mips: add initial support for qca956x referenced board

QCA9563 is CPU used on AP152 board :

    Clock speed : 750 MHz ,
    Arch :  Mips 74Kc,
    Eth : SGMII interface,
    MIMO config : 3 * 3 450M,
    2 * USB 2.0,

Signed-off-by: Rosy Song <rosysong@rosinson.com>

Changes for v2:
   - coding style cleanup
   - remove ununsed flash chip in defconfig
   - enable automatic icache / dcache size in defconfig

Changes for v3:
   - add detailed information for qca956x in commit message

Changes for v4:
   - remove pre-configured network settings in ap152.h

Changes for v5:
   - coding style cleanup
diff --git a/board/qca/ap152/ap152.c b/board/qca/ap152/ap152.c
new file mode 100644
index 0000000..30cd565
--- /dev/null
+++ b/board/qca/ap152/ap152.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Rosy Song <rosysong@rosinson.com>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/addrspace.h>
+#include <asm/types.h>
+#include <mach/ar71xx_regs.h>
+#include <mach/ddr.h>
+#include <mach/ath79.h>
+#include <debug_uart.h>
+
+#define RST_RESET_RTC_RESET_LSB 27
+#define RST_RESET_RTC_RESET_MASK 0x08000000
+#define RST_RESET_RTC_RESET_SET(x) \
+	(((x) << RST_RESET_RTC_RESET_LSB) & RST_RESET_RTC_RESET_MASK)
+
+#ifdef CONFIG_DEBUG_UART_BOARD_INIT
+void board_debug_uart_init(void)
+{
+	void __iomem *regs;
+	u32 val;
+
+	regs = map_physmem(AR71XX_GPIO_BASE, AR71XX_GPIO_SIZE,
+			   MAP_NOCACHE);
+
+	/* UART : RX18, TX22 done
+	 * GPIO18 as input, GPIO22 as output
+	 */
+	val = readl(regs + AR71XX_GPIO_REG_OE);
+	val |= QCA956X_GPIO(18);
+	val &= ~QCA956X_GPIO(22);
+	writel(val, regs + AR71XX_GPIO_REG_OE);
+
+	/*
+	 * Enable GPIO22 as UART0_SOUT
+	 */
+	val = readl(regs + QCA956X_GPIO_REG_OUT_FUNC5);
+	val &= ~QCA956X_GPIO_MUX_MASK(16);
+	val |= QCA956X_GPIO_OUT_MUX_UART0_SOUT << 16;
+	writel(val, regs + QCA956X_GPIO_REG_OUT_FUNC5);
+
+	/*
+	 * Enable GPIO18 as UART0_SIN
+	 */
+	val = readl(regs + QCA956X_GPIO_REG_IN_ENABLE0);
+	val &= ~QCA956X_GPIO_MUX_MASK(8);
+	val |= QCA956X_GPIO_IN_MUX_UART0_SIN << 8;
+	writel(val, regs + QCA956X_GPIO_REG_IN_ENABLE0);
+
+	/*
+	 * Enable GPIO22 output
+	 */
+	val = readl(regs + AR71XX_GPIO_REG_OUT);
+	val |= QCA956X_GPIO(22);
+	writel(val, regs + AR71XX_GPIO_REG_OUT);
+}
+#endif
+
+int board_early_init_f(void)
+{
+	u32 reg;
+	void __iomem *rst_regs = map_physmem(AR71XX_RESET_BASE,
+							 AR71XX_RESET_SIZE, MAP_NOCACHE);
+
+#ifndef CONFIG_SKIP_LOWLEVEL_INIT
+	/* CPU:775, DDR:650, AHB:258 */
+	qca956x_pll_init();
+	qca956x_ddr_init();
+#endif
+
+	/* Take WMAC out of reset */
+	reg = readl(rst_regs + QCA956X_RESET_REG_RESET_MODULE);
+	reg &= (~RST_RESET_RTC_RESET_SET(1));
+	writel(reg, rst_regs + QCA956X_RESET_REG_RESET_MODULE);
+
+	ath79_eth_reset();
+	return 0;
+}