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 
get_clock(void * data)23 static 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 
get_data(void * data)33 static 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 
set_clock(void * data,int state_high)43 static 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 
set_data(void * data,int state_high)63 static 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  */
gma_i2c_create(struct drm_device * dev,const u32 reg,const char * name)105 struct 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 
140 out_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  */
gma_i2c_destroy(struct gma_i2c_chan * chan)151 void 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 }
159