diff options
Diffstat (limited to 'drivers/infiniband/hw/hfi1/twsi.c')
| -rw-r--r-- | drivers/infiniband/hw/hfi1/twsi.c | 489 |
1 files changed, 489 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/hfi1/twsi.c b/drivers/infiniband/hw/hfi1/twsi.c new file mode 100644 index 000000000000..e82e52a63d35 --- /dev/null +++ b/drivers/infiniband/hw/hfi1/twsi.c @@ -0,0 +1,489 @@ +/* + * Copyright(c) 2015, 2016 Intel Corporation. + * + * 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 + * + * 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 + * + * 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 u8 scl_in(struct hfi1_devdata *dd, u32 target, int wait) +{ + u32 read_val, mask; + + mask = QSFP_HFI0_I2CCLK; + /* SCL 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_SCL_NUM; +} + +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 + * returns 0 if ok, -EIO on error + */ +int hfi1_twsi_reset(struct hfi1_devdata *dd, u32 target) +{ + int clock_cycles_left = 9; + u32 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); + + /* Check if SCL is low, if it is low then we have a slave device + * misbehaving and there is not much we can do. + */ + if (!scl_in(dd, target, 0)) + return -EIO; + + /* Check if SDA is low, if it is low then we have to clock SDA + * up to 9 times for the device to release the bus + */ + while (clock_cycles_left--) { + if (sda_in(dd, target, 0)) + return 0; + scl_out(dd, target, 0); + scl_out(dd, target, 1); + } + + return -EIO; +} + +#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 N-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) +{ + u8 *bp = buffer; + int ret = 1; + int i; + int offset_size; + + /* obtain the offset size, strip it from the device address */ + offset_size = (dev >> 8) & 0xff; + dev &= 0xff; + + /* allow at most a 2 byte offset */ + if (offset_size > 2) + goto bail; + + 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 */ + if (offset_size) { + ret = twsi_wr(dd, target, + dev | WRITE_CMD, HFI1_TWSI_START); + if (ret) { + stop_cmd(dd, target); + goto bail; + } + + for (i = 0; i < offset_size; i++) { + ret = twsi_wr(dd, target, + (addr >> (i * 8)) & 0xff, 0); + udelay(TWSI_BUF_WAIT_USEC); + if (ret) { + dd_dev_err(dd, "Failed to write byte %d of offset 0x%04X\n", + i, addr); + goto bail; + } + } + } + ret = twsi_wr(dd, target, dev | READ_CMD, HFI1_TWSI_START); + } + if (ret) { + stop_cmd(dd, target); + 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 N-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) +{ + const u8 *bp = buffer; + int ret = 1; + int i; + int offset_size; + + /* obtain the offset size, strip it from the device address */ + offset_size = (dev >> 8) & 0xff; + dev &= 0xff; + + /* allow at most a 2 byte offset */ + if (offset_size > 2) + goto bail; + + 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; + } + + for (i = 0; i < offset_size; i++) { + ret = twsi_wr(dd, target, (addr >> (i * 8)) & 0xff, 0); + udelay(TWSI_BUF_WAIT_USEC); + if (ret) { + dd_dev_err(dd, "Failed to write byte %d of offset 0x%04X\n", + i, addr); + goto bail; + } + } + + for (i = 0; i < len; i++) + if (twsi_wr(dd, target, *bp++, 0)) + goto failed_write; + + ret = 0; + +failed_write: + stop_cmd(dd, target); + +bail: + return ret; +} |