drivers/gpu/drm/i915/intel_i2c.c - kernel/msm-4.19 - Gitiles

 /*
  * 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/i2c.h>
 #include <linux/i2c-algo-bit.h>
 #include "drmP.h"
 #include "drm.h"
 #include "intel_drv.h"
 #include "i915_drm.h"
 #include "i915_drv.h"

 /* Intel GPIO access functions */

 #define I2C_RISEFALL_TIME 20

 static inline struct intel_gmbus *
 to_intel_gmbus(struct i2c_adapter *i2c)
 {
 	return container_of(i2c, struct intel_gmbus, adapter);
 }

 struct intel_gpio {
 	struct i2c_adapter adapter;
 	struct i2c_algo_bit_data algo;
 	struct drm_i915_private *dev_priv;
 	u32 reg;
 };

 void
 intel_i2c_reset(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	if (HAS_PCH_SPLIT(dev))
 		I915_WRITE(PCH_GMBUS0, 0);
 	else
 		I915_WRITE(GMBUS0, 0);
 }

 static void intel_i2c_quirk_set(struct drm_i915_private *dev_priv, bool enable)
 {
 	u32 val;

 	/* When using bit bashing for I2C, this bit needs to be set to 1 */
 	if (!IS_PINEVIEW(dev_priv->dev))
 		return;

 	val = I915_READ(DSPCLK_GATE_D);
 	if (enable)
 		val |= DPCUNIT_CLOCK_GATE_DISABLE;
 	else
 		val &= ~DPCUNIT_CLOCK_GATE_DISABLE;
 	I915_WRITE(DSPCLK_GATE_D, val);
 }

 static u32 get_reserved(struct intel_gpio *gpio)
 {
 	struct drm_i915_private *dev_priv = gpio->dev_priv;
 	struct drm_device *dev = dev_priv->dev;
 	u32 reserved = 0;

 	/* On most chips, these bits must be preserved in software. */
 	if (!IS_I830(dev) && !IS_845G(dev))
 		reserved = I915_READ_NOTRACE(gpio->reg) &
 					     (GPIO_DATA_PULLUP_DISABLE |
 					      GPIO_CLOCK_PULLUP_DISABLE);

 	return reserved;
 }

 static int get_clock(void *data)
 {
 	struct intel_gpio *gpio = data;
 	struct drm_i915_private *dev_priv = gpio->dev_priv;
 	u32 reserved = get_reserved(gpio);
 	I915_WRITE_NOTRACE(gpio->reg, reserved | GPIO_CLOCK_DIR_MASK);
 	I915_WRITE_NOTRACE(gpio->reg, reserved);
 	return (I915_READ_NOTRACE(gpio->reg) & GPIO_CLOCK_VAL_IN) != 0;
 }

 static int get_data(void *data)
 {
 	struct intel_gpio *gpio = data;
 	struct drm_i915_private *dev_priv = gpio->dev_priv;
 	u32 reserved = get_reserved(gpio);
 	I915_WRITE_NOTRACE(gpio->reg, reserved | GPIO_DATA_DIR_MASK);
 	I915_WRITE_NOTRACE(gpio->reg, reserved);
 	return (I915_READ_NOTRACE(gpio->reg) & GPIO_DATA_VAL_IN) != 0;
 }

 static void set_clock(void *data, int state_high)
 {
 	struct intel_gpio *gpio = data;
 	struct drm_i915_private *dev_priv = gpio->dev_priv;
 	u32 reserved = get_reserved(gpio);
 	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;

 	I915_WRITE_NOTRACE(gpio->reg, reserved | clock_bits);
 	POSTING_READ(gpio->reg);
 }

 static void set_data(void *data, int state_high)
 {
 	struct intel_gpio *gpio = data;
 	struct drm_i915_private *dev_priv = gpio->dev_priv;
 	u32 reserved = get_reserved(gpio);
 	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;

