drm/i915/dp: split out aux functionality to intel_dp_aux.c

Split out the DP aux functionality to a new intel_dp_aux.[ch]. This is a
surprisingly clean cut.

v2:
- Remove intel_dp_pack_aux declaration from intel_dp.h (Anshuman)
- Fixed some whitespace/comment checkpatch warnings

Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210120101834.19813-4-jani.nikula@intel.com

1 files changed, 692 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
new file mode 100644
index 000000000000..eaebf123310a
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -0,0 +1,692 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2020-2021 Intel Corporation
+ */
+
+#include "i915_drv.h"
+#include "i915_trace.h"
+#include "intel_display_types.h"
+#include "intel_dp_aux.h"
+#include "intel_pps.h"
+#include "intel_tc.h"
+
+u32 intel_dp_pack_aux(const u8 *src, int src_bytes)
+{
+	int i;
+	u32 v = 0;
+
+	if (src_bytes > 4)
+		src_bytes = 4;
+	for (i = 0; i < src_bytes; i++)
+		v |= ((u32)src[i]) << ((3 - i) * 8);
+	return v;
+}
+
+static void intel_dp_unpack_aux(u32 src, u8 *dst, int dst_bytes)
+{
+	int i;
+
+	if (dst_bytes > 4)
+		dst_bytes = 4;
+	for (i = 0; i < dst_bytes; i++)
+		dst[i] = src >> ((3 - i) * 8);
+}
+
+static u32
+intel_dp_aux_wait_done(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	i915_reg_t ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
+	const unsigned int timeout_ms = 10;
+	u32 status;
+	bool done;
+
+#define C (((status = intel_uncore_read_notrace(&i915->uncore, ch_ctl)) & DP_AUX_CH_CTL_SEND_BUSY) == 0)
+	done = wait_event_timeout(i915->gmbus_wait_queue, C,
+				  msecs_to_jiffies_timeout(timeout_ms));
+
+	/* just trace the final value */
+	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
+
+	if (!done)
+		drm_err(&i915->drm,
+			"%s: did not complete or timeout within %ums (status 0x%08x)\n",
+			intel_dp->aux.name, timeout_ms, status);
+#undef C
+
+	return status;
+}
+
+static u32 g4x_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+
+	if (index)
+		return 0;
+
+	/*
+	 * The clock divider is based off the hrawclk, and would like to run at
+	 * 2MHz.  So, take the hrawclk value and divide by 2000 and use that
+	 */
+	return DIV_ROUND_CLOSEST(RUNTIME_INFO(dev_priv)->rawclk_freq, 2000);
+}
+
+static u32 ilk_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	u32 freq;
+
+	if (index)
+		return 0;
+
+	/*
+	 * The clock divider is based off the cdclk or PCH rawclk, and would
+	 * like to run at 2MHz.  So, take the cdclk or PCH rawclk value and
+	 * divide by 2000 and use that
+	 */
+	if (dig_port->aux_ch == AUX_CH_A)
+		freq = dev_priv->cdclk.hw.cdclk;
+	else
+		freq = RUNTIME_INFO(dev_priv)->rawclk_freq;
+	return DIV_ROUND_CLOSEST(freq, 2000);
+}
+
+static u32 hsw_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+
+	if (dig_port->aux_ch != AUX_CH_A && HAS_PCH_LPT_H(dev_priv)) {
+		/* Workaround for non-ULT HSW */
+		switch (index) {
+		case 0: return 63;
+		case 1: return 72;
+		default: return 0;
+		}
+	}
+
+	return ilk_get_aux_clock_divider(intel_dp, index);
+}
+
+static u32 skl_get_aux_clock_divider(struct intel_dp *intel_dp, int index)
+{
+	/*
+	 * SKL doesn't need us to program the AUX clock divider (Hardware will
+	 * derive the clock from CDCLK automatically). We still implement the
+	 * get_aux_clock_divider vfunc to plug-in into the existing code.
