[deliverable/linux.git] / drivers / gpu / drm / drm_dp_helper.c

/*
 * 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, ...
 */

/* Helpers for DP link training */
static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
{
	return link_status[r - DP_LANE0_1_STATUS];
}

static u8 dp_get_lane_status(const 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(const 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(const 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(const 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(const 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(const 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(const 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);

/**
 * DOC: dp helpers
 *
 * The DisplayPort AUX channel is an abstraction to allow generic, driver-
 * independent access to AUX functionality. Drivers can take advantage of
 * this by filling in the fields of the drm_dp_aux structure.
 *
 * Transactions are described using a hardware-independent drm_dp_aux_msg
 * structure, which is passed into a driver's .transfer() implementation.
 * Both native and I2C-over-AUX transactions are supported.
 */

static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
			      unsigned int offset, void *buffer, size_t size)
{
	struct drm_dp_aux_msg msg;
	unsigned int retry;
	int err;

	memset(&msg, 0, sizeof(msg));
	msg.address = offset;
	msg.request = request;
	msg.buffer = buffer;
	msg.size = size;

	/*
	 * The specification doesn't give any recommendation on how often to
	 * retry native transactions. We used to retry 7 times like for
	 * aux i2c transactions but real world devices this wasn't
	 * sufficient, bump to 32 which makes Dell 4k monitors happier.
	 */
	for (retry = 0; retry < 32; retry++) {

		mutex_lock(&aux->hw_mutex);
		err = aux->transfer(aux, &msg);
		mutex_unlock(&aux->hw_mutex);
		if (err < 0) {
			if (err == -EBUSY)
				continue;

			return err;
		}


		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
		case DP_AUX_NATIVE_REPLY_ACK:
			if (err < size)
				return -EPROTO;
			return err;

		case DP_AUX_NATIVE_REPLY_NACK:
			return -EIO;

		case DP_AUX_NATIVE_REPLY_DEFER:
			usleep_range(400, 500);
			break;
		}
	}

	DRM_DEBUG_KMS("too many retries, giving up\n");
	return -EIO;
}

/**
 * drm_dp_dpcd_read() - read a series of bytes from the DPCD
 * @aux: DisplayPort AUX channel
 * @offset: address of the (first) register to read
 * @buffer: buffer to store the register values
 * @size: number of bytes in @buffer
 *
 * Returns the number of bytes transferred on success, or a negative error
 * code on failure. -EIO is returned if the request was NAKed by the sink or
 * if the retry count was exceeded. If not all bytes were transferred, this
 * function returns -EPROTO. Errors from the underlying AUX channel transfer
 * function, with the exception of -EBUSY (which causes the transaction to
 * be retried), are propagated to the caller.
 */
ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
			 void *buffer, size_t size)
{
	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
				  size);
}
EXPORT_SYMBOL(drm_dp_dpcd_read);

/**
 * drm_dp_dpcd_write() - write a series of bytes to the DPCD
 * @aux: DisplayPort AUX channel
 * @offset: address of the (first) register to write
 * @buffer: buffer containing the values to write
 * @size: number of bytes in @buffer
 *
 * Returns the number of bytes transferred on success, or a negative error
 * code on failure. -EIO is returned if the request was NAKed by the sink or
 * if the retry count was exceeded. If not all bytes were transferred, this
 * function returns -EPROTO. Errors from the underlying AUX channel transfer
 * function, with the exception of -EBUSY (which causes the transaction to
 * be retried), are propagated to the caller.
 */
ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
			  void *buffer, size_t size)
{
	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
				  size);
}
EXPORT_SYMBOL(drm_dp_dpcd_write);

/**
 * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
 * @aux: DisplayPort AUX channel
 * @status: buffer to store the link status in (must be at least 6 bytes)
 *
 * Returns the number of bytes transferred on success or a negative error
 * code on failure.
 */
int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
				 u8 status[DP_LINK_STATUS_SIZE])
{
	return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
				DP_LINK_STATUS_SIZE);
}
EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);

/**
 * drm_dp_link_probe() - probe a DisplayPort link for capabilities
 * @aux: DisplayPort AUX channel
 * @link: pointer to structure in which to return link capabilities
 *
 * The structure filled in by this function can usually be passed directly
 * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
 * configure the link based on the link's capabilities.
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
	u8 values[3];
	int err;

	memset(link, 0, sizeof(*link));

