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
