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drivers/ioexpander/gpio.c: support reading and writing gpio pins using cat and echo.

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This commit is contained in:
Valmantas Paliksa 2019-03-21 08:43:48 -06:00 committed by Gregory Nutt
parent f88597203d
commit 90ee863abe
1 changed files with 139 additions and 8 deletions
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145
drivers/ioexpander/gpio.c
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@ -1,7 +1,7 @@
/****************************************************************************
* drivers/ioexpander/gpio.c
*
* Copyright (C) 2016, 2018 Gregory Nutt. All rights reserved.
* Copyright (C) 2016, 2018-2019 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -45,6 +45,7 @@
#include <signal.h>
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#include <nuttx/fs/fs.h>
#include <nuttx/ioexpander/gpio.h>
@ -62,6 +63,7 @@ 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);
@ -75,7 +77,7 @@ static const struct file_operations g_gpio_drvrops =
gpio_close, /* close */
gpio_read, /* read */
gpio_write, /* write */
NULL, /* seek */
gpio_seek, /* seek */
gpio_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, NULL /* poll */
@ -129,6 +131,7 @@ static int gpio_handler(FAR struct gpio_dev_s *dev, uint8_t pin)
static int gpio_open(FAR struct file *filep)
{
filep->f_pos = 0;
return OK;
}
@ -156,7 +159,47 @@ static int gpio_close(FAR struct file *filep)
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 uint8_t *)&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;
}
/****************************************************************************
@ -165,12 +208,99 @@ static ssize_t gpio_read(FAR struct file *filep, FAR char *buffer,
* 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)
{
return (ssize_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)
{
return -EACCES;
}
/* Verfy 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;
}
/* 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;
}
/****************************************************************************
@ -189,7 +319,7 @@ static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
pid_t pid;
int ret;
int i;
int j;
int j = 0;
DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
inode = filep->f_inode;
@ -238,7 +368,8 @@ static int gpio_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
case GPIOC_PINTYPE:
{
FAR enum gpio_pintype_e *ptr = (FAR enum gpio_pintype_e *)((uintptr_t)arg);
FAR enum gpio_pintype_e *ptr =
(FAR enum gpio_pintype_e *)((uintptr_t)arg);
DEBUGASSERT(ptr != NULL);
*ptr = dev->gp_pintype;
@ -405,7 +536,8 @@ int gpio_pin_register(FAR struct gpio_dev_s *dev, int minor)
char devname[16];
int ret;
DEBUGASSERT(dev != NULL && dev->gp_ops != NULL && (unsigned int)minor < 100);
DEBUGASSERT(dev != NULL && dev->gp_ops != NULL &&
(unsigned int)minor < 100);
switch (dev->gp_pintype)
{
@ -421,7 +553,6 @@ int gpio_pin_register(FAR struct gpio_dev_s *dev, int minor)
DEBUGASSERT(dev->gp_ops->go_read != NULL &&
dev->gp_ops->go_write != NULL);
fmt = "/dev/gpout%u";
}
break;