gma500: Add the i2c bus support

Again this might be a candidate for sharing later.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/gma500/intel_i2c.c

+/*
+ * Copyright © 2006-2007 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Authors:
+ *	Eric Anholt <eric@anholt.net>
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-algo-bit.h>
+
+#include "psb_drv.h"
+#include "psb_intel_reg.h"
+
+/*
+ * Intel GPIO access functions
+ */
+
+#define I2C_RISEFALL_TIME 20
+
+static int get_clock(void *data)
+{
+	struct psb_intel_i2c_chan *chan = data;
+	struct drm_device *dev = chan->drm_dev;
+	u32 val;
+
+	val = REG_READ(chan->reg);
+	return (val & GPIO_CLOCK_VAL_IN) != 0;
+}
+
+static int get_data(void *data)
+{
+	struct psb_intel_i2c_chan *chan = data;
+	struct drm_device *dev = chan->drm_dev;
+	u32 val;
+
+	val = REG_READ(chan->reg);
+	return (val & GPIO_DATA_VAL_IN) != 0;
+}
+
+static void set_clock(void *data, int state_high)
+{
+	struct psb_intel_i2c_chan *chan = data;
+	struct drm_device *dev = chan->drm_dev;
+	u32 reserved = 0, clock_bits;
+
+	/* On most chips, these bits must be preserved in software. */
+	reserved =
+		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
+					   GPIO_CLOCK_PULLUP_DISABLE);
+
+	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;
+	REG_WRITE(chan->reg, reserved | clock_bits);
+	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
+}
+
+static void set_data(void *data, int state_high)
+{
+	struct psb_intel_i2c_chan *chan = data;
+	struct drm_device *dev = chan->drm_dev;
+	u32 reserved = 0, data_bits;
+
+	/* On most chips, these bits must be preserved in software. */
+	reserved =
+		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
+					   GPIO_CLOCK_PULLUP_DISABLE);
+
+	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;
+
+	REG_WRITE(chan->reg, reserved | data_bits);
+	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
+}
+
+/**
+ * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
+ * @dev: DRM device
+ * @output: driver specific output device
+ * @reg: GPIO reg to use
+ * @name: name for this bus
+ *
+ * Creates and registers a new i2c bus with the Linux i2c layer, for use
+ * in output probing and control (e.g. DDC or SDVO control functions).
+ *
+ * Possible values for @reg include:
+ *   %GPIOA
+ *   %GPIOB
+ *   %GPIOC
+ *   %GPIOD
+ *   %GPIOE
+ *   %GPIOF
+ *   %GPIOG
+ *   %GPIOH
+ * see PRM for details on how these different busses are used.
+ */
+struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
+					const u32 reg, const char *name)
+{
+	struct psb_intel_i2c_chan *chan;
+
+	chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
+	if (!chan)
+		goto out_free;
+
+	chan->drm_dev = dev;
+	chan->reg = reg;
+	snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
+	chan->adapter.owner = THIS_MODULE;
+	chan->adapter.algo_data = &chan->algo;
+	chan->adapter.dev.parent = &dev->pdev->dev;
+	chan->algo.setsda = set_data;
+	chan->algo.setscl = set_clock;
+	chan->algo.getsda = get_data;
+	chan->algo.getscl = get_clock;
+	chan->algo.udelay = 20;
+	chan->algo.timeout = usecs_to_jiffies(2200);
+	chan->algo.data = chan;
+
+	i2c_set_adapdata(&chan->adapter, chan);
+
+	if (i2c_bit_add_bus(&chan->adapter))
+		goto out_free;
+
+	/* JJJ:  raise SCL and SDA? */
+	set_data(chan, 1);
+	set_clock(chan, 1);
+	udelay(20);
+
+	return chan;
+
+out_free:
+	kfree(chan);
+	return NULL;
+}
+
+/**
+ * psb_intel_i2c_destroy - unregister and free i2c bus resources
+ * @output: channel to free
+ *
+ * Unregister the adapter from the i2c layer, then free the structure.
+ */
+void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
+{
+	if (!chan)
+		return;
+
+	i2c_del_adapter(&chan->adapter);
+	kfree(chan);
+}