	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
	if (err < 0)
		return err;

	link->revision = values[0];
	link->rate = drm_dp_bw_code_to_link_rate(values[1]);
	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;

	if (values[2] & DP_ENHANCED_FRAME_CAP)
		link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING;

	return 0;
}
EXPORT_SYMBOL(drm_dp_link_probe);

/**
 * drm_dp_link_power_up() - power up a DisplayPort link
 * @aux: DisplayPort AUX channel
 * @link: pointer to a structure containing the link configuration
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
	u8 value;
	int err;

	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
	if (link->revision < 0x11)
		return 0;

	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
	if (err < 0)
		return err;

	value &= ~DP_SET_POWER_MASK;
	value |= DP_SET_POWER_D0;

	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
	if (err < 0)
		return err;

	/*
	 * According to the DP 1.1 specification, a "Sink Device must exit the
	 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
	 * Control Field" (register 0x600).
	 */
	usleep_range(1000, 2000);

	return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_up);

/**
 * drm_dp_link_power_down() - power down a DisplayPort link
 * @aux: DisplayPort AUX channel
 * @link: pointer to a structure containing the link configuration
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
	u8 value;
	int err;

	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
	if (link->revision < 0x11)
		return 0;

	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
	if (err < 0)
		return err;

	value &= ~DP_SET_POWER_MASK;
	value |= DP_SET_POWER_D3;

	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
	if (err < 0)
		return err;

	return 0;
}
EXPORT_SYMBOL(drm_dp_link_power_down);

/**
 * drm_dp_link_configure() - configure a DisplayPort link
 * @aux: DisplayPort AUX channel
 * @link: pointer to a structure containing the link configuration
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
{
	u8 values[2];
	int err;

	values[0] = drm_dp_link_rate_to_bw_code(link->rate);
	values[1] = link->num_lanes;

	if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)
		values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;

	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
	if (err < 0)
		return err;

	return 0;
}
EXPORT_SYMBOL(drm_dp_link_configure);

/*
 * I2C-over-AUX implementation
 */

static u32 drm_dp_i2c_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;
}

/*
 * Transfer a single I2C-over-AUX message and handle various error conditions,
 * retrying the transaction as appropriate.  It is assumed that the
 * aux->transfer function does not modify anything in the msg other than the
 * reply field.
 */
static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
{
	unsigned int retry;
	int err;

	/*
	 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
	 * is required to retry at least seven times upon receiving AUX_DEFER
	 * before giving up the AUX transaction.
	 */
	for (retry = 0; retry < 7; retry++) {
		mutex_lock(&aux->hw_mutex);
		err = aux->transfer(aux, msg);
		mutex_unlock(&aux->hw_mutex);
		if (err < 0) {
			if (err == -EBUSY)
				continue;

			DRM_DEBUG_KMS("transaction failed: %d\n", err);
			return err;
		}


		switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
		case DP_AUX_NATIVE_REPLY_ACK:
			/*
			 * For I2C-over-AUX transactions this isn't enough, we
			 * need to check for the I2C ACK reply.
			 */
			break;

		case DP_AUX_NATIVE_REPLY_NACK:
			DRM_DEBUG_KMS("native nack\n");
			return -EREMOTEIO;

		case DP_AUX_NATIVE_REPLY_DEFER:
			DRM_DEBUG_KMS("native defer");
			/*
			 * We could check for I2C bit rate capabilities and if
			 * available adjust this interval. We could also be
			 * more careful with DP-to-legacy adapters where a
			 * long legacy cable may force very low I2C bit rates.
			 *
			 * For now just defer for long enough to hopefully be
			 * safe for all use-cases.
			 */
			usleep_range(500, 600);
			continue;

		default:
			DRM_ERROR("invalid native reply %#04x\n", msg->reply);
			return -EREMOTEIO;
		}

		switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
		case DP_AUX_I2C_REPLY_ACK:
			/*
			 * Both native ACK and I2C ACK replies received. We
			 * can assume the transfer was successful.
			 */
			if (err < msg->size)
				return -EPROTO;
			return 0;

		case DP_AUX_I2C_REPLY_NACK:
			DRM_DEBUG_KMS("I2C nack\n");
			aux->i2c_nack_count++;
			return -EREMOTEIO;

		case DP_AUX_I2C_REPLY_DEFER:
			DRM_DEBUG_KMS("I2C defer\n");
			aux->i2c_defer_count++;
			usleep_range(400, 500);
			continue;

		default:
			DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);
			return -EREMOTEIO;
		}
	}

