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incubator-nuttx/drivers/spi/spi_bitbang.c

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/****************************************************************************
* drivers/spi/spi_bitbang.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 <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/spi/spi.h>
#include <nuttx/spi/spi_bitbang.h>
#include <nuttx/mutex.h>
#ifdef CONFIG_SPI_BITBANG
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* This file holds the static, device-independent portion of the generic
* SPI-bit-bang driver. The full driver consists of 5 files:
*
* 1. drivers/spi/spi_bitbang.c: This file. This file holds the basic
* SPI driver framework and not perform any direct bit-bang operations.
* Rather, it will could out to board-specific logic to perform the
* low level data transfers.
* 2. include/nuttx/spi/spi_bitbang.h: This header file provides the
* data types and function prototypes needed to utilize the logic in
* this file.
* 3. boards/<arch>/<chip>/<board>/src/<file>: The implementation of the
* low-level bit-bang logic resides in some file in the board source
* directory. This board-specific logic includes the bit-bang skeleton
* logic provided in include/nuttx/spi/spi_bitbang.c.
* 4. include/nuttx/spi/spi_bitbang.c. Despite the .c extension, this is
* really an included file. It is used in this way: 1) The board-
* specific logic in boards/<arch>/<chip>/<board>/src/<file> provides
* some definitions then 2) includes include/nuttx/spi/spi_bitbang.c.
* That file will then use those definitions to implement the low-level
* bit-bang logic. The board-specific logic then calls
* spi_create_bitbang() in this file to instantiate the complete SPI
* driver.
*
* See include/nuttx/spi/spi_bitbang.c for more detailed usage
* information.
*/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* SPI methods */
static int spi_lock(FAR struct spi_dev_s *dev, bool lock);
static void spi_select(FAR struct spi_dev_s *dev, uint32_t devid,
bool selected);
static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev,
uint32_t frequency);
static void spi_setmode(FAR struct spi_dev_s *dev,
enum spi_mode_e mode);
static void spi_setbits(FAR struct spi_dev_s *dev, int nbits);
static uint32_t spi_send(FAR struct spi_dev_s *dev, uint32_t wd);
static void spi_exchange(FAR struct spi_dev_s *dev,
FAR const void *txbuffer, FAR void *rxbuffer,
size_t nwords);
#ifndef CONFIG_SPI_EXCHANGE
static void spi_sndblock(FAR struct spi_dev_s *dev,
FAR const void *buffer, size_t nwords);
static void spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer,
size_t nwords);
#endif
static uint8_t spi_status(FAR struct spi_dev_s *dev, uint32_t devid);
#ifdef CONFIG_SPI_CMDDATA
static int spi_cmddata(FAR struct spi_dev_s *dev, uint32_t devid,
bool cmd);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
/* SPI driver operations */
static const struct spi_ops_s g_spiops =
{
spi_lock, /* lock */
spi_select, /* select */
spi_setfrequency, /* setfrequency */
spi_setmode, /* setmode */
spi_setbits, /* setbits */
#ifdef CONFIG_SPI_HWFEATURES
0, /* hwfeatures */
#endif
spi_status, /* status */
#ifdef CONFIG_SPI_CMDDATA
spi_cmddata, /* cmddata */
#endif
spi_send, /* send */
#ifdef CONFIG_SPI_EXCHANGE
spi_exchange, /* exchange */
#else
spi_sndblock, /* sndblock */
spi_recvblock, /* recvblock */
#endif
0 /* registercallback */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: spi_lock
*
* Description:
* On SPI buses where there are multiple devices, it will be necessary to
* lock SPI to have exclusive access to the buses for a sequence of
* transfers. The bus should be locked before the chip is selected. After
* locking the SPI bus, the caller should then also call the setfrequency,
* setbits, and setmode methods to make sure that the SPI is properly
* configured for the device. If the SPI bus is being shared, then it
* may have been left in an incompatible state.
*
* Input Parameters:
* dev - Device-specific state data
* lock - true: Lock spi bus, false: unlock SPI bus
*
* Returned Value:
* None
*
****************************************************************************/
static int spi_lock(FAR struct spi_dev_s *dev, bool lock)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
int ret;
spiinfo("lock=%d\n", lock);
if (lock)
{
ret = nxmutex_lock(&priv->lock);
}
else
{
ret = nxmutex_unlock(&priv->lock);
}
return ret;
}
/****************************************************************************
* Name: spi_select
*
* Description:
* Set/clear the chip select line for the selected device.
