drivers/gpu/drm/radeon/atombios_dp.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright 2007-8 Advanced Micro Devices, Inc.
  * Copyright 2008 Red Hat Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  * Authors: Dave Airlie
  *          Alex Deucher
  */
 #include "drmP.h"
 #include "radeon_drm.h"
 #include "radeon.h"

 #include "atom.h"
 #include "atom-bits.h"
 #include "drm_dp_helper.h"

 #define DP_LINK_STATUS_SIZE	6

 /* move these to drm_dp_helper.c/h */

 static const int dp_clocks[] = {
 	54000,  // 1 lane, 1.62 Ghz
 	90000,  // 1 lane, 2.70 Ghz
 	108000, // 2 lane, 1.62 Ghz
 	180000, // 2 lane, 2.70 Ghz
 	216000, // 4 lane, 1.62 Ghz
 	360000, // 4 lane, 2.70 Ghz
 };

 static const int num_dp_clocks = sizeof(dp_clocks) / sizeof(int);

 int dp_lanes_for_mode_clock(int max_link_bw, int mode_clock)
 {
 	int i;

 	switch (max_link_bw) {
 	case DP_LINK_BW_1_62:
 	default:
 		for (i = 0; i < num_dp_clocks; i++) {
 			if (i % 2)
 				continue;
 			if (dp_clocks[i] > mode_clock) {
 				if (i < 2)
 					return 1;
 				else if (i < 4)
 					return 2;
 				else
 					return 4;
 			}
 		}
 		break;
 	case DP_LINK_BW_2_7:
 		for (i = 0; i < num_dp_clocks; i++) {
 			if (dp_clocks[i] > mode_clock) {
 				if (i < 2)
 					return 1;
 				else if (i < 4)
 					return 2;
 				else
 					return 4;
 			}
 		}
 		break;
 	}

 	return 0;
 }

 int dp_link_clock_for_mode_clock(int max_link_bw, int mode_clock)
 {
 	int i;

 	switch (max_link_bw) {
 	case DP_LINK_BW_1_62:
 	default:
 		return 162000;
 		break;
 	case DP_LINK_BW_2_7:
 		for (i = 0; i < num_dp_clocks; i++) {
 			if (dp_clocks[i] > mode_clock)
 				return (i % 2) ? 270000 : 162000;
 		}
 	}

 	return 0;
 }

 bool radeon_process_aux_ch(struct radeon_i2c_chan *chan, u8 *req_bytes,
 			   int num_bytes, u8 *read_byte,
 			   u8 read_buf_len, u8 delay)
 {
 	struct drm_device *dev = chan->dev;
 	struct radeon_device *rdev = dev->dev_private;
 	PROCESS_AUX_CHANNEL_TRANSACTION_PS_ALLOCATION args;
 	int index = GetIndexIntoMasterTable(COMMAND, ProcessAuxChannelTransaction);
 	unsigned char *base;

 	memset(&args, 0, sizeof(args));

 	base = (unsigned char *)rdev->mode_info.atom_context->scratch;

 	memcpy(base, req_bytes, num_bytes);

 	args.lpAuxRequest = 0;
 	args.lpDataOut = 16;
 	args.ucDataOutLen = 0;
 	args.ucChannelID = chan->rec.i2c_id;
 	args.ucDelay = delay / 10;

 	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);

 	if (args.ucReplyStatus) {
 		DRM_ERROR("failed to get auxch %02x%02x %02x %02x 0x%02x %02x\n",
 			  req_bytes[1], req_bytes[0], req_bytes[2], req_bytes[3],
 			  chan->rec.i2c_id, args.ucReplyStatus);
 		return false;
 	}

 	if (args.ucDataOutLen && read_byte && read_buf_len) {
 		if (read_buf_len < args.ucDataOutLen) {
 			DRM_ERROR("Buffer to small for return answer %d %d\n",
 				  read_buf_len, args.ucDataOutLen);
 			return false;
 		}
 		{
 			int len = min(read_buf_len, args.ucDataOutLen);
 			memcpy(read_byte, base + 16, len);
 		}
 	}
 	return true;
 }

 static u8 radeon_dp_encoder_service(struct radeon_device *rdev, int action, int dp_clock,
 				    uint8_t ucconfig, uint8_t lane_num)
 {
 	DP_ENCODER_SERVICE_PARAMETERS args;
 	int index = GetIndexIntoMasterTable(COMMAND, DPEncoderService);

 	memset(&args, 0, sizeof(args));
 	args.ucLinkClock = dp_clock / 10;
 	args.ucConfig = ucconfig;
 	args.ucAction = action;
 	args.ucLaneNum = lane_num;
 	args.ucStatus = 0;

