/****************************************************************************
* arch/arm/src/sam3u/sam3u_spi.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Authors: Gregory Nutt <gnutt@nuttx.org>
* Diego Sanchez <dsanchez@nx-engineering.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdint.h>
#include <stdbool.h>
#include <semaphore.h>
#include <errno.h>
#include <debug.h>
#include <arch/board/board.h>
#include <nuttx/arch.h>
#include <nuttx/spi.h>
#include "up_internal.h"
#include "up_arch.h"
#include "chip.h"
#include "sam3u_internal.h"
#include "sam3u_pmc.h"
#include "sam3u_spi.h"
#ifdef CONFIG_SAM3U_SPI
/****************************************************************************
* Definitions
****************************************************************************/
/* Check if SPI debut is enabled (non-standard.. no support in
* include/debug.h
*/
#ifndef CONFIG_DEBUG
# undef CONFIG_DEBUG_VERBOSE
# undef CONFIG_DEBUG_SPI
#endif
#ifdef CONFIG_DEBUG_SPI
# define spidbg lldbg
# ifdef CONFIG_DEBUG_VERBOSE
# define spivdbg lldbg
# else
# define spivdbg(x...)
# endif
#else
# define spidbg(x...)
# define spivdbg(x...)
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* The state of one chip select */
#ifndef CONFIG_SPI_OWNBUS
struct sam3u_chipselect_s
{
uint32_t frequency; /* Requested clock frequency */
uint32_t actual; /* Actual clock frequency */
uint8_t nbits; /* Width of word in bits (8 to 16) */
uint8_t mode; /* Mode 0,1,2,3 */
};
#endif
/* The overall state of the SPI interface */
struct sam3u_spidev_s
{
struct spi_dev_s spidev; /* Externally visible part of the SPI interface */
#ifndef CONFIG_SPI_OWNBUS
sem_t exclsem; /* Held while chip is selected for mutual exclusion */
struct sam3u_chipselect_s csstate[4];
#endif
uint8_t cs; /* Chip select number */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Helpers */
#if defined(CONFIG_DEBUG_SPI) && defined(CONFIG_DEBUG_VERBOSE)
static void spi_dumpregs(FAR const char *msg);
#else
# define spi_dumpregs(msg)
#endif
static inline void spi_flush(void);
static inline uint32_t spi_cs2pcs(FAR struct sam3u_spidev_s *priv);
/* SPI methods */
#ifndef CONFIG_SPI_OWNBUS
static int spi_lock(FAR struct spi_dev_s *dev, bool lock);
#endif
static void spi_select(FAR struct spi_dev_s *dev, enum spi_dev_e 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 uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t ch);
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
/****************************************************************************
* Private Data
****************************************************************************/
/* SPI driver operations */
static const struct spi_ops_s g_spiops =
{
#ifndef CONFIG_SPI_OWNBUS
.lock = spi_lock,
#endif
.select = spi_select,
.setfrequency = spi_setfrequency,
.setmode = spi_setmode,
.setbits = spi_setbits,
.status = sam3u_spistatus,
#ifdef CONFIG_SPI_CMDDATA
.cmddata = sam3u_spicmddata,
#endif
.send = spi_send,
#ifdef CONFIG_SPI_EXCHANGE
.exchange = spi_exchange,
#else
.sndblock = spi_sndblock,
.recvblock = spi_recvblock,
#endif
.registercallback = 0, /* Not implemented */
};
/* SPI device structure */
static struct sam3u_spidev_s g_spidev =
{
.spidev = { &g_spiops },
};
/* This array maps chip select numbers (0-3) to CSR register addresses */
static const uint32_t g_csraddr[4] =
{
SAM3U_SPI_CSR0, SAM3U_SPI_CSR1, SAM3U_SPI_CSR2, SAM3U_SPI_CSR3
};
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: spi_dumpregs
*
* Description:
* Dump the contents of all SPI registers
*
* Input Parameters:
* msg - Message to print before the register data
*
* Returned Value:
* None
*
****************************************************************************/
#if defined(CONFIG_DEBUG_SPI) && defined(CONFIG_DEBUG_VERBOSE)
static void spi_dumpregs(FAR const char *msg)
{
spivdbg("%s:\n", msg);
spivdbg(" MR:%08x SR:%08x IMR:%08x\n",
