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 <hskinnemoen@atmel.com>
Tested-by: Guennadi Liakhovetski <lg@denx.de>

1 files changed, 25 insertions, 17 deletions

diff --git a/common/cmd_spi.c b/common/cmd_spi.c
index 7604422..40ee7e7 100644
--- a/common/cmd_spi.c
+++ b/common/cmd_spi.c
@@ -37,20 +37,20 @@
 #   define MAX_SPI_BYTES 32	/* Maximum number of bytes we can handle */
 #endif
 
-/*
- * External table of chip select functions (see the appropriate board
- * support for the actual definition of the table).
- */
-extern spi_chipsel_type spi_chipsel[];
-extern int spi_chipsel_cnt;
+#ifndef CONFIG_DEFAULT_SPI_BUS
+#   define CONFIG_DEFAULT_SPI_BUS	0
+#endif
+#ifndef CONFIG_DEFAULT_SPI_MODE
+#   define CONFIG_DEFAULT_SPI_MODE	SPI_MODE_0
+#endif
 
 /*
  * Values from last command.
  */
-static int   device;
-static int   bitlen;
-static uchar dout[MAX_SPI_BYTES];
-static uchar din[MAX_SPI_BYTES];
+static unsigned int	device;
+static int   		bitlen;
+static uchar 		dout[MAX_SPI_BYTES];
+static uchar 		din[MAX_SPI_BYTES];
 
 /*
  * SPI read/write
@@ -65,6 +65,7 @@ static uchar din[MAX_SPI_BYTES];
 
 int do_spi (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 {
+	struct spi_slave *slave;
 	char  *cp = 0;
 	uchar tmp;
 	int   j;
@@ -101,19 +102,24 @@ int do_spi (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 		}
 	}
 
-	if ((device < 0) || (device >=  spi_chipsel_cnt)) {
-		printf("Invalid device %d, giving up.\n", device);
-		return 1;
-	}
 	if ((bitlen < 0) || (bitlen >  (MAX_SPI_BYTES * 8))) {
 		printf("Invalid bitlen %d, giving up.\n", bitlen);
 		return 1;
 	}
 
-	debug ("spi_chipsel[%d] = %08X\n",
-		device, (uint)spi_chipsel[device]);
+	/* FIXME: Make these parameters run-time configurable */
+	slave = spi_setup_slave(CONFIG_DEFAULT_SPI_BUS, device, 1000000,
+			CONFIG_DEFAULT_SPI_MODE);
+	if (!slave) {
+		printf("Invalid device %d, giving up.\n", device);
+		return 1;
+	}
+
+	debug ("spi chipsel = %08X\n", device);
 
-	if(spi_xfer(spi_chipsel[device], bitlen, dout, din) != 0) {
+	spi_claim_bus(slave);
+	if(spi_xfer(slave, bitlen, dout, din,
+				SPI_XFER_BEGIN | SPI_XFER_END) != 0) {
 		printf("Error with the SPI transaction.\n");
 		rcode = 1;
 	} else {
@@ -123,6 +129,8 @@ int do_spi (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 		}
 		printf("\n");
 	}
+	spi_release_bus(slave);
+	spi_free_slave(slave);
 
 	return rcode;
 }