 	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
 	return args.ucStatus;
 }

 u8 radeon_dp_getsinktype(struct radeon_connector *radeon_connector)
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
 	struct drm_device *dev = radeon_connector->base.dev;
 	struct radeon_device *rdev = dev->dev_private;

 	return radeon_dp_encoder_service(rdev, ATOM_DP_ACTION_GET_SINK_TYPE, 0,
 					 radeon_dig_connector->dp_i2c_bus->rec.i2c_id, 0);
 }

 union dig_transmitter_control {
 	DIG_TRANSMITTER_CONTROL_PS_ALLOCATION v1;
 	DIG_TRANSMITTER_CONTROL_PARAMETERS_V2 v2;
 };

 bool radeon_dp_aux_native_write(struct radeon_connector *radeon_connector, uint16_t address,
 				uint8_t send_bytes, uint8_t *send)
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
 	struct drm_device *dev = radeon_connector->base.dev;
 	struct radeon_device *rdev = dev->dev_private;
 	u8 msg[20];
 	u8 msg_len, dp_msg_len;
 	bool ret;

 	dp_msg_len = 4;
 	msg[0] = address;
 	msg[1] = address >> 8;
 	msg[2] = AUX_NATIVE_WRITE << 4;
 	dp_msg_len += send_bytes;
 	msg[3] = (dp_msg_len << 4) | (send_bytes - 1);

 	if (send_bytes > 16)
 		return false;

 	memcpy(&msg[4], send, send_bytes);
 	msg_len = 4 + send_bytes;
 	ret = radeon_process_aux_ch(radeon_dig_connector->dp_i2c_bus, msg, msg_len, NULL, 0, 0);
 	return ret;
 }

 bool radeon_dp_aux_native_read(struct radeon_connector *radeon_connector, uint16_t address,
 			       uint8_t delay, uint8_t expected_bytes,
 			       uint8_t *read_p)
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
 	struct drm_device *dev = radeon_connector->base.dev;
 	struct radeon_device *rdev = dev->dev_private;
 	u8 msg[20];
 	u8 msg_len, dp_msg_len;
 	bool ret = false;
 	msg_len = 4;
 	dp_msg_len = 4;
 	msg[0] = address;
 	msg[1] = address >> 8;
 	msg[2] = AUX_NATIVE_READ << 4;
 	msg[3] = (dp_msg_len) << 4;
 	msg[3] |= expected_bytes - 1;

 	ret = radeon_process_aux_ch(radeon_dig_connector->dp_i2c_bus, msg, msg_len, read_p, expected_bytes, delay);
 	return ret;
 }

 void radeon_dp_getdpcd(struct radeon_connector *radeon_connector)
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
 	u8 msg[25];
 	int ret;

 	ret = radeon_dp_aux_native_read(radeon_connector, DP_DPCD_REV, 0, 8, msg);
 	if (ret) {
 		memcpy(radeon_dig_connector->dpcd, msg, 8);
 		{
 			int i;
 			printk("DPCD: ");
 			for (i = 0; i < 8; i++)
 				printk("%02x ", msg[i]);
 			printk("\n");
 		}
 	}
 	radeon_dig_connector->dpcd[0] = 0;
 	return;
 }

 static bool atom_dp_get_link_status(struct radeon_connector *radeon_connector,
 				    u8 link_status[DP_LINK_STATUS_SIZE])
 {
 	int ret;
 	ret = radeon_dp_aux_native_read(radeon_connector, DP_LANE0_1_STATUS, 100,
 					DP_LINK_STATUS_SIZE, link_status);
 	if (!ret) {
 		DRM_ERROR("displayport link status failed\n");
 		return false;
 	}

