[PATCH 33/41] IB/hfi1: add QSFP twsi routines

Mike Marciniszyn
2015-06-11T23:11:26Z

drivers/infiniband/hw/hfi1/twsi.c | 518 +++++++++++++++++++++++++++++++++++++
drivers/infiniband/hw/hfi1/twsi.h | 68 +++++
2 files changed, 586 insertions(+)
create mode 100644 drivers/infiniband/hw/hfi1/twsi.c
create mode 100644 drivers/infiniband/hw/hfi1/twsi.h

diff --git a/drivers/infiniband/hw/hfi1/twsi.c b/drivers/infiniband/hw/hfi1/twsi.c
new file mode 100644
index 0000000..ea54fd2
--- /dev/null
+++ b/drivers/infiniband/hw/hfi1/twsi.c
@@ -0,0 +1,518 @@
+/*
+ *
+ * This file is provided under a dual BSD/GPLv2 license. When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * BSD LICENSE
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * 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.
+ * - Neither the name of Intel Corporation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/pci.h>
+#include <linux/vmalloc.h>
+
+#include "hfi.h"
+#include "twsi.h"
+
+/*
+ * "Two Wire Serial Interface" support.
+ *
+ * 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 hfi1_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 hfi1_devdata *dd, u32 target)
+{
+ /*
+ * implicit read of EXTStatus is as good as explicit
+ * read of scratch, if all we want to do is flush
+ * writes.
+ */
+ hfi1_gpio_mod(dd, target, 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 hfi1_devdata *dd, u32 target, u8 bit)
+{
+ u32 mask;
+
+ udelay(1);
+
+ mask = QSFP_HFI0_I2CCLK;
+
+ /* SCL is meant to be bare-drain, so never set "OUT", just DIR */
+ hfi1_gpio_mod(dd, target, 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 & hfi1_gpio_mod(dd, target, 0, 0, 0))
+ break;
+ udelay(2);
+ }
+ if (rise_usec <= 0)
+ dd_dev_err(dd, "SCL interface stuck low > %d uSec\n",
+ SCL_WAIT_USEC);
+ }
+ i2c_wait_for_writes(dd, target);
+}
+
+static void sda_out(struct hfi1_devdata *dd, u32 target, u8 bit)
+{
+ u32 mask;
+
+ mask = QSFP_HFI0_I2CDAT;
+
+ /* SDA is meant to be bare-drain, so never set "OUT", just DIR */
+ hfi1_gpio_mod(dd, target, 0, bit ? 0 : mask, mask);
+
+ i2c_wait_for_writes(dd, target);
+ udelay(2);
+}
+
+static u8 sda_in(struct hfi1_devdata *dd, u32 target, int wait)
+{
+ u32 read_val, mask;
+
+ mask = QSFP_HFI0_I2CDAT;
+ /* SDA is meant to be bare-drain, so never set "OUT", just DIR */
+ hfi1_gpio_mod(dd, target, 0, 0, mask);
+ read_val = hfi1_gpio_mod(dd, target, 0, 0, 0);
+ if (wait)
+ i2c_wait_for_writes(dd, target);
+ return (read_val & mask) >> GPIO_SDA_NUM;
+}
+
+/**
+ * i2c_ackrcv - see if ack following write is true
+ * @dd: the hfi1_ib device
+ */
+static int i2c_ackrcv(struct hfi1_devdata *dd, u32 target)
+{
+ u8 ack_received;
+
+ /* AT ENTRY SCL = LOW */
+ /* change direction, ignore data */
+ ack_received = sda_in(dd, target, 1);
+ scl_out(dd, target, 1);
+ ack_received = sda_in(dd, target, 1) == 0;
+ scl_out(dd, target, 0);
+ return ack_received;
+}
+
+static void stop_cmd(struct hfi1_devdata *dd, u32 target);
+
+/**
+ * rd_byte - read a byte, sending STOP on last, else ACK
+ * @dd: the hfi1_ib device
+ *
+ * Returns byte shifted out of device
+ */
+static int rd_byte(struct hfi1_devdata *dd, u32 target, int last)
+{
+ int bit_cntr, data;
+
+ data = 0;
+