getreg32(SAM3U_SPI_MR), getreg32(SAM3U_SPI_SR),
getreg32(SAM3U_SPI_IMR));
spivdbg(" CSR0:%08x CSR1:%08x CSR2:%08x CSR3:%08x\n",
getreg32(SAM3U_SPI_CSR0), getreg32(SAM3U_SPI_CSR1),
getreg32(SAM3U_SPI_CSR2), getreg32(SAM3U_SPI_CSR3));
spivdbg(" WPCR:%08x WPSR:%08x\n",
getreg32(SAM3U_SPI_WPCR), getreg32(SAM3U_SPI_WPSR));
}
#endif
/****************************************************************************
* Name: spi_flush
*
* Description:
* Make sure that there are now dangling SPI transfer in progress
*
* Input Parameters:
* priv - Device-specific state data
*
* Returned Value:
* None
*
****************************************************************************/
static inline void spi_flush(void)
{
/* Make sure the no TX activity is in progress... waiting if necessary */
while ((getreg32(SAM3U_SPI_SR) & SPI_INT_TXEMPTY) == 0);
/* Then make sure that there is no pending RX data .. reading as
* discarding as necessary.
*/
while ((getreg32(SAM3U_SPI_SR) & SPI_INT_RDRF) != 0)
{
(void)getreg32(SAM3U_SPI_RDR);
}
}
/****************************************************************************
* Name: spi_cs2pcs
*
* Description:
* Map the chip select number to the bit-set PCS field used in the SPI
* registers. A chip select number is used for indexing and identifying
* chip selects. However, the chip select information is represented by
* a bit set in the SPI regsisters. This function maps those chip select
* numbers to the correct bit set:
*
* CS Returned Spec Effective
* No. PCS Value NPCS
* ---- -------- -------- --------
* 0 0000 xxx0 1110
* 1 0001 xx01 1101
* 2 0011 x011 1011
* 3 0111 0111 0111
*
* Input Parameters:
* priv - Device-specific state data
*
* Returned Value:
* None
*
****************************************************************************/
static inline uint32_t spi_cs2pcs(FAR struct sam3u_spidev_s *priv)
{
return ((uint32_t)1 << (priv->cs)) - 1;
}
/****************************************************************************
* Name: spi_lock
*
* Description:
* On SPI busses where there are multiple devices, it will be necessary to
* lock SPI to have exclusive access to the busses 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 buss 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
*
****************************************************************************/
#ifndef CONFIG_SPI_OWNBUS
static int spi_lock(FAR struct spi_dev_s *dev, bool lock)
{
FAR struct sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
spivdbg("lock=%d\n", lock);
if (lock)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(&priv->exclsem) != 0)
{
/* The only case that an error should occur here is if the wait was awakened
* by a signal.
*/
ASSERT(errno == EINTR);
}
}
else
{
(void)sem_post(&priv->exclsem);
}
return OK;
}
#endif
/****************************************************************************
* Name: spi_select
*
* Description:
* This function does not actually set the chip select line. Rather, it
* simply maps the device ID into a chip select number and retains that
* chip select number for later use.
*
* Input Parameters:
* dev - Device-specific state data
* frequency - The SPI frequency requested
*
* Returned Value:
* Returns the actual frequency selected
*
****************************************************************************/
static void spi_select(FAR struct spi_dev_s *dev, enum spi_dev_e devid, bool selected)
{
FAR struct sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
uint32_t regval;
/* Are we selecting or de-selecting the device? */
spivdbg("selected=%d\n", selected);
if (selected)
{
/* At this point, we expect no chip selected */
DEBUGASSERT(priv->cs == 0xff);
/* Get the chip select number used with this SPI device */
priv->cs = sam3u_spicsnumber(devid);
spivdbg("cs=%d\n", priv->cs);
DEBUGASSERT(priv->cs >= 0 && priv->cs <= 3);
/* Before writing the TDR, the PCS field in the SPI_MR register must be set
* in order to select a slave.
