From 1cacd0f7b0d35f8e3d3f8a69ecb3b5e436d6b9e8 Mon Sep 17 00:00:00 2001
From: Jonas Gorski <jogo@openwrt.org>
Date: Sun, 22 Dec 2013 13:25:25 +0100
Subject: [PATCH 52/56] MIPS: BCM63XX: fixup mapped SPI flash access on boot

Some bootloaders leave the flash access in an invalid state with dual
read enabled; fix it by disabling it and falling back to simple fast
reads.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
---
 arch/mips/bcm63xx/dev-flash.c | 51 ++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

--- a/arch/mips/bcm63xx/dev-flash.c
+++ b/arch/mips/bcm63xx/dev-flash.c
@@ -16,6 +16,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
 #include <linux/mtd/physmap.h>
+#include <linux/mtd/spi-nor.h>
 
 #include <bcm63xx_cpu.h>
 #include <bcm63xx_dev_flash.h>
@@ -110,9 +111,59 @@ static int __init bcm63xx_detect_flash_t
 	}
 }
 
+#define HSSPI_FLASH_CTRL_REG		0x14
+#define FLASH_CTRL_READ_OPCODE_MASK	0xff
+#define FLASH_CTRL_ADDR_BYTES_MASK	(0x3 << 8)
+#define FLASH_CTRL_ADDR_BYTES_2		(0 << 8)
+#define FLASH_CTRL_ADDR_BYTES_3		(1 << 8)
+#define FLASH_CTRL_ADDR_BYTES_4		(2 << 8)
+#define FLASH_CTRL_DUMMY_BYTES_SHIFT	10
+#define FLASH_CTRL_DUMMY_BYTES_MASK	(0x3 << FLASH_CTRL_DUMMY_BYTES_SHIFT)
+#define FLASH_CTRL_MB_EN		(1 << 23)
+
 void __init bcm63xx_flash_detect(void)
 {
 	flash_type = bcm63xx_detect_flash_type();
+
+	/* ensure flash mapping has sane values */
+	if (flash_type == BCM63XX_FLASH_TYPE_SERIAL &&
+	    (BCMCPU_IS_6318() || BCMCPU_IS_6328() || BCMCPU_IS_6362() ||
+	     BCMCPU_IS_63268())) {
+		u32 val = bcm_rset_readl(RSET_HSSPI, HSSPI_FLASH_CTRL_REG);
+
+		if (val & FLASH_CTRL_MB_EN) {
+			/* cfe might configure non working dual-io mode */
+			val &= ~FLASH_CTRL_MB_EN;
+			val &= ~FLASH_CTRL_READ_OPCODE_MASK;
+			val &= ~FLASH_CTRL_DUMMY_BYTES_MASK;
+			val |= 1 << FLASH_CTRL_DUMMY_BYTES_SHIFT;
+
+			switch (val & FLASH_CTRL_ADDR_BYTES_MASK) {
+			case FLASH_CTRL_ADDR_BYTES_3:
+				val |= SPINOR_OP_READ_FAST;
+				break;
+			case FLASH_CTRL_ADDR_BYTES_4:
+				val |= SPINOR_OP_READ_FAST_4B;
+				break;
+			case FLASH_CTRL_ADDR_BYTES_2:
+			default:
+				pr_warn("unsupported address byte mode (%x), not fixing up\n",
+					val & FLASH_CTRL_ADDR_BYTES_MASK);
+				return;
+			}
+		} else {
+			/* ensure dummy bytes is set to 1 for _FAST reads */
+			u8 cmd = val & FLASH_CTRL_READ_OPCODE_MASK;
+
+			if (cmd != SPINOR_OP_READ_FAST && cmd != SPINOR_OP_READ_FAST_4B)
+				return;
+
+			val &= ~FLASH_CTRL_DUMMY_BYTES_MASK;
+			val |= 1 << FLASH_CTRL_DUMMY_BYTES_SHIFT;
+		}
+
+		bcm_rset_writel(RSET_HSSPI, val, HSSPI_FLASH_CTRL_REG);
+	}
 }
 
 int __init bcm63xx_flash_register(void)
