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Commit 2230b76b authored by Bryan Wu's avatar Bryan Wu Committed by David Woodhouse
Browse files

[MTD] m25p80: add FAST_READ access support to M25Pxx 



Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent afc4bca6

drivers/mtd/devices/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -77,6 +77,13 @@ config MTD_M25P80 
	  if you want to specify device partitioning or to use a device which

	  doesn't support the JEDEC ID instruction.



config M25PXX_USE_FAST_READ

	bool "Use FAST_READ OPCode allowing SPI CLK <= 50MHz"

	depends on MTD_M25P80

	default y

	help

	  This option enables FAST_READ access supported by ST M25Pxx.



config MTD_SLRAM

	tristate "Uncached system RAM"

	help

drivers/mtd/devices/m25p80.c

+21 −10
Original line number Diff line number Diff line
@@ -33,7 +33,7 @@ 
/* Flash opcodes. */

#define	OPCODE_WREN		0x06	/* Write enable */

#define	OPCODE_RDSR		0x05	/* Read status register */

#define	OPCODE_READ		0x03	/* Read data bytes (low frequency) */

#define	OPCODE_NORM_READ	0x03	/* Read data bytes (low frequency) */

#define	OPCODE_FAST_READ	0x0b	/* Read data bytes (high frequency) */

#define	OPCODE_PP		0x02	/* Page program (up to 256 bytes) */

#define	OPCODE_BE_4K 		0x20	/* Erase 4KiB block */
@@ -52,7 +52,15 @@ 


/* Define max times to check status register before we give up. */

#define	MAX_READY_WAIT_COUNT	100000

#define	CMD_SIZE		4



#ifdef CONFIG_M25PXX_USE_FAST_READ

#define OPCODE_READ 	OPCODE_FAST_READ

#define FAST_READ_DUMMY_BYTE 1

#else

#define OPCODE_READ 	OPCODE_NORM_READ

#define FAST_READ_DUMMY_BYTE 0

#endif



#ifdef CONFIG_MTD_PARTITIONS

#define	mtd_has_partitions()	(1)
@@ -68,7 +76,7 @@ struct m25p { 
	struct mtd_info		mtd;

	unsigned		partitioned:1;

	u8			erase_opcode;

	u8			command[4];

	u8			command[CMD_SIZE + FAST_READ_DUMMY_BYTE];

};



static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
@@ -167,7 +175,7 @@ static int erase_sector(struct m25p *flash, u32 offset) 
	flash->command[2] = offset >> 8;

	flash->command[3] = offset;



	spi_write(flash->spi, flash->command, sizeof(flash->command));

	spi_write(flash->spi, flash->command, CMD_SIZE);



	return 0;

}
@@ -253,8 +261,12 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len, 
	spi_message_init(&m);

	memset(t, 0, (sizeof t));



	/* NOTE:

	 * OPCODE_FAST_READ (if available) is faster.

	 * Should add 1 byte DUMMY_BYTE.

	 */

	t[0].tx_buf = flash->command;

	t[0].len = sizeof(flash->command);

	t[0].len = CMD_SIZE + FAST_READ_DUMMY_BYTE;

	spi_message_add_tail(&t[0], &m);



	t[1].rx_buf = buf;
@@ -287,7 +299,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len, 


	spi_sync(flash->spi, &m);



	*retlen = m.actual_length - sizeof(flash->command);

	*retlen = m.actual_length - CMD_SIZE - FAST_READ_DUMMY_BYTE;



	mutex_unlock(&flash->lock);
@@ -325,7 +337,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len, 
	memset(t, 0, (sizeof t));



	t[0].tx_buf = flash->command;

	t[0].len = sizeof(flash->command);

	t[0].len = CMD_SIZE;

	spi_message_add_tail(&t[0], &m);



	t[1].tx_buf = buf;
@@ -354,7 +366,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len, 


		spi_sync(flash->spi, &m);



		*retlen = m.actual_length - sizeof(flash->command);

		*retlen = m.actual_length - CMD_SIZE;

	} else {

		u32 i;
@@ -364,7 +376,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len, 
		t[1].len = page_size;

		spi_sync(flash->spi, &m);



		*retlen = m.actual_length - sizeof(flash->command);

		*retlen = m.actual_length - CMD_SIZE;



		/* write everything in PAGESIZE chunks */

		for (i = page_size; i < len; i += page_size) {
@@ -387,8 +399,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len, 
			spi_sync(flash->spi, &m);



			if (retlen)

				*retlen += m.actual_length

					- sizeof(flash->command);

				*retlen += m.actual_length - CMD_SIZE;

		}

	}