+	 */
+	return index ? 0 : 1;
+}
+
+static u32 g4x_get_aux_send_ctl(struct intel_dp *intel_dp,
+				int send_bytes,
+				u32 aux_clock_divider)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_i915_private *dev_priv =
+			to_i915(dig_port->base.base.dev);
+	u32 precharge, timeout;
+
+	if (IS_GEN(dev_priv, 6))
+		precharge = 3;
+	else
+		precharge = 5;
+
+	if (IS_BROADWELL(dev_priv))
+		timeout = DP_AUX_CH_CTL_TIME_OUT_600us;
+	else
+		timeout = DP_AUX_CH_CTL_TIME_OUT_400us;
+
+	return DP_AUX_CH_CTL_SEND_BUSY |
+	       DP_AUX_CH_CTL_DONE |
+	       DP_AUX_CH_CTL_INTERRUPT |
+	       DP_AUX_CH_CTL_TIME_OUT_ERROR |
+	       timeout |
+	       DP_AUX_CH_CTL_RECEIVE_ERROR |
+	       (send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
+	       (precharge << DP_AUX_CH_CTL_PRECHARGE_2US_SHIFT) |
+	       (aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT);
+}
+
+static u32 skl_get_aux_send_ctl(struct intel_dp *intel_dp,
+				int send_bytes,
+				u32 unused)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_i915_private *i915 =
+			to_i915(dig_port->base.base.dev);
+	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
+	u32 ret;
+
+	ret = DP_AUX_CH_CTL_SEND_BUSY |
+	      DP_AUX_CH_CTL_DONE |
+	      DP_AUX_CH_CTL_INTERRUPT |
+	      DP_AUX_CH_CTL_TIME_OUT_ERROR |
+	      DP_AUX_CH_CTL_TIME_OUT_MAX |
+	      DP_AUX_CH_CTL_RECEIVE_ERROR |
+	      (send_bytes << DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT) |
+	      DP_AUX_CH_CTL_FW_SYNC_PULSE_SKL(32) |
+	      DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
+
+	if (intel_phy_is_tc(i915, phy) &&
+	    dig_port->tc_mode == TC_PORT_TBT_ALT)
+		ret |= DP_AUX_CH_CTL_TBT_IO;
+
+	return ret;
+}
+
+static int
+intel_dp_aux_xfer(struct intel_dp *intel_dp,
+		  const u8 *send, int send_bytes,
+		  u8 *recv, int recv_size,
+		  u32 aux_send_ctl_flags)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_i915_private *i915 =
+			to_i915(dig_port->base.base.dev);
+	struct intel_uncore *uncore = &i915->uncore;
+	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
+	bool is_tc_port = intel_phy_is_tc(i915, phy);
+	i915_reg_t ch_ctl, ch_data[5];
+	u32 aux_clock_divider;
+	enum intel_display_power_domain aux_domain;
+	intel_wakeref_t aux_wakeref;
+	intel_wakeref_t pps_wakeref;
+	int i, ret, recv_bytes;
+	int try, clock = 0;
+	u32 status;
+	bool vdd;
+
+	ch_ctl = intel_dp->aux_ch_ctl_reg(intel_dp);
+	for (i = 0; i < ARRAY_SIZE(ch_data); i++)
+		ch_data[i] = intel_dp->aux_ch_data_reg(intel_dp, i);
+
+	if (is_tc_port)
+		intel_tc_port_lock(dig_port);
+
+	aux_domain = intel_aux_power_domain(dig_port);
+
+	aux_wakeref = intel_display_power_get(i915, aux_domain);
+	pps_wakeref = intel_pps_lock(intel_dp);
+
+	/*
+	 * We will be called with VDD already enabled for dpcd/edid/oui reads.
+	 * In such cases we want to leave VDD enabled and it's up to upper layers
+	 * to turn it off. But for eg. i2c-dev access we need to turn it on/off
+	 * ourselves.
+	 */
+	vdd = intel_pps_vdd_on_unlocked(intel_dp);
+
+	/*
+	 * dp aux is extremely sensitive to irq latency, hence request the
+	 * lowest possible wakeup latency and so prevent the cpu from going into
+	 * deep sleep states.
