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nuttx/drivers/ioexpander/gpio.c

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/****************************************************************************
* drivers/ioexpander/gpio.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <assert.h>
#include <debug.h>
#include <errno.h>
#include <unistd.h>
#include <nuttx/fs/fs.h>
#include <nuttx/spinlock.h>
#include <nuttx/ioexpander/gpio.h>
#ifdef CONFIG_DEV_GPIO
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int gpio_handler(FAR struct gpio_dev_s *dev, uint8_t pin);
static int gpio_open(FAR struct file *filep);
static int gpio_close(FAR struct file *filep);
static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t gpio_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static off_t gpio_seek(FAR struct file *filep, off_t offset, int whence);
static int gpio_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_gpio_drvrops =
{
gpio_open, /* open */
gpio_close, /* close */
gpio_read, /* read */
gpio_write, /* write */
gpio_seek, /* seek */
gpio_ioctl, /* ioctl */
NULL /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: gpio_handler
*
* Description:
* GPIO interrupt callback function.
*
****************************************************************************/
static int gpio_handler(FAR struct gpio_dev_s *dev, uint8_t pin)
{
int i;
DEBUGASSERT(dev != NULL);
for (i = 0; i < CONFIG_DEV_GPIO_NSIGNALS; i++)
{
FAR struct gpio_signal_s *signal = &dev->gp_signals[i];
if (signal->gp_pid == 0)
{
break;
}
nxsig_notification(signal->gp_pid, &signal->gp_event,
SI_QUEUE, &signal->gp_work);
}
return OK;
}
/****************************************************************************
* Name: gpio_open
*
* Description:
* Standard character driver open method.
*
****************************************************************************/
static int gpio_open(FAR struct file *filep)
{
filep->f_pos = 0;
return OK;
}
/****************************************************************************
* Name: gpio_close
*
* Description:
* Standard character driver close method.
*
****************************************************************************/
static int gpio_close(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: gpio_read
*
* Description:
* Standard character driver read method.
*
****************************************************************************/
static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct inode *inode;
FAR struct gpio_dev_s *dev;
int ret;
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private != NULL);
dev = inode->i_private;
DEBUGASSERT(buffer != NULL);
if (buflen == 0)
{
return 0; /* Zero will be interpreted as the End-of-File. */
}
/* Check for End-of-File.
*
* REVISIT: Returning End-of-File after one byte has been written permits
* you to cat or echo the GPIO. This, however, is an un-natural use of a
* file position since there is no file position associated with a GPIO.
* It also makes the read() method difficult to use programmatically.
*/
if (filep->f_pos > 0)
{
return 0;
}
/* Read the GPIO value */
ret = dev->gp_ops->go_read(dev, (FAR bool *)&buffer[0]);
if (ret < 0)
{
return ret;
}
/* Convert the GPIO value to ASCII and increment the file position */
buffer[0] += '0';
filep->f_pos = 1;
return 1;
}
/****************************************************************************
* Name: gpio_write
*
* Description:
* Standard character driver write method.
*
* REVISIT: The read() method obeys the semantics of a file position and
* requires re-opening the driver or seeking to address 0. The write()
* method does not. This is an inconsistency.
*
****************************************************************************/
static ssize_t gpio_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
FAR struct inode *inode;
FAR struct gpio_dev_s *dev;
int ret;
bool val;
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private != NULL);
dev = inode->i_private;
DEBUGASSERT(buffer != NULL);
/* Check if this pin is write-able */
if (dev->gp_pintype != GPIO_OUTPUT_PIN &&
dev->gp_pintype != GPIO_OUTPUT_PIN_OPENDRAIN)
{
return -EACCES;
}
/* Verify that a buffer containing data was provided */
DEBUGASSERT(buffer != NULL);
if (buflen != 0)
{
/* Only values '0' and '1' can be written */
if (buffer[0] == '0')
{
val = 0;
}
else if (buffer[0] == '1')
{
val = 1;
}
else
{
return -EINVAL;
}
/* Write the GPIO value */
ret = dev->gp_ops->go_write(dev, val);
if (ret < 0)
{
return ret;
}
/* One byte written */
return 1;
}
return 0;
}
/****************************************************************************
* Name: gpio_seek
*
* Description:
* Reset read flag on seek to 0
*
* REVISIT: Seeking address zero is required to return addition GPIO
* values from read(). This, however, is an un-natural use of a file
* position since there is no file position associated with a GPIO. It
* also makes the read() method difficult to use programmatically.
*
****************************************************************************/
static off_t gpio_seek(FAR struct file *filep, off_t offset, int whence)
{
/* Only SEEK_SET is supported, return ENOSYS for other valid options */
if (whence == SEEK_CUR || whence == SEEK_END)
{
return -ENOSYS;
}
/* Only Offset zero makes sense, POSIX permits setting the file position
* beyond the end of the file, but that makes little sense here.
