spi: pl022: Add support for chip select extension

Add support for a extended PL022 which has an extra register for controlling up
to five chip select signals. This controller is found on the AXM5516 SoC.
Unfortunately the PrimeCell identification registers are identical to a
standard ARM PL022. To work around this, the peripheral ID must be overridden
in the device tree using the "arm,primecell-periphid" property with the value
0x000b6022.

Signed-off-by: Anders Berg <anders.berg@avagotech.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/linux/amba/bus.h

@@ -44,10 +44,15 @@ struct amba_driver {
 	const struct amba_id	*id_table;
 };
 
+/*
+ * Constants for the designer field of the Peripheral ID register. When bit 7
+ * is set to '1', bits [6:0] should be the JEP106 manufacturer identity code.
+ */
 enum amba_vendor {
 	AMBA_VENDOR_ARM = 0x41,
 	AMBA_VENDOR_ST = 0x80,
 	AMBA_VENDOR_QCOM = 0x51,
+	AMBA_VENDOR_LSI = 0xb6,
 };
 
 extern struct bus_type amba_bustype;