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 };
  47
  48 void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
  49 {
  50         enum mctrl_gpio_idx i;
  51         struct gpio_desc *desc_array[UART_GPIO_MAX];
  52         int value_array[UART_GPIO_MAX];
  53         unsigned int count = 0;
  54
  55         for (i = 0; i < UART_GPIO_MAX; i++)
  56                 if (gpios->gpio[i] && 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_value(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         return gpios->gpio[gidx];
  69 }
  70 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
  71
  72 unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
  73 {
  74         enum mctrl_gpio_idx i;
  75
  76         for (i = 0; i < UART_GPIO_MAX; i++) {
  77                 if (gpios->gpio[i] && !mctrl_gpios_desc[i].dir_out) {
  78                         if (gpiod_get_value(gpios->gpio[i]))
  79                                 *mctrl |= mctrl_gpios_desc[i].mctrl;
  80                         else
  81                                 *mctrl &= ~mctrl_gpios_desc[i].mctrl;
  82                 }
  83         }
  84
  85         return *mctrl;
  86 }
  87 EXPORT_SYMBOL_GPL(mctrl_gpio_get);
  88
  89 struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
  90 {
  91         struct mctrl_gpios *gpios;
  92         enum mctrl_gpio_idx i;
  93
  94         gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
  95         if (!gpios)
  96                 return ERR_PTR(-ENOMEM);
  97
  98         for (i = 0; i < UART_GPIO_MAX; i++) {
  99                 enum gpiod_flags flags;
 100
 101                 if (mctrl_gpios_desc[i].dir_out)
 102                         flags = GPIOD_OUT_LOW;
 103                 else
 104                         flags = GPIOD_IN;
 105
 106                 gpios->gpio[i] =
 107                         devm_gpiod_get_index_optional(dev,
 108                                                       mctrl_gpios_desc[i].name,
 109                                                       idx, flags);
 110
 111                 if (IS_ERR(gpios->gpio[i]))
 112                         return ERR_CAST(gpios->gpio[i]);
 113         }
 114
 115         return gpios;
 116 }
 117 EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
 118
 119 #define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
 120 static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
 121 {
 122         struct mctrl_gpios *gpios = context;
 123         struct uart_port *port = gpios->port;
 124         u32 mctrl = gpios->mctrl_prev;
 125         u32 mctrl_diff;
 126         unsigned long flags;
 127
 128         mctrl_gpio_get(gpios, &mctrl);
 129
 130         spin_lock_irqsave(&port->lock, flags);
 131
 132         mctrl_diff = mctrl ^ gpios->mctrl_prev;
 133         gpios->mctrl_prev = mctrl;
 134
 135         if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {
 136                 if ((mctrl_diff & mctrl) & TIOCM_RI)
 137                         port->icount.rng++;
 138
 139                 if ((mctrl_diff & mctrl) & TIOCM_DSR)
 140                         port->icount.dsr++;
 141
 142                 if (mctrl_diff & TIOCM_CD)
 143                         uart_handle_dcd_change(port, mctrl & TIOCM_CD);
 144
 145                 if (mctrl_diff & TIOCM_CTS)
 146                         uart_handle_cts_change(port, mctrl & TIOCM_CTS);
 147
 148                 wake_up_interruptible(&port->state->port.delta_msr_wait);
 149         }
 150
 151         spin_unlock_irqrestore(&port->lock, flags);
 152
 153         return IRQ_HANDLED;
 154 }
 155
 156 struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
 157 {
 158         struct mctrl_gpios *gpios;
 159         enum mctrl_gpio_idx i;
 160
 161         gpios = mctrl_gpio_init_noauto(port->dev, idx);
 162         if (IS_ERR(gpios))
 163                 return gpios;
 164
 165         gpios->port = port;
 166
 167         for (i = 0; i < UART_GPIO_MAX; ++i) {
 168                 int ret;
 169
 170                 if (!gpios->gpio[i] || mctrl_gpios_desc[i].dir_out)
 171                         continue;
 172
 173                 ret = gpiod_to_irq(gpios->gpio[i]);
 174                 if (ret <= 0) {
 175                         dev_err(port->dev,
 176                                 "failed to find corresponding irq for %s (idx=%d, err=%d)\n",
 177                                 mctrl_gpios_desc[i].name, idx, ret);
 178                         return ERR_PTR(ret);
 179                 }
 180                 gpios->irq[i] = ret;
 181
 182                 /* irqs should only be enabled in .enable_ms */
 183                 irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);
 184
 185                 ret = devm_request_irq(port->dev, gpios->irq[i],
 186                                        mctrl_gpio_irq_handle,
 187                                        IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),
 188                                        gpios);
 189                 if (ret) {
 190                         /* alternatively implement polling */
 191                         dev_err(port->dev,
 192                                 "failed to request irq for %s (idx=%d, err=%d)\n",
 193                                 mctrl_gpios_desc[i].name, idx, ret);
 194                         return ERR_PTR(ret);
 195                 }
 196         }
 197
 198         return gpios;
 199 }
 200 EXPORT_SYMBOL_GPL(mctrl_gpio_init);
 201
 202 void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
 203 {
 204         enum mctrl_gpio_idx i;
 205
 206         for (i = 0; i < UART_GPIO_MAX; i++) {
 207                 if (gpios->irq[i])
 208                         devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);
 209
 210                 if (gpios->gpio[i])
 211                         devm_gpiod_put(dev, gpios->gpio[i]);
 212         }
 213         devm_kfree(dev, gpios);
 214 }
 215 EXPORT_SYMBOL_GPL(mctrl_gpio_free);
 216
 217 void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
 218 {
 219         enum mctrl_gpio_idx i;
 220
 221         /* .enable_ms may be called multiple times */
 222         if (gpios->mctrl_on)
 223                 return;
 224
 225         gpios->mctrl_on = true;
 226
 227         /* get initial status of modem lines GPIOs */
 228         mctrl_gpio_get(gpios, &gpios->mctrl_prev);
 229
 230         for (i = 0; i < UART_GPIO_MAX; ++i) {
 231                 if (!gpios->irq[i])
 232                         continue;
 233
 234                 enable_irq(gpios->irq[i]);
 235         }
 236 }
 237 EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
 238
 239 void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
 240 {
 241         enum mctrl_gpio_idx i;
 242
 243         if (!gpios->mctrl_on)
 244                 return;
 245
 246         gpios->mctrl_on = false;
 247
 248         for (i = 0; i < UART_GPIO_MAX; ++i) {
 249                 if (!gpios->irq[i])
 250                         continue;
 251
 252                 disable_irq(gpios->irq[i]);
 253         }
 254 }
 255 EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
 256
 257 MODULE_LICENSE("GPL");