 	I915_WRITE_NOTRACE(gpio->reg, reserved | data_bits);
 	POSTING_READ(gpio->reg);
 }

 static struct i2c_adapter *
 intel_gpio_create(struct drm_i915_private *dev_priv, u32 pin)
 {
 	static const int map_pin_to_reg[] = {
 		0,
 		GPIOB,
 		GPIOA,
 		GPIOC,
 		GPIOD,
 		GPIOE,
 		0,
 		GPIOF,
 	};
 	struct intel_gpio *gpio;

 	if (pin >= ARRAY_SIZE(map_pin_to_reg) || !map_pin_to_reg[pin])
 		return NULL;

 	gpio = kzalloc(sizeof(struct intel_gpio), GFP_KERNEL);
 	if (gpio == NULL)
 		return NULL;

 	gpio->reg = map_pin_to_reg[pin];
 	if (HAS_PCH_SPLIT(dev_priv->dev))
 		gpio->reg += PCH_GPIOA - GPIOA;
 	gpio->dev_priv = dev_priv;

 	snprintf(gpio->adapter.name, sizeof(gpio->adapter.name),
 		 "i915 GPIO%c", "?BACDE?F"[pin]);
 	gpio->adapter.owner = THIS_MODULE;
 	gpio->adapter.algo_data	= &gpio->algo;
 	gpio->adapter.dev.parent = &dev_priv->dev->pdev->dev;
 	gpio->algo.setsda = set_data;
 	gpio->algo.setscl = set_clock;
 	gpio->algo.getsda = get_data;
 	gpio->algo.getscl = get_clock;
 	gpio->algo.udelay = I2C_RISEFALL_TIME;
 	gpio->algo.timeout = usecs_to_jiffies(2200);
 	gpio->algo.data = gpio;

 	if (i2c_bit_add_bus(&gpio->adapter))
 		goto out_free;

 	return &gpio->adapter;

 out_free:
 	kfree(gpio);
 	return NULL;
 }

 static int
 intel_i2c_quirk_xfer(struct drm_i915_private *dev_priv,
 		     struct i2c_adapter *adapter,
 		     struct i2c_msg *msgs,
 		     int num)
 {
 	struct intel_gpio *gpio = container_of(adapter,
 					       struct intel_gpio,
 					       adapter);
 	int ret;

 	intel_i2c_reset(dev_priv->dev);

 	intel_i2c_quirk_set(dev_priv, true);
 	set_data(gpio, 1);
 	set_clock(gpio, 1);
 	udelay(I2C_RISEFALL_TIME);

 	ret = adapter->algo->master_xfer(adapter, msgs, num);

 	set_data(gpio, 1);
 	set_clock(gpio, 1);
 	intel_i2c_quirk_set(dev_priv, false);

 	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 = adapter->algo_data;
 	int i, reg_offset;

 	if (bus->force_bit)
 		return intel_i2c_quirk_xfer(dev_priv,
 					    bus->force_bit, msgs, num);

 	reg_offset = HAS_PCH_SPLIT(dev_priv->dev) ? PCH_GMBUS0 - GMBUS0 : 0;

 	I915_WRITE(GMBUS0 + reg_offset, bus->reg0);

 	for (i = 0; i < num; i++) {
 		u16 len = msgs[i].len;
 		u8 *buf = msgs[i].buf;

 		if (msgs[i].flags & I2C_M_RD) {
 			I915_WRITE(GMBUS1 + reg_offset,
 				   GMBUS_CYCLE_WAIT | (i + 1 == num ? GMBUS_CYCLE_STOP : 0) |
 				   (len << GMBUS_BYTE_COUNT_SHIFT) |
 				   (msgs[i].addr << GMBUS_SLAVE_ADDR_SHIFT) |
 				   GMBUS_SLAVE_READ | GMBUS_SW_RDY);
 			POSTING_READ(GMBUS2+reg_offset);
 			do {
 				u32 val, loop = 0;

 				if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_RDY), 50))
 					goto timeout;
 				if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
 					goto clear_err;

 				val = I915_READ(GMBUS3 + reg_offset);
 				do {
 					*buf++ = val & 0xff;
 					val >>= 8;
 				} while (--len && ++loop < 4);
 			} while (len);
 		} else {
 			u32 val, loop;

 			val = loop = 0;
 			do {
 				val |= *buf++ << (8 * loop);
 			} while (--len && ++loop < 4);

