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Make better use of these deep FIFOs

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2958 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2010-10-01 03:28:41 +00:00
parent 11440645f9
commit 63d189c52a
1 changed files with 71 additions and 40 deletions
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111
arch/arm/src/lpc313x/lpc313x_spi.c
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@ -72,6 +72,10 @@
# undef CONFIG_DEBUG_SPIREGS
#endif
/* FIFOs ****************************************************************************/
#define SPI_FIFO_DEPTH 64 /* 64 words deep (8- or 16-bit words) */
/* Timing ***************************************************************************/
#define SPI_MAX_DIVIDER 65024 /* = 254 * (255 + 1) */
@ -118,7 +122,7 @@ static uint32_t spi_setfrequency(FAR struct spi_dev_s *dev, uint32_t frequenc
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 uint8_t spi_status(FAR struct spi_dev_s *dev, enum spi_dev_e devid);
static uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t wd);
static uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t word);
static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
FAR void *rxbuffer, size_t nwords);
#ifndef CONFIG_SPI_EXCHANGE
@ -376,16 +380,13 @@ static inline void spi_select_slave(FAR struct lpc313x_spidev_s *priv, uint8_t s
static inline uint16_t spi_readword(FAR struct lpc313x_spidev_s *priv)
{
/* Wait until the receive buffer is not empty */
/* Wait until the RX FIFO is not empty */
while ((spi_getreg(LPC313X_SPI_STATUS) & SPI_STATUS_RXFIFOEMPTY) != 0)
;
while ((spi_getreg(LPC313X_SPI_STATUS) & SPI_STATUS_RXFIFOEMPTY) != 0);
/* Then return the received word */
uint32_t val = spi_getreg(LPC313X_SPI_FIFODATA);
return val;
return (uint16_t)spi_getreg(LPC313X_SPI_FIFODATA);
}
/************************************************************************************
@ -405,10 +406,9 @@ static inline uint16_t spi_readword(FAR struct lpc313x_spidev_s *priv)
static inline void spi_writeword(FAR struct lpc313x_spidev_s *priv, uint16_t word)
{
/* Wait until the transmit buffer is not full */
/* Wait until the TX FIFO is not full */
while ((spi_getreg(LPC313X_SPI_STATUS) & SPI_STATUS_TXFIFOFULL) != 0)
;
while ((spi_getreg(LPC313X_SPI_STATUS) & SPI_STATUS_TXFIFOFULL) != 0);
/* Then send the word */
@ -701,21 +701,21 @@ static uint8_t spi_status(FAR struct spi_dev_s *dev, enum spi_dev_e devid)
* 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.
* dev - Device-specific state data
* word - 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 uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t wd)
static uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t word)
{
FAR struct lpc313x_spidev_s *priv = (FAR struct lpc313x_spidev_s *)dev;
DEBUGASSERT(priv);
spi_writeword(priv, wd);
spi_writeword(priv, word);
return spi_readword(priv);
}
@ -743,6 +743,9 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
FAR void *rxbuffer, size_t nwords)
{
FAR struct lpc313x_spidev_s *priv = (FAR struct lpc313x_spidev_s *)dev;
unsigned int maxtx;
unsigned int ntx;
DEBUGASSERT(priv);
/* 8- or 16-bit mode? */
@ -755,21 +758,35 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
uint16_t *dest = (uint16_t*)rxbuffer;
uint16_t word;
while (nwords-- > 0)
while (nwords > 0)
{
/* Get the next word to write. Is there a source buffer? */
/* Fill up the TX FIFO */
word = src ? *src++ : 0xffff;
/* Exchange one word */
word = spi_send(dev, word);
/* Is there a buffer to receive the return value? */
if (dest)
maxtx = nwords > SPI_FIFO_DEPTH ? SPI_FIFO_DEPTH : nwords;
for (ntx = 0; ntx < maxtx; ntx++)
{
*dest++ = word;
/* Get the next word to write. Is there a source buffer? */
word = src ? *src++ : 0xffff;
/* Then send the word */
spi_writeword(priv, word);
}
nwords -= maxtx;
/* Then empty the RX FIFO */
while (ntx-- > 0)
{
word = spi_readword(priv);
/* Is there a buffer to receive the return value? */
if (dest)
{
*dest++ = word;
}
}
}
}
@ -781,22 +798,36 @@ static void spi_exchange(FAR struct spi_dev_s *dev, FAR const void *txbuffer,
uint8_t *dest = (uint8_t*)rxbuffer;
uint8_t word;
while (nwords-- > 0)
while (nwords > 0)
{
/* Get the next word to write. Is there a source buffer? */
/* Fill up the TX FIFO */
word = src ? *src++ : 0xff;
/* Exchange one word */
word = (uint8_t)spi_send(dev, (uint16_t)word);
/* Is there a buffer to receive the return value? */
if (dest)
maxtx = nwords > SPI_FIFO_DEPTH ? SPI_FIFO_DEPTH : nwords;
for (ntx = 0; ntx < maxtx; ntx++)
{
*dest++ = word;
}
/* Get the next word to write. Is there a source buffer? */
word = src ? *src++ : 0xff;
/* Then send the word */
spi_writeword(priv, (uint16_t)word);
}
nwords -= maxtx;
/* Then empty the RX FIFO */
while (ntx-- > 0)
{
word = (uint8_t)spi_readword(priv);
/* Is there a buffer to receive the return value? */
if (dest)
{
*dest++ = word;
}
}
}
}
}