*/
regval = getreg32(SAM3U_SPI_MR);
regval &= ~SPI_MR_PCS_MASK;
regval |= (spi_cs2pcs(priv) << SPI_MR_PCS_SHIFT);
putreg32(regval, SAM3U_SPI_MR);
}
else
{
/* At this point, we expect the chip to have already been selected */
#ifdef CONFIG_DEBUG
int cs = sam3u_spicsnumber(devid);
DEBUGASSERT(priv->cs == cs);
#endif
/* Mark no chip selected */
priv->cs = 0xff;
}
/* Perform any board-specific chip select operations. PIO chip select
* pins may be programmed by the board specific logic in one of two
* different ways. First, the pins may be programmed as SPI peripherals.
* In that case, the pins are completely controlled by the SPI driver.
* This sam3u_spiselect method still needs to be provided, but it may
* be only a stub.
*
* An alternative way to program the PIO chip select pins is as normal
* GPIO outputs. In that case, the automatic control of the CS pins is
* bypassed and this function must provide control of the chip select.
* NOTE: In this case, the GPIO output pin does *not* have to be the
* same as the NPCS pin normal associated with the chip select number.
*/
sam3u_spiselect(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 sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
uint32_t actual;
uint32_t scbr;
uint32_t dlybs;
uint32_t dlybct;
uint32_t regval;
uint32_t regaddr;
spivdbg("cs=%d frequency=%d\n", priv->cs, frequency);
DEBUGASSERT(priv->cs >= 0 && priv->cs <= 3);
/* Check if the requested frequency is the same as the frequency selection */
#ifndef CONFIG_SPI_OWNBUS
if (priv->csstate[priv->cs].frequency == frequency)
{
/* We are already at this frequency. Return the actual. */
return priv->csstate[priv->cs].actual;
}
#endif
/* Configure SPI to a frequency as close as possible to the requested frequency.
*
* SPCK frequency = MCK / SCBR, or SCBR = MCK / frequency
*/
scbr = SAM3U_MCK_FREQUENCY / frequency;
if (scbr < 8)
{
scbr = 8;
}
else if (scbr > 254)
{
scbr = 254;
}
scbr = (scbr + 1) & ~1;
/* Save the new scbr value */
regaddr = g_csraddr[priv->cs];
regval = getreg32(regaddr);
regval &= ~(SPI_CSR_SCBR_MASK|SPI_CSR_DLYBS_MASK|SPI_CSR_DLYBCT_MASK);
regval |= scbr << SPI_CSR_SCBR_SHIFT;
/* DLYBS: Delay Before SPCK. This field defines the delay from NPCS valid to the
* first valid SPCK transition. When DLYBS equals zero, the NPCS valid to SPCK
* transition is 1/2 the SPCK clock period. Otherwise, the following equations
* determine the delay:
*
* Delay Before SPCK = DLYBS / MCK
*
* For a 2uS delay
*
* DLYBS = MCK * 0.000002 = MCK / 500000
*/
dlybs = SAM3U_MCK_FREQUENCY / 500000;
regval |= dlybs << SPI_CSR_DLYBS_SHIFT;
/* DLYBCT: Delay Between Consecutive Transfers. This field defines the delay
* between two consecutive transfers with the same peripheral without removing
* the chip select. The delay is always inserted after each transfer and
* before removing the chip select if needed.
