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i.MX31: support GPIO as a chip-select in the mxc_spi driver 

Some SPI devices have special requirements on chip-select handling.
With this patch we can use a GPIO as a chip-select and strictly follow
the SPI_XFER_BEGIN and SPI_XFER_END flags.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
This commit is contained in:
Guennadi Liakhovetski 2009-02-13 09:26:40 +01:00 committed by Anatolij Gustschin
parent b30de3cccf
commit fc7a93c84f
1 changed files with 56 additions and 8 deletions
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64
drivers/spi/mxc_spi.c
View File

@ -21,6 +21,7 @@
#include <common.h>
#include <malloc.h>
#include <spi.h>
#include <asm/errno.h>
#include <asm/io.h>
#ifdef CONFIG_MX27
@ -32,6 +33,8 @@
#else
#include <asm/arch/mx31.h>
#define MXC_CSPIRXDATA 0x00
#define MXC_CSPITXDATA 0x04
#define MXC_CSPICTRL 0x08
@ -68,6 +71,7 @@ struct mxc_spi_slave {
struct spi_slave slave;
unsigned long base;
u32 ctrl_reg;
int gpio;
};
static inline struct mxc_spi_slave *to_mxc_spi_slave(struct spi_slave *slave)
@ -85,7 +89,8 @@ static inline void reg_write(unsigned long addr, u32 val)
*(volatile unsigned long*)addr = val;
}
static u32 spi_xchg_single(struct spi_slave *slave, u32 data, int bitlen)
static u32 spi_xchg_single(struct spi_slave *slave, u32 data, int bitlen,
unsigned long flags)
{
struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
unsigned int cfg_reg = reg_read(mxcs->base + MXC_CSPICTRL);
@ -96,6 +101,9 @@ static u32 spi_xchg_single(struct spi_slave *slave, u32 data, int bitlen)
if (cfg_reg != mxcs->ctrl_reg)
reg_write(mxcs->base + MXC_CSPICTRL, mxcs->ctrl_reg);
if (mxcs->gpio > 0 && (flags & SPI_XFER_BEGIN))
mx31_gpio_set(mxcs->gpio, mxcs->ctrl_reg & MXC_CSPICTRL_SSPOL);
reg_write(mxcs->base + MXC_CSPITXDATA, data);
reg_write(mxcs->base + MXC_CSPICTRL, mxcs->ctrl_reg | MXC_CSPICTRL_XCH);
@ -103,6 +111,11 @@ static u32 spi_xchg_single(struct spi_slave *slave, u32 data, int bitlen)
while (reg_read(mxcs->base + MXC_CSPICTRL) & MXC_CSPICTRL_XCH)
;
if (mxcs->gpio > 0 && (flags & SPI_XFER_END)) {
mx31_gpio_set(mxcs->gpio,
!(mxcs->ctrl_reg & MXC_CSPICTRL_SSPOL));
}
return reg_read(mxcs->base + MXC_CSPIRXDATA);
}
@ -121,7 +134,7 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
for (i = 0, in_l = (u32 *)din, out_l = (u32 *)dout;
i < n_blks;
i++, in_l++, out_l++, bitlen -= 32) {
u32 data = spi_xchg_single(slave, *out_l, bitlen);
u32 data = spi_xchg_single(slave, *out_l, bitlen, flags);
/* Check if we're only transfering 8 or 16 bits */
if (!i) {
@ -139,16 +152,55 @@ void spi_init(void)
{
}
static int decode_cs(struct mxc_spi_slave *mxcs, unsigned int cs)
{
int ret;
/*
* Some SPI devices require active chip-select over multiple
* transactions, we achieve this using a GPIO. Still, the SPI
* controller has to be configured to use one of its own chipselects.
* To use this feature you have to call spi_setup_slave() with
* cs = internal_cs | (gpio << 8), and you have to use some unused
* on this SPI controller cs between 0 and 3.
*/
if (cs > 3) {
mxcs->gpio = cs >> 8;
cs &= 3;
ret = mx31_gpio_direction(mxcs->gpio, MX31_GPIO_DIRECTION_OUT);
if (ret) {
printf("mxc_spi: cannot setup gpio %d\n", mxcs->gpio);
return -EINVAL;
}
} else {
mxcs->gpio = -1;
}
return cs;
}
struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
unsigned int max_hz, unsigned int mode)
{
unsigned int ctrl_reg;
struct mxc_spi_slave *mxcs;
int ret;
if (bus >= sizeof(spi_bases) / sizeof(spi_bases[0]) ||
cs > 3)
if (bus >= ARRAY_SIZE(spi_bases))
return NULL;
mxcs = malloc(sizeof(struct mxc_spi_slave));
if (!mxcs)
return NULL;
ret = decode_cs(mxcs, cs);
if (ret < 0) {
free(mxcs);
return NULL;
}
cs = ret;
ctrl_reg = MXC_CSPICTRL_CHIPSELECT(cs) |
MXC_CSPICTRL_BITCOUNT(31) |
MXC_CSPICTRL_DATARATE(7) | /* FIXME: calculate data rate */
@ -162,10 +214,6 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
if (mode & SPI_CS_HIGH)
ctrl_reg |= MXC_CSPICTRL_SSPOL;
mxcs = malloc(sizeof(struct mxc_spi_slave));
if (!mxcs)
return NULL;
mxcs->slave.bus = bus;
mxcs->slave.cs = cs;
mxcs->base = spi_bases[bus];