MIPS: ath79: add common SPI controller device

Several boards are using the built-in SPI controller of the
AR71XX/AR724X/AR913X SoCs. This patch adds common platform_device
and helper code to register it. Additionally, the patch registers
the SPI bus on the PB44 board.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Cc: Kathy Giori <Kathy.Giori@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1956/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/ath79/dev-spi.c b/arch/mips/ath79/dev-spi.c
new file mode 100644
index 0000000..aa30163
--- /dev/null
+++ b/arch/mips/ath79/dev-spi.c
@@ -0,0 +1,38 @@
+/*
+ *  Atheros AR71XX/AR724X/AR913X SPI controller device
+ *
+ *  Copyright (C) 2008-2010 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ */
+
+#include <linux/platform_device.h>
+#include <asm/mach-ath79/ar71xx_regs.h>
+#include "dev-spi.h"
+
+static struct resource ath79_spi_resources[] = {
+	{
+		.start	= AR71XX_SPI_BASE,
+		.end	= AR71XX_SPI_BASE + AR71XX_SPI_SIZE - 1,
+		.flags	= IORESOURCE_MEM,
+	},
+};
+
+static struct platform_device ath79_spi_device = {
+	.name		= "ath79-spi",
+	.id		= -1,
+	.resource	= ath79_spi_resources,
+	.num_resources	= ARRAY_SIZE(ath79_spi_resources),
+};
+
+void __init ath79_register_spi(struct ath79_spi_platform_data *pdata,
+			       struct spi_board_info const *info,
+			       unsigned n)
+{
+	spi_register_board_info(info, n);
+	ath79_spi_device.dev.platform_data = pdata;
+	platform_device_register(&ath79_spi_device);
+}