nds32: spi: Support spi dm driver.

From: rick <[email protected]>

Support spi driver and can detect MX25U1635E flash on AE3XX board.

Verification:

sf probe 0:0 50000000 0
spi_flash_std_probe(sf_Probr.c)

	spi_flash_probe_slave(sf_Probr.c)
	SF: Detected mx25u1635e with page size 256 Bytes, erase size 4 KiB, total 2 MiB
	NDS32 # sf test 0x100000 0x1000
	SPI flash test:
	0 erase: 34 ticks, 117 KiB/s 0.936 Mbps
	1 check: 15 ticks, 266 KiB/s 2.128 Mbps
	2 write: 21 ticks, 190 KiB/s 1.520 Mbps
	3 read: 11 ticks, 363 KiB/s 2.904 Mbps
	Test passed
	0 erase: 34 ticks, 117 KiB/s 0.936 Mbps
	1 check: 15 ticks, 266 KiB/s 2.128 Mbps
	2 write: 21 ticks, 190 KiB/s 1.520 Mbps
	3 read: 11 ticks, 363 KiB/s 2.904 Mbps

---
 drivers/spi/Kconfig         |    7 +
 drivers/spi/Makefile        |    1 +
 drivers/spi/nds_ae3xx_spi.c |  499 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 507 insertions(+)
 create mode 100644 drivers/spi/nds_ae3xx_spi.c

index 3c5582a..88da9a4 100644
@@ -210,6 +210,13 @@ config FSL_QSPI
 	  used to access the SPI NOR flash on platforms embedding this
 	  Freescale IP core.
 
+config NDS_AE3XX_SPI
+	bool "Andestech AE3XX SPI driver"
+	help
+	  Enable the Andestech AE3XX SPI driver. This driver can be
+	  used to access the SPI flash on platforms embedding this
+	  Andestech IP core.
+
 config TI_QSPI
 	bool "TI QSPI driver"
 	help

index 9f8b86d..cd7c755 100644
@@ -35,6 +35,7 @@ obj-$(CONFIG_MPC8XXX_SPI) += mpc8xxx_spi.o
 obj-$(CONFIG_MVEBU_A3700_SPI) += mvebu_a3700_spi.o
 obj-$(CONFIG_MXC_SPI) += mxc_spi.o
 obj-$(CONFIG_MXS_SPI) += mxs_spi.o
+obj-$(CONFIG_NDS_AE3XX_SPI) += nds_ae3xx_spi.o
 obj-$(CONFIG_OMAP3_SPI) += omap3_spi.o
 obj-$(CONFIG_PIC32_SPI) += pic32_spi.o
 obj-$(CONFIG_ROCKCHIP_SPI) += rk_spi.o

1.7.9.5