*
* Input Parameters:
* dev - Device-specific state data
* devid - Identifies the device to be selected
* selected - select or de-select device
*
* Returned Value:
* None
*
****************************************************************************/
static void spi_select(FAR struct spi_dev_s *dev, uint32_t devid,
bool selected)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
spiinfo("devid=%d selected=%d\n", devid, selected);
DEBUGASSERT(priv && priv->low->select);
priv->low->select(priv, devid, selected);
}
/****************************************************************************
* Name: spi_setfrequency
*
* Description:
* Set the SPI frequency.
*
* Input Parameters:
* dev - Device-specific state data
* frequency - The SPI frequency requested
*
* Returned Value:
* Returns the actual frequency selected
*
****************************************************************************/
static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev,
uint32_t frequency)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
uint32_t actual;
DEBUGASSERT(priv && priv->low->setfrequency);
actual = priv->low->setfrequency(priv, frequency);
spiinfo("frequency=%d holdtime=%d actual=%d\n",
frequency, priv->holdtime, actual);
return actual;
}
/****************************************************************************
* Name: spi_setmode
*
* Description:
* Set the SPI mode. Optional. See enum spi_mode_e for mode definitions
*
* Input Parameters:
* dev - Device-specific state data
* mode - The SPI mode requested
*
* Returned Value:
* none
*
****************************************************************************/
static void spi_setmode(FAR struct spi_dev_s *dev, enum spi_mode_e mode)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
DEBUGASSERT(priv && priv->low->setmode);
priv->low->setmode(priv, mode);
spiinfo("mode=%d exchange=%p\n", mode, priv->exchange);
}
/****************************************************************************
* Name: spi_setbits
*
* Description:
* Set the number if bits per word.
*
* Input Parameters:
* dev - Device-specific state data
* nbits - The number of bits requests
*
* Returned Value:
* none
*
****************************************************************************/
static void spi_setbits(FAR struct spi_dev_s *dev, int nbits)
{
#ifdef CONFIG_SPI_BITBANG_VARWIDTH
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
spiinfo("nbits=%d\n", nbits);
DEBUGASSERT(priv && nbits > 0 && nbits <= 16);
priv->nbits = nbits;
#else
spiinfo("nbits=%d\n", nbits);
DEBUGASSERT(nbits == 8);
#endif
}
/****************************************************************************
* Name: spi_send
*
* Description:
* Exchange one word on SPI
*
* Input Parameters:
* dev - Device-specific state data
* wd - The word to send. the size of the data is determined by the
* number of bits selected for the SPI interface.
*
* Returned Value:
* response
*
****************************************************************************/
static uint32_t spi_send(FAR struct spi_dev_s *dev, uint32_t wd)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
DEBUGASSERT(priv && priv->low && priv->low->exchange);
return priv->low->exchange(priv, (uint16_t)wd);
}
/****************************************************************************
* Name: spi_exchange
*
* Description:
* Exahange a block of data from SPI. Required.
*
* Input Parameters:
* dev - Device-specific state data
* txbuffer - A pointer to the buffer of data to be sent
* rxbuffer - A pointer to the buffer in which to receive data
* nwords - the length of data that to be exchanged in units of words.
* The wordsize is determined by the number of bits-per-word
* selected for the SPI interface. If nbits <= 8, the data is
* packed into uint8_t's; if nbits >8, the data is packed into
* uint16_t's
*
* Returned Value:
* None
*
****************************************************************************/
static void spi_exchange(FAR struct spi_dev_s *dev,
FAR const void *txbuffer, FAR void *rxbuffer,
size_t nwords)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
FAR const uint8_t *src = (FAR const uint8_t *)txbuffer;
FAR uint8_t *dest = (FAR uint8_t *)rxbuffer;
uint16_t dataout;
uint16_t datain;
spiinfo("txbuffer=%p rxbuffer=%p nwords=%d\n", txbuffer, rxbuffer, nwords);
DEBUGASSERT(priv && priv->low && priv->low->exchange);
/* If there is no data source, send 0xff */
if (!src)
{
dataout = 0xff;
}
/* Exchange each word */
while (nwords-- > 0)
{
/* If there is source data, get the next word from the source */
if (src)
{
dataout = (uint16_t)*src++;
#ifdef CONFIG_SPI_BITBANG_VARWIDTH
if (priv->nbits > 8)
{
#ifdef CONFIG_ENDIAN_BIG
dataout <<= 8;
dataout |= *src++;
#else
dataout |= (uint16_t)(*src++) << 8;
#endif
}
#endif
}
/* Exchange the word of data */
datain = priv->low->exchange(priv, dataout);
/* If there is a data sink, transfer the data to the receive buffer */
if (dest)
{
#ifdef CONFIG_SPI_BITBANG_VARWIDTH
if (priv->nbits > 8)
{
#ifdef CONFIG_ENDIAN_BIG
*dest++ = (uint8_t)(datain >> 8);
*dest++ = (uint8_t)datain;
#else
*dest++ = (uint8_t)datain;
*dest++ = (uint8_t)(datain >> 8);
#endif
}
#else
*dest++ = (uint8_t)datain;
#endif
}
}
}
/****************************************************************************
* Name: spi_sndblock
*
* Description:
* Send a block of data on SPI
*
* Input Parameters:
* dev - Device-specific state data
* buffer - A pointer to the buffer of data to be sent
* nwords - the length of data to send from the buffer in number of words.
