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>
diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
index 0ac4e90..fad9840 100644
--- a/drivers/spi/mxc_spi.c
+++ b/drivers/spi/mxc_spi.c
@@ -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 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 @@
*(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 @@
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 @@
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 @@
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 @@
{
}
+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 @@
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];