[PATCH] SPI: Freescale iMX SPI controller driver (BIS+)

Add the SPI controller driver for Freescale i.MX(S/L/1).
Main features summary:

 > Per chip setup via board specific code and/or protocol driver.
 > Per transfer setup.
 > PIO transfers.
 > DMA transfers.
 > Managing of NULL tx / rx buffer for rd only / wr only transfers.

This patch replace patch-2.6.20-rc4-spi_imx with the following changes:
 > Few cosmetic changes.
 > Function map_dma_buffers now return 0 for success and -1 for failure.
 > Solved a bug inside spi_imx_probe function (wrong error path).
 > Solved a bug inside setup function (bad undo setup for max_speed_hz).
 > For read-only transfers, always write zero bytes.

This is almost the same as the 'BIS' version sent by Andrea, except for
updating the 'DUMMY' byte so that read-only transfers shift out zeroes.
That part of the API changed recently, since some half duplex peripheral
chips require that semantic.

Signed-off-by: Andrea Paterniani <a.paterniani@swapp-eng.it>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/Kconfig

@@ -75,6 +75,13 @@ config SPI_BUTTERFLY
 	  inexpensive battery powered microcontroller evaluation board.
 	  This same cable can be used to flash new firmware.
 
+config SPI_IMX
+	tristate "Freescale iMX SPI controller"
+	depends on SPI_MASTER && ARCH_IMX && EXPERIMENTAL
+	help
+	  This enables using the Freescale iMX SPI controller in master
+	  mode.
+
 config SPI_MPC83xx
 	tristate "Freescale MPC83xx SPI controller"
 	depends on SPI_MASTER && PPC_83xx && EXPERIMENTAL
@@ -94,6 +101,7 @@ config SPI_OMAP_UWIRE
 	help
 	  This hooks up to the MicroWire controller on OMAP1 chips.
 
+
 config SPI_PXA2XX
 	tristate "PXA2xx SSP SPI master"
 	depends on SPI_MASTER && ARCH_PXA && EXPERIMENTAL

drivers/spi/Makefile

@@ -13,6 +13,7 @@ obj-$(CONFIG_SPI_MASTER)		+= spi.o
 # SPI master controller drivers (bus)
 obj-$(CONFIG_SPI_BITBANG)		+= spi_bitbang.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi_butterfly.o
+obj-$(CONFIG_SPI_IMX)			+= spi_imx.o
 obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
 obj-$(CONFIG_SPI_OMAP_UWIRE)		+= omap_uwire.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o

include/asm-arm/arch-imx/spi_imx.h

@@ -0,0 +1,72 @@
+/*
+ * include/asm-arm/arch-imx/spi_imx.h
+ *
+ * Copyright (C) 2006 SWAPP
+ *	Andrea Paterniani <a.paterniani@swapp-eng.it>
+ *
+ * Initial version inspired by:
+ *	linux-2.6.17-rc3-mm1/include/asm-arm/arch-pxa/pxa2xx_spi.h
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef SPI_IMX_H_
+#define SPI_IMX_H_
+
+
+/*-------------------------------------------------------------------------*/
+/**
+ * struct spi_imx_master - device.platform_data for SPI controller devices.
+ * @num_chipselect: chipselects are used to distinguish individual
+ *	SPI slaves, and are numbered from zero to num_chipselects - 1.
+ *	each slave has a chipselect signal, but it's common that not
+ *	every chipselect is connected to a slave.
+ * @enable_dma: if true enables DMA driven transfers.
+*/
+struct spi_imx_master {
+	u8 num_chipselect;
+	u8 enable_dma:1;
+};
+/*-------------------------------------------------------------------------*/
+
+
+/*-------------------------------------------------------------------------*/
+/**
+ * struct spi_imx_chip - spi_board_info.controller_data for SPI
+ * slave devices, copied to spi_device.controller_data.
+ * @enable_loopback : used for test purpouse to internally connect RX and TX
+ *	sections.
+ * @enable_dma : enables dma transfer (provided that controller driver has
+ *	dma enabled too).
+ * @ins_ss_pulse : enable /SS pulse insertion between SPI burst.
+ * @bclk_wait : number of bclk waits between each bits_per_word SPI burst.
+ * @cs_control : function pointer to board-specific function to assert/deassert
+ *	I/O port to control HW generation of devices chip-select.
+*/
+struct spi_imx_chip {
+	u8	enable_loopback:1;
+	u8	enable_dma:1;
+	u8	ins_ss_pulse:1;
+	u16	bclk_wait:15;
+	void (*cs_control)(u32 control);
+};
+
+/* Chip-select state */
+#define SPI_CS_ASSERT			(1 << 0)
+#define SPI_CS_DEASSERT			(1 << 1)
+/*-------------------------------------------------------------------------*/
+
+
+#endif /* SPI_IMX_H_*/