/*
* Transfer (i.e. exchange) one "word" with selected SPI device.
* Typically one word is 8-bits (an octet), but it does not need to be,
* this function is word-width agnostic - when using the SSC.
* However, for PIO bit-banging, then one word is explicitly
* unconditionally assumed to be exactly 8-bits in length.
*
* input: "out" is word to be send to slave SPI device
* returns: one word read from the slave SPI device
*
* It is the caller's responsibility to ensure that the
* chip select (SPI_NOTCS) is correctly asserted.
*/
static unsigned int spi_xfer_one_word(const unsigned int out)
{
unsigned int in = 0;
#if defined(CONFIG_SOFT_SPI) /* Use PIO Bit-Banging for SPI */
signed int i;
for(i=7; i>=0; i--) /* for each bit in turn ... */
{ /* do 8 bits, msb first */
SPI_SCL(0); /* SPI_CLK = low */
SPI_SDA(out & (1u<<i)); /* output next bit on SPI_DOUT */
SPI_DELAY; /* clock low cycle */
SPI_SCL(1); /* SPI_CLK = high */
SPI_DELAY; /* sample on RISING clock edge */
in <<= 1; /* shift */
in |= SPI_READ; /* get next bit from SPI_DIN */
}
#else /* Use SSC for SPI */
/* write out data 'out' */
ssc_write(SSC_TBUF, out);
/* wait for Receive Buffer Full flag to be asserted */
while ((ssc_read(SSC_STAT) & SSC_STAT_RIR) == 0)
{
; /* busy poll - do nothing */
}
/* read in data */
in = ssc_read(SSC_RBUF);
#endif /* CONFIG_SOFT_SPI */
/* return exchanged data */
return in;
}
/**
* \brief Synchronous Serial Controller Handler.
*
*/
void SSC_Handler(void)
{
uint32_t ul_data;
ssc_get_status(SSC);
ssc_read(SSC, &ul_data);
g_uc_rx_buff[g_uc_rx_index++] = ul_data;
if (BUFFER_SIZE == g_uc_rx_index) {
g_uc_rx_done = 1;
ssc_disable_interrupt(SSC, SSC_IDR_RXRDY);
}
}
/*
* initialise the SSC to talk to the slave SPI device.
*/
extern void spi_init(void)
{
//DECLARE_GLOBAL_DATA_PTR;
spi_chipsel_type const chipsel = spi_chipsel[0]; /* SPI Device #0 */
#if !defined(CONFIG_SOFT_SPI) /* Use SSC for SPI */
unsigned long reg;
const unsigned long bits_per_word = 8; /* one word == 8-bits */
const unsigned long mode = CFG_STM_SPI_MODE /* | SPI_LOOP */;
//const unsigned long fcomms = gd->bd->bi_emifrq*1000*1000;
const unsigned long hz = CFG_STM_SPI_FREQUENCY;
//unsigned long sscbrg = fcomms/(2*hz);
#endif /* CONFIG_SOFT_SPI */
/*init pio15.0-pio15.3*/
configSpi();
/* de-assert SPI CS */
(*chipsel)(0);
#if !defined(CONFIG_SOFT_SPI) /* Use SSC for SPI */
/* program the SSC's Baud-Rate Generator */
if ((sscbrg < 0x07u) || (sscbrg > (0x1u << 16)))
{
printk("ERROR: Unable to set SSC buad-rate generator to 0x%04x\n",
sscbrg);
return;
}
/* TODO: program pre-scaler for slower baud rates */
if (sscbrg == (0x1 << 16)) /* 16-bit counter wraps */
{
sscbrg = 0x0; /* slowest possible clock frequency */
}
ssc_write(SSC_BRG,sscbrg);
#if 0 /* QQQ */
printk("info: fcomms=%uMHz, SPI=%uHz, brg=0x%04x\n",
fcomms/1000/1000, hz, sscbrg);
#endif
/* Disable I2C sub-system */
ssc_write( SSC_I2C, 0x0);
/* Perform a S/W reset the SSC */
reg = ssc_read( SSC_CON);
reg |= SSC_CON_SR; /* enable software reset */
ssc_write( SSC_CON, reg);
udelay(1); /* let reset propagate */
reg = ssc_read( SSC_CON);
reg &= ~SSC_CON_SR; /* disable software reset */
ssc_write( SSC_CON, reg);
/* Configure & enable the SSC's control register */
reg = ssc_read(SSC_CON);
reg |= SSC_CON_EN; /* Enable the SSC */
reg |= SSC_CON_MS; /* set SSC as the SPI master */
if (mode & SPI_CPOL)
reg |= SSC_CON_PO; /* Clock idles at logic 1 */
else
reg &= ~SSC_CON_PO; /* Clock idles at logic 0 */
if (mode & SPI_CPHA)
reg |= SSC_CON_PH; /* Pulse in first half-cycle */
else
reg &= ~SSC_CON_PH; /* Pulse in second half-cycle */
if (mode & SPI_LSB_FIRST)
reg &= ~SSC_CON_HB; /* LSB first */
else
reg |= SSC_CON_HB; /* MSB first */
if (mode & SPI_LOOP)
reg |= SSC_CON_LPB; /* put SSC in loop-back mode */
else
reg &= ~SSC_CON_LPB; /* remove SSC from loop-back mode */
reg &= ~0x0ful; /* set bit width */
reg |= (bits_per_word - 1ul); /* set bit width */
ssc_write(SSC_CON,reg);
/* clear the status register */
(void)ssc_read(SSC_RBUF);
#endif /* CONFIG_SOFT_SPI */
/* now probe the serial flash, to ensure it is the correct one */
spi_probe_serial_flash(chipsel);
}