 			I915_WRITE(GMBUS3 + reg_offset, val);
 			I915_WRITE(GMBUS1 + reg_offset,
 				   (i + 1 == num ? GMBUS_CYCLE_STOP : GMBUS_CYCLE_WAIT) |
 				   (msgs[i].len << GMBUS_BYTE_COUNT_SHIFT) |
 				   (msgs[i].addr << GMBUS_SLAVE_ADDR_SHIFT) |
 				   GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
 			POSTING_READ(GMBUS2+reg_offset);

 			while (len) {
 				if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_RDY), 50))
 					goto timeout;
 				if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
 					goto clear_err;

 				val = loop = 0;
 				do {
 					val |= *buf++ << (8 * loop);
 				} while (--len && ++loop < 4);

 				I915_WRITE(GMBUS3 + reg_offset, val);
 				POSTING_READ(GMBUS2+reg_offset);
 			}
 		}

 		if (i + 1 < num && wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_WAIT_PHASE), 50))
 			goto timeout;
 		if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
 			goto clear_err;
 	}

 	goto done;

 clear_err:
 	/* 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(GMBUS1 + reg_offset, GMBUS_SW_CLR_INT);
 	I915_WRITE(GMBUS1 + reg_offset, 0);

 done:
 	/* Mark the GMBUS interface as disabled. We will re-enable it at the
 	 * start of the next xfer, till then let it sleep.
 	 */
 	I915_WRITE(GMBUS0 + reg_offset, 0);
 	return i;

 timeout:
 	DRM_INFO("GMBUS timed out, falling back to bit banging on pin %d [%s]\n",
 		 bus->reg0 & 0xff, bus->adapter.name);
 	I915_WRITE(GMBUS0 + reg_offset, 0);

 	/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
 	bus->force_bit = intel_gpio_create(dev_priv, bus->reg0 & 0xff);
 	if (!bus->force_bit)
 		return -ENOMEM;

 	return intel_i2c_quirk_xfer(dev_priv, bus->force_bit, msgs, num);
 }

 static u32 gmbus_func(struct i2c_adapter *adapter)
 {
 	struct intel_gmbus *bus = container_of(adapter,
 					       struct intel_gmbus,
 					       adapter);

 	if (bus->force_bit)
 		bus->force_bit->algo->functionality(bus->force_bit);

 	return (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
 };

 /**
  * intel_gmbus_setup - instantiate all Intel i2c GMBuses
  * @dev: DRM device
  */
 int intel_setup_gmbus(struct drm_device *dev)
 {
 	static const char *names[GMBUS_NUM_PORTS] = {
 		"disabled",
 		"ssc",
 		"vga",
 		"panel",
 		"dpc",
 		"dpb",
 		"reserved",
 		"dpd",
 	};
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret, i;

 	dev_priv->gmbus = kcalloc(sizeof(struct intel_gmbus), GMBUS_NUM_PORTS,
 				  GFP_KERNEL);
 	if (dev_priv->gmbus == NULL)
 		return -ENOMEM;

 	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
 		struct intel_gmbus *bus = &dev_priv->gmbus[i];

 		bus->adapter.owner = THIS_MODULE;
 		bus->adapter.class = I2C_CLASS_DDC;
 		snprintf(bus->adapter.name,
 			 sizeof(bus->adapter.name),
 			 "i915 gmbus %s",
 			 names[i]);

 		bus->adapter.dev.parent = &dev->pdev->dev;
 		bus->adapter.algo_data	= dev_priv;

 		bus->adapter.algo = &gmbus_algorithm;
 		ret = i2c_add_adapter(&bus->adapter);
 		if (ret)
 			goto err;