+	 */
+	cpu_latency_qos_update_request(&intel_dp->pm_qos, 0);
+
+	intel_pps_check_power_unlocked(intel_dp);
+
+	/* Try to wait for any previous AUX channel activity */
+	for (try = 0; try < 3; try++) {
+		status = intel_uncore_read_notrace(uncore, ch_ctl);
+		if ((status & DP_AUX_CH_CTL_SEND_BUSY) == 0)
+			break;
+		msleep(1);
+	}
+	/* just trace the final value */
+	trace_i915_reg_rw(false, ch_ctl, status, sizeof(status), true);
+
+	if (try == 3) {
+		const u32 status = intel_uncore_read(uncore, ch_ctl);
+
+		if (status != intel_dp->aux_busy_last_status) {
+			drm_WARN(&i915->drm, 1,
+				 "%s: not started (status 0x%08x)\n",
+				 intel_dp->aux.name, status);
+			intel_dp->aux_busy_last_status = status;
+		}
+
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* Only 5 data registers! */
+	if (drm_WARN_ON(&i915->drm, send_bytes > 20 || recv_size > 20)) {
+		ret = -E2BIG;
+		goto out;
+	}
+
+	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
+		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
+							  send_bytes,
+							  aux_clock_divider);
+
+		send_ctl |= aux_send_ctl_flags;
+
+		/* Must try at least 3 times according to DP spec */
+		for (try = 0; try < 5; try++) {
+			/* Load the send data into the aux channel data registers */
+			for (i = 0; i < send_bytes; i += 4)
+				intel_uncore_write(uncore,
+						   ch_data[i >> 2],
+						   intel_dp_pack_aux(send + i,
+								     send_bytes - i));
+
+			/* Send the command and wait for it to complete */
+			intel_uncore_write(uncore, ch_ctl, send_ctl);
+
+			status = intel_dp_aux_wait_done(intel_dp);
+
+			/* Clear done status and any errors */
+			intel_uncore_write(uncore,
+					   ch_ctl,
+					   status |
+					   DP_AUX_CH_CTL_DONE |
+					   DP_AUX_CH_CTL_TIME_OUT_ERROR |
+					   DP_AUX_CH_CTL_RECEIVE_ERROR);
+
+			/*
+			 * DP CTS 1.2 Core Rev 1.1, 4.2.1.1 & 4.2.1.2
+			 *   400us delay required for errors and timeouts
+			 *   Timeout errors from the HW already meet this
+			 *   requirement so skip to next iteration
+			 */
+			if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR)
+				continue;
+
+			if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
+				usleep_range(400, 500);
+				continue;
+			}
+			if (status & DP_AUX_CH_CTL_DONE)
+				goto done;
+		}
+	}
+
+	if ((status & DP_AUX_CH_CTL_DONE) == 0) {
+		drm_err(&i915->drm, "%s: not done (status 0x%08x)\n",
+			intel_dp->aux.name, status);
+		ret = -EBUSY;
+		goto out;
+	}
+
+done:
+	/*
+	 * Check for timeout or receive error. Timeouts occur when the sink is
+	 * not connected.
+	 */
+	if (status & DP_AUX_CH_CTL_RECEIVE_ERROR) {
+		drm_err(&i915->drm, "%s: receive error (status 0x%08x)\n",
+			intel_dp->aux.name, status);
+		ret = -EIO;
+		goto out;
+	}
+
+	/*
+	 * Timeouts occur when the device isn't connected, so they're "normal"
+	 * -- don't fill the kernel log with these
+	 */
+	if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
+		drm_dbg_kms(&i915->drm, "%s: timeout (status 0x%08x)\n",
+			    intel_dp->aux.name, status);
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	/* Unload any bytes sent back from the other side */
+	recv_bytes = ((status & DP_AUX_CH_CTL_MESSAGE_SIZE_MASK) >>
+		      DP_AUX_CH_CTL_MESSAGE_SIZE_SHIFT);
+
+	/*
+	 * By BSpec: "Message sizes of 0 or >20 are not allowed."
+	 * We have no idea of what happened so we return -EBUSY so
+	 * drm layer takes care for the necessary retries.
+	 */
+	if (recv_bytes == 0 || recv_bytes > 20) {
+		drm_dbg_kms(&i915->drm,
+			    "%s: Forbidden recv_bytes = %d on aux transaction\n",
+			    intel_dp->aux.name, recv_bytes);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (recv_bytes > recv_size)
+		recv_bytes = recv_size;
+
+	for (i = 0; i < recv_bytes; i += 4)
+		intel_dp_unpack_aux(intel_uncore_read(uncore, ch_data[i >> 2]),
+				    recv + i, recv_bytes - i);
+
+	ret = recv_bytes;
+out:
+	cpu_latency_qos_update_request(&intel_dp->pm_qos, PM_QOS_DEFAULT_VALUE);
+
+	if (vdd)
+		intel_pps_vdd_off_unlocked(intel_dp, false);
+
+	intel_pps_unlock(intel_dp, pps_wakeref);
+	intel_display_power_put_async(i915, aux_domain, aux_wakeref);
+
+	if (is_tc_port)
+		intel_tc_port_unlock(dig_port);
+
+	return ret;
+}
+
+#define BARE_ADDRESS_SIZE	3
+#define HEADER_SIZE		(BARE_ADDRESS_SIZE + 1)
+
+static void
+intel_dp_aux_header(u8 txbuf[HEADER_SIZE],
+		    const struct drm_dp_aux_msg *msg)
+{
+	txbuf[0] = (msg->request << 4) | ((msg->address >> 16) & 0xf);
+	txbuf[1] = (msg->address >> 8) & 0xff;
+	txbuf[2] = msg->address & 0xff;
+	txbuf[3] = msg->size - 1;
+}
+
+static u32 intel_dp_aux_xfer_flags(const struct drm_dp_aux_msg *msg)
+{
+	/*
+	 * If we're trying to send the HDCP Aksv, we need to set a the Aksv
+	 * select bit to inform the hardware to send the Aksv after our header
+	 * since we can't access that data from software.