	DRM_DEBUG_KMS("too many retries, giving up\n");
	return -EREMOTEIO;
}

static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
			   int num)
{
	struct drm_dp_aux *aux = adapter->algo_data;
	unsigned int i, j;
	struct drm_dp_aux_msg msg;
	int err = 0;

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

	for (i = 0; i < num; i++) {
		msg.address = msgs[i].addr;
		msg.request = (msgs[i].flags & I2C_M_RD) ?
			DP_AUX_I2C_READ :
			DP_AUX_I2C_WRITE;
		msg.request |= DP_AUX_I2C_MOT;
		/* Send a bare address packet to start the transaction.
		 * Zero sized messages specify an address only (bare
		 * address) transaction.
		 */
		msg.buffer = NULL;
		msg.size = 0;
		err = drm_dp_i2c_do_msg(aux, &msg);
		if (err < 0)
			break;
		/*
		 * Many hardware implementations support FIFOs larger than a
		 * single byte, but it has been empirically determined that
		 * transferring data in larger chunks can actually lead to
		 * decreased performance. Therefore each message is simply
		 * transferred byte-by-byte.
		 */
		for (j = 0; j < msgs[i].len; j++) {
			msg.buffer = msgs[i].buf + j;
			msg.size = 1;

			err = drm_dp_i2c_do_msg(aux, &msg);
			if (err < 0)
				break;
		}
		if (err < 0)
			break;
	}
	if (err >= 0)
		err = num;
	/* Send a bare address packet to close out the transaction.
	 * Zero sized messages specify an address only (bare
	 * address) transaction.
	 */
	msg.request &= ~DP_AUX_I2C_MOT;
	msg.buffer = NULL;
	msg.size = 0;
	(void)drm_dp_i2c_do_msg(aux, &msg);

	return err;
}

static const struct i2c_algorithm drm_dp_i2c_algo = {
	.functionality = drm_dp_i2c_functionality,
	.master_xfer = drm_dp_i2c_xfer,
};

/**
 * drm_dp_aux_register() - initialise and register aux channel
 * @aux: DisplayPort AUX channel
 *
 * Returns 0 on success or a negative error code on failure.
 */
int drm_dp_aux_register(struct drm_dp_aux *aux)
{
	mutex_init(&aux->hw_mutex);

	aux->ddc.algo = &drm_dp_i2c_algo;
	aux->ddc.algo_data = aux;
	aux->ddc.retries = 3;

	aux->ddc.class = I2C_CLASS_DDC;
	aux->ddc.owner = THIS_MODULE;
	aux->ddc.dev.parent = aux->dev;
	aux->ddc.dev.of_node = aux->dev->of_node;

	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
		sizeof(aux->ddc.name));

	return i2c_add_adapter(&aux->ddc);
}
EXPORT_SYMBOL(drm_dp_aux_register);

