atmel_spi: Driver for the Atmel SPI controller

This adds a driver for the SPI controller found on most AT91 and AVR32
chips, implementing the new SPI API.

Changed in v4:
  - Update to new API
  - Handle zero-length transfers appropriately. The user may send a
    zero-length SPI transfer with SPI_XFER_END set in order to
    deactivate the chip select after a series of transfers with chip
    select active. This is useful e.g. when polling the status
    register of DataFlash.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

include/asm-avr32/arch-at32ap700x/chip-features.h

@@ -25,6 +25,7 @@
 /* Currently, all the AP700x chips have these */
 #define AT32AP700x_CHIP_HAS_USART
 #define AT32AP700x_CHIP_HAS_MMCI
+#define AT32AP700x_CHIP_HAS_SPI
 
 /* Only AP7000 has ethernet interface */
 #ifdef CONFIG_AT32AP7000

include/asm-avr32/arch-at32ap700x/clk.h

@@ -74,6 +74,12 @@ static inline unsigned long get_mci_clk_rate(void)
 	return get_pbb_clk_rate();
 }
 #endif
+#ifdef AT32AP700x_CHIP_HAS_SPI
+static inline unsigned long get_spi_clk_rate(unsigned int dev_id)
+{
+	return get_pba_clk_rate();
+}
+#endif
 
 extern void clk_init(void);
 

include/asm-avr32/arch-at32ap700x/gpio.h

@@ -216,5 +216,9 @@ void gpio_enable_macb1(void);
 #ifdef AT32AP700x_CHIP_HAS_MMCI
 void gpio_enable_mmci(void);
 #endif
+#ifdef AT32AP700x_CHIP_HAS_SPI
+void gpio_enable_spi0(unsigned long cs_mask);
+void gpio_enable_spi1(unsigned long cs_mask);
+#endif
 
 #endif /* __ASM_AVR32_ARCH_GPIO_H__ */