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incubator-nuttx/drivers/leds/userled_upper.c

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/****************************************************************************
* drivers/leds/userled_upper.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.
*
****************************************************************************/
/* This file provides a driver for a LED input devices.
*
* The LEDs driver exports a standard character driver interface. By
* convention, the LED driver is registered as an input device at
* /dev/btnN where N uniquely identifies the driver instance.
*/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/leds/userled.h>
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure provides the state of one LED driver */
struct userled_upperhalf_s
{
/* Saved binding to the lower half LED driver */
FAR const struct userled_lowerhalf_s *lu_lower;
userled_set_t lu_supported; /* The set of supported LEDs */
userled_set_t lu_ledset; /* Current state of LEDs */
sem_t lu_exclsem; /* Supports exclusive access to the device */
/* The following is a singly linked list of open references to the
* LED device.
*/
FAR struct userled_open_s *lu_open;
};
/* This structure describes the state of one open LED driver instance */
struct userled_open_s
{
/* Supports a singly linked list */
FAR struct userled_open_s *bo_flink;
/* The following will be true if we are closing */
volatile bool bo_closing;
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Semaphore helpers */
static inline int userled_takesem(sem_t *sem);
#define userled_givesem(s) nxsem_post(s);
/* Character driver methods */
static int userled_open(FAR struct file *filep);
static int userled_close(FAR struct file *filep);
static ssize_t userled_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
static int userled_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations userled_fops =
{
userled_open, /* open */
userled_close, /* close */
NULL, /* read */
userled_write, /* write */
NULL, /* seek */
userled_ioctl, /* ioctl */
NULL /* poll */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, NULL /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: userled_takesem
****************************************************************************/
static inline int userled_takesem(sem_t *sem)
{
return nxsem_wait(sem);
}
/****************************************************************************
* Name: userled_open
****************************************************************************/
static int userled_open(FAR struct file *filep)
{
FAR struct inode *inode;
FAR struct userled_upperhalf_s *priv;
FAR struct userled_open_s *opriv;
int ret;
DEBUGASSERT(filep && filep->f_inode);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private);
priv = (FAR struct userled_upperhalf_s *)inode->i_private;
/* Get exclusive access to the driver structure */
ret = userled_takesem(&priv->lu_exclsem);
if (ret < 0)
{
lederr("ERROR: userled_takesem failed: %d\n", ret);
return ret;
}
/* Allocate a new open structure */
opriv = (FAR struct userled_open_s *)
kmm_zalloc(sizeof(struct userled_open_s));
if (!opriv)
{
lederr("ERROR: Failed to allocate open structure\n");
ret = -ENOMEM;
goto errout_with_sem;
}
/* Attach the open structure to the device */
opriv->bo_flink = priv->lu_open;
priv->lu_open = opriv;
/* Attach the open structure to the file structure */
filep->f_priv = (FAR void *)opriv;
ret = OK;
errout_with_sem:
userled_givesem(&priv->lu_exclsem);
return ret;
}
/****************************************************************************
* Name: userled_close
****************************************************************************/
static int userled_close(FAR struct file *filep)
{
FAR struct inode *inode;
FAR struct userled_upperhalf_s *priv;
FAR struct userled_open_s *opriv;
FAR struct userled_open_s *curr;
FAR struct userled_open_s *prev;
irqstate_t flags;
bool closing;
int ret;
DEBUGASSERT(filep && filep->f_priv && filep->f_inode);
opriv = filep->f_priv;
inode = filep->f_inode;
DEBUGASSERT(inode->i_private);
priv = (FAR struct userled_upperhalf_s *)inode->i_private;
/* Handle an improbable race conditions with the following atomic test
* and set.
*
* This is actually a pretty feeble attempt to handle this. The
* improbable race condition occurs if two different threads try to
* close the LED driver at the same time. The rule: don't do
* that! It is feeble because we do not really enforce stale pointer
* detection anyway.
