/*
* Copyright (c) 2012 Intel Corporation. All rights reserved.
* Copyright (c) 2006 - 2012 QLogic Corporation. All rights reserved.
* Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
* General Public License (GPL) Version 2, available from the file
* COPYING in the main directory of this source tree, or the
* OpenIB.org BSD license below:
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
*
* - Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* - Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/vmalloc.h>
#include "qib.h"
/*
* QLogic_IB "Two Wire Serial Interface" driver.
* Originally written for a not-quite-i2c serial eeprom, which is
* still used on some supported boards. Later boards have added a
* variety of other uses, most board-specific, so the bit-boffing
* part has been split off to this file, while the other parts
* have been moved to chip-specific files.
*
* We have also dropped all pretense of fully generic (e.g. pretend
* we don't know whether '1' is the higher voltage) interface, as
* the restrictions of the generic i2c interface (e.g. no access from
* driver itself) make it unsuitable for this use.
*/
#define READ_CMD 1
#define WRITE_CMD 0
/**
* i2c_wait_for_writes - wait for a write
* @dd: the qlogic_ib device
*
* We use this instead of udelay directly, so we can make sure
* that previous register writes have been flushed all the way
* to the chip. Since we are delaying anyway, the cost doesn't
* hurt, and makes the bit twiddling more regular
*/
static void i2c_wait_for_writes(struct qib_devdata *dd)
{
/*
* implicit read of EXTStatus is as good as explicit
* read of scratch, if all we want to do is flush
* writes.
*/
dd->f_gpio_mod(dd, 0, 0, 0);
rmb(); /* inlined, so prevent compiler reordering */
}
/*
* QSFP modules are allowed to hold SCL low for 500uSec. Allow twice that
* for "almost compliant" modules
*/
#define SCL_WAIT_USEC 1000
/* BUF_WAIT is time bus must be free between STOP or ACK and to next START.
* Should be 20, but some chips need more.
*/
#define TWSI_BUF_WAIT_USEC 60
static void scl_out(struct qib_devdata *dd, u8 bit)
{
u32 mask;
udelay(1);
mask = 1UL << dd->gpio_scl_num;
/* SCL is meant to be bare-drain, so never set "OUT", just DIR */
dd->f_gpio_mod(dd, 0, bit ? 0 : mask, mask);
/*
* Allow for slow slaves by simple
* delay for falling edge, sampling on rise.
*/
if (!bit)
udelay(2);
else {
int rise_usec;
for (rise_usec = SCL_WAIT_USEC; rise_usec > 0; rise_usec -= 2) {
if (mask & dd->f_gpio_mod(dd, 0, 0, 0))
break;
udelay(2);
}
if (rise_usec <= 0)
qib_dev_err(dd, "SCL interface stuck low > %d uSec\n",
SCL_WAIT_USEC);
}
i2c_wait_for_writes(dd);
}
static void sda_out(struct qib_devdata *dd, u8 bit)
{
u32 mask;
mask = 1UL << dd->gpio_sda_num;
/* SDA is meant to be bare-drain, so never set "OUT", just DIR */
dd->f_gpio_mod(dd, 0, bit ? 0 : mask, mask);
i2c_wait_for_writes(dd);
udelay(2);
}
static u8 sda_in(struct qib_devdata *dd, int wait)
{
int bnum;
u32 read_val, mask;
bnum = dd->gpio_sda_num;
mask = (1UL << bnum);
/* SDA is meant to be bare-drain, so never set "OUT", just DIR */
dd->f_gpio_mod(dd, 0, 0, mask);
read_val = dd->f_gpio_mod(dd, 0, 0, 0);
if (wait)
i2c_wait_for_writes(dd);
return (read_val & mask) >> bnum;
}
/**
* i2c_ackrcv - see if ack following write is true
* @dd: the qlogic_ib device
*/
static int i2c_ackrcv(struct qib_devdata *dd)
{
u8 ack_received;
/* AT ENTRY SCL = LOW */
/* change direction, ignore data */
ack_received = sda_in(dd, 1);
scl_out(dd, 1);
ack_received = sda_in(dd, 1) == 0;
scl_out(dd, 0);
return ack_received;
}
static void stop_cmd(struct qib_devdata *dd);
/**
* rd_byte - read a byte, sending STOP on last, else ACK
* @dd: the qlogic_ib device
*
* Returns byte shifted out of device
*/