/**
 * drm_dp_aux_unregister() - unregister an AUX adapter
 * @aux: DisplayPort AUX channel
 */
void drm_dp_aux_unregister(struct drm_dp_aux *aux)
{
	i2c_del_adapter(&aux->ddc);
}
EXPORT_SYMBOL(drm_dp_aux_unregister);
Commit	Line	Data
a4fc5ed6 KP	1	/*
	2	* Copyright © 2009 Keith Packard
	3	*
	4	* Permission to use, copy, modify, distribute, and sell this software and its
	5	* documentation for any purpose is hereby granted without fee, provided that
	6	* the above copyright notice appear in all copies and that both that copyright
	7	* notice and this permission notice appear in supporting documentation, and
	8	* that the name of the copyright holders not be used in advertising or
	9	* publicity pertaining to distribution of the software without specific,
	10	* written prior permission. The copyright holders make no representations
	11	* about the suitability of this software for any purpose. It is provided "as
	12	* is" without express or implied warranty.
	13	*
	14	* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
	15	* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
	16	* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
	17	* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
	18	* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
	19	* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	20	* OF THIS SOFTWARE.
	21	*/
	22
	23	#include <linux/kernel.h>
	24	#include <linux/module.h>
	25	#include <linux/delay.h>
a4fc5ed6 KP	26	#include <linux/init.h>
	27	#include <linux/errno.h>
	28	#include <linux/sched.h>
	29	#include <linux/i2c.h>
760285e7 DH	30	#include <drm/drm_dp_helper.h>
760285e7 DH	31	#include <drm/drmP.h>
a4fc5ed6	32
28164fda DV	33	/**
	34	* DOC: dp helpers
	35	*
	36	* These functions contain some common logic and helpers at various abstraction
	37	* levels to deal with Display Port sink devices and related things like DP aux
	38	* channel transfers, EDID reading over DP aux channels, decoding certain DPCD
	39	* blocks, ...
	40	*/
	41
1ffdff13	42	/* Helpers for DP link training */
0aec2881	43	static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
1ffdff13 DV	44	{
	45	return link_status[r - DP_LANE0_1_STATUS];
	46	}
	47
0aec2881	48	static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
1ffdff13 DV	49	int lane)
	50	{
	51	int i = DP_LANE0_1_STATUS + (lane >> 1);
	52	int s = (lane & 1) * 4;
	53	u8 l = dp_link_status(link_status, i);
	54	return (l >> s) & 0xf;
	55	}
	56
0aec2881	57	bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
1ffdff13 DV	58	int lane_count)
	59	{
	60	u8 lane_align;
	61	u8 lane_status;
	62	int lane;
	63
	64	lane_align = dp_link_status(link_status,
	65	DP_LANE_ALIGN_STATUS_UPDATED);
	66	if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
	67	return false;
	68	for (lane = 0; lane < lane_count; lane++) {
	69	lane_status = dp_get_lane_status(link_status, lane);
	70	if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
	71	return false;
	72	}
	73	return true;
	74	}
	75	EXPORT_SYMBOL(drm_dp_channel_eq_ok);
	76
0aec2881	77	bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
1ffdff13 DV	78	int lane_count)
	79	{
	80	int lane;
	81	u8 lane_status;
	82
	83	for (lane = 0; lane < lane_count; lane++) {
	84	lane_status = dp_get_lane_status(link_status, lane);
	85	if ((lane_status & DP_LANE_CR_DONE) == 0)
	86	return false;
	87	}
	88	return true;
	89	}
	90	EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
0f037bde	91
0aec2881	92	u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
0f037bde DV	93	int lane)
	94	{
	95	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
	96	int s = ((lane & 1) ?
	97	DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
	98	DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
	99	u8 l = dp_link_status(link_status, i);
	100
	101	return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
	102	}
	103	EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);
	104
0aec2881	105	u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
