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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
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