Merge v5.3-rc1 into drm-misc-next

Noralf needs some SPI patches in 5.3 to merge some work on tinydrm.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>

1 files changed, 965 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_gmbus.c b/drivers/gpu/drm/i915/display/intel_gmbus.c
new file mode 100644
index 000000000000..4f6a9bd5af47
--- /dev/null
+++ b/drivers/gpu/drm/i915/display/intel_gmbus.c
@@ -0,0 +1,965 @@
+/*
+ * Copyright (c) 2006 Dave Airlie <airlied@linux.ie>
+ * Copyright © 2006-2008,2010 Intel Corporation
+ *   Jesse Barnes <jesse.barnes@intel.com>
+ *
+ * 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 (including the next
+ * paragraph) 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 AUTHORS OR COPYRIGHT HOLDERS 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:
+ *	Eric Anholt <eric@anholt.net>
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include <linux/export.h>
+#include <linux/i2c-algo-bit.h>
+#include <linux/i2c.h>
+
+#include <drm/drm_hdcp.h>
+#include <drm/i915_drm.h>
+
+#include "i915_drv.h"
+#include "intel_drv.h"
+#include "intel_gmbus.h"
+
+struct gmbus_pin {
+	const char *name;
+	enum i915_gpio gpio;
+};
+
+/* Map gmbus pin pairs to names and registers. */
+static const struct gmbus_pin gmbus_pins[] = {
+	[GMBUS_PIN_SSC] = { "ssc", GPIOB },
+	[GMBUS_PIN_VGADDC] = { "vga", GPIOA },
+	[GMBUS_PIN_PANEL] = { "panel", GPIOC },
+	[GMBUS_PIN_DPC] = { "dpc", GPIOD },
+	[GMBUS_PIN_DPB] = { "dpb", GPIOE },
+	[GMBUS_PIN_DPD] = { "dpd", GPIOF },
+};
+
+static const struct gmbus_pin gmbus_pins_bdw[] = {
+	[GMBUS_PIN_VGADDC] = { "vga", GPIOA },
+	[GMBUS_PIN_DPC] = { "dpc", GPIOD },
+	[GMBUS_PIN_DPB] = { "dpb", GPIOE },
+	[GMBUS_PIN_DPD] = { "dpd", GPIOF },
+};
+
+static const struct gmbus_pin gmbus_pins_skl[] = {
+	[GMBUS_PIN_DPC] = { "dpc", GPIOD },
+	[GMBUS_PIN_DPB] = { "dpb", GPIOE },
+	[GMBUS_PIN_DPD] = { "dpd", GPIOF },
+};
+
+static const struct gmbus_pin gmbus_pins_bxt[] = {
+	[GMBUS_PIN_1_BXT] = { "dpb", GPIOB },
+	[GMBUS_PIN_2_BXT] = { "dpc", GPIOC },
+	[GMBUS_PIN_3_BXT] = { "misc", GPIOD },
+};
+
+static const struct gmbus_pin gmbus_pins_cnp[] = {
+	[GMBUS_PIN_1_BXT] = { "dpb", GPIOB },
+	[GMBUS_PIN_2_BXT] = { "dpc", GPIOC },
+	[GMBUS_PIN_3_BXT] = { "misc", GPIOD },
+	[GMBUS_PIN_4_CNP] = { "dpd", GPIOE },
+};
+
+static const struct gmbus_pin gmbus_pins_icp[] = {
+	[GMBUS_PIN_1_BXT] = { "dpa", GPIOB },
+	[GMBUS_PIN_2_BXT] = { "dpb", GPIOC },
+	[GMBUS_PIN_9_TC1_ICP] = { "tc1", GPIOJ },
+	[GMBUS_PIN_10_TC2_ICP] = { "tc2", GPIOK },
+	[GMBUS_PIN_11_TC3_ICP] = { "tc3", GPIOL },
+	[GMBUS_PIN_12_TC4_ICP] = { "tc4", GPIOM },
+};
+
+static const struct gmbus_pin gmbus_pins_mcc[] = {
+	[GMBUS_PIN_1_BXT] = { "dpa", GPIOB },
+	[GMBUS_PIN_2_BXT] = { "dpb", GPIOC },
+	[GMBUS_PIN_9_TC1_ICP] = { "dpc", GPIOJ },
+};
+
+/* pin is expected to be valid */
+static const struct gmbus_pin *get_gmbus_pin(struct drm_i915_private *dev_priv,
+					     unsigned int pin)
+{
+	if (HAS_PCH_MCC(dev_priv))
+		return &gmbus_pins_mcc[pin];
+	else if (HAS_PCH_ICP(dev_priv))
+		return &gmbus_pins_icp[pin];
+	else if (HAS_PCH_CNP(dev_priv))