0f037bde DV	106	int lane)
	107	{
	108	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
	109	int s = ((lane & 1) ?
	110	DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
	111	DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
	112	u8 l = dp_link_status(link_status, i);
	113
	114	return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
	115	}
	116	EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
	117
0aec2881	118	void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
1a644cd4 DV	119	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
	120	udelay(100);
	121	else
	122	mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
	123	}
	124	EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
	125
0aec2881	126	void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
1a644cd4 DV	127	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
	128	udelay(400);
	129	else
	130	mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
	131	}
	132	EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
3b5c662e DV	133
	134	u8 drm_dp_link_rate_to_bw_code(int link_rate)
	135	{
	136	switch (link_rate) {
	137	case 162000:
	138	default:
	139	return DP_LINK_BW_1_62;
	140	case 270000:
	141	return DP_LINK_BW_2_7;
	142	case 540000:
	143	return DP_LINK_BW_5_4;
	144	}
	145	}
	146	EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
	147
	148	int drm_dp_bw_code_to_link_rate(u8 link_bw)
	149	{
	150	switch (link_bw) {
	151	case DP_LINK_BW_1_62:
	152	default:
	153	return 162000;
	154	case DP_LINK_BW_2_7:
	155	return 270000;
	156	case DP_LINK_BW_5_4:
	157	return 540000;
	158	}
	159	}
	160	EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
c197db75 TR	161
	162	/**
	163	* DOC: dp helpers
	164	*
	165	* The DisplayPort AUX channel is an abstraction to allow generic, driver-
	166	* independent access to AUX functionality. Drivers can take advantage of
	167	* this by filling in the fields of the drm_dp_aux structure.
	168	*
	169	* Transactions are described using a hardware-independent drm_dp_aux_msg
	170	* structure, which is passed into a driver's .transfer() implementation.
	171	* Both native and I2C-over-AUX transactions are supported.
c197db75 TR	172	*/
	173
	174	static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
	175	unsigned int offset, void *buffer, size_t size)
	176	{
	177	struct drm_dp_aux_msg msg;
	178	unsigned int retry;
	179	int err;
	180
	181	memset(&msg, 0, sizeof(msg));
	182	msg.address = offset;
	183	msg.request = request;
	184	msg.buffer = buffer;
	185	msg.size = size;
	186
	187	/*
	188	* The specification doesn't give any recommendation on how often to
19a93f04 DA	189	* retry native transactions. We used to retry 7 times like for
	190	* aux i2c transactions but real world devices this wasn't
	191	* sufficient, bump to 32 which makes Dell 4k monitors happier.
c197db75	192	*/
19a93f04	193	for (retry = 0; retry < 32; retry++) {
4f71d0cb DA	194
4f71d0cb DA	195	mutex_lock(&aux->hw_mutex);
c197db75	196	err = aux->transfer(aux, &msg);
4f71d0cb	197	mutex_unlock(&aux->hw_mutex);
c197db75 TR	198	if (err < 0) {
	199	if (err == -EBUSY)
	200	continue;
	201
	202	return err;
	203	}
	204
c197db75 TR	205
	206	switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
	207	case DP_AUX_NATIVE_REPLY_ACK:
aa17edff DA	208	if (err < size)
aa17edff DA	209	return -EPROTO;
c197db75 TR	210	return err;
	211
	212	case DP_AUX_NATIVE_REPLY_NACK:
	213	return -EIO;
	214
	215	case DP_AUX_NATIVE_REPLY_DEFER:
	216	usleep_range(400, 500);
	217	break;
	218	}
	219	}
	220
743b1e32	221	DRM_DEBUG_KMS("too many retries, giving up\n");
c197db75 TR	222	return -EIO;
	223	}
	224
	225	/**
	226	* drm_dp_dpcd_read() - read a series of bytes from the DPCD
	227	* @aux: DisplayPort AUX channel
	228	* @offset: address of the (first) register to read
	229	* @buffer: buffer to store the register values
	230	* @size: number of bytes in @buffer
	231	*
	232	* Returns the number of bytes transferred on success, or a negative error
	233	* code on failure. -EIO is returned if the request was NAKed by the sink or