static int rd_byte(struct qib_devdata *dd, int last)
{
int bit_cntr, data;
data = 0;
for (bit_cntr = 7; bit_cntr >= 0; --bit_cntr) {
data <<= 1;
scl_out(dd, 1);
data |= sda_in(dd, 0);
scl_out(dd, 0);
}
if (last) {
scl_out(dd, 1);
stop_cmd(dd);
} else {
sda_out(dd, 0);
scl_out(dd, 1);
scl_out(dd, 0);
sda_out(dd, 1);
}
return data;
}
/**
* wr_byte - write a byte, one bit at a time
* @dd: the qlogic_ib device
* @data: the byte to write
*
* Returns 0 if we got the following ack, otherwise 1
*/
static int wr_byte(struct qib_devdata *dd, u8 data)
{
int bit_cntr;
u8 bit;
for (bit_cntr = 7; bit_cntr >= 0; bit_cntr--) {
bit = (data >> bit_cntr) & 1;
sda_out(dd, bit);
scl_out(dd, 1);
scl_out(dd, 0);
}
return (!i2c_ackrcv(dd)) ? 1 : 0;
}
/*
* issue TWSI start sequence:
* (both clock/data high, clock high, data low while clock is high)
*/
static void start_seq(struct qib_devdata *dd)
{
sda_out(dd, 1);
scl_out(dd, 1);
sda_out(dd, 0);
udelay(1);
scl_out(dd, 0);
}
/**
* stop_seq - transmit the stop sequence
* @dd: the qlogic_ib device
*
* (both clock/data low, clock high, data high while clock is high)
*/
static void stop_seq(struct qib_devdata *dd)
{
scl_out(dd, 0);
sda_out(dd, 0);
scl_out(dd, 1);
sda_out(dd, 1);
}
/**
* stop_cmd - transmit the stop condition
* @dd: the qlogic_ib device
*
* (both clock/data low, clock high, data high while clock is high)
*/
static void stop_cmd(struct qib_devdata *dd)
{
stop_seq(dd);
udelay(TWSI_BUF_WAIT_USEC);
}
/**
* qib_twsi_reset - reset I2C communication
* @dd: the qlogic_ib device
*/
int qib_twsi_reset(struct qib_devdata *dd)
{
int clock_cycles_left = 9;
int was_high = 0;
u32 pins, mask;
/* Both SCL and SDA should be high. If not, there
* is something wrong.
*/
mask = (1UL << dd->gpio_scl_num) | (1UL << dd->gpio_sda_num);
/*
* Force pins to desired innocuous state.
* This is the default power-on state with out=0 and dir=0,
* So tri-stated and should be floating high (barring HW problems)
*/
dd->f_gpio_mod(dd, 0, 0, mask);
/*
* Clock nine times to get all listeners into a sane state.
* If SDA does not go high at any point, we are wedged.
* One vendor recommends then issuing START followed by STOP.
* we cannot use our "normal" functions to do that, because
* if SCL drops between them, another vendor's part will
* wedge, dropping SDA and keeping it low forever, at the end of
* the next transaction (even if it was not the device addressed).
* So our START and STOP take place with SCL held high.
*/
while (clock_cycles_left--) {
scl_out(dd, 0);
scl_out(dd, 1);
/* Note if SDA is high, but keep clocking to sync slave */
was_high |= sda_in(dd, 0);
}
if (was_high) {
/*
* We saw a high, which we hope means the slave is sync'd.
* Issue START, STOP, pause for T_BUF.
*/
pins = dd->f_gpio_mod(dd, 0, 0, 0);
if ((pins & mask) != mask)
qib_dev_err(dd, "GPIO pins not at rest: %d\n",
pins & mask);
/* Drop SDA to issue START */
udelay(1); /* Guarantee .6 uSec setup */
sda_out(dd, 0);
udelay(1); /* Guarantee .6 uSec hold */
/* At this point, SCL is high, SDA low. Raise SDA for STOP */
sda_out(dd, 1);
udelay(TWSI_BUF_WAIT_USEC);
}
return !was_high;
}
#define QIB_TWSI_START 0x100
#define QIB_TWSI_STOP 0x200
/* Write byte to TWSI, optionally prefixed with START or suffixed with
* STOP.
* returns 0 if OK (ACK received), else != 0
*/
static int qib_twsi_wr(struct qib_devdata *dd, int data, int flags)
{
int ret = 1;
if (flags & QIB_TWSI_START)
start_seq(dd);
ret = wr_byte(dd, data); /* Leaves SCL low (from i2c_ackrcv()) */
if (flags & QIB_TWSI_STOP)
stop_cmd(dd);
return ret;
}
/* Added functionality for IBA7220-based cards */
#define QIB_TEMP_DEV 0x98
/*
* qib_twsi_blk_rd
* Formerly called qib_eeprom_internal_read, and only used for eeprom,
* but now the general interface for data transfer from twsi devices.
