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
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de>
*/
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include "siox.h"
#define DRIVER_NAME "siox-gpio"
struct siox_gpio_ddata {
struct gpio_desc *din;
struct gpio_desc *dout;
struct gpio_desc *dclk;
struct gpio_desc *dld;
};
static unsigned int siox_clkhigh_ns = 1000;
static unsigned int siox_loadhigh_ns;
static unsigned int siox_bytegap_ns;
static int siox_gpio_pushpull(struct siox_master *smaster,
size_t setbuf_len, const u8 setbuf[],
size_t getbuf_len, u8 getbuf[])
{
struct siox_gpio_ddata *ddata = siox_master_get_devdata(smaster);
size_t i;
size_t cycles = max(setbuf_len, getbuf_len);
/* reset data and clock */
gpiod_set_value_cansleep(ddata->dout, 0);
gpiod_set_value_cansleep(ddata->dclk, 0);
gpiod_set_value_cansleep(ddata->dld, 1);
ndelay(siox_loadhigh_ns);
gpiod_set_value_cansleep(ddata->dld, 0);
for (i = 0; i < cycles; ++i) {
u8 set = 0, get = 0;
size_t j;
if (i >= cycles - setbuf_len)
set = setbuf[i - (cycles - setbuf_len)];
for (j = 0; j < 8; ++j) {
get <<= 1;
if (gpiod_get_value_cansleep(ddata->din))
get |= 1;
/* DOUT is logically inverted */
gpiod_set_value_cansleep(ddata->dout, !(set & 0x80));
set <<= 1;
gpiod_set_value_cansleep(ddata->dclk, 1);
ndelay(siox_clkhigh_ns);
gpiod_set_value_cansleep(ddata->dclk, 0);
}
if (i < getbuf_len)
getbuf[i] = get;
ndelay(siox_bytegap_ns);
}
gpiod_set_value_cansleep(ddata->dld, 1);
ndelay(siox_loadhigh_ns);
gpiod_set_value_cansleep(ddata->dld, 0);
/*
* Resetting dout isn't necessary protocol wise, but it makes the
* signals more pretty because the dout level is deterministic between
* cycles. Note that this only affects dout between the master and the
* first siox device. dout for the later devices depend on the output of
* the previous siox device.
*/
gpiod_set_value_cansleep(ddata->dout, 0);
return 0;
}
static int siox_gpio_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct siox_gpio_ddata *ddata;
int ret;
struct siox_master *smaster;
smaster = siox_master_alloc(&pdev->dev, sizeof(*ddata));
if (!smaster) {
dev_err(dev, "failed to allocate siox master\n");
return -ENOMEM;
}
platform_set_drvdata(pdev, smaster);
ddata = siox_master_get_devdata(smaster);
ddata->din = devm_gpiod_get(dev, "din", GPIOD_IN);
if (IS_ERR(ddata->din)) {
ret = PTR_ERR(ddata->din);
dev_err(dev, "Failed to get %s GPIO: %d\n", "din", ret);
goto err;
}
ddata->dout = devm_gpiod_get(dev, "dout", GPIOD_OUT_LOW);
if (IS_ERR(ddata->dout)) {
ret = PTR_ERR(ddata->dout);
dev_err(dev, "Failed to get %s GPIO: %d\n", "dout", ret);
goto err;
}
ddata->dclk = devm_gpiod_get(dev, "dclk", GPIOD_OUT_LOW);
if (IS_ERR(ddata->dclk)) {
ret = PTR_ERR(ddata->dclk);
dev_err(dev, "Failed to get %s GPIO: %d\n", "dclk", ret);
goto err;
}
ddata->dld = devm_gpiod_get(dev, "dld", GPIOD_OUT_LOW);
if (IS_ERR(ddata->dld)) {
ret = PTR_ERR(ddata->dld);
dev_err(dev, "Failed to get %s GPIO: %d\n", "dld", ret);
goto err;
}
smaster->pushpull = siox_gpio_pushpull;
/* XXX: determine automatically like spi does */
smaster->busno = 0;
ret = siox_master_register(smaster);
if (ret) {
dev_err(dev, "Failed to register siox master: %d\n", ret);
err:
siox_master_put(smaster);
}
return ret;
}
static int siox_gpio_remove(struct platform_device *pdev)
{
struct siox_master *master = platform_get_drvdata(pdev);
siox_master_unregister(master);
return 0;
}
static const struct of_device_id siox_gpio_dt_ids[] = {
{ .compatible = "eckelmann,siox-gpio", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, siox_gpio_dt_ids);
static struct platform_driver siox_gpio_driver = {
.probe = siox_gpio_probe,
.remove = siox_gpio_remove,
.driver = {
.name = DRIVER_NAME,
.of_match_table = siox_gpio_dt_ids,
},
};
module_platform_driver(siox_gpio_driver);
MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);
|
