diff options
Diffstat (limited to 'drivers/infiniband/hw/qib/qib_twsi.c')
| -rw-r--r-- | drivers/infiniband/hw/qib/qib_twsi.c | 501 |
1 files changed, 501 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/qib/qib_twsi.c b/drivers/infiniband/hw/qib/qib_twsi.c new file mode 100644 index 000000000..f56986644 --- /dev/null +++ b/drivers/infiniband/hw/qib/qib_twsi.c @@ -0,0 +1,501 @@ +/* + * 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; +} |