atmel_spi.c
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/*
* Copyright (C) 2007 Atmel Corporation
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <spi.h>
#include <malloc.h>
#include <asm/io.h>
#include <asm/arch/clk.h>
#include <asm/arch/hardware.h>
#include "atmel_spi.h"
static int spi_has_wdrbt(struct atmel_spi_slave *slave)
{
unsigned int ver;
ver = spi_readl(slave, VERSION);
return (ATMEL_SPI_VERSION_REV(ver) >= 0x210);
}
void spi_init()
{
}
struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct atmel_spi_slave *as;
unsigned int scbr;
u32 csrx;
void *regs;
if (!spi_cs_is_valid(bus, cs))
return NULL;
switch (bus) {
case 0:
regs = (void *)ATMEL_BASE_SPI0;
break;
#ifdef ATMEL_BASE_SPI1
case 1:
regs = (void *)ATMEL_BASE_SPI1;
break;
#endif
#ifdef ATMEL_BASE_SPI2
case 2:
regs = (void *)ATMEL_BASE_SPI2;
break;
#endif
#ifdef ATMEL_BASE_SPI3
case 3:
regs = (void *)ATMEL_BASE_SPI3;
break;
#endif
default:
return NULL;
}
scbr = (get_spi_clk_rate(bus) + max_hz - 1) / max_hz;
if (scbr > ATMEL_SPI_CSRx_SCBR_MAX)
/* Too low max SCK rate */
return NULL;
if (scbr < 1)
scbr = 1;
csrx = ATMEL_SPI_CSRx_SCBR(scbr);
csrx |= ATMEL_SPI_CSRx_BITS(ATMEL_SPI_BITS_8);
if (!(mode & SPI_CPHA))
csrx |= ATMEL_SPI_CSRx_NCPHA;
if (mode & SPI_CPOL)
csrx |= ATMEL_SPI_CSRx_CPOL;
as = spi_alloc_slave(struct atmel_spi_slave, bus, cs);
if (!as)
return NULL;
as->regs = regs;
as->mr = ATMEL_SPI_MR_MSTR | ATMEL_SPI_MR_MODFDIS
| ATMEL_SPI_MR_PCS(~(1 << cs) & 0xf);
if (spi_has_wdrbt(as))
as->mr |= ATMEL_SPI_MR_WDRBT;
spi_writel(as, CSR(cs), csrx);
return &as->slave;
}
void spi_free_slave(struct spi_slave *slave)
{
struct atmel_spi_slave *as = to_atmel_spi(slave);
free(as);
}
int spi_claim_bus(struct spi_slave *slave)
{
struct atmel_spi_slave *as = to_atmel_spi(slave);
/* Enable the SPI hardware */
spi_writel(as, CR, ATMEL_SPI_CR_SPIEN);
/*
* Select the slave. This should set SCK to the correct
* initial state, etc.
*/
spi_writel(as, MR, as->mr);
return 0;
}
void spi_release_bus(struct spi_slave *slave)
{
struct atmel_spi_slave *as = to_atmel_spi(slave);
/* Disable the SPI hardware */
spi_writel(as, CR, ATMEL_SPI_CR_SPIDIS);
}
int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct atmel_spi_slave *as = to_atmel_spi(slave);
unsigned int len_tx;
unsigned int len_rx;
unsigned int len;
u32 status;
const u8 *txp = dout;
u8 *rxp = din;
u8 value;
if (bitlen == 0)
/* Finish any previously submitted transfers */
goto out;
/*
* TODO: The controller can do non-multiple-of-8 bit
* transfers, but this driver currently doesn't support it.
*
* It's also not clear how such transfers are supposed to be
* represented as a stream of bytes...this is a limitation of
* the current SPI interface.
*/
if (bitlen % 8) {
/* Errors always terminate an ongoing transfer */
flags |= SPI_XFER_END;
goto out;
}
len = bitlen / 8;
/*
* The controller can do automatic CS control, but it is
* somewhat quirky, and it doesn't really buy us much anyway
* in the context of U-Boot.
*/
if (flags & SPI_XFER_BEGIN) {
spi_cs_activate(slave);
/*
* sometimes the RDR is not empty when we get here,
* in theory that should not happen, but it DOES happen.
* Read it here to be on the safe side.
* That also clears the OVRES flag. Required if the
* following loop exits due to OVRES!
*/
spi_readl(as, RDR);
}
for (len_tx = 0, len_rx = 0; len_rx < len; ) {
status = spi_readl(as, SR);
if (status & ATMEL_SPI_SR_OVRES)
return -1;
if (len_tx < len && (status & ATMEL_SPI_SR_TDRE)) {
if (txp)
value = *txp++;
else
value = 0;
spi_writel(as, TDR, value);
len_tx++;
}
if (status & ATMEL_SPI_SR_RDRF) {
value = spi_readl(as, RDR);
if (rxp)
*rxp++ = value;
len_rx++;
}
}
out:
if (flags & SPI_XFER_END) {
/*
* Wait until the transfer is completely done before
* we deactivate CS.
*/
do {
status = spi_readl(as, SR);
} while (!(status & ATMEL_SPI_SR_TXEMPTY));
spi_cs_deactivate(slave);
}
return 0;
}