 		/* By default use a conservative clock rate */
 		bus->reg0 = i | GMBUS_RATE_100KHZ;

 		/* XXX force bit banging until GMBUS is fully debugged */
 		bus->force_bit = intel_gpio_create(dev_priv, i);
 	}

 	intel_i2c_reset(dev_priv->dev);

 	return 0;

 err:
 	while (--i) {
 		struct intel_gmbus *bus = &dev_priv->gmbus[i];
 		i2c_del_adapter(&bus->adapter);
 	}
 	kfree(dev_priv->gmbus);
 	dev_priv->gmbus = NULL;
 	return ret;
 }

 void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
 {
 	struct intel_gmbus *bus = to_intel_gmbus(adapter);

 	/* speed:
 	 * 0x0 = 100 KHz
 	 * 0x1 = 50 KHz
 	 * 0x2 = 400 KHz
 	 * 0x3 = 1000 Khz
 	 */
 	bus->reg0 = (bus->reg0 & ~(0x3 << 8)) | (speed << 8);
 }

 void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit)
 {
 	struct intel_gmbus *bus = to_intel_gmbus(adapter);

 	if (force_bit) {
 		if (bus->force_bit == NULL) {
 			struct drm_i915_private *dev_priv = adapter->algo_data;
 			bus->force_bit = intel_gpio_create(dev_priv,
 							   bus->reg0 & 0xff);
 		}
 	} else {
 		if (bus->force_bit) {
 			i2c_del_adapter(bus->force_bit);
 			kfree(bus->force_bit);
 			bus->force_bit = NULL;
 		}
 	}
 }

 void intel_teardown_gmbus(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int i;

 	if (dev_priv->gmbus == NULL)
 		return;

 	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
 		struct intel_gmbus *bus = &dev_priv->gmbus[i];
 		if (bus->force_bit) {
 			i2c_del_adapter(bus->force_bit);
 			kfree(bus->force_bit);
 		}
 		i2c_del_adapter(&bus->adapter);
 	}

 	kfree(dev_priv->gmbus);
 	dev_priv->gmbus = NULL;
 }
	/*
	* 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/i2c.h>
	#include <linux/i2c-algo-bit.h>
	#include "drmP.h"
	#include "drm.h"
	#include "intel_drv.h"
	#include "i915_drm.h"
	#include "i915_drv.h"

	/* Intel GPIO access functions */

	#define I2C_RISEFALL_TIME 20

	static inline struct intel_gmbus *
	to_intel_gmbus(struct i2c_adapter *i2c)
	{
	return container_of(i2c, struct intel_gmbus, adapter);
	}

	struct intel_gpio {
	struct i2c_adapter adapter;
	struct i2c_algo_bit_data algo;
	struct drm_i915_private *dev_priv;
	u32 reg;
	};

	void
	intel_i2c_reset(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	if (HAS_PCH_SPLIT(dev))
	I915_WRITE(PCH_GMBUS0, 0);
	else
	I915_WRITE(GMBUS0, 0);
	}

	static void intel_i2c_quirk_set(struct drm_i915_private *dev_priv, bool enable)
	{
	u32 val;

	/* When using bit bashing for I2C, this bit needs to be set to 1 */
	if (!IS_PINEVIEW(dev_priv->dev))
	return;

	val = I915_READ(DSPCLK_GATE_D);
	if (enable)
	val \|= DPCUNIT_CLOCK_GATE_DISABLE;
	else
	val &= ~DPCUNIT_CLOCK_GATE_DISABLE;
	I915_WRITE(DSPCLK_GATE_D, val);
	}

	static u32 get_reserved(struct intel_gpio *gpio)
	{
	struct drm_i915_private *dev_priv = gpio->dev_priv;
	struct drm_device *dev = dev_priv->dev;
	u32 reserved = 0;