*/
flags = enter_critical_section();
closing = opriv->bo_closing;
opriv->bo_closing = true;
leave_critical_section(flags);
if (closing)
{
/* Another thread is doing the close */
return OK;
}
/* Get exclusive access to the driver structure */
ret = userled_takesem(&priv->lu_exclsem);
if (ret < 0)
{
lederr("ERROR: userled_takesem failed: %d\n", ret);
return ret;
}
/* Find the open structure in the list of open structures for the device */
for (prev = NULL, curr = priv->lu_open;
curr && curr != opriv;
prev = curr, curr = curr->bo_flink);
DEBUGASSERT(curr);
if (!curr)
{
lederr("ERROR: Failed to find open entry\n");
ret = -ENOENT;
goto errout_with_exclsem;
}
/* Remove the structure from the device */
if (prev)
{
prev->bo_flink = opriv->bo_flink;
}
else
{
priv->lu_open = opriv->bo_flink;
}
/* And free the open structure */
kmm_free(opriv);
ret = OK;
errout_with_exclsem:
userled_givesem(&priv->lu_exclsem);
return ret;
}
/****************************************************************************
* Name: userled_write
****************************************************************************/
static ssize_t userled_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
FAR struct inode *inode;
FAR struct userled_upperhalf_s *priv;
FAR const struct userled_lowerhalf_s *lower;
userled_set_t ledset;
int ret;
DEBUGASSERT(filep && filep->f_inode);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private);
priv = (FAR struct userled_upperhalf_s *)inode->i_private;
/* Make sure that the buffer is sufficiently large to hold at least one
* complete sample.
*
* REVISIT: Should also check buffer alignment.
*/
if (len < sizeof(userled_set_t))
{
lederr("ERROR: buffer too small: %lu\n", (unsigned long)len);
return -EINVAL;
}
/* Get the LED set to write.
* REVISIT: if sizeof(userled_set_t) > 1, then we will have to address
* some buffer alignment issues.
*/
DEBUGASSERT(buffer != NULL);
ledset = *(userled_set_t *)buffer;
/* Get exclusive access to the driver structure */
ret = userled_takesem(&priv->lu_exclsem);
if (ret < 0)
{
lederr("ERROR: userled_takesem failed: %d\n", ret);
return ret;
}
/* Read and return the current state of the LEDs */
lower = priv->lu_lower;
DEBUGASSERT(lower && lower->ll_setall);
lower->ll_setall(lower, ledset);
userled_givesem(&priv->lu_exclsem);
return (ssize_t)sizeof(userled_set_t);
}
/****************************************************************************
* Name: userled_ioctl
****************************************************************************/
static int userled_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode;
FAR struct userled_upperhalf_s *priv;
FAR const struct userled_lowerhalf_s *lower;
int ret;
DEBUGASSERT(filep != NULL && filep->f_priv != NULL &&
filep->f_inode != NULL);
inode = filep->f_inode;
DEBUGASSERT(inode->i_private);
priv = (FAR struct userled_upperhalf_s *)inode->i_private;
/* Get exclusive access to the driver structure */
ret = userled_takesem(&priv->lu_exclsem);
if (ret < 0)
{
lederr("ERROR: userled_takesem failed: %d\n", ret);
return ret;
}
/* Handle the ioctl command */
ret = -EINVAL;
switch (cmd)
{
/* Command: ULEDIOC_SUPPORTED
* Description: Report the set of LEDs supported by the hardware;
* Argument: A pointer to writeable userled_set_t value in which to
* return the set of supported LEDs.
* Return: Zero (OK) on success. Minus one will be returned on
* failure with the errno value set appropriately.
*/
case ULEDIOC_SUPPORTED:
{
FAR userled_set_t *supported = (FAR userled_set_t *)((uintptr_t)arg);
/* Verify that a non-NULL pointer was provided */
if (supported)
{
*supported = priv->lu_supported;
ret = OK;
}
}
break;
/* Command: ULEDIOC_SETLED
* Description: Set the state of one LED.
* Argument: A read-only pointer to an instance of struct userled_s
* Return: Zero (OK) on success. Minus one will be returned on
* failure with the errno value set appropriately.