*/
if (whence == SEEK_SET && offset == 0)
{
filep->f_pos = 0;
return 0;
}
return -EINVAL;
}
/****************************************************************************
* Name: gpio_ioctl
*
* Description:
* Standard character driver ioctl method.
*
****************************************************************************/
static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode;
FAR struct gpio_dev_s *dev;
irqstate_t flags;
pid_t pid;
int ret;
int i;
int j = 0;
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private != NULL);
dev = inode->i_private;
DEBUGASSERT(dev->gp_ops != NULL);
switch (cmd)
{
/* Command: GPIOC_WRITE
* Description: Set the value of an output GPIO
* Argument: 0=output a low value; 1=output a high value
*/
case GPIOC_WRITE:
if (dev->gp_pintype == GPIO_OUTPUT_PIN ||
dev->gp_pintype == GPIO_OUTPUT_PIN_OPENDRAIN)
{
DEBUGASSERT(arg == 0ul || arg == 1ul);
DEBUGASSERT(dev->gp_ops->go_write != NULL);
ret = dev->gp_ops->go_write(dev, (bool)arg);
}
else
{
ret = -EACCES;
}
break;
/* Command: GPIOC_READ
* Description: Read the value of an input or output GPIO
* Argument: A pointer to an bool value to receive the result:
* false=low value; true=high value.
*/
case GPIOC_READ:
{
FAR bool *ptr = (FAR bool *)((uintptr_t)arg);
DEBUGASSERT(ptr != NULL);
DEBUGASSERT(dev->gp_ops->go_read != NULL);
ret = dev->gp_ops->go_read(dev, ptr);
DEBUGASSERT(ret < 0 || *ptr == 0 || *ptr == 1);
}
break;
/* Command: GPIOC_PINTYPE
* Description: Return the GPIO pin type.
* Argument: A pointer to an instance of type enum gpio_pintype_e
*/
case GPIOC_PINTYPE:
{
FAR enum gpio_pintype_e *ptr =
(FAR enum gpio_pintype_e *)((uintptr_t)arg);
DEBUGASSERT(ptr != NULL);
*ptr = dev->gp_pintype;
ret = OK;
}
break;
/* Command: GPIOC_REGISTER
* Description: Register to receive a signal whenever there an
* interrupt is received on an input gpio pin. This
* feature, of course, depends upon interrupt GPIO
* support from the platform.
* Argument: The number of signal to be generated when the
* interrupt occurs.
*/
case GPIOC_REGISTER:
if (arg && dev->gp_pintype >= GPIO_INTERRUPT_PIN)
{
pid = getpid();
flags = spin_lock_irqsave(NULL);
for (i = 0; i < CONFIG_DEV_GPIO_NSIGNALS; i++)
{
FAR struct gpio_signal_s *signal = &dev->gp_signals[i];
if (signal->gp_pid == 0 || signal->gp_pid == pid)
{
memcpy(&signal->gp_event, (FAR void *)arg,
sizeof(signal->gp_event));
signal->gp_pid = pid;
ret = OK;
break;
}
}
spin_unlock_irqrestore(NULL, flags);
if (i == 0)
{
/* Register our handler */
DEBUGASSERT(dev->gp_ops->go_attach != NULL);
ret = dev->gp_ops->go_attach(dev,
(pin_interrupt_t)gpio_handler);
if (ret >= 0)
{
/* Enable pin interrupts */
DEBUGASSERT(dev->gp_ops->go_enable != NULL);
ret = dev->gp_ops->go_enable(dev, true);
}
}
else if (i == CONFIG_DEV_GPIO_NSIGNALS)
{
ret = -EBUSY;
}
}
else
{
ret = -EACCES;
}
break;
/* Command: GPIOC_UNREGISTER
* Description: Stop receiving signals for pin interrupts.
* Argument: None.
*/
case GPIOC_UNREGISTER:
if (dev->gp_pintype >= GPIO_INTERRUPT_PIN)
{
pid = getpid();
flags = spin_lock_irqsave(NULL);
for (i = 0; i < CONFIG_DEV_GPIO_NSIGNALS; i++)
{
if (pid == dev->gp_signals[i].gp_pid)
{
for (j = i + 1; j < CONFIG_DEV_GPIO_NSIGNALS; j++)
{
if (dev->gp_signals[j].gp_pid == 0)
{
break;
}
}
if (i != --j)
{
memcpy(&dev->gp_signals[i], &dev->gp_signals[j],
sizeof(dev->gp_signals[i]));
}
dev->gp_signals[j].gp_pid = 0;
nxsig_cancel_notification(&dev->gp_signals[j].gp_work);
ret = OK;
break;
}
}
spin_unlock_irqrestore(NULL, flags);
if (i == 0 && j == 0)
{
/* Make sure that the pin interrupt is disabled */
DEBUGASSERT(dev->gp_ops->go_enable != NULL);
ret = dev->gp_ops->go_enable(dev, false);
if (ret >= 0)
{
/* Detach the handler */
DEBUGASSERT(dev->gp_ops->go_attach != NULL);
ret = dev->gp_ops->go_attach(dev, NULL);
}
}
else if (i == CONFIG_DEV_GPIO_NSIGNALS)
{
ret = -EINVAL;
}
}
else
{
ret = -EACCES;
}
break;
/* Command: GPIOC_SETPINTYPE
* Description: Set the GPIO pin type.
