u-boot/drivers/spi/mxs_spi.c
Marek Vasut 2c4321444a MX28: SPI: Supercharge the SPI driver
This change implements DMA chaining into SPI driver. This allows
the transfers to go much faster, while also fixing SF issues.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Otavio Salvador <otavio@ossystems.com.br>
Cc: Stefano Babic <sbabic@denx.de>
2012-09-01 14:58:29 +02:00

379 lines
9.5 KiB
C

/*
* Freescale i.MX28 SPI driver
*
* Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
* on behalf of DENX Software Engineering GmbH
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* NOTE: This driver only supports the SPI-controller chipselects,
* GPIO driven chipselects are not supported.
*/
#include <common.h>
#include <malloc.h>
#include <spi.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/arch/clock.h>
#include <asm/arch/imx-regs.h>
#include <asm/arch/sys_proto.h>
#include <asm/arch/dma.h>
#define MXS_SPI_MAX_TIMEOUT 1000000
#define MXS_SPI_PORT_OFFSET 0x2000
#define MXS_SSP_CHIPSELECT_MASK 0x00300000
#define MXS_SSP_CHIPSELECT_SHIFT 20
#define MXSSSP_SMALL_TRANSFER 512
/*
* CONFIG_MXS_SPI_DMA_ENABLE: Experimental mixed PIO/DMA support for MXS SPI
* host. Use with utmost caution!
*
* Enabling this is not yet recommended since this
* still doesn't support transfers to/from unaligned
* addresses. Therefore this driver will not work
* for example with saving environment. This is
* caused by DMA alignment constraints on MXS.
*/
struct mxs_spi_slave {
struct spi_slave slave;
uint32_t max_khz;
uint32_t mode;
struct mxs_ssp_regs *regs;
};
static inline struct mxs_spi_slave *to_mxs_slave(struct spi_slave *slave)
{
return container_of(slave, struct mxs_spi_slave, slave);
}
void spi_init(void)
{
}
int spi_cs_is_valid(unsigned int bus, unsigned int cs)
{
/* MXS SPI: 4 ports and 3 chip selects maximum */
if (bus > 3 || cs > 2)
return 0;
else
return 1;
}
struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
struct mxs_spi_slave *mxs_slave;
uint32_t addr;
struct mxs_ssp_regs *ssp_regs;
int reg;
if (!spi_cs_is_valid(bus, cs)) {
printf("mxs_spi: invalid bus %d / chip select %d\n", bus, cs);
return NULL;
}
mxs_slave = calloc(sizeof(struct mxs_spi_slave), 1);
if (!mxs_slave)
return NULL;
if (mxs_dma_init_channel(bus))
goto err_init;
addr = MXS_SSP0_BASE + (bus * MXS_SPI_PORT_OFFSET);
mxs_slave->slave.bus = bus;
mxs_slave->slave.cs = cs;
mxs_slave->max_khz = max_hz / 1000;
mxs_slave->mode = mode;
mxs_slave->regs = (struct mxs_ssp_regs *)addr;
ssp_regs = mxs_slave->regs;
reg = readl(&ssp_regs->hw_ssp_ctrl0);
reg &= ~(MXS_SSP_CHIPSELECT_MASK);
reg |= cs << MXS_SSP_CHIPSELECT_SHIFT;
writel(reg, &ssp_regs->hw_ssp_ctrl0);
return &mxs_slave->slave;
err_init:
free(mxs_slave);
return NULL;
}
void spi_free_slave(struct spi_slave *slave)
{
struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave);
free(mxs_slave);
}
int spi_claim_bus(struct spi_slave *slave)
{
struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave);
struct mxs_ssp_regs *ssp_regs = mxs_slave->regs;
uint32_t reg = 0;
mxs_reset_block(&ssp_regs->hw_ssp_ctrl0_reg);
writel(SSP_CTRL0_BUS_WIDTH_ONE_BIT, &ssp_regs->hw_ssp_ctrl0);
