1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
|
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2018 Arm Ltd.
* Author: Liviu Dudau <liviu.dudau@foss.arm.com>
*
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <i2c.h>
#include <asm/io.h>
#include <clk.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/io.h>
#define I2C_CONTROL_REG 0x00
#define I2C_SET_REG 0x00
#define I2C_CLEAR_REG 0x04
#define SCL BIT(0)
#define SDA BIT(1)
struct versatile_i2c_priv {
phys_addr_t base;
u32 delay;
};
static inline void versatile_sda_set(struct versatile_i2c_priv *priv, u8 state)
{
writel(SDA, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
udelay(priv->delay);
}
static inline int versatile_sda_get(struct versatile_i2c_priv *priv)
{
int v = !!(readl(priv->base + I2C_CONTROL_REG) & SDA);
udelay(priv->delay);
return v;
}
static inline void versatile_scl_set(struct versatile_i2c_priv *priv, u8 state)
{
writel(SCL, priv->base + (state ? I2C_SET_REG : I2C_CLEAR_REG));
udelay(priv->delay);
}
static inline int versatile_scl_get(struct versatile_i2c_priv *priv)
{
int v = !!(readl(priv->base + I2C_CONTROL_REG) & SCL);
udelay(priv->delay);
return v;
}
/* start: SDA goes from high to low while SCL is high */
static void versatile_i2c_start(struct versatile_i2c_priv *priv)
{
udelay(priv->delay);
versatile_sda_set(priv, 1);
versatile_scl_set(priv, 1);
versatile_sda_set(priv, 0);
}
/* stop: SDA goes from low to high while SCL is high */
static void versatile_i2c_stop(struct versatile_i2c_priv *priv)
{
versatile_scl_set(priv, 0);
versatile_sda_set(priv, 0);
versatile_scl_set(priv, 1);
versatile_sda_set(priv, 1);
}
/* read a bit from the SDA line (data or ACK/NACK) */
static u8 versatile_i2c_read_bit(struct versatile_i2c_priv *priv)
{
versatile_scl_set(priv, 0);
versatile_sda_set(priv, 1);
versatile_scl_set(priv, 1);
udelay(priv->delay);
return (u8)versatile_sda_get(priv);
}
/* write a bit on the SDA line */
static void versatile_i2c_write_bit(struct versatile_i2c_priv *priv, u8 bit)
{
versatile_scl_set(priv, 0);
versatile_sda_set(priv, bit);
versatile_scl_set(priv, 1);
udelay(priv->delay);
}
/* send a reset sequence of 9 clocks with SDA high */
static void versatile_i2c_reset_bus(struct versatile_i2c_priv *priv)
{
int i;
for (i = 0; i < 9; i++)
versatile_i2c_write_bit(priv, 1);
versatile_i2c_stop(priv);
}
/* write byte without start/stop sequence */
static int versatile_i2c_write_byte(struct versatile_i2c_priv *priv, u8 byte)
{
u8 nak, i;
for (i = 0; i < 8; i++) {
versatile_i2c_write_bit(priv, byte & 0x80);
byte <<= 1;
}
/* read ACK */
nak = versatile_i2c_read_bit(priv);
versatile_scl_set(priv, 0);
return nak; /* not a nack is an ack */
}
static int versatile_i2c_read_byte(struct versatile_i2c_priv *priv,
u8 *byte, u8 ack)
{
u8 i;
*byte = 0;
for (i = 0; i < 8; i++) {
*byte <<= 1;
*byte |= versatile_i2c_read_bit(priv);
}
/* write the nack */
versatile_i2c_write_bit(priv, ack);
return 0;
}
static int versatile_i2c_send_slave_addr(struct versatile_i2c_priv *priv,
struct i2c_msg *msg)
{
u8 addr;
int ret;
if (msg->flags & I2C_M_TEN) {
/* 10-bit address, send extended address code first */
addr = 0xf0 | ((msg->addr >> 7) & 0x06);
ret = versatile_i2c_write_byte(priv, addr);
if (ret) {
versatile_i2c_stop(priv);
return -EIO;
}
/* remaining bits */
ret = versatile_i2c_write_byte(priv, msg->addr & 0xff);
if (ret) {
versatile_i2c_stop(priv);
return -EIO;
}
/* reads need to resend the addr */
if (msg->flags & I2C_M_RD) {
versatile_i2c_start(priv);
addr |= 1;
ret = versatile_i2c_write_byte(priv, addr);
if (ret) {
versatile_i2c_stop(priv);
return -EIO;
}
}
} else {
/* normal 7-bit address */
addr = msg->addr << 1;
if (msg->flags & I2C_M_RD)
addr |= 1;
ret = versatile_i2c_write_byte(priv, addr);
if (ret) {
versatile_i2c_stop(priv);
return -EIO;
}
}
return 0;
}
static int versatile_i2c_message_xfer(struct versatile_i2c_priv *priv,
struct i2c_msg *msg)
{
int i, ret;
u8 ack;
versatile_i2c_start(priv);
if (versatile_i2c_send_slave_addr(priv, msg))
return -EIO;
for (i = 0; i < msg->len; i++) {
if (msg->flags & I2C_M_RD) {
ack = (msg->len - i - 1) == 0 ? 1 : 0;
ret = versatile_i2c_read_byte(priv, &msg->buf[i], ack);
} else {
ret = versatile_i2c_write_byte(priv, msg->buf[i]);
}
if (ret)
break;
}
versatile_i2c_stop(priv);
return ret;
}
static int versatile_i2c_xfer(struct udevice *bus,
struct i2c_msg *msg, int nmsgs)
{
struct versatile_i2c_priv *priv = dev_get_priv(bus);
int ret;
for ( ; nmsgs > 0; nmsgs--, msg++) {
ret = versatile_i2c_message_xfer(priv, msg);
if (ret)
return -EREMOTEIO;
}
return 0;
}
static int versatile_i2c_chip_probe(struct udevice *bus,
uint chip, uint chip_flags)
{
/* probe the presence of a slave by writing a 0-size message */
struct i2c_msg msg = { .addr = chip, .flags = chip_flags,
.len = 0, .buf = NULL };
struct versatile_i2c_priv *priv = dev_get_priv(bus);
return versatile_i2c_message_xfer(priv, &msg);
}
static int versatile_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
struct versatile_i2c_priv *priv = dev_get_priv(bus);
priv->delay = 1000000 / (speed << 2);
versatile_i2c_reset_bus(priv);
return 0;
}
static int versatile_i2c_probe(struct udevice *dev)
{
struct versatile_i2c_priv *priv = dev_get_priv(dev);
priv->base = (phys_addr_t)dev_read_addr(dev);
priv->delay = 25; /* 25us * 4 = 100kHz */
return 0;
}
static const struct dm_i2c_ops versatile_i2c_ops = {
.xfer = versatile_i2c_xfer,
.probe_chip = versatile_i2c_chip_probe,
.set_bus_speed = versatile_i2c_set_bus_speed,
};
static const struct udevice_id versatile_i2c_of_match[] = {
{ .compatible = "arm,versatile-i2c" },
{ }
};
U_BOOT_DRIVER(versatile_i2c) = {
.name = "i2c-bus-versatile",
.id = UCLASS_I2C,
.of_match = versatile_i2c_of_match,
.probe = versatile_i2c_probe,
.priv_auto = sizeof(struct versatile_i2c_priv),
.ops = &versatile_i2c_ops,
};
|
