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mtd: nand: xway: add some more documentation

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This adds some register documentation which should make it easier to
understand how this controller works. In addition it makes now use of
BIT() macro and adds some more defines.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Hauke Mehrtens 2016-06-20 23:32:07 +02:00 committed by Boris Brezillon
parent 97b671315e
commit 3d8cec2234
1 changed files with 15 additions and 6 deletions
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21
drivers/mtd/nand/xway_nand.c
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@ -16,20 +16,29 @@
#define EBU_ADDSEL1 0x24
#define EBU_NAND_CON 0xB0
#define EBU_NAND_WAIT 0xB4
#define NAND_WAIT_RD BIT(0) /* NAND flash status output */
#define NAND_WAIT_WR_C BIT(3) /* NAND Write/Read complete */
#define EBU_NAND_ECC0 0xB8
#define EBU_NAND_ECC_AC 0xBC
/* nand commands */
#define NAND_CMD_ALE (1 << 2)
#define NAND_CMD_CLE (1 << 3)
#define NAND_CMD_CS (1 << 4)
/*
* nand commands
* The pins of the NAND chip are selected based on the address bits of the
* "register" read and write. There are no special registers, but an
* address range and the lower address bits are used to activate the
* correct line. For example when the bit (1 << 2) is set in the address
* the ALE pin will be activated.
*/
#define NAND_CMD_ALE BIT(2) /* address latch enable */
#define NAND_CMD_CLE BIT(3) /* command latch enable */
#define NAND_CMD_CS BIT(4) /* chip select */
#define NAND_CMD_SE BIT(5) /* spare area access latch */
#define NAND_CMD_WP BIT(6) /* write protect */
#define NAND_WRITE_CMD_RESET 0xff
#define NAND_WRITE_CMD (NAND_CMD_CS | NAND_CMD_CLE)
#define NAND_WRITE_ADDR (NAND_CMD_CS | NAND_CMD_ALE)
#define NAND_WRITE_DATA (NAND_CMD_CS)
#define NAND_READ_DATA (NAND_CMD_CS)
#define NAND_WAIT_WR_C (1 << 3)
#define NAND_WAIT_RD (0x1)
/* we need to tel the ebu which addr we mapped the nand to */
#define ADDSEL1_MASK(x) (x << 4)