+		return &gmbus_pins_cnp[pin];
+	else if (IS_GEN9_LP(dev_priv))
+		return &gmbus_pins_bxt[pin];
+	else if (IS_GEN9_BC(dev_priv))
+		return &gmbus_pins_skl[pin];
+	else if (IS_BROADWELL(dev_priv))
+		return &gmbus_pins_bdw[pin];
+	else
+		return &gmbus_pins[pin];
+}
+
+bool intel_gmbus_is_valid_pin(struct drm_i915_private *dev_priv,
+			      unsigned int pin)
+{
+	unsigned int size;
+
+	if (HAS_PCH_MCC(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_mcc);
+	else if (HAS_PCH_ICP(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_icp);
+	else if (HAS_PCH_CNP(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_cnp);
+	else if (IS_GEN9_LP(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_bxt);
+	else if (IS_GEN9_BC(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_skl);
+	else if (IS_BROADWELL(dev_priv))
+		size = ARRAY_SIZE(gmbus_pins_bdw);
+	else
+		size = ARRAY_SIZE(gmbus_pins);
+
+	return pin < size && get_gmbus_pin(dev_priv, pin)->name;
+}
+
+/* Intel GPIO access functions */
+
+#define I2C_RISEFALL_TIME 10
+
+static inline struct intel_gmbus *
+to_intel_gmbus(struct i2c_adapter *i2c)
+{
+	return container_of(i2c, struct intel_gmbus, adapter);
+}
+
+void
+intel_gmbus_reset(struct drm_i915_private *dev_priv)
+{
+	I915_WRITE(GMBUS0, 0);
+	I915_WRITE(GMBUS4, 0);
+}
+
+static void pnv_gmbus_clock_gating(struct drm_i915_private *dev_priv,
+				   bool enable)
+{
+	u32 val;
+
+	/* When using bit bashing for I2C, this bit needs to be set to 1 */
+	val = I915_READ(DSPCLK_GATE_D);
+	if (!enable)
+		val |= PNV_GMBUSUNIT_CLOCK_GATE_DISABLE;
+	else
+		val &= ~PNV_GMBUSUNIT_CLOCK_GATE_DISABLE;
+	I915_WRITE(DSPCLK_GATE_D, val);
+}
+
+static void pch_gmbus_clock_gating(struct drm_i915_private *dev_priv,
+				   bool enable)
+{
+	u32 val;
+
+	val = I915_READ(SOUTH_DSPCLK_GATE_D);
+	if (!enable)
+		val |= PCH_GMBUSUNIT_CLOCK_GATE_DISABLE;
+	else
+		val &= ~PCH_GMBUSUNIT_CLOCK_GATE_DISABLE;
+	I915_WRITE(SOUTH_DSPCLK_GATE_D, val);
+}
+
+static void bxt_gmbus_clock_gating(struct drm_i915_private *dev_priv,
+				   bool enable)
+{
+	u32 val;
+
+	val = I915_READ(GEN9_CLKGATE_DIS_4);
+	if (!enable)
+		val |= BXT_GMBUS_GATING_DIS;
+	else
+		val &= ~BXT_GMBUS_GATING_DIS;
+	I915_WRITE(GEN9_CLKGATE_DIS_4, val);
+}
+
+static u32 get_reserved(struct intel_gmbus *bus)
+{
+	struct drm_i915_private *i915 = bus->dev_priv;
+	struct intel_uncore *uncore = &i915->uncore;
+	u32 reserved = 0;
+
+	/* On most chips, these bits must be preserved in software. */
+	if (!IS_I830(i915) && !IS_I845G(i915))
+		reserved = intel_uncore_read_notrace(uncore, bus->gpio_reg) &
+			   (GPIO_DATA_PULLUP_DISABLE |
+			    GPIO_CLOCK_PULLUP_DISABLE);
+
+	return reserved;
+}
+
+static int get_clock(void *data)
+{
+	struct intel_gmbus *bus = data;
+	struct intel_uncore *uncore = &bus->dev_priv->uncore;
+	u32 reserved = get_reserved(bus);
+
+	intel_uncore_write_notrace(uncore,
+				   bus->gpio_reg,
+				   reserved | GPIO_CLOCK_DIR_MASK);
+	intel_uncore_write_notrace(uncore, bus->gpio_reg, reserved);
+
+	return (intel_uncore_read_notrace(uncore, bus->gpio_reg) &
+		GPIO_CLOCK_VAL_IN) != 0;
+}
+