+ for (bit_cntr = 7; bit_cntr >= 0; --bit_cntr) {
+ data <<= 1;
+ scl_out(dd, target, 1);
+ data |= sda_in(dd, target, 0);
+ scl_out(dd, target, 0);
+ }
+ if (last) {
+ scl_out(dd, target, 1);
+ stop_cmd(dd, target);
+ } else {
+ sda_out(dd, target, 0);
+ scl_out(dd, target, 1);
+ scl_out(dd, target, 0);
+ sda_out(dd, target, 1);
+ }
+ return data;
+}
+
+/**
+ * wr_byte - write a byte, one bit at a time
+ * @dd: the hfi1_ib device
+ * @data: the byte to write
+ *
+ * Returns 0 if we got the following ack, otherwise 1
+ */
+static int wr_byte(struct hfi1_devdata *dd, u32 target, u8 data)
+{
+ int bit_cntr;
+ u8 bit;
+
+ for (bit_cntr = 7; bit_cntr >= 0; bit_cntr--) {
+ bit = (data >> bit_cntr) & 1;
+ sda_out(dd, target, bit);
+ scl_out(dd, target, 1);
+ scl_out(dd, target, 0);
+ }
+ return (!i2c_ackrcv(dd, target)) ? 1 : 0;
+}
+
+/*
+ * issue TWSI start sequence:
+ * (both clock/data high, clock high, data low while clock is high)
+ */
+static void start_seq(struct hfi1_devdata *dd, u32 target)
+{
+ sda_out(dd, target, 1);
+ scl_out(dd, target, 1);
+ sda_out(dd, target, 0);
+ udelay(1);
+ scl_out(dd, target, 0);
+}
+
+/**
+ * stop_seq - transmit the stop sequence
+ * @dd: the hfi1_ib device
+ *
+ * (both clock/data low, clock high, data high while clock is high)
+ */
+static void stop_seq(struct hfi1_devdata *dd, u32 target)
+{
+ scl_out(dd, target, 0);
+ sda_out(dd, target, 0);
+ scl_out(dd, target, 1);
+ sda_out(dd, target, 1);
+}
+
+/**
+ * stop_cmd - transmit the stop condition
+ * @dd: the hfi1_ib device
+ *
+ * (both clock/data low, clock high, data high while clock is high)
+ */
+static void stop_cmd(struct hfi1_devdata *dd, u32 target)
+{
+ stop_seq(dd, target);
+ udelay(TWSI_BUF_WAIT_USEC);
+}
+
+/**
+ * hfi1_twsi_reset - reset I2C communication
+ * @dd: the hfi1_ib device
+ */
+
+int hfi1_twsi_reset(struct hfi1_devdata *dd, u32 target)
+{
+ 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 = QSFP_HFI0_I2CCLK | QSFP_HFI0_I2CDAT;
+
+ /*
+ * 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)
+ */
+ hfi1_gpio_mod(dd, target, 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, target, 0);
+ scl_out(dd, target, 1);
+ /* Note if SDA is high, but keep clocking to sync slave */
+ was_high |= sda_in(dd, target, 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 = hfi1_gpio_mod(dd, target, 0, 0, 0);
+ if ((pins & mask) != mask)
+ dd_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, target, 0);
+ udelay(1); /* Guarantee .6 uSec hold */
+ /* At this point, SCL is high, SDA low. Raise SDA for STOP */
+ sda_out(dd, target, 1);
+ udelay(TWSI_BUF_WAIT_USEC);
+ }
+
+ return !was_high;
+}
+
+#define HFI1_TWSI_START 0x100
+#define HFI1_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 twsi_wr(struct hfi1_devdata *dd, u32 target, int data, int flags)
+{
+ int ret = 1;
+
+ if (flags & HFI1_TWSI_START)
+ start_seq(dd, target);
+
+ /* Leaves SCL low (from i2c_ackrcv()) */
+ ret = wr_byte(dd, target, data);
+
+ if (flags & HFI1_TWSI_STOP)
+ stop_cmd(dd, target);
+ return ret;
+}
+
+/* Added functionality for IBA7220-based cards */
+#define HFI1_TEMP_DEV 0x98
+
+/*
+ * hfi1_twsi_blk_rd
+ * General interface for data transfer from twsi devices.
