From d255bb0e78d1cac5b7c8c98cb77a095f5f16de0d Mon Sep 17 00:00:00 2001 From: Haavard Skinnemoen Date: Fri, 16 May 2008 11:10:31 +0200 Subject: SPI API improvements This patch gets rid of the spi_chipsel table and adds a handful of new functions that makes the SPI layer cleaner and more flexible. Instead of the spi_chipsel table, each board that wants to use SPI gets to implement three hooks: * spi_cs_activate(): Activates the chipselect for a given slave * spi_cs_deactivate(): Deactivates the chipselect for a given slave * spi_cs_is_valid(): Determines if the given bus/chipselect combination can be activated. Not all drivers may need those extra functions however. If that's the case, the board code may just leave them out (assuming they know what the driver needs) or rely on the linker to strip them out (assuming --gc-sections is being used.) To set up communication parameters for a given slave, the driver needs to call spi_setup_slave(). This returns a pointer to an opaque spi_slave struct which must be passed as a parameter to subsequent SPI calls. This struct can be freed by calling spi_free_slave(), but most driver probably don't want to do this. Before starting one or more SPI transfers, the driver must call spi_claim_bus() to gain exclusive access to the SPI bus and initialize the hardware. When all transfers are done, the driver must call spi_release_bus() to make the bus available to others, and possibly shut down the SPI controller hardware. spi_xfer() behaves mostly the same as before, but it now takes a spi_slave parameter instead of a spi_chipsel function pointer. It also got a new parameter, flags, which is used to specify chip select behaviour. This may be extended with other flags in the future. This patch has been build-tested on all powerpc and arm boards involved. I have not tested NIOS since I don't have a toolchain for it installed, so I expect some breakage there even though I've tried fixing up everything I could find by visual inspection. I have run-time tested this on AVR32 ATNGW100 using the atmel_spi and DataFlash drivers posted as a follow-up. I'd like some help testing other boards that use the existing SPI API. But most of all, I'd like some comments on the new API. Is this stuff usable for everyone? If not, why? Changed in v4: - Build fixes for various boards, drivers and commands - Provide common struct spi_slave definition that can be extended by drivers - Pass a struct spi_slave * to spi_cs_activate and spi_cs_deactivate - Make default bus and mode build-time configurable - Override default SPI bus ID and mode on mx32ads and imx31_litekit. Changed in v3: - Add opaque struct spi_slave for controller-specific data associated with a slave. - Add spi_claim_bus() and spi_release_bus() - Add spi_free_slave() - spi_setup() is now called spi_setup_slave() and returns a struct spi_slave - soft_spi now supports four SPI modes (CPOL|CPHA) - Add bus parameter to spi_setup_slave() - Convert the new i.MX32 SPI driver - Convert the new MC13783 RTC driver Changed in v2: - Convert the mpc8xxx_spi driver and the mpc8349emds board to the new API. Signed-off-by: Haavard Skinnemoen Tested-by: Guennadi Liakhovetski --- drivers/spi/mpc8xxx_spi.c | 54 +++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 47 insertions(+), 7 deletions(-) (limited to 'drivers/spi/mpc8xxx_spi.c') diff --git a/drivers/spi/mpc8xxx_spi.c b/drivers/spi/mpc8xxx_spi.c index 2fe838c45d..136fb50052 100644 --- a/drivers/spi/mpc8xxx_spi.c +++ b/drivers/spi/mpc8xxx_spi.c @@ -24,6 +24,7 @@ #include #if defined(CONFIG_MPC8XXX_SPI) && defined(CONFIG_HARD_SPI) +#include #include #include @@ -37,6 +38,34 @@ #define SPI_TIMEOUT 1000 +struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, + unsigned int max_hz, unsigned int mode) +{ + struct spi_slave *slave; + + if (!spi_cs_is_valid(bus, cs)) + return NULL; + + slave = malloc(sizeof(struct spi_slave)); + if (!slave) + return NULL; + + slave->bus = bus; + slave->cs = cs; + + /* + * TODO: Some of the code in spi_init() should probably move + * here, or into spi_claim_bus() below. + */ + + return slave; +} + +void spi_free_slave(struct spi_slave *slave) +{ + free(slave); +} + void spi_init(void) { volatile spi8xxx_t *spi = &((immap_t *) (CFG_IMMR))->spi; @@ -53,7 +82,18 @@ void spi_init(void) spi->com = 0; /* LST bit doesn't do anything, so disregard */ } -int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din) +int spi_claim_bus(struct spi_slave *slave) +{ + return 0; +} + +void spi_release_bus(struct spi_slave *slave) +{ + +} + +int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout, + void *din, unsigned long flags) { volatile spi8xxx_t *spi = &((immap_t *) (CFG_IMMR))->spi; unsigned int tmpdout, tmpdin, event; @@ -61,11 +101,11 @@ int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din) int tm, isRead = 0; unsigned char charSize = 32; - debug("spi_xfer: chipsel %08X dout %08X din %08X bitlen %d\n", - (int)chipsel, *(uint *) dout, *(uint *) din, bitlen); + debug("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n", + slave->bus, slave->cs, *(uint *) dout, *(uint *) din, bitlen); - if (chipsel != NULL) - (*chipsel) (1); /* select the target chip */ + if (flags & SPI_XFER_BEGIN) + spi_cs_activate(slave); spi->event = 0xffffffff; /* Clear all SPI events */ @@ -135,8 +175,8 @@ int spi_xfer(spi_chipsel_type chipsel, int bitlen, uchar *dout, uchar *din) debug("*** spi_xfer: transfer ended. Value=%08x\n", tmpdin); } - if (chipsel != NULL) - (*chipsel) (0); /* deselect the target chip */ + if (flags & SPI_XFER_END) + spi_cs_deactivate(slave); return 0; } -- cgit