+static int get_data(void *data)
+{
+	struct intel_gmbus *bus = data;
+	struct intel_uncore *uncore = &bus->dev_priv->uncore;
+	u32 reserved = get_reserved(bus);
+
+	intel_uncore_write_notrace(uncore,
+				   bus->gpio_reg,
+				   reserved | GPIO_DATA_DIR_MASK);
+	intel_uncore_write_notrace(uncore, bus->gpio_reg, reserved);
+
+	return (intel_uncore_read_notrace(uncore, bus->gpio_reg) &
+		GPIO_DATA_VAL_IN) != 0;
+}
+
+static void set_clock(void *data, int state_high)
+{
+	struct intel_gmbus *bus = data;
+	struct intel_uncore *uncore = &bus->dev_priv->uncore;
+	u32 reserved = get_reserved(bus);
+	u32 clock_bits;
+
+	if (state_high)
+		clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
+	else
+		clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
+			     GPIO_CLOCK_VAL_MASK;
+
+	intel_uncore_write_notrace(uncore,
+				   bus->gpio_reg,
+				   reserved | clock_bits);
+	intel_uncore_posting_read(uncore, bus->gpio_reg);
+}
+
+static void set_data(void *data, int state_high)
+{
+	struct intel_gmbus *bus = data;
+	struct intel_uncore *uncore = &bus->dev_priv->uncore;
+	u32 reserved = get_reserved(bus);
+	u32 data_bits;
+
+	if (state_high)
+		data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
+	else
+		data_bits = GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
+			GPIO_DATA_VAL_MASK;
+
+	intel_uncore_write_notrace(uncore, bus->gpio_reg, reserved | data_bits);
+	intel_uncore_posting_read(uncore, bus->gpio_reg);
+}
+
+static int
+intel_gpio_pre_xfer(struct i2c_adapter *adapter)
+{
+	struct intel_gmbus *bus = container_of(adapter,
+					       struct intel_gmbus,
+					       adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	intel_gmbus_reset(dev_priv);
+
+	if (IS_PINEVIEW(dev_priv))
+		pnv_gmbus_clock_gating(dev_priv, false);
+
+	set_data(bus, 1);
+	set_clock(bus, 1);
+	udelay(I2C_RISEFALL_TIME);
+	return 0;
+}
+
+static void
+intel_gpio_post_xfer(struct i2c_adapter *adapter)
+{
+	struct intel_gmbus *bus = container_of(adapter,
+					       struct intel_gmbus,
+					       adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	set_data(bus, 1);
+	set_clock(bus, 1);
+
+	if (IS_PINEVIEW(dev_priv))
+		pnv_gmbus_clock_gating(dev_priv, true);
+}
+
+static void
+intel_gpio_setup(struct intel_gmbus *bus, unsigned int pin)
+{
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+	struct i2c_algo_bit_data *algo;
+
+	algo = &bus->bit_algo;
+
+	bus->gpio_reg = GPIO(get_gmbus_pin(dev_priv, pin)->gpio);
+	bus->adapter.algo_data = algo;
+	algo->setsda = set_data;
+	algo->setscl = set_clock;
+	algo->getsda = get_data;
+	algo->getscl = get_clock;
+	algo->pre_xfer = intel_gpio_pre_xfer;
+	algo->post_xfer = intel_gpio_post_xfer;
+	algo->udelay = I2C_RISEFALL_TIME;
+	algo->timeout = usecs_to_jiffies(2200);
+	algo->data = bus;
+}
+
+static int gmbus_wait(struct drm_i915_private *dev_priv, u32 status, u32 irq_en)
+{
+	DEFINE_WAIT(wait);
+	u32 gmbus2;
+	int ret;
+
+	/* Important: The hw handles only the first bit, so set only one! Since
+	 * we also need to check for NAKs besides the hw ready/idle signal, we
+	 * need to wake up periodically and check that ourselves.
