/*
* Copyright © 2009 Keith Packard
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of the copyright holders not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. The copyright holders make no representations
* about the suitability of this software for any purpose. It is provided "as
* is" without express or implied warranty.
*
* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
* OF THIS SOFTWARE.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include <drm/drm_dp_helper.h>
#include <drm/drmP.h>
/**
* DOC: dp helpers
*
* These functions contain some common logic and helpers at various abstraction
* levels to deal with Display Port sink devices and related things like DP aux
* channel transfers, EDID reading over DP aux channels, decoding certain DPCD
* blocks, ...
*/
/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
static int
i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
uint8_t write_byte, uint8_t *read_byte)
{
struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
int ret;
ret = (*algo_data->aux_ch)(adapter, mode,
write_byte, read_byte);
return ret;
}
/*
* I2C over AUX CH
*/
/*
* Send the address. If the I2C link is running, this 'restarts'
* the connection with the new address, this is used for doing
* a write followed by a read (as needed for DDC)
*/
static int
i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
{
struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
int mode = MODE_I2C_START;
int ret;
if (reading)
mode |= MODE_I2C_READ;
else
mode |= MODE_I2C_WRITE;
algo_data->address = address;
algo_data->running = true;
ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
return ret;
}
/*
* Stop the I2C transaction. This closes out the link, sending
* a bare address packet with the MOT bit turned off
*/
static void
i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
{
struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
int mode = MODE_I2C_STOP;
if (reading)
mode |= MODE_I2C_READ;
else
mode |= MODE_I2C_WRITE;
if (algo_data->running) {
(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
algo_data->running = false;
}
}
/*
* Write a single byte to the current I2C address, the
* the I2C link must be running or this returns -EIO
*/
static int
i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
{
struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
int ret;
if (!algo_data->running)
return -EIO;
ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
return ret;
}
/*
* Read a single byte from the current I2C address, the
* I2C link must be running or this returns -EIO
*/
static int
i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
{
struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
int ret;
if (!algo_data->running)
return -EIO;
ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
return ret;
}
static int
i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
struct i2c_msg *msgs,
int num)
{
int ret = 0;
bool reading = false;
int m;
int b;
for (m = 0; m < num; m++) {
u16 len = msgs[m].len;
u8 *buf = msgs[m].buf;
reading = (msgs[m].flags & I2C_M_RD) != 0;
ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
if (ret < 0)
break;
if (reading) {
for (b = 0; b < len; b++) {
ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
if (ret < 0)
break;
}
} else {
for (b = 0; b < len; b++) {
ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
if (ret < 0)
break;
}
}
if (ret < 0)
break;
}
if (ret >= 0)
ret = num;
i2c_algo_dp_aux_stop(adapter, reading);
DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
return ret;
}
static u32
i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
I2C_FUNC_SMBUS_READ_BLOCK_DATA |
I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
I2C_FUNC_10BIT_ADDR;
}
static const struct i2c_algorithm i2c_dp_aux_algo = {
.master_xfer = i2c_algo_dp_aux_xfer,
.functionality = i2c_algo_dp_aux_functionality,
};
static void
i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
{
(void) i2c_algo_dp_aux_address(adapter, 0, false);
(void) i2c_algo_dp_aux_stop(adapter, false);
}
static int
i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
{
adapter->algo = &i2c_dp_aux_algo;
adapter->retries = 3;
i2c_dp_aux_reset_bus(adapter);
return 0;
}
/**
* i2c_dp_aux_add_bus() - register an i2c adapter using the aux ch helper
* @adapter: i2c adapter to register
*
* This registers an i2c adapater that uses dp aux channel as it's underlaying
* transport. The driver needs to fill out the &i2c_algo_dp_aux_data structure
* and store it in the algo_data member of the @adapter argument. This will be
* used by the i2c over dp aux algorithm to drive the hardware.
*
* RETURNS:
* 0 on success, -ERRNO on failure.
*/
int
i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
{
int error;
error = i2c_dp_aux_prepare_bus(adapter);
if (error)
return error;
error = i2c_add_adapter(adapter);
return error;
}
EXPORT_SYMBOL(i2c_dp_aux_add_bus);
/* Helpers for DP link training */
static u8 dp_link_status(u8 link_status[DP_LINK_STATUS_SIZE], int r)
{
return link_status[r - DP_LANE0_1_STATUS];
}
static u8 dp_get_lane_status(u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_LANE0_1_STATUS + (lane >> 1);
int s = (lane & 1) * 4;
u8 l = dp_link_status(link_status, i);
return (l >> s) & 0xf;
}
bool drm_dp_channel_eq_ok(u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
u8 lane_align;
u8 lane_status;
int lane;
lane_align = dp_link_status(link_status,
DP_LANE_ALIGN_STATUS_UPDATED);
if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
return false;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_channel_eq_ok);
bool drm_dp_clock_recovery_ok(u8 link_status[DP_LINK_STATUS_SIZE],
int lane_count)
{
int lane;
u8 lane_status;
for (lane = 0; lane < lane_count; lane++) {
lane_status = dp_get_lane_status(link_status, lane);
if ((lane_status & DP_LANE_CR_DONE) == 0)
return false;
}
return true;
}
EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
u8 drm_dp_get_adjust_request_voltage(u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);
u8 drm_dp_get_adjust_request_pre_emphasis(u8 link_status[DP_LINK_STATUS_SIZE],
int lane)
{
int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
int s = ((lane & 1) ?
DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
u8 l = dp_link_status(link_status, i);
return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
}
EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
void drm_dp_link_train_clock_recovery_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
udelay(100);
else
mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
}
EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
void drm_dp_link_train_channel_eq_delay(u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
udelay(400);
else
mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
}
EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
u8 drm_dp_link_rate_to_bw_code(int link_rate)
{
switch (link_rate) {
case 162000:
default:
return DP_LINK_BW_1_62;
case 270000:
return DP_LINK_BW_2_7;
case 540000:
return DP_LINK_BW_5_4;
}
}
EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
int drm_dp_bw_code_to_link_rate(u8 link_bw)
{
switch (link_bw) {
case DP_LINK_BW_1_62:
default:
return 162000;
case DP_LINK_BW_2_7:
return 270000;
case DP_LINK_BW_5_4:
return 540000;
}
}
EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
