382 lines
8.7 KiB
C
382 lines
8.7 KiB
C
/****************************************************************************
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* Driver for Solarflare Solarstorm network controllers and boards
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* Copyright 2005 Fen Systems Ltd.
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* Copyright 2006-2008 Solarflare Communications Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published
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* by the Free Software Foundation, incorporated herein by reference.
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*/
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#include <linux/delay.h>
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#include "net_driver.h"
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#include "i2c-direct.h"
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/*
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* I2C data (SDA) and clock (SCL) line read/writes with appropriate
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* delays.
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*/
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static inline void setsda(struct efx_i2c_interface *i2c, int state)
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{
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udelay(i2c->op->udelay);
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i2c->sda = state;
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i2c->op->setsda(i2c);
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udelay(i2c->op->udelay);
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}
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static inline void setscl(struct efx_i2c_interface *i2c, int state)
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{
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udelay(i2c->op->udelay);
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i2c->scl = state;
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i2c->op->setscl(i2c);
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udelay(i2c->op->udelay);
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}
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static inline int getsda(struct efx_i2c_interface *i2c)
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{
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int sda;
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udelay(i2c->op->udelay);
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sda = i2c->op->getsda(i2c);
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udelay(i2c->op->udelay);
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return sda;
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}
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static inline int getscl(struct efx_i2c_interface *i2c)
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{
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int scl;
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udelay(i2c->op->udelay);
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scl = i2c->op->getscl(i2c);
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udelay(i2c->op->udelay);
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return scl;
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}
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/*
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* I2C low-level protocol operations
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*
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*/
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static inline void i2c_release(struct efx_i2c_interface *i2c)
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{
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EFX_WARN_ON_PARANOID(!i2c->scl);
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EFX_WARN_ON_PARANOID(!i2c->sda);
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/* Devices may time out if operations do not end */
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setscl(i2c, 1);
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setsda(i2c, 1);
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EFX_BUG_ON_PARANOID(getsda(i2c) != 1);
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EFX_BUG_ON_PARANOID(getscl(i2c) != 1);
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}
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static inline void i2c_start(struct efx_i2c_interface *i2c)
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{
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/* We may be restarting immediately after a {send,recv}_bit,
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* so SCL will not necessarily already be high.
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*/
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EFX_WARN_ON_PARANOID(!i2c->sda);
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setscl(i2c, 1);
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setsda(i2c, 0);
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setscl(i2c, 0);
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setsda(i2c, 1);
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}
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static inline void i2c_send_bit(struct efx_i2c_interface *i2c, int bit)
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{
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EFX_WARN_ON_PARANOID(i2c->scl != 0);
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setsda(i2c, bit);
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setscl(i2c, 1);
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setscl(i2c, 0);
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setsda(i2c, 1);
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}
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static inline int i2c_recv_bit(struct efx_i2c_interface *i2c)
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{
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int bit;
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EFX_WARN_ON_PARANOID(i2c->scl != 0);
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EFX_WARN_ON_PARANOID(!i2c->sda);
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setscl(i2c, 1);
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bit = getsda(i2c);
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setscl(i2c, 0);
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return bit;
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}
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static inline void i2c_stop(struct efx_i2c_interface *i2c)
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{
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EFX_WARN_ON_PARANOID(i2c->scl != 0);
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setsda(i2c, 0);
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setscl(i2c, 1);
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setsda(i2c, 1);
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}
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/*
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* I2C mid-level protocol operations
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*
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*/
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/* Sends a byte via the I2C bus and checks for an acknowledgement from
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* the slave device.
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*/
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static int i2c_send_byte(struct efx_i2c_interface *i2c, u8 byte)
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{
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int i;
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/* Send byte */
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for (i = 0; i < 8; i++) {
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i2c_send_bit(i2c, !!(byte & 0x80));
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byte <<= 1;
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}
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/* Check for acknowledgement from slave */
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return (i2c_recv_bit(i2c) == 0 ? 0 : -EIO);
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}
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/* Receives a byte via the I2C bus and sends ACK/NACK to the slave device. */
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static u8 i2c_recv_byte(struct efx_i2c_interface *i2c, int ack)
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{
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u8 value = 0;
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int i;
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/* Receive byte */
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for (i = 0; i < 8; i++)
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value = (value << 1) | i2c_recv_bit(i2c);
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/* Send ACK/NACK */
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i2c_send_bit(i2c, (ack ? 0 : 1));
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return value;
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}
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/* Calculate command byte for a read operation */
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static inline u8 i2c_read_cmd(u8 device_id)
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{
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return ((device_id << 1) | 1);
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}
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/* Calculate command byte for a write operation */
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static inline u8 i2c_write_cmd(u8 device_id)
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{
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return ((device_id << 1) | 0);
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}
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int efx_i2c_check_presence(struct efx_i2c_interface *i2c, u8 device_id)
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{
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int rc;
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/* If someone is driving the bus low we just give up. */
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if (getsda(i2c) == 0 || getscl(i2c) == 0) {
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EFX_ERR(i2c->efx, "%s someone is holding the I2C bus low."
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" Giving up.\n", __func__);
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return -EFAULT;
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}
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/* Pretend to initiate a device write */
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i2c_start(i2c);
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rc = i2c_send_byte(i2c, i2c_write_cmd(device_id));
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if (rc)
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goto out;
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out:
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i2c_stop(i2c);
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i2c_release(i2c);
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return rc;
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}
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/* This performs a fast read of one or more consecutive bytes from an
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* I2C device. Not all devices support consecutive reads of more than
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* one byte; for these devices use efx_i2c_read() instead.
