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mtd: bcm47xxsflash: support reading flash out of mapping window

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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>
This commit is contained in:
Rafał Miłecki 2017-02-08 23:53:44 +01:00 committed by Brian Norris
parent 9c8d7ff32a
commit ccc38234fd
2 changed files with 24 additions and 3 deletions
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24
drivers/mtd/devices/bcm47xxsflash.c
View File

@ -105,15 +105,33 @@ static int bcm47xxsflash_read(struct mtd_info *mtd, loff_t from, size_t len,
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,

3
drivers/mtd/devices/bcm47xxsflash.h
View File

@ -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