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EFM32 SPI: setfrequency() needs to return actual frequency; simplify nbits usages by removing conditional logic

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This commit is contained in:
Gregory Nutt 2014-10-27 07:07:30 -06:00
parent a7b9bf776e
commit 80efa803b9
1 changed files with 25 additions and 43 deletions
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68
arch/arm/src/efm32/efm32_spi.c
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@ -166,11 +166,11 @@ struct efm32_spidev_s
sem_t exclsem; /* Supports mutually exclusive access */
uint32_t frequency; /* Requested clock frequency */
uint32_t actual; /* Actual clock frequency */
uint8_t nbits; /* Width of word in bits (8 or 16) */
uint8_t mode; /* Mode 0,1,2,3 */
#endif
bool initialized; /* True: Already initialized */
uint8_t nbits; /* Width of word in bits (8 or 16) */
bool initialized; /* True: Already initialized */
};
/****************************************************************************
@ -182,7 +182,6 @@ static uint32_t spi_getreg(const struct efm32_spiconfig_s *config,
unsigned int regoffset);
static void spi_putreg(const struct efm32_spiconfig_s *config,
unsigned int regoffset, uint32_t regval);
static bool spi_16bitmode(struct efm32_spidev_s *priv);
static void spi_rxflush(const struct efm32_spiconfig_s *config);
static void spi_wait_status(const struct efm32_spiconfig_s *config,
uint32_t mask, uint32_t match);
@ -389,34 +388,6 @@ static void spi_putreg(const struct efm32_spiconfig_s *config,
putreg32(regval, regaddr);
}
/****************************************************************************
* Name: spi_16bitmode
*
* Description:
* Return true if the transfer is performed on 16-bit (vs 8-bit) data.
*
* Input Parameters:
* priv - Device-specific state data
*
* Returned Value:
* True: 16-bit; false: 8-bit
*
****************************************************************************/
static bool spi_16bitmode(struct efm32_spidev_s *priv)
{
#ifndef CONFIG_SPI_OWNBUS
return (priv->nbits > 8) ? true : false;
#else
uint32_t regval;
regval = spi_getreg(config, EFM32_USART_FRAME_OFFSET);
regval &= _USART_FRAME_DATABITS_MASK;
regval >>= _USART_FRAME_DATABITS_SHIFT;
return (regval > _USART_FRAME_DATABITS_EIGHT);
#endif
}
/****************************************************************************
* Name: spi_rxflush
*
@ -645,7 +616,7 @@ static void spi_dmarxsetup(struct efm32_spidev_s *priv, void *rxbuffer,
/* 8- or 16-bit mode? */
if (spi_16bitmode(priv))
if (priv->nbits > 8)
{
/* 16-bit mode -- is there a buffer to receive data in? */
@ -703,7 +674,7 @@ static void spi_dmatxsetup(struct efm32_spidev_s *priv, const void *txbuffer,
/* 8- or 16-bit mode? */
if (spi_16bitmode(priv))
if (priv->nbits > 8)
{
/* 16-bit mode -- is there a buffer to receive data in? */
@ -874,6 +845,7 @@ static uint32_t spi_setfrequency(struct spi_dev_s *dev, uint32_t frequency)
struct efm32_spidev_s *priv = (struct efm32_spidev_s *)dev;
const struct efm32_spiconfig_s *config;
uint32_t clkdiv;
uint32_t actual;
DEBUGASSERT(priv && priv->config);
config = priv->config;
@ -881,9 +853,15 @@ static uint32_t spi_setfrequency(struct spi_dev_s *dev, uint32_t frequency)
/* Has the frequency changed? */
#ifndef CONFIG_SPI_OWNBUS
if (frequency != priv->frequency)
if (frequency == priv->frequency)
{
/* No... just return the actual frequency from the last calcualtion */
actual = priv->actual;
}
else
#endif
{
/* We want to use integer division to avoid forcing in float division
* utils, and yet keep rounding effect errors to a minimum.
*
@ -928,7 +906,14 @@ static uint32_t spi_setfrequency(struct spi_dev_s *dev, uint32_t frequency)
clkdiv &= _USART_CLKDIV_DIV_MASK;
spi_putreg(config, EFM32_USART_CLKDIV_OFFSET, clkdiv);
spivdbg("Frequency %d\n", frequency);
/* The actual frequency is then given by:
*
* br = fHFPERCLK / (2 * (1 + CLKDIV / 256))
* = 128 * fHFPERCLK / (256 + CLKDIV)
*/
actual = (BOARD_HFPERCLK_FREQUENCY << 7) / ( 256 + clkdiv);
spivdbg("frequency=%u actual=%u\n", frequency, actual);
#ifndef CONFIG_SPI_OWNBUS
/* Save the frequency selection so that subsequent reconfigurations
@ -936,10 +921,11 @@ static uint32_t spi_setfrequency(struct spi_dev_s *dev, uint32_t frequency)
*/
priv->frequency = frequency;
}
priv->actual = actual;
#endif
}
return frequency;
return actual;
}
/****************************************************************************
@ -1041,10 +1027,8 @@ static void spi_setbits(struct spi_dev_s *dev, int nbits)
/* Has the number of bits changed? */
#ifndef CONFIG_SPI_OWNBUS
if (nbits != priv->nbits)
{
#endif
regval = spi_getreg(config, EFM32_USART_CTRL_OFFSET);
if (nbits < 0)
{
@ -1122,14 +1106,12 @@ static void spi_setbits(struct spi_dev_s *dev, int nbits)
regval |= setting;
spi_putreg(config, EFM32_USART_FRAME_OFFSET, regval);
#ifndef CONFIG_SPI_OWNBUS
/* Save the selection so the subsequence re-configurations will be
* faster
*/
priv->nbits = nbits;
}
#endif
}
/****************************************************************************
@ -1292,7 +1274,7 @@ static void spi_exchange(struct spi_dev_s *dev, const void *txbuffer,
/* 8- or 16-bit mode? */
if (spi_16bitmode(priv))
if (priv->nbits > 8)
{
/* 16-bit mode */
@ -1592,9 +1574,9 @@ static int spi_portinitialize(struct efm32_spidev_s *priv)
#ifndef CONFIG_SPI_OWNBUS
priv->frequency = 0;
priv->nbits = 8;
priv->mode = SPIDEV_MODE0;
#endif
priv->nbits = 8;
/* 8 bits */