kernel: backport bcm47xxsflash support for reading 32 MiB flashes

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

1 files changed, 81 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/042-0006-mtd-bcm47xxsflash-support-reading-flash-out-of-mappi.patch b/target/linux/generic/patches-4.4/042-0006-mtd-bcm47xxsflash-support-reading-flash-out-of-mappi.patch
new file mode 100644
index 0000000000..ecdae2a871
--- /dev/null
+++ b/target/linux/generic/patches-4.4/042-0006-mtd-bcm47xxsflash-support-reading-flash-out-of-mappi.patch
@@ -0,0 +1,81 @@
+From ccc38234fdc70120be79e7fb2df5c27ca5cd4c8a Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 8 Feb 2017 23:53:44 +0100
+Subject: [PATCH] mtd: bcm47xxsflash: support reading flash out of mapping
+ window
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+For reading flash content we use MMIO but it's possible to read only
+first 16 MiB this way. It's simply an arch design/limitation.
+To support flash sizes bigger than 16 MiB implement indirect access
+using ChipCommon registers.
+This has been tested using MX25L25635F.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Acked-by: Marek Vasut <marek.vasut@gmail.com>
+Signed-off-by: Brian Norris <computersforpeace@gmail.com>
+---
+ drivers/mtd/devices/bcm47xxsflash.c | 24 +++++++++++++++++++++---
+ drivers/mtd/devices/bcm47xxsflash.h |  3 +++
+ 2 files changed, 24 insertions(+), 3 deletions(-)
+
+--- a/drivers/mtd/devices/bcm47xxsflash.c
++++ b/drivers/mtd/devices/bcm47xxsflash.c
+@@ -105,15 +105,33 @@ static int bcm47xxsflash_read(struct mtd
+ 			      size_t *retlen, u_char *buf)
+ {
+ 	struct bcm47xxsflash *b47s = mtd->priv;
++	size_t orig_len = len;
+ 
+ 	/* Check address range */
+ 	if ((from + len) > mtd->size)
+ 		return -EINVAL;
+ 
+-	memcpy_fromio(buf, b47s->window + from, len);
+-	*retlen = len;
++	/* Read as much as possible using fast MMIO window */
++	if (from < BCM47XXSFLASH_WINDOW_SZ) {
++		size_t memcpy_len;
+ 
+-	return len;
++		memcpy_len = min(len, (size_t)(BCM47XXSFLASH_WINDOW_SZ - from));
++		memcpy_fromio(buf, b47s->window + from, memcpy_len);
++		from += memcpy_len;
++		len -= memcpy_len;
++		buf += memcpy_len;
++	}
++
++	/* Use indirect access for content out of the window */
++	for (; len; len--) {
++		b47s->cc_write(b47s, BCMA_CC_FLASHADDR, from++);
++		bcm47xxsflash_cmd(b47s, OPCODE_ST_READ4B);
++		*buf++ = b47s->cc_read(b47s, BCMA_CC_FLASHDATA);
++	}
++
++	*retlen = orig_len;
++
++	return orig_len;
+ }
+ 
+ static int bcm47xxsflash_write_st(struct mtd_info *mtd, u32 offset, size_t len,
+--- a/drivers/mtd/devices/bcm47xxsflash.h
++++ b/drivers/mtd/devices/bcm47xxsflash.h
+@@ -3,6 +3,8 @@
+ 
+ #include <linux/mtd/mtd.h>
+ 
++#define BCM47XXSFLASH_WINDOW_SZ			SZ_16M
++
+ /* Used for ST flashes only. */
+ #define OPCODE_ST_WREN		0x0006		/* Write Enable */
+ #define OPCODE_ST_WRDIS		0x0004		/* Write Disable */
+@@ -16,6 +18,7 @@
+ #define OPCODE_ST_RES		0x03ab		/* Read Electronic Signature */
+ #define OPCODE_ST_CSA		0x1000		/* Keep chip select asserted */
+ #define OPCODE_ST_SSE		0x0220		/* Sub-sector Erase */
++#define OPCODE_ST_READ4B	0x6313		/* Read Data Bytes in 4Byte addressing mode */
+ 
+ /* Used for Atmel flashes only. */
+ #define OPCODE_AT_READ				0x07e8