* Argument: The enum gpio_pintype_e type.
*/
case GPIOC_SETPINTYPE:
{
enum gpio_pintype_e pintype = (enum gpio_pintype_e)arg;
/* Check if the argument is a valid pintype */
if (pintype < GPIO_INPUT_PIN || pintype >= GPIO_NPINTYPES)
{
ret = -EINVAL;
break;
}
/* Check if the pintype actually needs to be changed */
if (dev->gp_pintype == pintype)
{
/* Pintype remains the same, no need to change anything */
ret = OK;
break;
}
/* Disable interrupt if pin had an interrupt pintype previously */
if (dev->gp_pintype >= GPIO_INTERRUPT_PIN)
{
DEBUGASSERT(dev->gp_ops->go_enable != NULL);
ret = dev->gp_ops->go_enable(dev, false);
if (ret < 0)
{
break;
}
}
/* Change pintype */
DEBUGASSERT(dev->gp_ops->go_setpintype != NULL);
ret = dev->gp_ops->go_setpintype(dev, pintype);
if (ret < 0)
{
break;
}
/* Additional DEBUGASSERTs to make sure the right operations are
* available after the pintype has been changed.
*/
DEBUGASSERT(dev->gp_pintype == pintype);
DEBUGASSERT(dev->gp_ops != NULL);
DEBUGASSERT(dev->gp_ops->go_read != NULL);
DEBUGASSERT(dev->gp_ops->go_setpintype != NULL);
if (pintype >= GPIO_OUTPUT_PIN && pintype < GPIO_INTERRUPT_PIN)
{
DEBUGASSERT(dev->gp_ops->go_write != NULL);
}
else if (pintype >= GPIO_INTERRUPT_PIN)
{
DEBUGASSERT(dev->gp_ops->go_attach != NULL);
DEBUGASSERT(dev->gp_ops->go_enable != NULL);
}
}
break;
/* Unrecognized command */
default:
ret = -ENOTTY;
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: gpio_pin_register
*
* Description:
* Register GPIO pin device driver at /dev/gpioN, where N is the provided
* minor number.
*
****************************************************************************/
int gpio_pin_register(FAR struct gpio_dev_s *dev, int minor)
{
char devname[32];
int ret;
DEBUGASSERT(dev != NULL && dev->gp_ops != NULL);
switch (dev->gp_pintype)
{
case GPIO_INPUT_PIN:
case GPIO_INPUT_PIN_PULLUP:
case GPIO_INPUT_PIN_PULLDOWN:
{
DEBUGASSERT(dev->gp_ops->go_read != NULL);
}
break;
case GPIO_OUTPUT_PIN:
case GPIO_OUTPUT_PIN_OPENDRAIN:
{
DEBUGASSERT(dev->gp_ops->go_read != NULL &&
dev->gp_ops->go_write != NULL);
}
break;
default:
{
DEBUGASSERT(dev->gp_ops->go_read != NULL &&
dev->gp_ops->go_attach != NULL &&
dev->gp_ops->go_enable != NULL);
/* Make sure that the pin interrupt is disabled */
ret = dev->gp_ops->go_enable(dev, false);
if (ret < 0)
{
return ret;
}
}
break;
}
snprintf(devname, sizeof(devname), "/dev/gpio%u", (unsigned int)minor);
gpioinfo("Registering %s\n", devname);
return register_driver(devname, &g_gpio_drvrops, 0666, dev);
}
/****************************************************************************
* Name: gpio_pin_unregister
*
* Description:
* Unregister GPIO pin device driver at /dev/gpioN, where N is the provided
* minor number.
*
****************************************************************************/
int gpio_pin_unregister(FAR struct gpio_dev_s *dev, int minor)
{
char devname[32];
snprintf(devname, sizeof(devname), "/dev/gpio%u", (unsigned int)minor);
gpioinfo("Unregistering %s\n", devname);
return unregister_driver(devname);
}
#endif /* CONFIG_DEV_GPIO */
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