+	 */
+	if (!HAS_GMBUS_IRQ(dev_priv))
+		irq_en = 0;
+
+	add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+	I915_WRITE_FW(GMBUS4, irq_en);
+
+	status |= GMBUS_SATOER;
+	ret = wait_for_us((gmbus2 = I915_READ_FW(GMBUS2)) & status, 2);
+	if (ret)
+		ret = wait_for((gmbus2 = I915_READ_FW(GMBUS2)) & status, 50);
+
+	I915_WRITE_FW(GMBUS4, 0);
+	remove_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+
+	if (gmbus2 & GMBUS_SATOER)
+		return -ENXIO;
+
+	return ret;
+}
+
+static int
+gmbus_wait_idle(struct drm_i915_private *dev_priv)
+{
+	DEFINE_WAIT(wait);
+	u32 irq_enable;
+	int ret;
+
+	/* Important: The hw handles only the first bit, so set only one! */
+	irq_enable = 0;
+	if (HAS_GMBUS_IRQ(dev_priv))
+		irq_enable = GMBUS_IDLE_EN;
+
+	add_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+	I915_WRITE_FW(GMBUS4, irq_enable);
+
+	ret = intel_wait_for_register_fw(&dev_priv->uncore,
+					 GMBUS2, GMBUS_ACTIVE, 0,
+					 10);
+
+	I915_WRITE_FW(GMBUS4, 0);
+	remove_wait_queue(&dev_priv->gmbus_wait_queue, &wait);
+
+	return ret;
+}
+
+static inline
+unsigned int gmbus_max_xfer_size(struct drm_i915_private *dev_priv)
+{
+	return INTEL_GEN(dev_priv) >= 9 ? GEN9_GMBUS_BYTE_COUNT_MAX :
+	       GMBUS_BYTE_COUNT_MAX;
+}
+
+static int
+gmbus_xfer_read_chunk(struct drm_i915_private *dev_priv,
+		      unsigned short addr, u8 *buf, unsigned int len,
+		      u32 gmbus0_reg, u32 gmbus1_index)
+{
+	unsigned int size = len;
+	bool burst_read = len > gmbus_max_xfer_size(dev_priv);
+	bool extra_byte_added = false;
+
+	if (burst_read) {
+		/*
+		 * As per HW Spec, for 512Bytes need to read extra Byte and
+		 * Ignore the extra byte read.
+		 */
+		if (len == 512) {
+			extra_byte_added = true;
+			len++;
+		}
+		size = len % 256 + 256;
+		I915_WRITE_FW(GMBUS0, gmbus0_reg | GMBUS_BYTE_CNT_OVERRIDE);
+	}
+
+	I915_WRITE_FW(GMBUS1,
+		      gmbus1_index |
+		      GMBUS_CYCLE_WAIT |
+		      (size << GMBUS_BYTE_COUNT_SHIFT) |
+		      (addr << GMBUS_SLAVE_ADDR_SHIFT) |
+		      GMBUS_SLAVE_READ | GMBUS_SW_RDY);
+	while (len) {
+		int ret;
+		u32 val, loop = 0;
+
+		ret = gmbus_wait(dev_priv, GMBUS_HW_RDY, GMBUS_HW_RDY_EN);
+		if (ret)
+			return ret;
+
+		val = I915_READ_FW(GMBUS3);
+		do {
+			if (extra_byte_added && len == 1)
+				break;
+
+			*buf++ = val & 0xff;
+			val >>= 8;
+		} while (--len && ++loop < 4);
+
+		if (burst_read && len == size - 4)
+			/* Reset the override bit */
+			I915_WRITE_FW(GMBUS0, gmbus0_reg);
+	}
+
+	return 0;
+}
+
+/*
+ * HW spec says that 512Bytes in Burst read need special treatment.
+ * But it doesn't talk about other multiple of 256Bytes. And couldn't locate
+ * an I2C slave, which supports such a lengthy burst read too for experiments.
+ *
+ * So until things get clarified on HW support, to avoid the burst read length
+ * in fold of 256Bytes except 512, max burst read length is fixed at 767Bytes.