	/* On most chips, these bits must be preserved in software. */
	if (!IS_I830(dev) && !IS_845G(dev))
	reserved = I915_READ_NOTRACE(gpio->reg) &
	(GPIO_DATA_PULLUP_DISABLE \|
	GPIO_CLOCK_PULLUP_DISABLE);

	return reserved;
	}

	static int get_clock(void *data)
	{
	struct intel_gpio *gpio = data;
	struct drm_i915_private *dev_priv = gpio->dev_priv;
	u32 reserved = get_reserved(gpio);
	I915_WRITE_NOTRACE(gpio->reg, reserved \| GPIO_CLOCK_DIR_MASK);
	I915_WRITE_NOTRACE(gpio->reg, reserved);
	return (I915_READ_NOTRACE(gpio->reg) & GPIO_CLOCK_VAL_IN) != 0;
	}

	static int get_data(void *data)
	{
	struct intel_gpio *gpio = data;
	struct drm_i915_private *dev_priv = gpio->dev_priv;
	u32 reserved = get_reserved(gpio);
	I915_WRITE_NOTRACE(gpio->reg, reserved \| GPIO_DATA_DIR_MASK);
	I915_WRITE_NOTRACE(gpio->reg, reserved);
	return (I915_READ_NOTRACE(gpio->reg) & GPIO_DATA_VAL_IN) != 0;
	}

	static void set_clock(void *data, int state_high)
	{
	struct intel_gpio *gpio = data;
	struct drm_i915_private *dev_priv = gpio->dev_priv;
	u32 reserved = get_reserved(gpio);
	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;

	I915_WRITE_NOTRACE(gpio->reg, reserved \| clock_bits);
	POSTING_READ(gpio->reg);
	}

	static void set_data(void *data, int state_high)
	{
	struct intel_gpio *gpio = data;
	struct drm_i915_private *dev_priv = gpio->dev_priv;
	u32 reserved = get_reserved(gpio);
	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;

	I915_WRITE_NOTRACE(gpio->reg, reserved \| data_bits);
	POSTING_READ(gpio->reg);
	}

	static struct i2c_adapter *
	intel_gpio_create(struct drm_i915_private *dev_priv, u32 pin)
	{
	static const int map_pin_to_reg[] = {
	0,
	GPIOB,
	GPIOA,
	GPIOC,
	GPIOD,
	GPIOE,
	0,
	GPIOF,
	};
	struct intel_gpio *gpio;

	if (pin >= ARRAY_SIZE(map_pin_to_reg) \|\| !map_pin_to_reg[pin])
	return NULL;

	gpio = kzalloc(sizeof(struct intel_gpio), GFP_KERNEL);
	if (gpio == NULL)
	return NULL;

	gpio->reg = map_pin_to_reg[pin];
	if (HAS_PCH_SPLIT(dev_priv->dev))
	gpio->reg += PCH_GPIOA - GPIOA;
	gpio->dev_priv = dev_priv;

	snprintf(gpio->adapter.name, sizeof(gpio->adapter.name),
	"i915 GPIO%c", "?BACDE?F"[pin]);
	gpio->adapter.owner = THIS_MODULE;
	gpio->adapter.algo_data = &gpio->algo;
	gpio->adapter.dev.parent = &dev_priv->dev->pdev->dev;
	gpio->algo.setsda = set_data;
	gpio->algo.setscl = set_clock;
	gpio->algo.getsda = get_data;
	gpio->algo.getscl = get_clock;
	gpio->algo.udelay = I2C_RISEFALL_TIME;
	gpio->algo.timeout = usecs_to_jiffies(2200);
	gpio->algo.data = gpio;

	if (i2c_bit_add_bus(&gpio->adapter))
	goto out_free;

	return &gpio->adapter;

	out_free:
	kfree(gpio);
	return NULL;
	}

	static int
	intel_i2c_quirk_xfer(struct drm_i915_private *dev_priv,
	struct i2c_adapter *adapter,
	struct i2c_msg *msgs,
	int num)
	{
	struct intel_gpio *gpio = container_of(adapter,
	struct intel_gpio,
	adapter);
	int ret;

	intel_i2c_reset(dev_priv->dev);

	intel_i2c_quirk_set(dev_priv, true);
	set_data(gpio, 1);
	set_clock(gpio, 1);
	udelay(I2C_RISEFALL_TIME);

	ret = adapter->algo->master_xfer(adapter, msgs, num);

	set_data(gpio, 1);
	set_clock(gpio, 1);
	intel_i2c_quirk_set(dev_priv, false);

