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 
25 struct mctrl_gpios {
26 	struct gpio_desc *gpio[UART_GPIO_MAX];
27 };
28 
29 static 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 
44 void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
45 {
46 	enum mctrl_gpio_idx i;
47 	struct gpio_desc *desc_array[UART_GPIO_MAX];
48 	int value_array[UART_GPIO_MAX];
49 	unsigned int count = 0;
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 			desc_array[count] = gpios->gpio[i];
55 			value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl);
56 			count++;
57 		}
58 	gpiod_set_array(count, desc_array, value_array);
59 }
60 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
61 
62 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
63 				      enum mctrl_gpio_idx gidx)
64 {
65 	return gpios->gpio[gidx];
66 }
67 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
68 
69 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
70 {
71 	enum mctrl_gpio_idx i;
72 
73 	for (i = 0; i < UART_GPIO_MAX; i++) {
74 		if (gpios->gpio[i] && !mctrl_gpios_desc[i].dir_out) {
75 			if (gpiod_get_value(gpios->gpio[i]))
76 				*mctrl |= mctrl_gpios_desc[i].mctrl;
77 			else
78 				*mctrl &= ~mctrl_gpios_desc[i].mctrl;
79 		}
80 	}
81 
82 	return *mctrl;
83 }
84 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
85 
86 struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
87 {
88 	struct mctrl_gpios *gpios;
89 	enum mctrl_gpio_idx i;
90 	int err;
91 
92 	gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
93 	if (!gpios)
94 		return ERR_PTR(-ENOMEM);
95 
96 	for (i = 0; i < UART_GPIO_MAX; i++) {
97 		gpios->gpio[i] = devm_gpiod_get_index(dev,
98 						      mctrl_gpios_desc[i].name,
99 						      idx);
100 
101 		/*
102 		 * The GPIOs are maybe not all filled,
103 		 * this is not an error.
104 		 */
105 		if (IS_ERR_OR_NULL(gpios->gpio[i]))
106 			continue;
107 
108 		if (mctrl_gpios_desc[i].dir_out)
109 			err = gpiod_direction_output(gpios->gpio[i], 0);
110 		else
111 			err = gpiod_direction_input(gpios->gpio[i]);
112 		if (err) {
113 			dev_dbg(dev, "Unable to set direction for %s GPIO",
114 				mctrl_gpios_desc[i].name);
115 			devm_gpiod_put(dev, gpios->gpio[i]);
116 			gpios->gpio[i] = NULL;
117 		}
118 	}
119 
120 	return gpios;
121 }
122 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
123 
124 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
125 {
126 	enum mctrl_gpio_idx i;
127 
128 	for (i = 0; i < UART_GPIO_MAX; i++)
129 		if (!IS_ERR_OR_NULL(gpios->gpio[i]))
130 			devm_gpiod_put(dev, gpios->gpio[i]);
131 	devm_kfree(dev, gpios);
132 }
133 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
134