+ */
+#define INTEL_GMBUS_BURST_READ_MAX_LEN		767U
+
+static int
+gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
+		u32 gmbus0_reg, u32 gmbus1_index)
+{
+	u8 *buf = msg->buf;
+	unsigned int rx_size = msg->len;
+	unsigned int len;
+	int ret;
+
+	do {
+		if (HAS_GMBUS_BURST_READ(dev_priv))
+			len = min(rx_size, INTEL_GMBUS_BURST_READ_MAX_LEN);
+		else
+			len = min(rx_size, gmbus_max_xfer_size(dev_priv));
+
+		ret = gmbus_xfer_read_chunk(dev_priv, msg->addr, buf, len,
+					    gmbus0_reg, gmbus1_index);
+		if (ret)
+			return ret;
+
+		rx_size -= len;
+		buf += len;
+	} while (rx_size != 0);
+
+	return 0;
+}
+
+static int
+gmbus_xfer_write_chunk(struct drm_i915_private *dev_priv,
+		       unsigned short addr, u8 *buf, unsigned int len,
+		       u32 gmbus1_index)
+{
+	unsigned int chunk_size = len;
+	u32 val, loop;
+
+	val = loop = 0;
+	while (len && loop < 4) {
+		val |= *buf++ << (8 * loop++);
+		len -= 1;
+	}
+
+	I915_WRITE_FW(GMBUS3, val);
+	I915_WRITE_FW(GMBUS1,
+		      gmbus1_index | GMBUS_CYCLE_WAIT |
+		      (chunk_size << GMBUS_BYTE_COUNT_SHIFT) |
+		      (addr << GMBUS_SLAVE_ADDR_SHIFT) |
+		      GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
+	while (len) {
+		int ret;
+
+		val = loop = 0;
+		do {
+			val |= *buf++ << (8 * loop);
+		} while (--len && ++loop < 4);
+
+		I915_WRITE_FW(GMBUS3, val);
+
+		ret = gmbus_wait(dev_priv, GMBUS_HW_RDY, GMBUS_HW_RDY_EN);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int
+gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
+		 u32 gmbus1_index)
+{
+	u8 *buf = msg->buf;
+	unsigned int tx_size = msg->len;
+	unsigned int len;
+	int ret;
+
+	do {
+		len = min(tx_size, gmbus_max_xfer_size(dev_priv));
+
+		ret = gmbus_xfer_write_chunk(dev_priv, msg->addr, buf, len,
+					     gmbus1_index);
+		if (ret)
+			return ret;
+
+		buf += len;
+		tx_size -= len;
+	} while (tx_size != 0);
+
+	return 0;
+}
+
+/*
+ * The gmbus controller can combine a 1 or 2 byte write with another read/write
+ * that immediately follows it by using an "INDEX" cycle.
+ */
+static bool
+gmbus_is_index_xfer(struct i2c_msg *msgs, int i, int num)
+{
+	return (i + 1 < num &&
+		msgs[i].addr == msgs[i + 1].addr &&
+		!(msgs[i].flags & I2C_M_RD) &&
+		(msgs[i].len == 1 || msgs[i].len == 2) &&
+		msgs[i + 1].len > 0);
+}
+
+static int
+gmbus_index_xfer(struct drm_i915_private *dev_priv, struct i2c_msg *msgs,
+		 u32 gmbus0_reg)
+{
+	u32 gmbus1_index = 0;
+	u32 gmbus5 = 0;
+	int ret;
+
+	if (msgs[0].len == 2)
+		gmbus5 = GMBUS_2BYTE_INDEX_EN |
+			 msgs[0].buf[1] | (msgs[0].buf[0] << 8);
+	if (msgs[0].len == 1)
+		gmbus1_index = GMBUS_CYCLE_INDEX |
+			       (msgs[0].buf[0] << GMBUS_SLAVE_INDEX_SHIFT);
+
+	/* GMBUS5 holds 16-bit index */
+	if (gmbus5)
+		I915_WRITE_FW(GMBUS5, gmbus5);
+
+	if (msgs[1].flags & I2C_M_RD)
+		ret = gmbus_xfer_read(dev_priv, &msgs[1], gmbus0_reg,
+				      gmbus1_index);
+	else
+		ret = gmbus_xfer_write(dev_priv, &msgs[1], gmbus1_index);
+
+	/* Clear GMBUS5 after each index transfer */
+	if (gmbus5)
+		I915_WRITE_FW(GMBUS5, 0);
+
+	return ret;
+}
+
+static int
+do_gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num,
+	      u32 gmbus0_source)
+{
+	struct intel_gmbus *bus = container_of(adapter,
