveadd);
}
/*
* Begin I2C transaction with expected start status, at given address.
* Common to i2c_probe, i2c_read and i2c_write.
* Expected address status will derive from direction bit (bit 0) in addr.
*/
static int i2c_begin(int expected_start_status, u8 addr)
{
int status, expected_addr_status;
/* compute expected address status from direction bit in addr */
if (addr & 1) /* reading */
expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK;
else /* writing */
expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
/* assert START */
status = twsi_start(expected_start_status);
/* send out the address if the start went well */
if (status == 0)
status = twsi_send(addr, expected_addr_status);
/* return ok or status of first failure to caller */
return status;
}
/*
* I2C probe called by cmd_i2c when doing 'i2c probe'.
* Begin read, nak data byte, end.
*/
int i2c_probe(uchar chip)
{
u8 dummy_byte;
int status;
/* begin i2c read */
status = i2c_begin(MVTWSI_STATUS_START, (chip << 1) | 1);
/* dummy read was accepted: receive byte but NAK it. */
if (status == 0)
status = twsi_recv(&dummy_byte);
/* Stop transaction */
twsi_stop(0);
/* return 0 or status of first failure */
return status;
}
/*
* I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
* Begin write, send address byte(s), begin read, receive data bytes, end.
*
* NOTE: some EEPROMS want a stop right before the second start, while
* some will choke if it is there. Deciding which we should do is eeprom
* stuff, not i2c, but at the moment the APIs won't let us put it in
* cmd_eeprom, so we have to choose here, and for the moment that'll be
* a repeated start without a preceding stop.
*/
int i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
{
int status;
/* begin i2c write to send the address bytes */
status = i2c_begin(MVTWSI_STATUS_START, (dev << 1));
/* send addr bytes */
while ((status == 0) && alen--)
status = twsi_send(addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK);
/* begin i2c read to receive eeprom data bytes */
if (status == 0)
status = i2c_begin(
MVTWSI_STATUS_REPEATED_START, (dev << 1) | 1);
/* prepare ACK if at least one byte must be received */
if (length > 0)
twsi_control_flags |= MVTWSI_CONTROL_ACK;
/* now receive actual bytes */
while ((status == 0) && length--) {
/* reset NAK if we if no more to read now */
if (length == 0)
twsi_control_flags &= ~MVTWSI_CONTROL_ACK;
/* read current byte */
status = twsi_recv(data++);
}
/* Stop transaction */
status = twsi_stop(status);
/* return 0 or status of first failure */
return status;
}
/*
* I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
* Begin write, send address byte(s), send data bytes, end.
*/
int i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
{
int status;
/* begin i2c write to send the eeprom adress bytes then data bytes */
status = i2c_begin(MVTWSI_STATUS_START, (dev << 1));
/* send addr bytes */
while ((status == 0) && alen--)
status = twsi_send(addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK);
/* send data bytes */
while ((status == 0) && (length-- > 0))
status = twsi_send(*(data++), MVTWSI_STATUS_DATA_W_ACK);
/* Stop transaction */
status = twsi_stop(status);
/* return 0 or status of first failure */
return status;
}
/*
* Bus set routine: we only support bus 0.
*/
int i2c_set_bus_num(unsigned int bus)
{
if (bus > 0) {
return -1;
}
return 0;
}
/*
* Bus get routine: hard-return bus 0.
*/
unsigned int i2c_get_bus_num(void)
{
return 0;
}