From: Dean Luick Date: Wed, 3 Feb 2016 22:36:14 +0000 (-0800) Subject: staging/rdma/hfi1: Correct TWSI reset X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=cfe3e656d8cd5ff03b8f0ce24f920f306313b013;p=linux-beck.git staging/rdma/hfi1: Correct TWSI reset Change the TWSI reset function so it will stop the reset once the lines are in an expected state. Reviewed-by: Easwar Hariharan Reviewed-by: Dean Luick Signed-off-by: Pablo Cacho Signed-off-by: Jubin John Signed-off-by: Doug Ledford --- diff --git a/drivers/staging/rdma/hfi1/qsfp.c b/drivers/staging/rdma/hfi1/qsfp.c index 0e1a49294d99..c9d1e64ef681 100644 --- a/drivers/staging/rdma/hfi1/qsfp.c +++ b/drivers/staging/rdma/hfi1/qsfp.c @@ -5,7 +5,7 @@ * * GPL LICENSE SUMMARY * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 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 @@ -18,7 +18,7 @@ * * BSD LICENSE * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 Intel Corporation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -106,7 +106,6 @@ int i2c_write(struct hfi1_pportdata *ppd, u32 target, int i2c_addr, int offset, if (ret) { hfi1_dev_porterr(ppd->dd, ppd->port, "I2C write interface reset failed\n"); - ret = -EIO; goto done; } @@ -179,7 +178,6 @@ int i2c_read(struct hfi1_pportdata *ppd, u32 target, int i2c_addr, int offset, if (ret) { hfi1_dev_porterr(ppd->dd, ppd->port, "I2C read interface reset failed\n"); - ret = -EIO; goto done; } @@ -213,7 +211,7 @@ int qsfp_write(struct hfi1_pportdata *ppd, u32 target, int addr, void *bp, hfi1_dev_porterr(ppd->dd, ppd->port, "QSFP write interface reset failed\n"); mutex_unlock(&ppd->dd->qsfp_i2c_mutex); - return -EIO; + return ret; } while (count < len) { @@ -279,7 +277,7 @@ int qsfp_read(struct hfi1_pportdata *ppd, u32 target, int addr, void *bp, hfi1_dev_porterr(ppd->dd, ppd->port, "QSFP read interface reset failed\n"); mutex_unlock(&ppd->dd->qsfp_i2c_mutex); - return -EIO; + return ret; } while (count < len) { diff --git a/drivers/staging/rdma/hfi1/twsi.c b/drivers/staging/rdma/hfi1/twsi.c index 7c579b343844..d7dfdd231669 100644 --- a/drivers/staging/rdma/hfi1/twsi.c +++ b/drivers/staging/rdma/hfi1/twsi.c @@ -5,7 +5,7 @@ * * GPL LICENSE SUMMARY * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 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 @@ -18,7 +18,7 @@ * * BSD LICENSE * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 Intel Corporation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -136,6 +136,19 @@ static void scl_out(struct hfi1_devdata *dd, u32 target, u8 bit) 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; @@ -274,13 +287,12 @@ static void stop_cmd(struct hfi1_devdata *dd, u32 target) /** * 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; - int was_high = 0; - u32 pins, mask; + u32 mask; /* Both SCL and SDA should be high. If not, there * is something wrong. @@ -294,43 +306,23 @@ int hfi1_twsi_reset(struct hfi1_devdata *dd, u32 target) */ 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. + /* 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); - /* 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; + return -EIO; } #define HFI1_TWSI_START 0x100 diff --git a/drivers/staging/rdma/hfi1/twsi.h b/drivers/staging/rdma/hfi1/twsi.h index 5907e029613d..6cb30e59b00f 100644 --- a/drivers/staging/rdma/hfi1/twsi.h +++ b/drivers/staging/rdma/hfi1/twsi.h @@ -7,7 +7,7 @@ * * GPL LICENSE SUMMARY * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 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 @@ -20,7 +20,7 @@ * * BSD LICENSE * - * Copyright(c) 2015 Intel Corporation. + * Copyright(c) 2015, 2016 Intel Corporation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -54,8 +54,9 @@ struct hfi1_devdata; -/* Bit position of SDA pin in ASIC_QSFP* registers */ +/* Bit position of SDA/SCL pins in ASIC_QSFP* registers */ #define GPIO_SDA_NUM 1 +#define GPIO_SCL_NUM 0 /* these functions must be called with qsfp_lock held */ int hfi1_twsi_reset(struct hfi1_devdata *dd, u32 target);