+					       struct intel_gmbus,
+					       adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+	int i = 0, inc, try = 0;
+	int ret = 0;
+
+	/* Display WA #0868: skl,bxt,kbl,cfl,glk,cnl */
+	if (IS_GEN9_LP(dev_priv))
+		bxt_gmbus_clock_gating(dev_priv, false);
+	else if (HAS_PCH_SPT(dev_priv) || HAS_PCH_CNP(dev_priv))
+		pch_gmbus_clock_gating(dev_priv, false);
+
+retry:
+	I915_WRITE_FW(GMBUS0, gmbus0_source | bus->reg0);
+
+	for (; i < num; i += inc) {
+		inc = 1;
+		if (gmbus_is_index_xfer(msgs, i, num)) {
+			ret = gmbus_index_xfer(dev_priv, &msgs[i],
+					       gmbus0_source | bus->reg0);
+			inc = 2; /* an index transmission is two msgs */
+		} else if (msgs[i].flags & I2C_M_RD) {
+			ret = gmbus_xfer_read(dev_priv, &msgs[i],
+					      gmbus0_source | bus->reg0, 0);
+		} else {
+			ret = gmbus_xfer_write(dev_priv, &msgs[i], 0);
+		}
+
+		if (!ret)
+			ret = gmbus_wait(dev_priv,
+					 GMBUS_HW_WAIT_PHASE, GMBUS_HW_WAIT_EN);
+		if (ret == -ETIMEDOUT)
+			goto timeout;
+		else if (ret)
+			goto clear_err;
+	}
+
+	/* Generate a STOP condition on the bus. Note that gmbus can't generata
+	 * a STOP on the very first cycle. To simplify the code we
+	 * unconditionally generate the STOP condition with an additional gmbus
+	 * cycle. */
+	I915_WRITE_FW(GMBUS1, GMBUS_CYCLE_STOP | GMBUS_SW_RDY);
+
+	/* Mark the GMBUS interface as disabled after waiting for idle.
+	 * We will re-enable it at the start of the next xfer,
+	 * till then let it sleep.
+	 */
+	if (gmbus_wait_idle(dev_priv)) {
+		DRM_DEBUG_KMS("GMBUS [%s] timed out waiting for idle\n",
+			 adapter->name);
+		ret = -ETIMEDOUT;
+	}
+	I915_WRITE_FW(GMBUS0, 0);
+	ret = ret ?: i;
+	goto out;
+
+clear_err:
+	/*
+	 * Wait for bus to IDLE before clearing NAK.
+	 * If we clear the NAK while bus is still active, then it will stay
+	 * active and the next transaction may fail.
+	 *
+	 * If no ACK is received during the address phase of a transaction, the
+	 * adapter must report -ENXIO. It is not clear what to return if no ACK
+	 * is received at other times. But we have to be careful to not return
+	 * spurious -ENXIO because that will prevent i2c and drm edid functions
+	 * from retrying. So return -ENXIO only when gmbus properly quiescents -
+	 * timing out seems to happen when there _is_ a ddc chip present, but
+	 * it's slow responding and only answers on the 2nd retry.
+	 */
+	ret = -ENXIO;
+	if (gmbus_wait_idle(dev_priv)) {
+		DRM_DEBUG_KMS("GMBUS [%s] timed out after NAK\n",
+			      adapter->name);
+		ret = -ETIMEDOUT;
+	}
+
+	/* Toggle the Software Clear Interrupt bit. This has the effect
+	 * of resetting the GMBUS controller and so clearing the
+	 * BUS_ERROR raised by the slave's NAK.
+	 */
+	I915_WRITE_FW(GMBUS1, GMBUS_SW_CLR_INT);
+	I915_WRITE_FW(GMBUS1, 0);
+	I915_WRITE_FW(GMBUS0, 0);
+
+	DRM_DEBUG_KMS("GMBUS [%s] NAK for addr: %04x %c(%d)\n",
+			 adapter->name, msgs[i].addr,
+			 (msgs[i].flags & I2C_M_RD) ? 'r' : 'w', msgs[i].len);
+
+	/*
+	 * Passive adapters sometimes NAK the first probe. Retry the first
+	 * message once on -ENXIO for GMBUS transfers; the bit banging algorithm
+	 * has retries internally. See also the retry loop in
+	 * drm_do_probe_ddc_edid, which bails out on the first -ENXIO.