*/
case ULEDIOC_SETLED:
{
FAR struct userled_s *userled = (FAR struct userled_s *)
((uintptr_t)arg);
int led;
bool ledon;
/* Verify that a non-NULL pointer was provided */
if (userled)
{
led = userled->ul_led;
ledon = userled->ul_on;
/* Check that a valid LED is being set */
if ((size_t)led < 8 * sizeof(userled_set_t) &&
(priv->lu_supported & (1 << led)) != 0)
{
/* Update the LED state */
if (ledon)
{
priv->lu_ledset |= (1 << led);
}
else
{
priv->lu_ledset &= ~(1 << led);
}
/* Set the LED state */
lower = priv->lu_lower;
DEBUGASSERT(lower != NULL && lower->ll_setled != NULL);
lower->ll_setled(lower, led, ledon);
ret = OK;
}
}
}
break;
/* Command: ULEDIOC_SETALL
* Description: Set the state of all LEDs.
* Argument: A value of type userled_set_t cast to unsigned long
* Return: Zero (OK) on success. Minus one will be returned on
* failure with the errno value set appropriately.
*/
case ULEDIOC_SETALL:
{
userled_set_t ledset = (userled_set_t)((uintptr_t)arg);
/* Verify that a valid LED set was provided */
if ((ledset & ~priv->lu_supported) == 0)
{
/* Update the LED state */
priv->lu_ledset = ledset;
/* Set the new LED state */
lower = priv->lu_lower;
DEBUGASSERT(lower != NULL && lower->ll_setall != NULL);
lower->ll_setall(lower, ledset);
ret = OK;
}
}
break;
/* Command: ULEDIOC_GETALL
* Description: Get the state of all LEDs.
* Argument: A write-able pointer to a userled_set_t memory location
* in which to return the LED state.
* Return: Zero (OK) on success. Minus one will be returned on
* failure with the errno value set appropriately.
*/
case ULEDIOC_GETALL:
{
FAR userled_set_t *ledset = (FAR userled_set_t *)((uintptr_t)arg);
/* Verify that a non-NULL pointer was provided */
if (ledset)
{
#ifdef CONFIG_USERLED_LOWER_READSTATE
lower = priv->lu_lower;
DEBUGASSERT(lower != NULL && lower->ll_getall != NULL);
lower->ll_getall(lower, ledset);
#else
*ledset = priv->lu_ledset;
#endif
ret = OK;
}
}
break;
default:
lederr("ERROR: Unrecognized command: %d\n", cmd);
ret = -ENOTTY;
break;
}
userled_givesem(&priv->lu_exclsem);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: userled_register
*
* Description:
* Bind the lower half LED driver to an instance of the upper half
* LED driver and register the composite character driver as the
* specified device.
*
* Input Parameters:
* devname - The name of the LED device to be registered.
* This should be a string of the form "/dev/ledN" where N is the
* minor device number.
* lower - An instance of the platform-specific LED lower half driver.
*
* Returned Value:
* Zero (OK) is returned on success. Otherwise a negated errno value is
* returned to indicate the nature of the failure.
*
****************************************************************************/
int userled_register(FAR const char *devname,
FAR const struct userled_lowerhalf_s *lower)
{
FAR struct userled_upperhalf_s *priv;
int ret;
DEBUGASSERT(devname && lower);
/* Allocate a new LED driver instance */
priv = (FAR struct userled_upperhalf_s *)
kmm_zalloc(sizeof(struct userled_upperhalf_s));
if (!priv)
{
lederr("ERROR: Failed to allocate device structure\n");
return -ENOMEM;
}
/* Initialize the new LED driver instance */
priv->lu_lower = lower;
nxsem_init(&priv->lu_exclsem, 0, 1);
DEBUGASSERT(lower && lower->ll_supported);
priv->lu_supported = lower->ll_supported(lower);
DEBUGASSERT(lower && lower->ll_setall);
priv->lu_ledset = 0;
lower->ll_setall(lower, priv->lu_ledset);
/* And register the LED driver */
ret = register_driver(devname, &userled_fops, 0666, priv);
if (ret < 0)
{
lederr("ERROR: register_driver failed: %d\n", ret);
goto errout_with_priv;
}
return OK;
errout_with_priv:
nxsem_destroy(&priv->lu_exclsem);
kmm_free(priv);
return ret;
}
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