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
|
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2015 Google, Inc
* Written by Simon Glass <sjg@chromium.org>
*/
#include <common.h>
#include <dm.h>
#include <errno.h>
#include <i2c.h>
#include <asm/gpio.h>
DECLARE_GLOBAL_DATA_PTR;
struct i2c_arbitrator_priv {
struct gpio_desc ap_claim;
struct gpio_desc ec_claim;
uint slew_delay_us;
uint wait_retry_ms;
uint wait_free_ms;
};
int i2c_arbitrator_deselect(struct udevice *mux, struct udevice *bus,
uint channel)
{
struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
int ret;
debug("%s: %s\n", __func__, mux->name);
ret = dm_gpio_set_value(&priv->ap_claim, 0);
udelay(priv->slew_delay_us);
return ret;
}
int i2c_arbitrator_select(struct udevice *mux, struct udevice *bus,
uint channel)
{
struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
unsigned start;
int ret;
debug("%s: %s\n", __func__, mux->name);
/* Start a round of trying to claim the bus */
start = get_timer(0);
do {
unsigned start_retry;
int waiting = 0;
/* Indicate that we want to claim the bus */
ret = dm_gpio_set_value(&priv->ap_claim, 1);
if (ret)
goto err;
udelay(priv->slew_delay_us);
/* Wait for the EC to release it */
start_retry = get_timer(0);
while (get_timer(start_retry) < priv->wait_retry_ms) {
ret = dm_gpio_get_value(&priv->ec_claim);
if (ret < 0) {
goto err;
} else if (!ret) {
/* We got it, so return */
return 0;
}
if (!waiting)
waiting = 1;
}
/* It didn't release, so give up, wait, and try again */
ret = dm_gpio_set_value(&priv->ap_claim, 0);
if (ret)
goto err;
mdelay(priv->wait_retry_ms);
} while (get_timer(start) < priv->wait_free_ms);
/* Give up, release our claim */
printf("I2C: Could not claim bus, timeout %lu\n", get_timer(start));
ret = -ETIMEDOUT;
ret = 0;
err:
return ret;
}
static int i2c_arbitrator_probe(struct udevice *dev)
{
struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
const void *blob = gd->fdt_blob;
int node = dev_of_offset(dev);
int ret;
debug("%s: %s\n", __func__, dev->name);
priv->slew_delay_us = fdtdec_get_int(blob, node, "slew-delay-us", 0);
priv->wait_retry_ms = fdtdec_get_int(blob, node, "wait-retry-us", 0) /
1000;
priv->wait_free_ms = fdtdec_get_int(blob, node, "wait-free-us", 0) /
1000;
ret = gpio_request_by_name(dev, "our-claim-gpio", 0, &priv->ap_claim,
GPIOD_IS_OUT);
if (ret)
goto err;
ret = gpio_request_by_name(dev, "their-claim-gpios", 0, &priv->ec_claim,
GPIOD_IS_IN);
if (ret)
goto err_ec_gpio;
return 0;
err_ec_gpio:
dm_gpio_free(dev, &priv->ap_claim);
err:
debug("%s: ret=%d\n", __func__, ret);
return ret;
}
static int i2c_arbitrator_remove(struct udevice *dev)
{
struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
dm_gpio_free(dev, &priv->ap_claim);
dm_gpio_free(dev, &priv->ec_claim);
return 0;
}
static const struct i2c_mux_ops i2c_arbitrator_ops = {
.select = i2c_arbitrator_select,
.deselect = i2c_arbitrator_deselect,
};
static const struct udevice_id i2c_arbitrator_ids[] = {
{ .compatible = "i2c-arb-gpio-challenge" },
{ }
};
U_BOOT_DRIVER(i2c_arbitrator) = {
.name = "i2c_arbitrator",
.id = UCLASS_I2C_MUX,
.of_match = i2c_arbitrator_ids,
.probe = i2c_arbitrator_probe,
.remove = i2c_arbitrator_remove,
.ops = &i2c_arbitrator_ops,
.priv_auto_alloc_size = sizeof(struct i2c_arbitrator_priv),
};
|