	234	* if the retry count was exceeded. If not all bytes were transferred, this
	235	* function returns -EPROTO. Errors from the underlying AUX channel transfer
	236	* function, with the exception of -EBUSY (which causes the transaction to
	237	* be retried), are propagated to the caller.
	238	*/
	239	ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
	240	void *buffer, size_t size)
	241	{
	242	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
	243	size);
	244	}
	245	EXPORT_SYMBOL(drm_dp_dpcd_read);
	246
	247	/**
	248	* drm_dp_dpcd_write() - write a series of bytes to the DPCD
	249	* @aux: DisplayPort AUX channel
	250	* @offset: address of the (first) register to write
	251	* @buffer: buffer containing the values to write
	252	* @size: number of bytes in @buffer
	253	*
	254	* Returns the number of bytes transferred on success, or a negative error
	255	* code on failure. -EIO is returned if the request was NAKed by the sink or
	256	* if the retry count was exceeded. If not all bytes were transferred, this
	257	* function returns -EPROTO. Errors from the underlying AUX channel transfer
	258	* function, with the exception of -EBUSY (which causes the transaction to
	259	* be retried), are propagated to the caller.
	260	*/
	261	ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
	262	void *buffer, size_t size)
	263	{
	264	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
	265	size);
	266	}
	267	EXPORT_SYMBOL(drm_dp_dpcd_write);
8d4adc6a TR	268
	269	/**
	270	* drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
	271	* @aux: DisplayPort AUX channel
	272	* @status: buffer to store the link status in (must be at least 6 bytes)
	273	*
	274	* Returns the number of bytes transferred on success or a negative error
	275	* code on failure.
	276	*/
	277	int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
	278	u8 status[DP_LINK_STATUS_SIZE])
	279	{
	280	return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
	281	DP_LINK_STATUS_SIZE);
	282	}
	283	EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
516c0f7c TR	284
	285	/**
	286	* drm_dp_link_probe() - probe a DisplayPort link for capabilities
	287	* @aux: DisplayPort AUX channel
	288	* @link: pointer to structure in which to return link capabilities
	289	*
	290	* The structure filled in by this function can usually be passed directly
	291	* into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
	292	* configure the link based on the link's capabilities.
	293	*
	294	* Returns 0 on success or a negative error code on failure.
	295	*/
	296	int drm_dp_link_probe(struct drm_dp_aux aux, struct drm_dp_link link)
	297	{
	298	u8 values[3];
	299	int err;
	300
	301	memset(link, 0, sizeof(*link));
	302
	303	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
	304	if (err < 0)
	305	return err;
	306
	307	link->revision = values[0];
	308	link->rate = drm_dp_bw_code_to_link_rate(values[1]);
	309	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
	310
	311	if (values[2] & DP_ENHANCED_FRAME_CAP)
	312	link->capabilities \|= DP_LINK_CAP_ENHANCED_FRAMING;
	313
	314	return 0;
	315	}
	316	EXPORT_SYMBOL(drm_dp_link_probe);
	317
	318	/**
	319	* drm_dp_link_power_up() - power up a DisplayPort link
	320	* @aux: DisplayPort AUX channel
	321	* @link: pointer to a structure containing the link configuration
	322	*
	323	* Returns 0 on success or a negative error code on failure.
	324	*/
	325	int drm_dp_link_power_up(struct drm_dp_aux aux, struct drm_dp_link link)
	326	{
	327	u8 value;
	328	int err;
	329
	330	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
	331	if (link->revision < 0x11)
	332	return 0;
	333
	334	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
	335	if (err < 0)
	336	return err;
	337
	338	value &= ~DP_SET_POWER_MASK;
	339	value \|= DP_SET_POWER_D0;
	340
	341	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
	342	if (err < 0)
	343	return err;
	344
	345	/*
	346	* According to the DP 1.1 specification, a "Sink Device must exit the