+	 */
+	if ((msg->request & ~DP_AUX_I2C_MOT) == DP_AUX_NATIVE_WRITE &&
+	    msg->address == DP_AUX_HDCP_AKSV)
+		return DP_AUX_CH_CTL_AUX_AKSV_SELECT;
+
+	return 0;
+}
+
+static ssize_t
+intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	struct intel_dp *intel_dp = container_of(aux, struct intel_dp, aux);
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+	u8 txbuf[20], rxbuf[20];
+	size_t txsize, rxsize;
+	u32 flags = intel_dp_aux_xfer_flags(msg);
+	int ret;
+
+	intel_dp_aux_header(txbuf, msg);
+
+	switch (msg->request & ~DP_AUX_I2C_MOT) {
+	case DP_AUX_NATIVE_WRITE:
+	case DP_AUX_I2C_WRITE:
+	case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+		txsize = msg->size ? HEADER_SIZE + msg->size : BARE_ADDRESS_SIZE;
+		rxsize = 2; /* 0 or 1 data bytes */
+
+		if (drm_WARN_ON(&i915->drm, txsize > 20))
+			return -E2BIG;
+
+		drm_WARN_ON(&i915->drm, !msg->buffer != !msg->size);
+
+		if (msg->buffer)
+			memcpy(txbuf + HEADER_SIZE, msg->buffer, msg->size);
+
+		ret = intel_dp_aux_xfer(intel_dp, txbuf, txsize,
+					rxbuf, rxsize, flags);
+		if (ret > 0) {
+			msg->reply = rxbuf[0] >> 4;
+
+			if (ret > 1) {
+				/* Number of bytes written in a short write. */
+				ret = clamp_t(int, rxbuf[1], 0, msg->size);
+			} else {
+				/* Return payload size. */
+				ret = msg->size;
+			}
+		}
+		break;
+
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ:
+		txsize = msg->size ? HEADER_SIZE : BARE_ADDRESS_SIZE;
+		rxsize = msg->size + 1;
+
+		if (drm_WARN_ON(&i915->drm, rxsize > 20))
+			return -E2BIG;
+
+		ret = intel_dp_aux_xfer(intel_dp, txbuf, txsize,
+					rxbuf, rxsize, flags);
+		if (ret > 0) {
+			msg->reply = rxbuf[0] >> 4;
+			/*
+			 * Assume happy day, and copy the data. The caller is
+			 * expected to check msg->reply before touching it.
+			 *
+			 * Return payload size.