+	 */
+	if (ret == -ENXIO && i == 0 && try++ == 0) {
+		DRM_DEBUG_KMS("GMBUS [%s] NAK on first message, retry\n",
+			      adapter->name);
+		goto retry;
+	}
+
+	goto out;
+
+timeout:
+	DRM_DEBUG_KMS("GMBUS [%s] timed out, falling back to bit banging on pin %d\n",
+		      bus->adapter.name, bus->reg0 & 0xff);
+	I915_WRITE_FW(GMBUS0, 0);
+
+	/*
+	 * Hardware may not support GMBUS over these pins? Try GPIO bitbanging
+	 * instead. Use EAGAIN to have i2c core retry.
+	 */
+	ret = -EAGAIN;
+
+out:
+	/* Display WA #0868: skl,bxt,kbl,cfl,glk,cnl */
+	if (IS_GEN9_LP(dev_priv))
+		bxt_gmbus_clock_gating(dev_priv, true);
+	else if (HAS_PCH_SPT(dev_priv) || HAS_PCH_CNP(dev_priv))
+		pch_gmbus_clock_gating(dev_priv, true);
+
+	return ret;
+}
+
+static int
+gmbus_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, int num)
+{
+	struct intel_gmbus *bus =
+		container_of(adapter, struct intel_gmbus, adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+	intel_wakeref_t wakeref;
+	int ret;
+
+	wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
+
+	if (bus->force_bit) {
+		ret = i2c_bit_algo.master_xfer(adapter, msgs, num);
+		if (ret < 0)
+			bus->force_bit &= ~GMBUS_FORCE_BIT_RETRY;
+	} else {
+		ret = do_gmbus_xfer(adapter, msgs, num, 0);
+		if (ret == -EAGAIN)
+			bus->force_bit |= GMBUS_FORCE_BIT_RETRY;
+	}
+
+	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS, wakeref);
+
+	return ret;
+}
+
+int intel_gmbus_output_aksv(struct i2c_adapter *adapter)
+{
+	struct intel_gmbus *bus =
+		container_of(adapter, struct intel_gmbus, adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+	u8 cmd = DRM_HDCP_DDC_AKSV;
+	u8 buf[DRM_HDCP_KSV_LEN] = { 0 };
+	struct i2c_msg msgs[] = {
+		{
+			.addr = DRM_HDCP_DDC_ADDR,
+			.flags = 0,
+			.len = sizeof(cmd),
+			.buf = &cmd,
+		},
+		{
+			.addr = DRM_HDCP_DDC_ADDR,
+			.flags = 0,
+			.len = sizeof(buf),
+			.buf = buf,
+		}
+	};
+	intel_wakeref_t wakeref;
+	int ret;
+
+	wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
+	mutex_lock(&dev_priv->gmbus_mutex);
+
+	/*
+	 * In order to output Aksv to the receiver, use an indexed write to
+	 * pass the i2c command, and tell GMBUS to use the HW-provided value
+	 * instead of sourcing GMBUS3 for the data.
+	 */
+	ret = do_gmbus_xfer(adapter, msgs, ARRAY_SIZE(msgs), GMBUS_AKSV_SELECT);
+
+	mutex_unlock(&dev_priv->gmbus_mutex);
+	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS, wakeref);
+
+	return ret;
+}
+
+static u32 gmbus_func(struct i2c_adapter *adapter)
+{
+	return i2c_bit_algo.functionality(adapter) &
+		(I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+		/* I2C_FUNC_10BIT_ADDR | */
+		I2C_FUNC_SMBUS_READ_BLOCK_DATA |
+		I2C_FUNC_SMBUS_BLOCK_PROC_CALL);
+}
+
+static const struct i2c_algorithm gmbus_algorithm = {
+	.master_xfer	= gmbus_xfer,
+	.functionality	= gmbus_func
+};
+
+static void gmbus_lock_bus(struct i2c_adapter *adapter,
+			   unsigned int flags)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	mutex_lock(&dev_priv->gmbus_mutex);
+}
+
+static int gmbus_trylock_bus(struct i2c_adapter *adapter,
+			     unsigned int flags)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	return mutex_trylock(&dev_priv->gmbus_mutex);
+}
+
+static void gmbus_unlock_bus(struct i2c_adapter *adapter,
+			     unsigned int flags)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	mutex_unlock(&dev_priv->gmbus_mutex);
+}
+
+static const struct i2c_lock_operations gmbus_lock_ops = {
+	.lock_bus =    gmbus_lock_bus,
+	.trylock_bus = gmbus_trylock_bus,
+	.unlock_bus =  gmbus_unlock_bus,
+};
+
+/**
+ * intel_gmbus_setup - instantiate all Intel i2c GMBuses
+ * @dev_priv: i915 device private
+ */
+int intel_gmbus_setup(struct drm_i915_private *dev_priv)
+{
+	struct pci_dev *pdev = dev_priv->drm.pdev;
+	struct intel_gmbus *bus;
+	unsigned int pin;
+	int ret;
+
+	if (!HAS_DISPLAY(dev_priv))
+		return 0;
+
+	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
+		dev_priv->gpio_mmio_base = VLV_DISPLAY_BASE;
+	else if (!HAS_GMCH(dev_priv))
+		/*
+		 * Broxton uses the same PCH offsets for South Display Engine,
+		 * even though it doesn't have a PCH.