	347	* power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
348	* Control Field" (register 0x600).
349	*/
350	usleep_range(1000, 2000);
351
352	return 0;
353	}
354	EXPORT_SYMBOL(drm_dp_link_power_up);
355
d816f077 RC	356	/**
	357	* drm_dp_link_power_down() - power down a DisplayPort link
	358	* @aux: DisplayPort AUX channel
	359	* @link: pointer to a structure containing the link configuration
	360	*
	361	* Returns 0 on success or a negative error code on failure.
	362	*/
	363	int drm_dp_link_power_down(struct drm_dp_aux aux, struct drm_dp_link link)
	364	{
	365	u8 value;
	366	int err;
	367
	368	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
	369	if (link->revision < 0x11)
	370	return 0;
	371
	372	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
	373	if (err < 0)
	374	return err;
	375
	376	value &= ~DP_SET_POWER_MASK;
	377	value \|= DP_SET_POWER_D3;
	378
	379	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
	380	if (err < 0)
	381	return err;
	382
	383	return 0;
	384	}
	385	EXPORT_SYMBOL(drm_dp_link_power_down);
	386
516c0f7c TR	387	/**
	388	* drm_dp_link_configure() - configure a DisplayPort link
	389	* @aux: DisplayPort AUX channel
	390	* @link: pointer to a structure containing the link configuration
	391	*
	392	* Returns 0 on success or a negative error code on failure.
	393	*/
	394	int drm_dp_link_configure(struct drm_dp_aux aux, struct drm_dp_link link)
	395	{
	396	u8 values[2];
	397	int err;
	398
	399	values[0] = drm_dp_link_rate_to_bw_code(link->rate);
	400	values[1] = link->num_lanes;
	401
	402	if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)
	403	values[1] \|= DP_LANE_COUNT_ENHANCED_FRAME_EN;
	404
	405	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
	406	if (err < 0)
	407	return err;
	408
	409	return 0;
	410	}
	411	EXPORT_SYMBOL(drm_dp_link_configure);
88759686 TR	412
	413	/*
	414	* I2C-over-AUX implementation
	415	*/
	416
	417	static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
	418	{
	419	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \|
	420	I2C_FUNC_SMBUS_READ_BLOCK_DATA \|
	421	I2C_FUNC_SMBUS_BLOCK_PROC_CALL \|
	422	I2C_FUNC_10BIT_ADDR;
	423	}
	424
	425	/*
	426	* Transfer a single I2C-over-AUX message and handle various error conditions,
732d50b4 AD	427	* retrying the transaction as appropriate. It is assumed that the
	428	* aux->transfer function does not modify anything in the msg other than the
	429	* reply field.
88759686 TR	430	*/
	431	static int drm_dp_i2c_do_msg(struct drm_dp_aux aux, struct drm_dp_aux_msg msg)
	432	{
	433	unsigned int retry;
	434	int err;
	435
	436	/*
	437	* DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
	438	* is required to retry at least seven times upon receiving AUX_DEFER
	439	* before giving up the AUX transaction.
	440	*/
	441	for (retry = 0; retry < 7; retry++) {
4f71d0cb	442	mutex_lock(&aux->hw_mutex);
88759686	443	err = aux->transfer(aux, msg);
4f71d0cb	444	mutex_unlock(&aux->hw_mutex);
88759686 TR	445	if (err < 0) {
	446	if (err == -EBUSY)
	447	continue;
	448
	449	DRM_DEBUG_KMS("transaction failed: %d\n", err);
	450	return err;
	451	}
	452
88759686 TR	453
	454	switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
	455	case DP_AUX_NATIVE_REPLY_ACK:
	456	/*
	457	* For I2C-over-AUX transactions this isn't enough, we
	458	* need to check for the I2C ACK reply.
	459	*/
	460	break;
	461
	462	case DP_AUX_NATIVE_REPLY_NACK:
	463	DRM_DEBUG_KMS("native nack\n");
	464	return -EREMOTEIO;
	465
	466	case DP_AUX_NATIVE_REPLY_DEFER:
	467	DRM_DEBUG_KMS("native defer");
	468	/*
	469	* We could check for I2C bit rate capabilities and if
	470	* available adjust this interval. We could also be
	471	* more careful with DP-to-legacy adapters where a
	472	* long legacy cable may force very low I2C bit rates.
	473	*
	474	* For now just defer for long enough to hopefully be
	475	* safe for all use-cases.
	476	*/
	477	usleep_range(500, 600);
	478	continue;
	479
	480	default:
	481	DRM_ERROR("invalid native reply %#04x\n", msg->reply);