*
* Delay Between Consecutive Transfers = (32 x DLYBCT) / MCK
*
* For a 5uS delay:
*
* DLYBCT = MCK * 0.000005 / 32 = MCK / 200000 / 32
*/
dlybct = SAM3U_MCK_FREQUENCY / 200000 / 32;
regval |= dlybct << SPI_CSR_DLYBCT_SHIFT;
putreg32(regval, regaddr);
/* Calculate the new actual frequency */
actual = SAM3U_MCK_FREQUENCY / scbr;
spivdbg("csr[%08x]=%08x actual=%d\n", regaddr, regval, actual);
/* Save the frequency setting */
#ifndef CONFIG_SPI_OWNBUS
priv->csstate[priv->cs].frequency = frequency;
priv->csstate[priv->cs].actual = actual;
#endif
spidbg("Frequency %d->%d\n", frequency, 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 sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
uint32_t regval;
uint32_t regaddr;
spivdbg("cs=%d mode=%d\n", priv->cs, mode);
DEBUGASSERT(priv->cs >= 0 && priv->cs <= 3);
/* Has the mode changed? */
#ifndef CONFIG_SPI_OWNBUS
if (mode != priv->csstate[priv->cs].mode)
{
#endif
/* Yes... Set the mode appropriately */
regaddr = g_csraddr[priv->cs];
regval = getreg32(regaddr);
regval &= ~(SPI_CSR_CPOL|SPI_CSR_NCPHA);
switch (mode)
{
case SPIDEV_MODE0: /* CPOL=0; NCPHA=0 */
break;
case SPIDEV_MODE1: /* CPOL=0; NCPHA=1 */
regval |= SPI_CSR_NCPHA;
break;
case SPIDEV_MODE2: /* CPOL=1; NCPHA=0 */
regval |= SPI_CSR_CPOL;
break;
case SPIDEV_MODE3: /* CPOL=1; NCPHA=1 */
regval |= (SPI_CSR_CPOL|SPI_CSR_NCPHA);
break;
default:
DEBUGASSERT(FALSE);
return;
}
putreg32(regval, regaddr);
spivdbg("csr[%08x]=%08x\n", regaddr, regval);
/* Save the mode so that subsequent re-configurations will be faster */
#ifndef CONFIG_SPI_OWNBUS
priv->csstate[priv->cs].mode = mode;
}
#endif
}
/****************************************************************************
* 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)
{
FAR struct sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
uint32_t regaddr;
uint32_t regval;
spivdbg("cs=%d nbits=%d\n", priv->cs, nbits);
DEBUGASSERT(priv && nbits > 7 && nbits < 17);
DEBUGASSERT(priv->cs >= 0 && priv->cs <= 3);
/* NOTE: The logic in spi_send and in spi_exchange only handles 8-bit
* data at the present time. So the following extra assertion is a
* reminder that we have to fix that someday.
*/
DEBUGASSERT(nbits == 8); /* Temporary -- FIX ME */
/* Has the number of bits changed? */
#ifndef CONFIG_SPI_OWNBUS
if (nbits != priv->csstate[priv->cs].nbits)
{
#endif
/* Yes... Set number of bits appropriately */
regaddr = g_csraddr[priv->cs];
regval = getreg32(regaddr);
regval &= ~SPI_CSR_BITS_MASK;
regval |= SPI_CSR_BITS(nbits);
putreg32(regval, regaddr);
spivdbg("csr[%08x]=%08x\n", regaddr, regval);
/* Save the selection so the subsequence re-configurations will be faster */
#ifndef CONFIG_SPI_OWNBUS
priv->csstate[priv->cs].nbits = nbits;
}
#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 uint16_t spi_send(FAR struct spi_dev_s *dev, uint16_t wd)
{
uint8_t txbyte;
uint8_t rxbyte;
/* spi_exchange can do this. Note: right now, this only deals with 8-bit
* words. If the SPI interface were configured for words of other sizes,
* this would fail.
*/
txbyte = (uint8_t)wd;
spi_exchange(dev, &txbyte, &rxbyte, 1);
spivdbg("Sent %02x received %02x\n", txbyte, rxbyte);
return (uint16_t)rxbyte;
}
/****************************************************************************
* 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 recieve 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 sam3u_spidev_s *priv = (FAR struct sam3u_spidev_s *)dev;
FAR uint8_t *rxptr = (FAR uint8_t*)rxbuffer;
FAR uint8_t *txptr = (FAR uint8_t*)txbuffer;
uint32_t pcs;
uint32_t data;
spivdbg("txbuffer=%p rxbuffer=%p nwords=%d\n", txbuffer, rxbuffer, nwords);
/* Set up PCS bits */
pcs = spi_cs2pcs(priv) << SPI_TDR_PCS_SHIFT;
/* Make sure that any previous transfer is flushed from the hardware */
spi_flush();
/* Loop, sending each word in the user-provied data buffer.
*
* Note 1: Right now, this only deals with 8-bit words. If the SPI
* interface were configured for words of other sizes, this
* would fail.
* Note 2: Good SPI performance would require that we implement DMA
* transfers!
* Note 3: This loop might be made more efficient. Would logic
* like the following improve the throughput? Or would it
* just add the risk of overruns?