 	DRM_INFO("link status %02x %02x %02x %02x %02x %02x\n",
 		 link_status[0], link_status[1], link_status[2],
 		 link_status[3], link_status[4], link_status[5]);
 	return true;
 }

 static void dp_set_power(struct radeon_connector *radeon_connector, u8 power_state)
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
 	if (radeon_dig_connector->dpcd[0] >= 0x11) {
 		radeon_dp_aux_native_write(radeon_connector, DP_SET_POWER, 1,
 					   &power_state);
 	}
 }

 static void dp_update_dpvs_emph(struct radeon_connector *radeon_connector,
 				u8 train_set[4])
 {
 	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;

 //	radeon_dp_digtransmitter_setup_vsemph();
 	radeon_dp_aux_native_write(radeon_connector, DP_TRAINING_LANE0_SET,
 				   0/* lc */, train_set);
 }

 static void dp_set_training(struct radeon_connector *radeon_connector,
 			    u8 training)
 {
 	radeon_dp_aux_native_write(radeon_connector, DP_TRAINING_PATTERN_SET,
 				   1, &training);
 }

 int radeon_dp_i2c_aux_ch(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;
 	struct radeon_i2c_chan *auxch = (struct radeon_i2c_chan *)adapter;
 	int ret = 0;
 	uint16_t address = algo_data->address;
 	uint8_t msg[5];
 	uint8_t reply[2];
 	int msg_len, dp_msg_len;
 	int reply_bytes;

 	/* Set up the command byte */
 	if (mode & MODE_I2C_READ)
 		msg[2] = AUX_I2C_READ << 4;
 	else
 		msg[2] = AUX_I2C_WRITE << 4;

 	if (!(mode & MODE_I2C_STOP))
 		msg[2] |= AUX_I2C_MOT << 4;

 	msg[0] = address;
 	msg[1] = address >> 8;

 	reply_bytes = 1;

 	msg_len = 4;
 	dp_msg_len = 3;
 	switch (mode) {
 	case MODE_I2C_WRITE:
 		msg[4] = write_byte;
 		msg_len++;
 		dp_msg_len += 2;
 		break;
 	case MODE_I2C_READ:
 		dp_msg_len += 1;
 		break;
 	default:
 		break;
 	}

 	msg[3] = (dp_msg_len) << 4;
 	ret = radeon_process_aux_ch(auxch, msg, msg_len, reply, reply_bytes, 0);

 	if (ret) {
 		if (read_byte)
 			*read_byte = reply[0];
 		return reply_bytes;
 	}
 	return -EREMOTEIO;
 }
	/*
	* Copyright 2007-8 Advanced Micro Devices, Inc.
	* Copyright 2008 Red Hat Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*
	* Authors: Dave Airlie
	* Alex Deucher
	*/
	#include "drmP.h"
	#include "radeon_drm.h"
	#include "radeon.h"

	#include "atom.h"
	#include "atom-bits.h"
	#include "drm_dp_helper.h"

	#define DP_LINK_STATUS_SIZE 6

	/* move these to drm_dp_helper.c/h */

	static const int dp_clocks[] = {
	54000, // 1 lane, 1.62 Ghz
	90000, // 1 lane, 2.70 Ghz
	108000, // 2 lane, 1.62 Ghz
	180000, // 2 lane, 2.70 Ghz
	216000, // 4 lane, 1.62 Ghz
	360000, // 4 lane, 2.70 Ghz
	};

	static const int num_dp_clocks = sizeof(dp_clocks) / sizeof(int);

	int dp_lanes_for_mode_clock(int max_link_bw, int mode_clock)
	{
	int i;

	switch (max_link_bw) {
	case DP_LINK_BW_1_62:
	default:
	for (i = 0; i < num_dp_clocks; i++) {
	if (i % 2)
	continue;
	if (dp_clocks[i] > mode_clock) {
	if (i < 2)
	return 1;
	else if (i < 4)
	return 2;
	else
	return 4;
	}
	}
	break;
	case DP_LINK_BW_2_7:
	for (i = 0; i < num_dp_clocks; i++) {
	if (dp_clocks[i] > mode_clock) {
	if (i < 2)
	return 1;
	else if (i < 4)
	return 2;
	else
	return 4;
	}
	}
	break;
	}

	return 0;
	}

	int dp_link_clock_for_mode_clock(int max_link_bw, int mode_clock)
	{
	int i;