* The wordsize is determined by the number of bits-per-word
* selected for the SPI interface. If nbits <= 8, the data is
* packed into uint8_t's; if nbits >8, the data is packed into
* uint16_t's
*
* Returned Value:
* None
*
****************************************************************************/
#ifndef CONFIG_SPI_EXCHANGE
static void spi_sndblock(FAR struct spi_dev_s *dev, FAR const void *buffer,
size_t nwords)
{
/* spi_exchange can do this. */
spi_exchange(dev, buffer, NULL, nwords);
}
#endif
/****************************************************************************
* Name: spi_recvblock
*
* Description:
* Revice a block of data from SPI
*
* Input Parameters:
* dev - Device-specific state data
* buffer - A pointer to the buffer in which to receive data
* nwords - the length of data that can be received in the buffer in number
* of words. The wordsize is determined by the number of
* bits-per-word selected for the SPI interface. If nbits <= 8,
* the data is packed into uint8_t's; if nbits >8, the data is
* packed into uint16_t's
*
* Returned Value:
* None
*
****************************************************************************/
#ifndef CONFIG_SPI_EXCHANGE
static void spi_recvblock(FAR struct spi_dev_s *dev, FAR void *buffer,
size_t nwords)
{
/* spi_exchange can do this. */
spi_exchange(dev, NULL, buffer, nwords);
}
#endif
/****************************************************************************
* Name: spi_status
*
* Description:
* Get status bits associated with the device associated with 'devid'
*
* Input Parameters:
* dev - Device-specific state data
* devid - Identifies the device of interest
*
* Returned Value:
* Bit encoded status byte
*
****************************************************************************/
static uint8_t spi_status(FAR struct spi_dev_s *dev, uint32_t devid)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
DEBUGASSERT(priv && priv->low && priv->low->status);
return priv->low->status(priv, devid);
}
/****************************************************************************
* Name: spi_cmddata
*
* Description:
* Control the SPI CMD/DATA like for the device associated with 'devid'
*
* Input Parameters:
* dev - Device-specific state data
* devid - Identifies the device of interest
* cmd - True:CMD False:DATA
*
* Returned Value:
* OK on success; a negated errno value on failure
*
****************************************************************************/
#ifdef CONFIG_SPI_CMDDATA
static int spi_cmddata(FAR struct spi_dev_s *dev, uint32_t devid,
bool cmd)
{
FAR struct spi_bitbang_s *priv = (FAR struct spi_bitbang_s *)dev;
DEBUGASSERT(priv && priv->low && priv->low->status);
return priv->low->cmddata(priv, devid, cmd);
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: spi_create_bitbang
*
* Description:
* Create an instance of the SPI bit-bang driver.
*
****************************************************************************/
FAR struct spi_dev_s *spi_create_bitbang(FAR const struct
spi_bitbang_ops_s *low)
{
FAR struct spi_bitbang_s *priv;
DEBUGASSERT(low);
/* Allocate an instance of the SPI bit bang structure */
priv = (FAR struct spi_bitbang_s *)
kmm_zalloc(sizeof(struct spi_bitbang_s));
if (!priv)
{
spierr("ERROR: Failed to allocate the device structure\n");
return NULL;
}
/* Initialize the driver structure */
priv->dev.ops = &g_spiops;
priv->low = low;
#ifdef CONFIG_SPI_BITBANG_VARWIDTH
priv->nbits = 8;
#endif
nxmutex_init(&priv->lock);
/* Select an initial state of mode 0, 8-bits, and 400KHz */
low->setmode(priv, SPIDEV_MODE0);
low->setfrequency(priv, 400000);
/* And return the initialized driver structure */
return &priv->dev;
}
#endif /* CONFIG_SPI_BITBANG */
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