reg = SSP_CTRL1_SSP_MODE_SPI | SSP_CTRL1_WORD_LENGTH_EIGHT_BITS;
reg |= (mxs_slave->mode & SPI_CPOL) ? SSP_CTRL1_POLARITY : 0;
reg |= (mxs_slave->mode & SPI_CPHA) ? SSP_CTRL1_PHASE : 0;
writel(reg, &ssp_regs->hw_ssp_ctrl1);
writel(0, &ssp_regs->hw_ssp_cmd0);
mx28_set_ssp_busclock(slave->bus, mxs_slave->max_khz);
return 0;
}
void spi_release_bus(struct spi_slave *slave)
{
}
static void mxs_spi_start_xfer(struct mxs_ssp_regs *ssp_regs)
{
writel(SSP_CTRL0_LOCK_CS, &ssp_regs->hw_ssp_ctrl0_set);
writel(SSP_CTRL0_IGNORE_CRC, &ssp_regs->hw_ssp_ctrl0_clr);
}
static void mxs_spi_end_xfer(struct mxs_ssp_regs *ssp_regs)
{
writel(SSP_CTRL0_LOCK_CS, &ssp_regs->hw_ssp_ctrl0_clr);
writel(SSP_CTRL0_IGNORE_CRC, &ssp_regs->hw_ssp_ctrl0_set);
}
static int mxs_spi_xfer_pio(struct mxs_spi_slave *slave,
char *data, int length, int write, unsigned long flags)
{
struct mxs_ssp_regs *ssp_regs = slave->regs;
if (flags & SPI_XFER_BEGIN)
mxs_spi_start_xfer(ssp_regs);
while (length--) {
/* We transfer 1 byte */
writel(1, &ssp_regs->hw_ssp_xfer_size);
if ((flags & SPI_XFER_END) && !length)
mxs_spi_end_xfer(ssp_regs);
if (write)
writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_clr);
else
writel(SSP_CTRL0_READ, &ssp_regs->hw_ssp_ctrl0_set);
writel(SSP_CTRL0_RUN, &ssp_regs->hw_ssp_ctrl0_set);
if (mxs_wait_mask_set(&ssp_regs->hw_ssp_ctrl0_reg,
SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
printf("MXS SPI: Timeout waiting for start\n");
return -ETIMEDOUT;
}
if (write)
writel(*data++, &ssp_regs->hw_ssp_data);
writel(SSP_CTRL0_DATA_XFER, &ssp_regs->hw_ssp_ctrl0_set);
if (!write) {
if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_status_reg,
SSP_STATUS_FIFO_EMPTY, MXS_SPI_MAX_TIMEOUT)) {
printf("MXS SPI: Timeout waiting for data\n");
return -ETIMEDOUT;
}
*data = readl(&ssp_regs->hw_ssp_data);
data++;
}
if (mxs_wait_mask_clr(&ssp_regs->hw_ssp_ctrl0_reg,
SSP_CTRL0_RUN, MXS_SPI_MAX_TIMEOUT)) {
printf("MXS SPI: Timeout waiting for finish\n");
return -ETIMEDOUT;
}
}
return 0;
}
static int mxs_spi_xfer_dma(struct mxs_spi_slave *slave,
char *data, int length, int write, unsigned long flags)
{
const int xfer_max_sz = 0xff00;
const int desc_count = DIV_ROUND_UP(length, xfer_max_sz) + 1;
struct mxs_ssp_regs *ssp_regs = slave->regs;
struct mxs_dma_desc *dp;
uint32_t ctrl0;
uint32_t cache_data_count;
int dmach;
int tl;
ALLOC_CACHE_ALIGN_BUFFER(struct mxs_dma_desc, desc, desc_count);
memset(desc, 0, sizeof(struct mxs_dma_desc) * desc_count);
ctrl0 = readl(&ssp_regs->hw_ssp_ctrl0);
ctrl0 |= SSP_CTRL0_DATA_XFER;
if (flags & SPI_XFER_BEGIN)
ctrl0 |= SSP_CTRL0_LOCK_CS;
if (!write)
ctrl0 |= SSP_CTRL0_READ;
writel(length, &ssp_regs->hw_ssp_xfer_size);
if (length % ARCH_DMA_MINALIGN)
cache_data_count = roundup(length, ARCH_DMA_MINALIGN);
else
cache_data_count = length;
if (write)
/* Flush data to DRAM so DMA can pick them up */
flush_dcache_range((uint32_t)data,
(uint32_t)(data + cache_data_count));
dmach = MXS_DMA_CHANNEL_AHB_APBH_SSP0 + slave->slave.bus;
dp = desc;
while (length) {
dp->address = (dma_addr_t)dp;
dp->cmd.address = (dma_addr_t)data;
/*
* This is correct, even though it does indeed look insane.