+		 */
+		dev_priv->gpio_mmio_base = PCH_DISPLAY_BASE;
+
+	mutex_init(&dev_priv->gmbus_mutex);
+	init_waitqueue_head(&dev_priv->gmbus_wait_queue);
+
+	for (pin = 0; pin < ARRAY_SIZE(dev_priv->gmbus); pin++) {
+		if (!intel_gmbus_is_valid_pin(dev_priv, pin))
+			continue;
+
+		bus = &dev_priv->gmbus[pin];
+
+		bus->adapter.owner = THIS_MODULE;
+		bus->adapter.class = I2C_CLASS_DDC;
+		snprintf(bus->adapter.name,
+			 sizeof(bus->adapter.name),
+			 "i915 gmbus %s",
+			 get_gmbus_pin(dev_priv, pin)->name);
+
+		bus->adapter.dev.parent = &pdev->dev;
+		bus->dev_priv = dev_priv;
+
+		bus->adapter.algo = &gmbus_algorithm;
+		bus->adapter.lock_ops = &gmbus_lock_ops;
+
+		/*
+		 * We wish to retry with bit banging
+		 * after a timed out GMBUS attempt.
+		 */
+		bus->adapter.retries = 1;
+
+		/* By default use a conservative clock rate */
+		bus->reg0 = pin | GMBUS_RATE_100KHZ;
+
+		/* gmbus seems to be broken on i830 */
+		if (IS_I830(dev_priv))
+			bus->force_bit = 1;
+
+		intel_gpio_setup(bus, pin);
+
+		ret = i2c_add_adapter(&bus->adapter);
+		if (ret)
+			goto err;
+	}
+
+	intel_gmbus_reset(dev_priv);
+
+	return 0;
+
+err:
+	while (pin--) {
+		if (!intel_gmbus_is_valid_pin(dev_priv, pin))
+			continue;
+
+		bus = &dev_priv->gmbus[pin];
+		i2c_del_adapter(&bus->adapter);
+	}
+	return ret;
+}
+
+struct i2c_adapter *intel_gmbus_get_adapter(struct drm_i915_private *dev_priv,
+					    unsigned int pin)
+{
+	if (WARN_ON(!intel_gmbus_is_valid_pin(dev_priv, pin)))
+		return NULL;
+
+	return &dev_priv->gmbus[pin].adapter;
+}
+
+void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+
+	bus->reg0 = (bus->reg0 & ~(0x3 << 8)) | speed;
+}
+
+void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+	struct drm_i915_private *dev_priv = bus->dev_priv;
+
+	mutex_lock(&dev_priv->gmbus_mutex);
+
+	bus->force_bit += force_bit ? 1 : -1;
+	DRM_DEBUG_KMS("%sabling bit-banging on %s. force bit now %d\n",
+		      force_bit ? "en" : "dis", adapter->name,
+		      bus->force_bit);
+
+	mutex_unlock(&dev_priv->gmbus_mutex);
+}
+
+bool intel_gmbus_is_forced_bit(struct i2c_adapter *adapter)
+{
+	struct intel_gmbus *bus = to_intel_gmbus(adapter);
+
+	return bus->force_bit;
+}
+
+void intel_gmbus_teardown(struct drm_i915_private *dev_priv)
+{
+	struct intel_gmbus *bus;
+	unsigned int pin;
+
+	for (pin = 0; pin < ARRAY_SIZE(dev_priv->gmbus); pin++) {
+		if (!intel_gmbus_is_valid_pin(dev_priv, pin))
+			continue;
+
+		bus = &dev_priv->gmbus[pin];
+		i2c_del_adapter(&bus->adapter);
+	}
+}