	switch (max_link_bw) {
	case DP_LINK_BW_1_62:
	default:
	return 162000;
	break;
	case DP_LINK_BW_2_7:
	for (i = 0; i < num_dp_clocks; i++) {
	if (dp_clocks[i] > mode_clock)
	return (i % 2) ? 270000 : 162000;
	}
	}

	return 0;
	}

	bool radeon_process_aux_ch(struct radeon_i2c_chan chan, u8 req_bytes,
	int num_bytes, u8 *read_byte,
	u8 read_buf_len, u8 delay)
	{
	struct drm_device *dev = chan->dev;
	struct radeon_device *rdev = dev->dev_private;
	PROCESS_AUX_CHANNEL_TRANSACTION_PS_ALLOCATION args;
	int index = GetIndexIntoMasterTable(COMMAND, ProcessAuxChannelTransaction);
	unsigned char *base;

	memset(&args, 0, sizeof(args));

	base = (unsigned char *)rdev->mode_info.atom_context->scratch;

	memcpy(base, req_bytes, num_bytes);

	args.lpAuxRequest = 0;
	args.lpDataOut = 16;
	args.ucDataOutLen = 0;
	args.ucChannelID = chan->rec.i2c_id;
	args.ucDelay = delay / 10;

	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);

	if (args.ucReplyStatus) {
	DRM_ERROR("failed to get auxch %02x%02x %02x %02x 0x%02x %02x\n",
	req_bytes[1], req_bytes[0], req_bytes[2], req_bytes[3],
	chan->rec.i2c_id, args.ucReplyStatus);
	return false;
	}

	if (args.ucDataOutLen && read_byte && read_buf_len) {
	if (read_buf_len < args.ucDataOutLen) {
	DRM_ERROR("Buffer to small for return answer %d %d\n",
	read_buf_len, args.ucDataOutLen);
	return false;
	}
	{
	int len = min(read_buf_len, args.ucDataOutLen);
	memcpy(read_byte, base + 16, len);
	}
	}
	return true;
	}

	static u8 radeon_dp_encoder_service(struct radeon_device *rdev, int action, int dp_clock,
	uint8_t ucconfig, uint8_t lane_num)
	{
	DP_ENCODER_SERVICE_PARAMETERS args;
	int index = GetIndexIntoMasterTable(COMMAND, DPEncoderService);

	memset(&args, 0, sizeof(args));
	args.ucLinkClock = dp_clock / 10;
	args.ucConfig = ucconfig;
	args.ucAction = action;
	args.ucLaneNum = lane_num;
	args.ucStatus = 0;

	atom_execute_table(rdev->mode_info.atom_context, index, (uint32_t *)&args);
	return args.ucStatus;
	}

	u8 radeon_dp_getsinktype(struct radeon_connector *radeon_connector)
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
	struct drm_device *dev = radeon_connector->base.dev;
	struct radeon_device *rdev = dev->dev_private;

	return radeon_dp_encoder_service(rdev, ATOM_DP_ACTION_GET_SINK_TYPE, 0,
	radeon_dig_connector->dp_i2c_bus->rec.i2c_id, 0);
	}

	union dig_transmitter_control {
	DIG_TRANSMITTER_CONTROL_PS_ALLOCATION v1;
	DIG_TRANSMITTER_CONTROL_PARAMETERS_V2 v2;
	};

	bool radeon_dp_aux_native_write(struct radeon_connector *radeon_connector, uint16_t address,
	uint8_t send_bytes, uint8_t *send)
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
	struct drm_device *dev = radeon_connector->base.dev;
	struct radeon_device *rdev = dev->dev_private;
	u8 msg[20];
	u8 msg_len, dp_msg_len;
	bool ret;

	dp_msg_len = 4;
	msg[0] = address;
	msg[1] = address >> 8;
	msg[2] = AUX_NATIVE_WRITE << 4;
	dp_msg_len += send_bytes;
	msg[3] = (dp_msg_len << 4) \| (send_bytes - 1);

	if (send_bytes > 16)
	return false;

	memcpy(&msg[4], send, send_bytes);
	msg_len = 4 + send_bytes;
	ret = radeon_process_aux_ch(radeon_dig_connector->dp_i2c_bus, msg, msg_len, NULL, 0, 0);
	return ret;
	}