+			 */
+			ret--;
+			memcpy(msg->buffer, rxbuf + 1, ret);
+		}
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static i915_reg_t g4x_aux_ctl_reg(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+		return DP_AUX_CH_CTL(aux_ch);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_CTL(AUX_CH_B);
+	}
+}
+
+static i915_reg_t g4x_aux_data_reg(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+		return DP_AUX_CH_DATA(aux_ch, index);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_DATA(AUX_CH_B, index);
+	}
+}
+
+static i915_reg_t ilk_aux_ctl_reg(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+		return DP_AUX_CH_CTL(aux_ch);
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+		return PCH_DP_AUX_CH_CTL(aux_ch);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_CTL(AUX_CH_A);
+	}
+}
+
+static i915_reg_t ilk_aux_data_reg(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+		return DP_AUX_CH_DATA(aux_ch, index);
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+		return PCH_DP_AUX_CH_DATA(aux_ch, index);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_DATA(AUX_CH_A, index);
+	}
+}
+
+static i915_reg_t skl_aux_ctl_reg(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+	case AUX_CH_E:
+	case AUX_CH_F:
+		return DP_AUX_CH_CTL(aux_ch);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_CTL(AUX_CH_A);
+	}
+}
+
+static i915_reg_t skl_aux_data_reg(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_D:
+	case AUX_CH_E:
+	case AUX_CH_F:
+		return DP_AUX_CH_DATA(aux_ch, index);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_DATA(AUX_CH_A, index);
+	}
+}
+
+static i915_reg_t tgl_aux_ctl_reg(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_USBC1:
+	case AUX_CH_USBC2:
+	case AUX_CH_USBC3:
+	case AUX_CH_USBC4:
+	case AUX_CH_USBC5:
+	case AUX_CH_USBC6:
+		return DP_AUX_CH_CTL(aux_ch);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_CTL(AUX_CH_A);
+	}
+}
+
+static i915_reg_t tgl_aux_data_reg(struct intel_dp *intel_dp, int index)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	switch (aux_ch) {
+	case AUX_CH_A:
+	case AUX_CH_B:
+	case AUX_CH_C:
+	case AUX_CH_USBC1:
+	case AUX_CH_USBC2:
+	case AUX_CH_USBC3:
+	case AUX_CH_USBC4:
+	case AUX_CH_USBC5:
+	case AUX_CH_USBC6:
+		return DP_AUX_CH_DATA(aux_ch, index);
+	default:
+		MISSING_CASE(aux_ch);
+		return DP_AUX_CH_DATA(AUX_CH_A, index);
+	}
+}
+
+void intel_dp_aux_fini(struct intel_dp *intel_dp)
+{
+	if (cpu_latency_qos_request_active(&intel_dp->pm_qos))
+		cpu_latency_qos_remove_request(&intel_dp->pm_qos);
+
+	kfree(intel_dp->aux.name);
+}
+
+void intel_dp_aux_init(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct intel_encoder *encoder = &dig_port->base;
+	enum aux_ch aux_ch = dig_port->aux_ch;
+
+	if (INTEL_GEN(dev_priv) >= 12) {
+		intel_dp->aux_ch_ctl_reg = tgl_aux_ctl_reg;
+		intel_dp->aux_ch_data_reg = tgl_aux_data_reg;
+	} else if (INTEL_GEN(dev_priv) >= 9) {
+		intel_dp->aux_ch_ctl_reg = skl_aux_ctl_reg;
+		intel_dp->aux_ch_data_reg = skl_aux_data_reg;
+	} else if (HAS_PCH_SPLIT(dev_priv)) {
+		intel_dp->aux_ch_ctl_reg = ilk_aux_ctl_reg;
+		intel_dp->aux_ch_data_reg = ilk_aux_data_reg;
+	} else {
+		intel_dp->aux_ch_ctl_reg = g4x_aux_ctl_reg;
+		intel_dp->aux_ch_data_reg = g4x_aux_data_reg;
+	}
+
+	if (INTEL_GEN(dev_priv) >= 9)
+		intel_dp->get_aux_clock_divider = skl_get_aux_clock_divider;
+	else if (IS_BROADWELL(dev_priv) || IS_HASWELL(dev_priv))
+		intel_dp->get_aux_clock_divider = hsw_get_aux_clock_divider;
+	else if (HAS_PCH_SPLIT(dev_priv))
+		intel_dp->get_aux_clock_divider = ilk_get_aux_clock_divider;
+	else
+		intel_dp->get_aux_clock_divider = g4x_get_aux_clock_divider;
+
+	if (INTEL_GEN(dev_priv) >= 9)
+		intel_dp->get_aux_send_ctl = skl_get_aux_send_ctl;
+	else
+		intel_dp->get_aux_send_ctl = g4x_get_aux_send_ctl;
+
+	drm_dp_aux_init(&intel_dp->aux);
+
+	/* Failure to allocate our preferred name is not critical */
+	if (INTEL_GEN(dev_priv) >= 12 && aux_ch >= AUX_CH_USBC1)
+		intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX USBC%c/%s",
+					       aux_ch - AUX_CH_USBC1 + '1',
+					       encoder->base.name);
+	else
+		intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX %c/%s",
+					       aux_ch_name(aux_ch),
+					       encoder->base.name);
+
+	intel_dp->aux.transfer = intel_dp_aux_transfer;
+	cpu_latency_qos_add_request(&intel_dp->pm_qos, PM_QOS_DEFAULT_VALUE);
+}