1/*
  2 * Copyright © 2006-2007 Intel Corporation
  3 *
  4 * This program is free software; you can redistribute it and/or modify it
  5 * under the terms and conditions of the GNU General Public License,
  6 * version 2, as published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope it will be useful, but WITHOUT
  9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 11 * more details.
 12 *
 13 * You should have received a copy of the GNU General Public License along with
 14 * this program; if not, write to the Free Software Foundation, Inc.,
 15 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 16 *
 17 * Authors:
 18 *	Eric Anholt <eric@anholt.net>
 19 */
 20#include <linux/export.h>
 21#include <linux/i2c.h>
 22#include <linux/i2c-algo-bit.h>
 23
 24#include "psb_drv.h"
 25#include "psb_intel_reg.h"
 26
 27/*
 28 * Intel GPIO access functions
 29 */
 30
 31#define I2C_RISEFALL_TIME 20
 32
 33static int get_clock(void *data)
 34{
 35	struct psb_intel_i2c_chan *chan = data;
 36	struct drm_device *dev = chan->drm_dev;
 37	u32 val;
 38
 39	val = REG_READ(chan->reg);
 40	return (val & GPIO_CLOCK_VAL_IN) != 0;
 41}
 42
 43static int get_data(void *data)
 44{
 45	struct psb_intel_i2c_chan *chan = data;
 46	struct drm_device *dev = chan->drm_dev;
 47	u32 val;
 48
 49	val = REG_READ(chan->reg);
 50	return (val & GPIO_DATA_VAL_IN) != 0;
 51}
 52
 53static void set_clock(void *data, int state_high)
 54{
 55	struct psb_intel_i2c_chan *chan = data;
 56	struct drm_device *dev = chan->drm_dev;
 57	u32 reserved = 0, clock_bits;
 58
 59	/* On most chips, these bits must be preserved in software. */
 60	reserved =
 61		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
 62					   GPIO_CLOCK_PULLUP_DISABLE);
 63
 64	if (state_high)
 65		clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
 66	else
 67		clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
 68		    GPIO_CLOCK_VAL_MASK;
 69	REG_WRITE(chan->reg, reserved | clock_bits);
 70	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
 71}
 72
 73static void set_data(void *data, int state_high)
 74{
 75	struct psb_intel_i2c_chan *chan = data;
 76	struct drm_device *dev = chan->drm_dev;
 77	u32 reserved = 0, data_bits;
 78
 79	/* On most chips, these bits must be preserved in software. */
 80	reserved =
 81		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
 82					   GPIO_CLOCK_PULLUP_DISABLE);
 83
 84	if (state_high)
 85		data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
 86	else
 87		data_bits =
 88		    GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
 89		    GPIO_DATA_VAL_MASK;
 90
 91	REG_WRITE(chan->reg, reserved | data_bits);
 92	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
 93}
 94
 95/**
 96 * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
 97 * @dev: DRM device
 98 * @output: driver specific output device
 99 * @reg: GPIO reg to use
100 * @name: name for this bus
101 *
102 * Creates and registers a new i2c bus with the Linux i2c layer, for use
103 * in output probing and control (e.g. DDC or SDVO control functions).
104 *
105 * Possible values for @reg include:
106 *   %GPIOA
107 *   %GPIOB
108 *   %GPIOC
109 *   %GPIOD
110 *   %GPIOE
111 *   %GPIOF
112 *   %GPIOG
113 *   %GPIOH
114 * see PRM for details on how these different busses are used.
115 */
116struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
117					const u32 reg, const char *name)
118{
119	struct psb_intel_i2c_chan *chan;
120
121	chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
122	if (!chan)
123		goto out_free;
124
125	chan->drm_dev = dev;
126	chan->reg = reg;
127	snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
128	chan->adapter.owner = THIS_MODULE;
129	chan->adapter.algo_data = &chan->algo;
130	chan->adapter.dev.parent = &dev->pdev->dev;
131	chan->algo.setsda = set_data;
132	chan->algo.setscl = set_clock;
133	chan->algo.getsda = get_data;
134	chan->algo.getscl = get_clock;
135	chan->algo.udelay = 20;
136	chan->algo.timeout = usecs_to_jiffies(2200);
137	chan->algo.data = chan;
138
139	i2c_set_adapdata(&chan->adapter, chan);
140
141	if (i2c_bit_add_bus(&chan->adapter))
142		goto out_free;
143
144	/* JJJ:  raise SCL and SDA? */
145	set_data(chan, 1);
146	set_clock(chan, 1);
147	udelay(20);
148
149	return chan;
150
151out_free:
152	kfree(chan);
153	return NULL;
154}
155
156/**
157 * psb_intel_i2c_destroy - unregister and free i2c bus resources
158 * @output: channel to free
159 *
160 * Unregister the adapter from the i2c layer, then free the structure.
161 */
162void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
163{
164	if (!chan)
165		return;
166
167	i2c_del_adapter(&chan->adapter);
168	kfree(chan);
169}