* I hereby have to, wholeheartedly, thank Freescale Inc.,
* for always inventing insane hardware and keeping me busy
* and employed ;-)
*/
if (write)
dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_READ;
else
dp->cmd.data = MXS_DMA_DESC_COMMAND_DMA_WRITE;
/*
* The DMA controller can transfer large chunks (64kB) at
* time by setting the transfer length to 0. Setting tl to
* 0x10000 will overflow below and make .data contain 0.
* Otherwise, 0xff00 is the transfer maximum.
*/
if (length >= 0x10000)
tl = 0x10000;
else
tl = min(length, xfer_max_sz);
dp->cmd.data |=
(tl << MXS_DMA_DESC_BYTES_OFFSET) |
(1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) |
MXS_DMA_DESC_HALT_ON_TERMINATE |
MXS_DMA_DESC_TERMINATE_FLUSH;
dp->cmd.pio_words[0] = ctrl0;
data += tl;
length -= tl;
mxs_dma_desc_append(dmach, dp);
dp++;
}
dp->address = (dma_addr_t)dp;
dp->cmd.address = (dma_addr_t)0;
dp->cmd.data = MXS_DMA_DESC_COMMAND_NO_DMAXFER |
(1 << MXS_DMA_DESC_PIO_WORDS_OFFSET) |
MXS_DMA_DESC_IRQ | MXS_DMA_DESC_DEC_SEM;
if (flags & SPI_XFER_END) {
ctrl0 &= ~SSP_CTRL0_LOCK_CS;
dp->cmd.pio_words[0] = ctrl0 | SSP_CTRL0_IGNORE_CRC;
}
mxs_dma_desc_append(dmach, dp);
if (mxs_dma_go(dmach))
return -EINVAL;
/* The data arrived into DRAM, invalidate cache over them */
if (!write) {
invalidate_dcache_range((uint32_t)data,
(uint32_t)(data + cache_data_count));
}
return 0;
}
int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
const void *dout, void *din, unsigned long flags)
{
struct mxs_spi_slave *mxs_slave = to_mxs_slave(slave);
struct mxs_ssp_regs *ssp_regs = mxs_slave->regs;
int len = bitlen / 8;
char dummy;
int write = 0;
char *data = NULL;
#ifdef CONFIG_MXS_SPI_DMA_ENABLE
int dma = 1;
#else
int dma = 0;
#endif
if (bitlen == 0) {
if (flags & SPI_XFER_END) {
din = (void *)&dummy;
len = 1;
} else
return 0;
}
/* Half-duplex only */
if (din && dout)
return -EINVAL;
/* No data */
if (!din && !dout)
return 0;
if (dout) {
data = (char *)dout;
write = 1;
} else if (din) {
data = (char *)din;
write = 0;
}
/*
* Check for alignment, if the buffer is aligned, do DMA transfer,
* PIO otherwise. This is a temporary workaround until proper bounce
* buffer is in place.
*/
if (dma) {
if (((uint32_t)data) & (ARCH_DMA_MINALIGN - 1))
dma = 0;
if (((uint32_t)len) & (ARCH_DMA_MINALIGN - 1))
dma = 0;
}
if (!dma || (len < MXSSSP_SMALL_TRANSFER)) {
writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_clr);
return mxs_spi_xfer_pio(mxs_slave, data, len, write, flags);
} else {
writel(SSP_CTRL1_DMA_ENABLE, &ssp_regs->hw_ssp_ctrl1_set);
return mxs_spi_xfer_dma(mxs_slave, data, len, write, flags);
}
}