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 #include <linux/err.h>
  18 #include <linux/device.h>
  19 #include <linux/irq.h>
  20 #include <linux/gpio/consumer.h>
  21 #include <linux/termios.h>
  22 #include <linux/serial_core.h>
  23 #include <linux/module.h>
  24
  25 #include "serial_mctrl_gpio.h"
  26
  27 struct mctrl_gpios {
  28         struct uart_port *port;
  29         struct gpio_desc *gpio[UART_GPIO_MAX];
  30         int irq[UART_GPIO_MAX];
  31         unsigned int mctrl_prev;
  32         bool mctrl_on;
  33 };
  34
  35 static const struct {
  36         const char *name;
  37         unsigned int mctrl;
  38         bool dir_out;
  39 } mctrl_gpios_desc[UART_GPIO_MAX] = {
  40         { "cts", TIOCM_CTS, false, },
  41         { "dsr", TIOCM_DSR, false, },
  42         { "dcd", TIOCM_CD, false, },
  43         { "rng", TIOCM_RNG, false, },
  44         { "rts", TIOCM_RTS, true, },
  45         { "dtr", TIOCM_DTR, true, },
  46         { "out1", TIOCM_OUT1, true, },
  47         { "out2", TIOCM_OUT2, true, },
  48 };
  49
  50 void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
  51 {
  52         enum mctrl_gpio_idx i;
  53         struct gpio_desc *desc_array[UART_GPIO_MAX];
  54         int value_array[UART_GPIO_MAX];
  55         unsigned int count = 0;
  56
  57         for (i = 0; i < UART_GPIO_MAX; i++)
  58                 if (gpios->gpio[i] && mctrl_gpios_desc[i].dir_out) {
  59                         desc_array[count] = gpios->gpio[i];
  60                         value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl);
  61                         count++;
  62                 }
  63         gpiod_set_array_value(count, desc_array, value_array);
  64 }
  65 EXPORT_SYMBOL_GPL(mctrl_gpio_set);
  66
  67 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
  68                                       enum mctrl_gpio_idx gidx)
  69 {
  70         return gpios->gpio[gidx];
  71 }
  72 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
  73
  74 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
  75 {
  76         enum mctrl_gpio_idx i;
  77
  78         for (i = 0; i < UART_GPIO_MAX; i++) {
  79                 if (gpios->gpio[i] && !mctrl_gpios_desc[i].dir_out) {
  80                         if (gpiod_get_value(gpios->gpio[i]))
  81                                 *mctrl |= mctrl_gpios_desc[i].mctrl;
  82                         else
  83                                 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
  84                 }
  85         }
  86
  87         return *mctrl;
  88 }
  89 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
  90
  91 struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
  92 {
  93         struct mctrl_gpios *gpios;
  94         enum mctrl_gpio_idx i;
  95
  96         gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
  97         if (!gpios)
  98                 return ERR_PTR(-ENOMEM);
  99
 100         for (i = 0; i < UART_GPIO_MAX; i++) {
 101                 enum gpiod_flags flags;
 102
 103                 if (mctrl_gpios_desc[i].dir_out)
 104                         flags = GPIOD_OUT_LOW;
 105                 else
 106                         flags = GPIOD_IN;
 107
 108                 gpios->gpio[i] =
 109                         devm_gpiod_get_index_optional(dev,
 110                                                       mctrl_gpios_desc[i].name,
 111                                                       idx, flags);
 112
 113                 if (IS_ERR(gpios->gpio[i]))
 114                         return ERR_CAST(gpios->gpio[i]);
 115         }
 116
 117         return gpios;
 118 }
 119 EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
 120
 121 #define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
 122 static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
 123 {
 124         struct mctrl_gpios *gpios = context;
 125         struct uart_port *port = gpios->port;
 126         u32 mctrl = gpios->mctrl_prev;
 127         u32 mctrl_diff;
 128
 129         mctrl_gpio_get(gpios, &mctrl);
 130
 131         mctrl_diff = mctrl ^ gpios->mctrl_prev;
 132         gpios->mctrl_prev = mctrl;
 133
 134         if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {
