1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright © 2006-2007 Intel Corporation
  4 *
  5 * Authors:
  6 *	Eric Anholt <eric@anholt.net>
  7 */
  8
  9#include <linux/delay.h>
 10#include <linux/export.h>
 11#include <linux/i2c-algo-bit.h>
 12#include <linux/i2c.h>
 13
 14#include "psb_drv.h"
 15#include "psb_intel_reg.h"
 16
 17/*
 18 * Intel GPIO access functions
 19 */
 20
 21#define I2C_RISEFALL_TIME 20
 22
 23static int get_clock(void *data)
 24{
 25	struct gma_i2c_chan *chan = data;
 26	struct drm_device *dev = chan->drm_dev;
 27	u32 val;
 28
 29	val = REG_READ(chan->reg);
 30	return (val & GPIO_CLOCK_VAL_IN) != 0;
 31}
 32
 33static int get_data(void *data)
 34{
 35	struct gma_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_DATA_VAL_IN) != 0;
 41}
 42
 43static void set_clock(void *data, int state_high)
 44{
 45	struct gma_i2c_chan *chan = data;
 46	struct drm_device *dev = chan->drm_dev;
 47	u32 reserved = 0, clock_bits;
 48
 49	/* On most chips, these bits must be preserved in software. */
 50	reserved =
 51		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
 52					   GPIO_CLOCK_PULLUP_DISABLE);
 53
 54	if (state_high)
 55		clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
 56	else
 57		clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
 58		    GPIO_CLOCK_VAL_MASK;
 59	REG_WRITE(chan->reg, reserved | clock_bits);
 60	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
 61}
 62
 63static void set_data(void *data, int state_high)
 64{
 65	struct gma_i2c_chan *chan = data;
 66	struct drm_device *dev = chan->drm_dev;
 67	u32 reserved = 0, data_bits;
 68
 69	/* On most chips, these bits must be preserved in software. */
 70	reserved =
 71		    REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
 72					   GPIO_CLOCK_PULLUP_DISABLE);
 73
 74	if (state_high)
 75		data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
 76	else
 77		data_bits =
 78		    GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
 79		    GPIO_DATA_VAL_MASK;
 80
 81	REG_WRITE(chan->reg, reserved | data_bits);
 82	udelay(I2C_RISEFALL_TIME);	/* wait for the line to change state */
 83}
 84
 85/**
 86 * gma_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
 87 * @dev: DRM device
 88 * @reg: GPIO reg to use
 89 * @name: name for this bus
 90 *
 91 * Creates and registers a new i2c bus with the Linux i2c layer, for use
 92 * in output probing and control (e.g. DDC or SDVO control functions).
 93 *
 94 * Possible values for @reg include:
 95 *   %GPIOA
 96 *   %GPIOB
 97 *   %GPIOC
 98 *   %GPIOD
 99 *   %GPIOE
100 *   %GPIOF
101 *   %GPIOG
102 *   %GPIOH
103 * see PRM for details on how these different busses are used.
104 */
105struct gma_i2c_chan *gma_i2c_create(struct drm_device *dev, const u32 reg,
106				    const char *name)
107{
108	struct gma_i2c_chan *chan;
109
110	chan = kzalloc(sizeof(struct gma_i2c_chan), GFP_KERNEL);
111	if (!chan)
112		goto out_free;
113
114	chan->drm_dev = dev;
115	chan->reg = reg;
116	snprintf(chan->base.name, I2C_NAME_SIZE, "intel drm %s", name);
117	chan->base.owner = THIS_MODULE;
118	chan->base.algo_data = &chan->algo;
119	chan->base.dev.parent = dev->dev;
120	chan->algo.setsda = set_data;
121	chan->algo.setscl = set_clock;
122	chan->algo.getsda = get_data;
123	chan->algo.getscl = get_clock;
124	chan->algo.udelay = 20;
125	chan->algo.timeout = usecs_to_jiffies(2200);
126	chan->algo.data = chan;
127
128	i2c_set_adapdata(&chan->base, chan);
129
130	if (i2c_bit_add_bus(&chan->base))
131		goto out_free;
132
133	/* JJJ:  raise SCL and SDA? */
134	set_data(chan, 1);
135	set_clock(chan, 1);
136	udelay(20);
137
138	return chan;
139
140out_free:
141	kfree(chan);
142	return NULL;
143}
144
145/**
146 * gma_i2c_destroy - unregister and free i2c bus resources
147 * @chan: channel to free
148 *
149 * Unregister the adapter from the i2c layer, then free the structure.
150 */
151void gma_i2c_destroy(struct gma_i2c_chan *chan)
152{
153	if (!chan)
154		return;
155
156	i2c_del_adapter(&chan->base);
157	kfree(chan);
158}