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*/
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int efx_i2c_fast_read(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset, u8 *data, unsigned int len)
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{
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int i;
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int rc;
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EFX_WARN_ON_PARANOID(getsda(i2c) != 1);
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EFX_WARN_ON_PARANOID(getscl(i2c) != 1);
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EFX_WARN_ON_PARANOID(data == NULL);
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EFX_WARN_ON_PARANOID(len < 1);
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/* Select device and starting offset */
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i2c_start(i2c);
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rc = i2c_send_byte(i2c, i2c_write_cmd(device_id));
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if (rc)
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goto out;
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rc = i2c_send_byte(i2c, offset);
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if (rc)
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goto out;
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/* Read data from device */
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i2c_start(i2c);
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rc = i2c_send_byte(i2c, i2c_read_cmd(device_id));
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if (rc)
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goto out;
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for (i = 0; i < (len - 1); i++)
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/* Read and acknowledge all but the last byte */
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data[i] = i2c_recv_byte(i2c, 1);
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/* Read last byte with no acknowledgement */
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data[i] = i2c_recv_byte(i2c, 0);
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out:
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i2c_stop(i2c);
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i2c_release(i2c);
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return rc;
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}
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/* This performs a fast write of one or more consecutive bytes to an
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* I2C device. Not all devices support consecutive writes of more
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* than one byte; for these devices use efx_i2c_write() instead.
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*/
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int efx_i2c_fast_write(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset,
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const u8 *data, unsigned int len)
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{
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int i;
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int rc;
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EFX_WARN_ON_PARANOID(getsda(i2c) != 1);
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EFX_WARN_ON_PARANOID(getscl(i2c) != 1);
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EFX_WARN_ON_PARANOID(len < 1);
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/* Select device and starting offset */
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i2c_start(i2c);
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rc = i2c_send_byte(i2c, i2c_write_cmd(device_id));
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if (rc)
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goto out;
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rc = i2c_send_byte(i2c, offset);
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if (rc)
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goto out;
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/* Write data to device */
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for (i = 0; i < len; i++) {
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rc = i2c_send_byte(i2c, data[i]);
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if (rc)
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goto out;
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}
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out:
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i2c_stop(i2c);
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i2c_release(i2c);
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return rc;
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}
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/* I2C byte-by-byte read */
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int efx_i2c_read(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset, u8 *data, unsigned int len)
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{
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int rc;
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/* i2c_fast_read with length 1 is a single byte read */
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for (; len > 0; offset++, data++, len--) {
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rc = efx_i2c_fast_read(i2c, device_id, offset, data, 1);
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if (rc)
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return rc;
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}
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return 0;
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}
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/* I2C byte-by-byte write */
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int efx_i2c_write(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset, const u8 *data, unsigned int len)
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{
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int rc;
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/* i2c_fast_write with length 1 is a single byte write */
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for (; len > 0; offset++, data++, len--) {
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rc = efx_i2c_fast_write(i2c, device_id, offset, data, 1);
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if (rc)
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return rc;
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mdelay(i2c->op->mdelay);
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}
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return 0;
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}
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/* This is just a slightly neater wrapper round efx_i2c_fast_write
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* in the case where the target doesn't take an offset
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*/
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int efx_i2c_send_bytes(struct efx_i2c_interface *i2c,
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u8 device_id, const u8 *data, unsigned int len)
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{
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return efx_i2c_fast_write(i2c, device_id, data[0], data + 1, len - 1);
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}
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/* I2C receiving of bytes - does not send an offset byte */
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int efx_i2c_recv_bytes(struct efx_i2c_interface *i2c, u8 device_id,
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u8 *bytes, unsigned int len)
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{
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int i;
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int rc;
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EFX_WARN_ON_PARANOID(getsda(i2c) != 1);
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EFX_WARN_ON_PARANOID(getscl(i2c) != 1);
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EFX_WARN_ON_PARANOID(len < 1);
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/* Select device */
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i2c_start(i2c);
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/* Read data from device */
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rc = i2c_send_byte(i2c, i2c_read_cmd(device_id));
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if (rc)
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goto out;
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for (i = 0; i < (len - 1); i++)
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/* Read and acknowledge all but the last byte */
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bytes[i] = i2c_recv_byte(i2c, 1);
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/* Read last byte with no acknowledgement */
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bytes[i] = i2c_recv_byte(i2c, 0);
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out:
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i2c_stop(i2c);
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i2c_release(i2c);
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return rc;
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}
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/* SMBus and some I2C devices will time out if the I2C clock is
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* held low for too long. This is most likely to happen in virtualised
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* systems (when the entire domain is descheduled) but could in
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* principle happen due to preemption on any busy system (and given the
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* potential length of an I2C operation turning preemption off is not
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* a sensible option). The following functions deal with the failure by
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* retrying up to a fixed number of times.
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*/
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#define I2C_MAX_RETRIES (10)
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/* The timeout problem will result in -EIO. If the wrapped function
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* returns any other error, pass this up and do not retry. */
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#define RETRY_WRAPPER(_f) \
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int retries = I2C_MAX_RETRIES; \
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int rc; \
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while (retries) { \
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rc = _f; \
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if (rc != -EIO) \
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return rc; \
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retries--; \
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} \
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return rc; \
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int efx_i2c_check_presence_retry(struct efx_i2c_interface *i2c, u8 device_id)
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{
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RETRY_WRAPPER(efx_i2c_check_presence(i2c, device_id))
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}
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int efx_i2c_read_retry(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset, u8 *data, unsigned int len)
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{
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RETRY_WRAPPER(efx_i2c_read(i2c, device_id, offset, data, len))
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}
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int efx_i2c_write_retry(struct efx_i2c_interface *i2c,
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u8 device_id, u8 offset, const u8 *data, unsigned int len)
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{
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RETRY_WRAPPER(efx_i2c_write(i2c, device_id, offset, data, len))
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}
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