	482	return -EREMOTEIO;
	483	}
	484
	485	switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
	486	case DP_AUX_I2C_REPLY_ACK:
	487	/*
	488	* Both native ACK and I2C ACK replies received. We
	489	* can assume the transfer was successful.
	490	*/
aa17edff DA	491	if (err < msg->size)
aa17edff DA	492	return -EPROTO;
88759686 TR	493	return 0;
	494
	495	case DP_AUX_I2C_REPLY_NACK:
	496	DRM_DEBUG_KMS("I2C nack\n");
e9cf6194	497	aux->i2c_nack_count++;
88759686 TR	498	return -EREMOTEIO;
	499
	500	case DP_AUX_I2C_REPLY_DEFER:
	501	DRM_DEBUG_KMS("I2C defer\n");
e9cf6194	502	aux->i2c_defer_count++;
88759686 TR	503	usleep_range(400, 500);
	504	continue;
	505
	506	default:
	507	DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);
	508	return -EREMOTEIO;
	509	}
	510	}
	511
743b1e32	512	DRM_DEBUG_KMS("too many retries, giving up\n");
88759686 TR	513	return -EREMOTEIO;
	514	}
	515
	516	static int drm_dp_i2c_xfer(struct i2c_adapter adapter, struct i2c_msg msgs,
	517	int num)
	518	{
	519	struct drm_dp_aux *aux = adapter->algo_data;
	520	unsigned int i, j;
ccdb516e AD	521	struct drm_dp_aux_msg msg;
ccdb516e AD	522	int err = 0;
88759686	523
ccdb516e	524	memset(&msg, 0, sizeof(msg));
88759686	525
ccdb516e AD	526	for (i = 0; i < num; i++) {
	527	msg.address = msgs[i].addr;
	528	msg.request = (msgs[i].flags & I2C_M_RD) ?
	529	DP_AUX_I2C_READ :
	530	DP_AUX_I2C_WRITE;
	531	msg.request \|= DP_AUX_I2C_MOT;
	532	/* Send a bare address packet to start the transaction.
	533	* Zero sized messages specify an address only (bare
	534	* address) transaction.
	535	*/
	536	msg.buffer = NULL;
	537	msg.size = 0;
	538	err = drm_dp_i2c_do_msg(aux, &msg);
	539	if (err < 0)
	540	break;
88759686 TR	541	/*
	542	* Many hardware implementations support FIFOs larger than a
	543	* single byte, but it has been empirically determined that
	544	* transferring data in larger chunks can actually lead to
	545	* decreased performance. Therefore each message is simply
	546	* transferred byte-by-byte.
	547	*/
	548	for (j = 0; j < msgs[i].len; j++) {
88759686 TR	549	msg.buffer = msgs[i].buf + j;
	550	msg.size = 1;
	551
	552	err = drm_dp_i2c_do_msg(aux, &msg);
	553	if (err < 0)
ccdb516e	554	break;
88759686	555	}
ccdb516e AD	556	if (err < 0)
ccdb516e AD	557	break;
88759686	558	}
ccdb516e AD	559	if (err >= 0)
	560	err = num;
	561	/* Send a bare address packet to close out the transaction.
	562	* Zero sized messages specify an address only (bare
	563	* address) transaction.
	564	*/
	565	msg.request &= ~DP_AUX_I2C_MOT;
	566	msg.buffer = NULL;
	567	msg.size = 0;
	568	(void)drm_dp_i2c_do_msg(aux, &msg);
88759686	569
ccdb516e	570	return err;
88759686 TR	571	}
	572
	573	static const struct i2c_algorithm drm_dp_i2c_algo = {
	574	.functionality = drm_dp_i2c_functionality,
	575	.master_xfer = drm_dp_i2c_xfer,
	576	};
	577
	578	/**
4f71d0cb	579	* drm_dp_aux_register() - initialise and register aux channel
88759686 TR	580	* @aux: DisplayPort AUX channel
	581	*
	582	* Returns 0 on success or a negative error code on failure.
	583	*/
4f71d0cb	584	int drm_dp_aux_register(struct drm_dp_aux *aux)
88759686	585	{
4f71d0cb DA	586	mutex_init(&aux->hw_mutex);
4f71d0cb DA	587
88759686 TR	588	aux->ddc.algo = &drm_dp_i2c_algo;
	589	aux->ddc.algo_data = aux;
	590	aux->ddc.retries = 3;
	591
	592	aux->ddc.class = I2C_CLASS_DDC;
	593	aux->ddc.owner = THIS_MODULE;
	594	aux->ddc.dev.parent = aux->dev;
	595	aux->ddc.dev.of_node = aux->dev->of_node;
	596
9dc40560 JN	597	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
9dc40560 JN	598	sizeof(aux->ddc.name));
88759686 TR	599
	600	return i2c_add_adapter(&aux->ddc);
	601	}
4f71d0cb	602	EXPORT_SYMBOL(drm_dp_aux_register);
88759686 TR	603
88759686 TR	604	/**
4f71d0cb	605	* drm_dp_aux_unregister() - unregister an AUX adapter
88759686 TR	606	* @aux: DisplayPort AUX channel
88759686 TR	607	*/
4f71d0cb	608	void drm_dp_aux_unregister(struct drm_dp_aux *aux)
88759686 TR	609	{
	610	i2c_del_adapter(&aux->ddc);
	611	}
4f71d0cb	612	EXPORT_SYMBOL(drm_dp_aux_unregister);