+ * One vestige of its former role is that it recognizes a device
+ * HFI1_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 hfi1_twsi_blk_rd(struct hfi1_devdata *dd, u32 target, int dev, int addr,
+ void *buffer, int len)
+{
+ int ret;
+ u8 *bp = buffer;
+
+ ret = 1;
+
+ if (dev == HFI1_TWSI_NO_DEV) {
+ /* legacy not-really-I2C */
+ addr = (addr << 1) | READ_CMD;
+ ret = twsi_wr(dd, target, addr, HFI1_TWSI_START);
+ } else {
+ /* Actual I2C */
+ ret = twsi_wr(dd, target, dev | WRITE_CMD, HFI1_TWSI_START);
+ if (ret) {
+ stop_cmd(dd, target);
+ 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 implicitly 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 = twsi_wr(dd, target, addr, 0);
+ udelay(TWSI_BUF_WAIT_USEC);
+
+ if (ret) {
+ dd_dev_err(dd,
+ "Failed to write interface read addr %02X\n",
+ addr);
+ ret = 1;
+ goto bail;
+ }
+ ret = twsi_wr(dd, target, dev | READ_CMD, HFI1_TWSI_START);
+ }
+ if (ret) {
+ stop_cmd(dd, target);
+ 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, target, !len);
+ }
+
+ ret = 0;
+
+bail:
+ return ret;
+}
+
+/*
+ * hfi1_twsi_blk_wr
+ * General interface for data transfer to twsi devices.
+ * One vestige of its former role is that it recognizes a device
+ * HFI1_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 hfi1_twsi_blk_wr(struct hfi1_devdata *dd, u32 target, 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 == HFI1_TWSI_NO_DEV) {
+ if (twsi_wr(dd, target, (addr << 1) | WRITE_CMD,
+ HFI1_TWSI_START)) {
+ goto failed_write;
+ }
+ } else {
+ /* Real I2C */
+ if (twsi_wr(dd, target,
+ dev | WRITE_CMD, HFI1_TWSI_START))
+ goto failed_write;
+ ret = twsi_wr(dd, target, addr, 0);
+ if (ret) {
+ dd_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 (twsi_wr(dd, target, *bp++, 0))
+ goto failed_write;
+
+ stop_cmd(dd, target);
+
+ /*
+ * 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 (twsi_wr(dd, target,
+ dev | READ_CMD, HFI1_TWSI_START)) {
+ stop_cmd(dd, target);
+ if (!--max_wait_time)
+ goto failed_write;
+ }
+ /* now read (and ignore) the resulting byte */
+ rd_byte(dd, target, 1);
+ }
+
+ ret = 0;
+ goto bail;
+
+failed_write:
+ stop_cmd(dd, target);
+ ret = 1;
+
+bail:
+ return ret;
+}
diff --git a/drivers/infiniband/hw/hfi1/twsi.h b/drivers/infiniband/hw/hfi1/twsi.h
new file mode 100644
index 0000000..5907e02
--- /dev/null
+++ b/drivers/infiniband/hw/hfi1/twsi.h
@@ -0,0 +1,68 @@
+#ifndef _TWSI_H
+#define _TWSI_H
+/*
+ *
+ * This file is provided under a dual BSD/GPLv2 license. When using or
+ * redistributing this file, you may do so under either license.
+ *
+ * GPL LICENSE SUMMARY
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * BSD LICENSE
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * 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.
+ * - Neither the name of Intel Corporation nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#define HFI1_TWSI_NO_DEV 0xFF
+
+struct hfi1_devdata;
+
+/* Bit position of SDA pin in ASIC_QSFP* registers */
+#define GPIO_SDA_NUM 1
+
+/* these functions must be called with qsfp_lock held */
+int hfi1_twsi_reset(struct hfi1_devdata *dd, u32 target);
+int hfi1_twsi_blk_rd(struct hfi1_devdata *dd, u32 target, int dev, int addr,
+ void *buffer, int len);
+int hfi1_twsi_blk_wr(struct hfi1_devdata *dd, u32 target, int dev, int addr,
+ const void *buffer, int len);
+
+
+#endif /* _TWSI_H */