*
* Get word 1;
* Send word 1; Now word 1 is "in flight"
* nwords--;
* for ( ; nwords > 0; nwords--)
* {
* Get word N.
* Wait for TDRE meaning that word N-1 has moved to the shift
* register.
* Disable interrupts to keep the following atomic
* Send word N. Now both work N-1 and N are "in flight"
* Wait for RDRF meaning that word N-1 is available
* Read word N-1.
* Re-enable interrupts.
* Save word N-1.
* }
* Wait for RDRF meaning that the final word is available
* Read the final word.
* Save the final word.
*/
for ( ; nwords > 0; nwords--)
{
/* Get the data to send (0xff if there is no data source) */
if (rxptr)
{
data = (uint32_t)*txptr++;
}
else
{
data = 0xffff;
}
/* Set the PCS field in the value written to the TDR */
data |= pcs;
/* Do we need to set the LASTXFER bit in the TDR value too? */
#ifdef CONFIG_SPI_VARSELECT
if (nwords == 1)
{
data |= SPI_TDR_LASTXFER;
}
#endif
/* Wait for any previous data written to the TDR to be transferred
* to the serializer.
*/
while ((getreg32(SAM3U_SPI_SR) & SPI_INT_TDRE) == 0);
/* Write the data to transmitted to the Transmit Data Register (TDR) */
putreg32(data, SAM3U_SPI_TDR);
/* Wait for the read data to be available in the RDR */
while ((getreg32(SAM3U_SPI_SR) & SPI_INT_RDRF) == 0);
/* Read the received data from the SPI Data Register */
data = getreg32(SAM3U_SPI_RDR);
if (rxptr)
{
*rxptr++ = (uint8_t)data;
}
}
}
/***************************************************************************
* 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 recieve 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
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_spiinitialize
*
* Description:
* Initialize the selected SPI port
*
* Input Parameter:
* Port number (for hardware that has mutiple SPI interfaces)
*
* Returned Value:
* Valid SPI device structure reference on succcess; a NULL on failure
*
****************************************************************************/
FAR struct spi_dev_s *up_spiinitialize(int port)
{
FAR struct sam3u_spidev_s *priv = &g_spidev;
irqstate_t flags;
uint32_t regval;
/* The SAM3U has only a single SPI port */
spivdbg("port=%d\n", port);
DEBUGASSERT(port == 0);
/* Set up the initial state */
priv->cs = 0xff;
/* Apply power to the SPI block */
flags = irqsave();
regval = getreg32(SAM3U_PMC_PCER);
regval |= (1 << SAM3U_PID_SPI);
#ifdef CONFIG_SAM3U_SPIINTERRUPT
regval |= (1 << SAM3U_IRQ_SPI);
#endif
putreg32(regval, SAM3U_PMC_PCER);
/* Configure multiplexed pins as connected on the board. Chip select pins
* must be configured by board-specific logic.
*/
sam3u_configgpio(GPIO_SPI0_MISO);
sam3u_configgpio(GPIO_SPI0_MOSI);
sam3u_configgpio(GPIO_SPI0_SPCK);
/* Disable SPI clocking */
putreg32(SPI_CR_SPIDIS, SAM3U_SPI_CR);
/* Execute a software reset of the SPI (twice) */
putreg32(SPI_CR_SWRST, SAM3U_SPI_CR);
putreg32(SPI_CR_SWRST, SAM3U_SPI_CR);
irqrestore(flags);
/* Configure the SPI mode register */
putreg32(SPI_MR_MSTR | SPI_MR_MODFDIS, SAM3U_SPI_MR);
/* And enable the SPI */
putreg32(SPI_CR_SPIEN, SAM3U_SPI_CR);
up_mdelay(20);
/* Flush any pending transfers */
(void)getreg32(SAM3U_SPI_SR);
(void)getreg32(SAM3U_SPI_RDR);
/* Initialize the SPI semaphore that enforces mutually exclusive access */
#ifndef CONFIG_SPI_OWNBUS
sem_init(&priv->exclsem, 0, 1);
#endif
spi_dumpregs("After initialization");
return &priv->spidev;
}
#endif /* CONFIG_SAM3U_SPI */
