drivers/tty/serial/serial_mctrl_gpio.c

   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 (gpios->gpio[i] && mctrl_gpios_desc[i].dir_out) {
  53                         desc_array[count] = gpios->gpio[i];
  54                         value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl);
  55                         count++;
  56                 }
  57         gpiod_set_array_value(count, desc_array, value_array);
  58 }
  59 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
  60
  61 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
  62                                       enum mctrl_gpio_idx gidx)
  63 {
  64         return gpios->gpio[gidx];
  65 }
  66 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
  67
  68 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
  69 {
  70         enum mctrl_gpio_idx i;
  71
  72         for (i = 0; i < UART_GPIO_MAX; i++) {
  73                 if (gpios->gpio[i] && !mctrl_gpios_desc[i].dir_out) {
  74                         if (gpiod_get_value(gpios->gpio[i]))
  75                                 *mctrl |= mctrl_gpios_desc[i].mctrl;
  76                         else
  77                                 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
  78                 }
  79         }
  80
  81         return *mctrl;
  82 }
  83 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
  84
  85 struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
  86 {
  87         struct mctrl_gpios *gpios;
  88         enum mctrl_gpio_idx i;
  89
  90         gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
  91         if (!gpios)
  92                 return ERR_PTR(-ENOMEM);
  93
  94         for (i = 0; i < UART_GPIO_MAX; i++) {
  95                 enum gpiod_flags flags;
  96
  97                 if (mctrl_gpios_desc[i].dir_out)
  98                         flags = GPIOD_OUT_LOW;
  99                 else
 100                         flags = GPIOD_IN;
 101
 102                 gpios->gpio[i] =
 103                         devm_gpiod_get_index_optional(dev,
 104                                                       mctrl_gpios_desc[i].name,
 105                                                       idx, flags);
 106
 107                 if (IS_ERR(gpios->gpio[i]))
 108                         return ERR_CAST(gpios->gpio[i]);
 109         }
 110
 111         return gpios;
 112 }
 113 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 114
 115 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 116 {
 117         enum mctrl_gpio_idx i;
 118
 119         for (i = 0; i < UART_GPIO_MAX; i++)
 120                 if (gpios->gpio[i])
 121                         devm_gpiod_put(dev, gpios->gpio[i]);
 122         devm_kfree(dev, gpios);
 123 }
 124 EXPORT_SYMBOL_GPL(mctrl_gpio_free);