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Commit ccc38234 authored by Rafał Miłecki's avatar Rafał Miłecki Committed by Brian Norris
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mtd: bcm47xxsflash: support reading flash out of mapping window 



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: default avatarRafał Miłecki <rafal@milecki.pl>
Acked-by: default avatarMarek Vasut <marek.vasut@gmail.com>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent 9c8d7ff3

drivers/mtd/devices/bcm47xxsflash.c

+21 −3
Original line number Diff line number Diff line
@@ -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,

drivers/mtd/devices/bcm47xxsflash.h

+3 −0
Original line number Diff line number Diff line
@@ -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