	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 = adapter->algo_data;
	int i, reg_offset;

	if (bus->force_bit)
	return intel_i2c_quirk_xfer(dev_priv,
	bus->force_bit, msgs, num);

	reg_offset = HAS_PCH_SPLIT(dev_priv->dev) ? PCH_GMBUS0 - GMBUS0 : 0;

	I915_WRITE(GMBUS0 + reg_offset, bus->reg0);

	for (i = 0; i < num; i++) {
	u16 len = msgs[i].len;
	u8 *buf = msgs[i].buf;

	if (msgs[i].flags & I2C_M_RD) {
	I915_WRITE(GMBUS1 + reg_offset,
	GMBUS_CYCLE_WAIT \| (i + 1 == num ? GMBUS_CYCLE_STOP : 0) \|
	(len << GMBUS_BYTE_COUNT_SHIFT) \|
	(msgs[i].addr << GMBUS_SLAVE_ADDR_SHIFT) \|
	GMBUS_SLAVE_READ \| GMBUS_SW_RDY);
	POSTING_READ(GMBUS2+reg_offset);
	do {
	u32 val, loop = 0;

	if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER \| GMBUS_HW_RDY), 50))
	goto timeout;
	if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
	goto clear_err;

	val = I915_READ(GMBUS3 + reg_offset);
	do {
	*buf++ = val & 0xff;
	val >>= 8;
	} while (--len && ++loop < 4);
	} while (len);
	} else {
	u32 val, loop;

	val = loop = 0;
	do {
	val \|= buf++ << (8 loop);
	} while (--len && ++loop < 4);

	I915_WRITE(GMBUS3 + reg_offset, val);
	I915_WRITE(GMBUS1 + reg_offset,
	(i + 1 == num ? GMBUS_CYCLE_STOP : GMBUS_CYCLE_WAIT) \|
	(msgs[i].len << GMBUS_BYTE_COUNT_SHIFT) \|
	(msgs[i].addr << GMBUS_SLAVE_ADDR_SHIFT) \|
	GMBUS_SLAVE_WRITE \| GMBUS_SW_RDY);
	POSTING_READ(GMBUS2+reg_offset);

	while (len) {
	if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER \| GMBUS_HW_RDY), 50))
	goto timeout;
	if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
	goto clear_err;

	val = loop = 0;
	do {
	val \|= buf++ << (8 loop);
	} while (--len && ++loop < 4);

	I915_WRITE(GMBUS3 + reg_offset, val);
	POSTING_READ(GMBUS2+reg_offset);
	}
	}

	if (i + 1 < num && wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER \| GMBUS_HW_WAIT_PHASE), 50))
	goto timeout;
	if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
	goto clear_err;
	}

	goto done;

	clear_err:
	/* 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(GMBUS1 + reg_offset, GMBUS_SW_CLR_INT);
	I915_WRITE(GMBUS1 + reg_offset, 0);

	done:
	/* Mark the GMBUS interface as disabled. We will re-enable it at the
	* start of the next xfer, till then let it sleep.
	*/
	I915_WRITE(GMBUS0 + reg_offset, 0);
	return i;

	timeout:
	DRM_INFO("GMBUS timed out, falling back to bit banging on pin %d [%s]\n",
	bus->reg0 & 0xff, bus->adapter.name);
	I915_WRITE(GMBUS0 + reg_offset, 0);