	bool radeon_dp_aux_native_read(struct radeon_connector *radeon_connector, uint16_t address,
	uint8_t delay, uint8_t expected_bytes,
	uint8_t *read_p)
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
	struct drm_device *dev = radeon_connector->base.dev;
	struct radeon_device *rdev = dev->dev_private;
	u8 msg[20];
	u8 msg_len, dp_msg_len;
	bool ret = false;
	msg_len = 4;
	dp_msg_len = 4;
	msg[0] = address;
	msg[1] = address >> 8;
	msg[2] = AUX_NATIVE_READ << 4;
	msg[3] = (dp_msg_len) << 4;
	msg[3] \|= expected_bytes - 1;

	ret = radeon_process_aux_ch(radeon_dig_connector->dp_i2c_bus, msg, msg_len, read_p, expected_bytes, delay);
	return ret;
	}

	void radeon_dp_getdpcd(struct radeon_connector *radeon_connector)
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
	u8 msg[25];
	int ret;

	ret = radeon_dp_aux_native_read(radeon_connector, DP_DPCD_REV, 0, 8, msg);
	if (ret) {
	memcpy(radeon_dig_connector->dpcd, msg, 8);
	{
	int i;
	printk("DPCD: ");
	for (i = 0; i < 8; i++)
	printk("%02x ", msg[i]);
	printk("\n");
	}
	}
	radeon_dig_connector->dpcd[0] = 0;
	return;
	}

	static bool atom_dp_get_link_status(struct radeon_connector *radeon_connector,
	u8 link_status[DP_LINK_STATUS_SIZE])
	{
	int ret;
	ret = radeon_dp_aux_native_read(radeon_connector, DP_LANE0_1_STATUS, 100,
	DP_LINK_STATUS_SIZE, link_status);
	if (!ret) {
	DRM_ERROR("displayport link status failed\n");
	return false;
	}

	DRM_INFO("link status %02x %02x %02x %02x %02x %02x\n",
	link_status[0], link_status[1], link_status[2],
	link_status[3], link_status[4], link_status[5]);
	return true;
	}

	static void dp_set_power(struct radeon_connector *radeon_connector, u8 power_state)
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
	if (radeon_dig_connector->dpcd[0] >= 0x11) {
	radeon_dp_aux_native_write(radeon_connector, DP_SET_POWER, 1,
	&power_state);
	}
	}

	static void dp_update_dpvs_emph(struct radeon_connector *radeon_connector,
	u8 train_set[4])
	{
	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;

	// radeon_dp_digtransmitter_setup_vsemph();
	radeon_dp_aux_native_write(radeon_connector, DP_TRAINING_LANE0_SET,
	0/* lc */, train_set);
	}

	static void dp_set_training(struct radeon_connector *radeon_connector,
	u8 training)
	{
	radeon_dp_aux_native_write(radeon_connector, DP_TRAINING_PATTERN_SET,
	1, &training);
	}

	int radeon_dp_i2c_aux_ch(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;
	struct radeon_i2c_chan auxch = (struct radeon_i2c_chan )adapter;
	int ret = 0;
	uint16_t address = algo_data->address;
	uint8_t msg[5];
	uint8_t reply[2];
	int msg_len, dp_msg_len;
	int reply_bytes;

	/* Set up the command byte */
	if (mode & MODE_I2C_READ)
	msg[2] = AUX_I2C_READ << 4;
	else
	msg[2] = AUX_I2C_WRITE << 4;

	if (!(mode & MODE_I2C_STOP))
	msg[2] \|= AUX_I2C_MOT << 4;

	msg[0] = address;
	msg[1] = address >> 8;

	reply_bytes = 1;

	msg_len = 4;
	dp_msg_len = 3;
	switch (mode) {
	case MODE_I2C_WRITE:
	msg[4] = write_byte;
	msg_len++;
	dp_msg_len += 2;
	break;
	case MODE_I2C_READ:
	dp_msg_len += 1;
	break;
	default:
	break;
	}

	msg[3] = (dp_msg_len) << 4;
	ret = radeon_process_aux_ch(auxch, msg, msg_len, reply, reply_bytes, 0);

	if (ret) {
	if (read_byte)
	*read_byte = reply[0];
	return reply_bytes;
	}
	return -EREMOTEIO;
	}