* One vestige of its former role is that it recognizes a device
* QIB_TWSI_NO_DEV and does the correct operation for the legacy part,
* which responded to all TWSI device codes, interpreting them as
* address within device. On all other devices found on board handled by
* this driver, the device is followed by a one-byte "address" which selects
* the "register" or "offset" within the device from which data should
* be read.
*/
int qib_twsi_blk_rd(struct qib_devdata *dd, int dev, int addr,
void *buffer, int len)
{
int ret;
u8 *bp = buffer;
ret = 1;
if (dev == QIB_TWSI_NO_DEV) {
/* legacy not-really-I2C */
addr = (addr << 1) | READ_CMD;
ret = qib_twsi_wr(dd, addr, QIB_TWSI_START);
} else {
/* Actual I2C */
ret = qib_twsi_wr(dd, dev | WRITE_CMD, QIB_TWSI_START);
if (ret) {
stop_cmd(dd);
ret = 1;
goto bail;
}
/*
* SFF spec claims we do _not_ stop after the addr
* but simply issue a start with the "read" dev-addr.
* Since we are implicitely waiting for ACK here,
* we need t_buf (nominally 20uSec) before that start,
* and cannot rely on the delay built in to the STOP
*/
ret = qib_twsi_wr(dd, addr, 0);
udelay(TWSI_BUF_WAIT_USEC);
if (ret) {
qib_dev_err(dd,
"Failed to write interface read addr %02X\n",
addr);
ret = 1;
goto bail;
}
ret = qib_twsi_wr(dd, dev | READ_CMD, QIB_TWSI_START);
}
if (ret) {
stop_cmd(dd);
ret = 1;
goto bail;
}
/*
* block devices keeps clocking data out as long as we ack,
* automatically incrementing the address. Some have "pages"
* whose boundaries will not be crossed, but the handling
* of these is left to the caller, who is in a better
* position to know.
*/
while (len-- > 0) {
/*
* Get and store data, sending ACK if length remaining,
* else STOP
*/
*bp++ = rd_byte(dd, !len);
}
ret = 0;
bail:
return ret;
}
/*
* qib_twsi_blk_wr
* Formerly called qib_eeprom_internal_write, and only used for eeprom,
* but now the general interface for data transfer to twsi devices.
* One vestige of its former role is that it recognizes a device
* QIB_TWSI_NO_DEV and does the correct operation for the legacy part,
* which responded to all TWSI device codes, interpreting them as
* address within device. On all other devices found on board handled by
* this driver, the device is followed by a one-byte "address" which selects
* the "register" or "offset" within the device to which data should
* be written.
*/
int qib_twsi_blk_wr(struct qib_devdata *dd, int dev, int addr,
const void *buffer, int len)
{
int sub_len;
const u8 *bp = buffer;
int max_wait_time, i;
int ret = 1;
while (len > 0) {
if (dev == QIB_TWSI_NO_DEV) {
if (qib_twsi_wr(dd, (addr << 1) | WRITE_CMD,
QIB_TWSI_START)) {
goto failed_write;
}
} else {
/* Real I2C */
if (qib_twsi_wr(dd, dev | WRITE_CMD, QIB_TWSI_START))
goto failed_write;
ret = qib_twsi_wr(dd, addr, 0);
if (ret) {
qib_dev_err(dd,
"Failed to write interface write addr %02X\n",
addr);
goto failed_write;
}
}
sub_len = min(len, 4);
addr += sub_len;
len -= sub_len;
for (i = 0; i < sub_len; i++)
if (qib_twsi_wr(dd, *bp++, 0))
goto failed_write;
stop_cmd(dd);
/*
* Wait for write complete by waiting for a successful
* read (the chip replies with a zero after the write
* cmd completes, and before it writes to the eeprom.
* The startcmd for the read will fail the ack until
* the writes have completed. We do this inline to avoid
* the debug prints that are in the real read routine
* if the startcmd fails.
* We also use the proper device address, so it doesn't matter
* whether we have real eeprom_dev. Legacy likes any address.
*/
max_wait_time = 100;
while (qib_twsi_wr(dd, dev | READ_CMD, QIB_TWSI_START)) {
stop_cmd(dd);
if (!--max_wait_time)
goto failed_write;
}
/* now read (and ignore) the resulting byte */
rd_byte(dd, 1);
}
ret = 0;
goto bail;
failed_write:
stop_cmd(dd);
ret = 1;
bail:
return ret;
}