	/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
	bus->force_bit = intel_gpio_create(dev_priv, bus->reg0 & 0xff);
	if (!bus->force_bit)
	return -ENOMEM;

	return intel_i2c_quirk_xfer(dev_priv, bus->force_bit, msgs, num);
	}

	static u32 gmbus_func(struct i2c_adapter *adapter)
	{
	struct intel_gmbus *bus = container_of(adapter,
	struct intel_gmbus,
	adapter);

	if (bus->force_bit)
	bus->force_bit->algo->functionality(bus->force_bit);

	return (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
	};

	/**
	* intel_gmbus_setup - instantiate all Intel i2c GMBuses
	* @dev: DRM device
	*/
	int intel_setup_gmbus(struct drm_device *dev)
	{
	static const char *names[GMBUS_NUM_PORTS] = {
	"disabled",
	"ssc",
	"vga",
	"panel",
	"dpc",
	"dpb",
	"reserved",
	"dpd",
	};
	struct drm_i915_private *dev_priv = dev->dev_private;
	int ret, i;

	dev_priv->gmbus = kcalloc(sizeof(struct intel_gmbus), GMBUS_NUM_PORTS,
	GFP_KERNEL);
	if (dev_priv->gmbus == NULL)
	return -ENOMEM;

	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
	struct intel_gmbus *bus = &dev_priv->gmbus[i];

	bus->adapter.owner = THIS_MODULE;
	bus->adapter.class = I2C_CLASS_DDC;
	snprintf(bus->adapter.name,
	sizeof(bus->adapter.name),
	"i915 gmbus %s",
	names[i]);

	bus->adapter.dev.parent = &dev->pdev->dev;
	bus->adapter.algo_data = dev_priv;

	bus->adapter.algo = &gmbus_algorithm;
	ret = i2c_add_adapter(&bus->adapter);
	if (ret)
	goto err;

	/* By default use a conservative clock rate */
	bus->reg0 = i \| GMBUS_RATE_100KHZ;

	/* XXX force bit banging until GMBUS is fully debugged */
	bus->force_bit = intel_gpio_create(dev_priv, i);
	}

	intel_i2c_reset(dev_priv->dev);

	return 0;

	err:
	while (--i) {
	struct intel_gmbus *bus = &dev_priv->gmbus[i];
	i2c_del_adapter(&bus->adapter);
	}
	kfree(dev_priv->gmbus);
	dev_priv->gmbus = NULL;
	return ret;
	}

	void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
	{
	struct intel_gmbus *bus = to_intel_gmbus(adapter);

	/* speed:
	* 0x0 = 100 KHz
	* 0x1 = 50 KHz
	* 0x2 = 400 KHz
	* 0x3 = 1000 Khz
	*/
	bus->reg0 = (bus->reg0 & ~(0x3 << 8)) \| (speed << 8);
	}

	void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit)
	{
	struct intel_gmbus *bus = to_intel_gmbus(adapter);

	if (force_bit) {
	if (bus->force_bit == NULL) {
	struct drm_i915_private *dev_priv = adapter->algo_data;
	bus->force_bit = intel_gpio_create(dev_priv,
	bus->reg0 & 0xff);
	}
	} else {
	if (bus->force_bit) {
	i2c_del_adapter(bus->force_bit);
	kfree(bus->force_bit);
	bus->force_bit = NULL;
	}
	}
	}

	void intel_teardown_gmbus(struct drm_device *dev)
	{
	struct drm_i915_private *dev_priv = dev->dev_private;
	int i;

	if (dev_priv->gmbus == NULL)
	return;

	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
	struct intel_gmbus *bus = &dev_priv->gmbus[i];
	if (bus->force_bit) {
	i2c_del_adapter(bus->force_bit);
	kfree(bus->force_bit);
	}
	i2c_del_adapter(&bus->adapter);
	}

	kfree(dev_priv->gmbus);
	dev_priv->gmbus = NULL;
	}