1/*
2 * Helpers for controlling modem lines via GPIO
3 *
4 * Copyright (C) 2014 Paratronic S.A.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 */
17
18#include <linux/err.h>
19#include <linux/device.h>
20#include <linux/gpio/consumer.h>
21#include <linux/termios.h>
22
23#include "serial_mctrl_gpio.h"
24
25struct mctrl_gpios {
26	struct gpio_desc *gpio[UART_GPIO_MAX];
27};
28
29static const struct {
30	const char *name;
31	unsigned int mctrl;
32	bool dir_out;
33} mctrl_gpios_desc[UART_GPIO_MAX] = {
34	{ "cts", TIOCM_CTS, false, },
35	{ "dsr", TIOCM_DSR, false, },
36	{ "dcd", TIOCM_CD, false, },
37	{ "rng", TIOCM_RNG, false, },
38	{ "rts", TIOCM_RTS, true, },
39	{ "dtr", TIOCM_DTR, true, },
40	{ "out1", TIOCM_OUT1, true, },
41	{ "out2", TIOCM_OUT2, true, },
42};
43
44void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
45{
46	enum mctrl_gpio_idx i;
47
48	if (IS_ERR_OR_NULL(gpios))
49		return;
50
51	for (i = 0; i < UART_GPIO_MAX; i++)
52		if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
53		    mctrl_gpios_desc[i].dir_out)
54			gpiod_set_value(gpios->gpio[i],
55					!!(mctrl & mctrl_gpios_desc[i].mctrl));
56}
57EXPORT_SYMBOL_GPL(mctrl_gpio_set);
58
59struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
60				      enum mctrl_gpio_idx gidx)
61{
62	if (!IS_ERR_OR_NULL(gpios) && !IS_ERR_OR_NULL(gpios->gpio[gidx]))
63		return gpios->gpio[gidx];
64	else
65		return NULL;
66}
67EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
68
69unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
70{
71	enum mctrl_gpio_idx i;
72
73	/*
74	 * return it unchanged if the structure is not allocated
75	 */
76	if (IS_ERR_OR_NULL(gpios))
77		return *mctrl;
78
79	for (i = 0; i < UART_GPIO_MAX; i++) {
80		if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
81		    !mctrl_gpios_desc[i].dir_out) {
82			if (gpiod_get_value(gpios->gpio[i]))
83				*mctrl |= mctrl_gpios_desc[i].mctrl;
84			else
85				*mctrl &= ~mctrl_gpios_desc[i].mctrl;
86		}
87	}
88
89	return *mctrl;
90}
91EXPORT_SYMBOL_GPL(mctrl_gpio_get);
92
93struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
94{
95	struct mctrl_gpios *gpios;
96	enum mctrl_gpio_idx i;
97	int err;
98
99	gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
100	if (!gpios)
101		return ERR_PTR(-ENOMEM);
102
103	for (i = 0; i < UART_GPIO_MAX; i++) {
104		gpios->gpio[i] = devm_gpiod_get_index(dev,
105						      mctrl_gpios_desc[i].name,
106						      idx);
107
108		/*
109		 * The GPIOs are maybe not all filled,
110		 * this is not an error.
111		 */
112		if (IS_ERR_OR_NULL(gpios->gpio[i]))
113			continue;
114
115		if (mctrl_gpios_desc[i].dir_out)
116			err = gpiod_direction_output(gpios->gpio[i], 0);
117		else
118			err = gpiod_direction_input(gpios->gpio[i]);
119		if (err) {
120			dev_dbg(dev, "Unable to set direction for %s GPIO",
121				mctrl_gpios_desc[i].name);
122			devm_gpiod_put(dev, gpios->gpio[i]);
123			gpios->gpio[i] = NULL;
124		}
125	}
126
127	return gpios;
128}
129EXPORT_SYMBOL_GPL(mctrl_gpio_init);
130
131void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
132{
133	enum mctrl_gpio_idx i;
134
135	if (IS_ERR_OR_NULL(gpios))
136		return;
137
138	for (i = 0; i < UART_GPIO_MAX; i++)
139		if (!IS_ERR_OR_NULL(gpios->gpio[i]))
140			devm_gpiod_put(dev, gpios->gpio[i]);
141	devm_kfree(dev, gpios);
142}
143EXPORT_SYMBOL_GPL(mctrl_gpio_free);
144