u-boot/drivers/i2c/mvtwsi.c
Albert Aribaud 306563a773 i2c: rewrite mvtwsi, support orion5x and kirkwood
This rewrite of the mvtwsi driver is 25% smaller and much
faster and simpler than the previous code.

Signed-off-by: Albert Aribaud <albert.aribaud@free.fr>
Acked-by: Prafulla Wadaskar<prafulla@marvell.com>
Acked-by: Heiko Schocher<hs@denx.de>
2010-08-30 14:10:35 +02:00

428 lines
12 KiB
C

/*
* Driver for the TWSI (i2c) controller found on the Marvell
* orion5x and kirkwood SoC families.
*
* Author: Albert Aribaud <albert.aribaud@free.fr>
* Copyright (c) 2010 Albert Aribaud.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#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) \
((u8) (CONFIG_SYS_TCLK / (10 * (m + 1) * 2 * (1 << n))))
/*
* These are required to be reprogrammed before enabling the controller
* because a reset loses them.
* Default values come from the spec, but a twsi_reset will change them.
* twsi_slave_address left uninitialized lest checkpatch.pl complains.
*/
/* Baudrate generator: m (bits 7..4) =4, n (bits 3..0) =4 */
static u8 twsi_baud_rate = 0x44; /* baudrate at controller reset */
/* Default frequency corresponding to default m=4, n=4 */
static u8 twsi_actual_speed = TWSI_FREQUENCY(4, 4);
/* Default slave address is 0 (so is an uninitialized static) */
static u8 twsi_slave_address;
/*
* 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(void)
{
/* 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(twsi_baud_rate, &twsi->baudrate);
/* set slave address even though we don't use it */
writel(twsi_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;
}
}
}
/* save baud rate and slave for later calls to twsi_reset */
twsi_baud_rate = baud;
twsi_actual_speed = highest_speed;
twsi_slave_address = slaveadd;
/* reset controller */
twsi_reset();
}
/*
* 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;
}