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 ---

Changes since v1: long lines split, mx31_gpio_* calls now also defined if CONFIG_MX31_GPIO is not defined (see patch 2/9), '!!' removed. Changes since v2: added braces in a multiline if, switched to ARRAY_SIZE(). Changes since v3: moved GPIO chipselect initialisation into a separate function, as suggested by Wolfgang Denk

drivers/spi/mxc_spi.c | 64 ++++++++++++++++++++++++++++++++++++++++++------ 1 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c index 3135817..daad1bb 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 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) { @@ -139,15 +152,54 @@ 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 >= ARRAY_SIZE(spi_bases)) + return NULL; + + mxcs = malloc(sizeof(struct mxc_spi_slave)); + if (!mxcs) + return NULL;

- if (bus >= sizeof(spi_bases) / sizeof(spi_bases[0]) || - cs > 3) + ret = decode_cs(mxcs, cs); + if (ret < 0) { + free(mxcs); return NULL; + } + + cs = ret;

ctrl_reg = MXC_CSPICTRL_CHIPSELECT(cs) | MXC_CSPICTRL_BITCOUNT(31) | @@ -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];