 135                 if ((mctrl_diff & mctrl) & TIOCM_RI)
 136                         port->icount.rng++;
 137
 138                 if ((mctrl_diff & mctrl) & TIOCM_DSR)
 139                         port->icount.dsr++;
 140
 141                 if (mctrl_diff & TIOCM_CD)
 142                         uart_handle_dcd_change(port, mctrl & TIOCM_CD);
 143
 144                 if (mctrl_diff & TIOCM_CTS)
 145                         uart_handle_cts_change(port, mctrl & TIOCM_CTS);
 146
 147                 wake_up_interruptible(&port->state->port.delta_msr_wait);
 148         }
 149
 150         return IRQ_HANDLED;
 151 }
 152
 153 struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 154 {
 155         struct mctrl_gpios *gpios;
 156         enum mctrl_gpio_idx i;
 157
 158         gpios = mctrl_gpio_init_noauto(port->dev, idx);
 159         if (IS_ERR(gpios))
 160                 return gpios;
 161
 162         gpios->port = port;
 163
 164         for (i = 0; i < UART_GPIO_MAX; ++i) {
 165                 int ret;
 166
 167                 if (!gpios->gpio[i] || mctrl_gpios_desc[i].dir_out)
 168                         continue;
 169
 170                 ret = gpiod_to_irq(gpios->gpio[i]);
 171                 if (ret <= 0) {
 172                         dev_err(port->dev,
 173                                 "failed to find corresponding irq for %s (idx=%d, err=%d)\n",
 174                                 mctrl_gpios_desc[i].name, idx, ret);
 175                         return ERR_PTR(ret);
 176                 }
 177                 gpios->irq[i] = ret;
 178
 179                 /* irqs should only be enabled in .enable_ms */
 180                 irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);
 181
 182                 ret = devm_request_irq(port->dev, gpios->irq[i],
 183                                        mctrl_gpio_irq_handle,
 184                                        IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),
 185                                        gpios);
 186                 if (ret) {
 187                         /* alternatively implement polling */
 188                         dev_err(port->dev,
 189                                 "failed to request irq for %s (idx=%d, err=%d)\n",
 190                                 mctrl_gpios_desc[i].name, idx, ret);
 191                         return ERR_PTR(ret);
 192                 }
 193         }
 194
 195         return gpios;
 196 }
 197 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 198
 199 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 200 {
 201         enum mctrl_gpio_idx i;
 202
 203         for (i = 0; i < UART_GPIO_MAX; i++) {
 204                 if (gpios->irq[i])
 205                         devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);
 206
 207                 if (gpios->gpio[i])
 208                         devm_gpiod_put(dev, gpios->gpio[i]);
 209         }
 210         devm_kfree(dev, gpios);
 211 }
 212 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
 213
 214 void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 215 {
 216         enum mctrl_gpio_idx i;
 217
 218         /* .enable_ms may be called multiple times */
 219         if (gpios->mctrl_on)
 220                 return;
 221
 222         gpios->mctrl_on = true;
 223
 224         /* get initial status of modem lines GPIOs */
 225         mctrl_gpio_get(gpios, &gpios->mctrl_prev);
 226
 227         for (i = 0; i < UART_GPIO_MAX; ++i) {
 228                 if (!gpios->irq[i])
 229                         continue;
 230
 231                 enable_irq(gpios->irq[i]);
 232         }
 233 }
 234 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
 235
 236 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 237 {
 238         enum mctrl_gpio_idx i;
 239
 240         if (!gpios->mctrl_on)
 241                 return;
 242
 243         gpios->mctrl_on = false;
 244
 245         for (i = 0; i < UART_GPIO_MAX; ++i) {
 246                 if (!gpios->irq[i])
 247                         continue;
 248
 249                 disable_irq(gpios->irq[i]);
 250         }
 251 }
 252 EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
 253
 254 MODULE_LICENSE("GPL");