274 lines
6.5 KiB
C
274 lines
6.5 KiB
C
/*
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* Copyright © 2009 Keith Packard
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*
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* Permission to use, copy, modify, distribute, and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting documentation, and
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* that the name of the copyright holders not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. The copyright holders make no representations
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* about the suitability of this software for any purpose. It is provided "as
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* is" without express or implied warranty.
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*
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* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
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* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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* OF THIS SOFTWARE.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/i2c.h>
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#include "intel_dp.h"
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#include "drmP.h"
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/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
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#define MODE_I2C_START 1
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#define MODE_I2C_WRITE 2
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#define MODE_I2C_READ 4
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#define MODE_I2C_STOP 8
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static int
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i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
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uint8_t write_byte, uint8_t *read_byte)
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{
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struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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uint16_t address = algo_data->address;
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uint8_t msg[5];
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uint8_t reply[2];
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int msg_bytes;
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int reply_bytes;
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int ret;
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/* Set up the command byte */
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if (mode & MODE_I2C_READ)
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msg[0] = AUX_I2C_READ << 4;
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else
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msg[0] = AUX_I2C_WRITE << 4;
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if (!(mode & MODE_I2C_STOP))
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msg[0] |= AUX_I2C_MOT << 4;
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msg[1] = address >> 8;
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msg[2] = address;
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switch (mode) {
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case MODE_I2C_WRITE:
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msg[3] = 0;
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msg[4] = write_byte;
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msg_bytes = 5;
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reply_bytes = 1;
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break;
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case MODE_I2C_READ:
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msg[3] = 0;
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msg_bytes = 4;
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reply_bytes = 2;
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break;
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default:
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msg_bytes = 3;
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reply_bytes = 1;
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break;
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}
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for (;;) {
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ret = (*algo_data->aux_ch)(adapter,
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msg, msg_bytes,
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reply, reply_bytes);
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if (ret < 0) {
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DRM_DEBUG("aux_ch failed %d\n", ret);
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return ret;
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}
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switch (reply[0] & AUX_I2C_REPLY_MASK) {
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case AUX_I2C_REPLY_ACK:
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if (mode == MODE_I2C_READ) {
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*read_byte = reply[1];
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}
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return reply_bytes - 1;
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case AUX_I2C_REPLY_NACK:
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DRM_DEBUG("aux_ch nack\n");
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return -EREMOTEIO;
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case AUX_I2C_REPLY_DEFER:
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DRM_DEBUG("aux_ch defer\n");
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udelay(100);
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break;
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default:
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DRM_ERROR("aux_ch invalid reply 0x%02x\n", reply[0]);
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return -EREMOTEIO;
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}
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}
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}
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/*
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* I2C over AUX CH
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*/
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/*
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* Send the address. If the I2C link is running, this 'restarts'
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* the connection with the new address, this is used for doing
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* a write followed by a read (as needed for DDC)
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*/
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static int
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i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
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{
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struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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int mode = MODE_I2C_START;
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int ret;
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if (reading)
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mode |= MODE_I2C_READ;
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else
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mode |= MODE_I2C_WRITE;
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algo_data->address = address;
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algo_data->running = true;
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ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
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return ret;
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}
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/*
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* Stop the I2C transaction. This closes out the link, sending
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* a bare address packet with the MOT bit turned off
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*/
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static void
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i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
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{
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struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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int mode = MODE_I2C_STOP;
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if (reading)
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mode |= MODE_I2C_READ;
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else
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mode |= MODE_I2C_WRITE;
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if (algo_data->running) {
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(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
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algo_data->running = false;
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}
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}
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/*
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* Write a single byte to the current I2C address, the
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* the I2C link must be running or this returns -EIO
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*/
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static int
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i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
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{
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struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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int ret;
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if (!algo_data->running)
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return -EIO;
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ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
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return ret;
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}
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/*
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* Read a single byte from the current I2C address, the
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* I2C link must be running or this returns -EIO
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*/
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static int
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i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
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{
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struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
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int ret;
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if (!algo_data->running)
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return -EIO;
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ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
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return ret;
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}
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static int
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i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
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struct i2c_msg *msgs,
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int num)
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{
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int ret = 0;
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bool reading = false;
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int m;
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int b;
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for (m = 0; m < num; m++) {
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u16 len = msgs[m].len;
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u8 *buf = msgs[m].buf;
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reading = (msgs[m].flags & I2C_M_RD) != 0;
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ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
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if (ret < 0)
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break;
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if (reading) {
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for (b = 0; b < len; b++) {
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ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
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if (ret < 0)
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break;
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}
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} else {
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for (b = 0; b < len; b++) {
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ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
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if (ret < 0)
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break;
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}
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}
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if (ret < 0)
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break;
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}
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if (ret >= 0)
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ret = num;
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i2c_algo_dp_aux_stop(adapter, reading);
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DRM_DEBUG("dp_aux_xfer return %d\n", ret);
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return ret;
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}
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static u32
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i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
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I2C_FUNC_SMBUS_READ_BLOCK_DATA |
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I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
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I2C_FUNC_10BIT_ADDR;
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}
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static const struct i2c_algorithm i2c_dp_aux_algo = {
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.master_xfer = i2c_algo_dp_aux_xfer,
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.functionality = i2c_algo_dp_aux_functionality,
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};
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static void
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i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
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{
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(void) i2c_algo_dp_aux_address(adapter, 0, false);
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(void) i2c_algo_dp_aux_stop(adapter, false);
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}
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static int
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i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
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{
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adapter->algo = &i2c_dp_aux_algo;
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adapter->retries = 3;
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i2c_dp_aux_reset_bus(adapter);
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return 0;
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}
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int
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i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
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{
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int error;
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error = i2c_dp_aux_prepare_bus(adapter);
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if (error)
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return error;
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error = i2c_add_adapter(adapter);
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return error;
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}
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EXPORT_SYMBOL(i2c_dp_aux_add_bus);
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