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         if (IS_ERR_OR_NULL(gpios))
  52                 return;
  53
  54         for (i = 0; i < UART_GPIO_MAX; i++)
  55                 if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
  56                     mctrl_gpios_desc[i].dir_out) {
  57                         desc_array[count] = gpios->gpio[i];
  58                         value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl);
  59                         count++;
  60                 }
  61         gpiod_set_array(count, desc_array, value_array);
  62 }
  63 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
  64
  65 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
  66                                       enum mctrl_gpio_idx gidx)
  67 {
  68         if (!IS_ERR_OR_NULL(gpios) && !IS_ERR_OR_NULL(gpios->gpio[gidx]))
  69                 return gpios->gpio[gidx];
  70         else
  71                 return NULL;
  72 }
  73 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
  74
  75 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
  76 {
  77         enum mctrl_gpio_idx i;
  78
  79         /*
  80          * return it unchanged if the structure is not allocated
  81          */
  82         if (IS_ERR_OR_NULL(gpios))
  83                 return *mctrl;
  84
  85         for (i = 0; i < UART_GPIO_MAX; i++) {
  86                 if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
  87                     !mctrl_gpios_desc[i].dir_out) {
  88                         if (gpiod_get_value(gpios->gpio[i]))
  89                                 *mctrl |= mctrl_gpios_desc[i].mctrl;
  90                         else
  91                                 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
  92                 }
  93         }
  94
  95         return *mctrl;
  96 }
  97 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
  98
  99 struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
 100 {
 101         struct mctrl_gpios *gpios;
 102         enum mctrl_gpio_idx i;
 103         int err;
 104
 105         gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
 106         if (!gpios)
 107                 return ERR_PTR(-ENOMEM);
 108
 109         for (i = 0; i < UART_GPIO_MAX; i++) {
 110                 gpios->gpio[i] = devm_gpiod_get_index(dev,
 111                                                       mctrl_gpios_desc[i].name,
 112                                                       idx);
 113
 114                 /*
 115                  * The GPIOs are maybe not all filled,
 116                  * this is not an error.
 117                  */
 118                 if (IS_ERR_OR_NULL(gpios->gpio[i]))
 119                         continue;
 120
 121                 if (mctrl_gpios_desc[i].dir_out)
 122                         err = gpiod_direction_output(gpios->gpio[i], 0);
 123                 else
 124                         err = gpiod_direction_input(gpios->gpio[i]);
 125                 if (err) {
 126                         dev_dbg(dev, "Unable to set direction for %s GPIO",
 127                                 mctrl_gpios_desc[i].name);
 128                         devm_gpiod_put(dev, gpios->gpio[i]);
 129                         gpios->gpio[i] = NULL;
 130                 }
 131         }
 132
 133         return gpios;
 134 }
 135 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 136
 137 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 138 {
 139         enum mctrl_gpio_idx i;
 140
 141         if (IS_ERR_OR_NULL(gpios))
 142                 return;
 143
 144         for (i = 0; i < UART_GPIO_MAX; i++)
 145                 if (!IS_ERR_OR_NULL(gpios->gpio[i]))
 146                         devm_gpiod_put(dev, gpios->gpio[i]);
 147         devm_kfree(dev, gpios);
 148 }
 149 EXPORT_SYMBOL_GPL(mctrl_gpio_free);