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 psb_intel_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 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_DATA_VAL_IN) != 0;
41}
42
43static void set_clock(void *data, int state_high)
44{
45	struct psb_intel_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 psb_intel_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 * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
87 * @dev: DRM device
88 * @output: driver specific output device
89 * @reg: GPIO reg to use
90 * @name: name for this bus
91 *
92 * Creates and registers a new i2c bus with the Linux i2c layer, for use
93 * in output probing and control (e.g. DDC or SDVO control functions).
94 *
95 * Possible values for @reg include:
96 *   %GPIOA
97 *   %GPIOB
98 *   %GPIOC
99 *   %GPIOD
100 *   %GPIOE
101 *   %GPIOF
102 *   %GPIOG
103 *   %GPIOH
104 * see PRM for details on how these different busses are used.
105 */
106struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
107					const u32 reg, const char *name)
108{
109	struct psb_intel_i2c_chan *chan;
110
111	chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
112	if (!chan)
113		goto out_free;
114
115	chan->drm_dev = dev;
116	chan->reg = reg;
117	snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
118	chan->adapter.owner = THIS_MODULE;
119	chan->adapter.algo_data = &chan->algo;
120	chan->adapter.dev.parent = &dev->pdev->dev;
121	chan->algo.setsda = set_data;
122	chan->algo.setscl = set_clock;
123	chan->algo.getsda = get_data;
124	chan->algo.getscl = get_clock;
125	chan->algo.udelay = 20;
126	chan->algo.timeout = usecs_to_jiffies(2200);
127	chan->algo.data = chan;
128
129	i2c_set_adapdata(&chan->adapter, chan);
130
131	if (i2c_bit_add_bus(&chan->adapter))
132		goto out_free;
133
134	/* JJJ:  raise SCL and SDA? */
135	set_data(chan, 1);
136	set_clock(chan, 1);
137	udelay(20);
138
139	return chan;
140
141out_free:
142	kfree(chan);
143	return NULL;
144}
145
146/**
147 * psb_intel_i2c_destroy - unregister and free i2c bus resources
148 * @output: channel to free
149 *
150 * Unregister the adapter from the i2c layer, then free the structure.
151 */
152void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
153{
154	if (!chan)
155		return;
156
157	i2c_del_adapter(&chan->adapter);
158	kfree(chan);
159}
160