On Wednesday, December 11, 2013 at 03:33:58 PM, Huang Shijie wrote:

On Wed, Dec 11, 2013 at 11:02:18AM +0100, Marek Vasut wrote:

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+
+	/* the two fundamental primitives */
+	int (*read_xfer)(struct spi_nor *nor, struct spi_nor_xfer_cfg
*cfg, +			 u8 *buf, size_t len);
+	int (*write_xfer)(struct spi_nor *nor, struct spi_nor_xfer_cfg
*cfg, +			  u8 *buf, size_t len);
+
+	int (*read_reg)(struct spi_nor *nor, u8 opcode, u8 *buf, int
len); +	int (*write_reg)(struct spi_nor *nor, u8 opcode, u8 

*buf,

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int len, +			int write_enable);

This stuff -- I mean 'read SPI NOR register' and 'write SPI NOR
register'. I would love to see an API which grows as needed, not an API
which is bloated by unused function right from the start.

I should send out my fsl-quadspi driver in the next version.

The read_reg/write_reg are implemented by the m25p80 and fsl-quadspi
now.

I think Lee's driver can implemente the read_xfer/write_xfer.

OK
 

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+	const struct spi_device_id *(*read_id)(struct spi_nor *nor);
+	int (*wait_till_ready)(struct spi_nor *nor);
+
+	/* write */
+	void (*write)(struct spi_nor *nor, loff_t to,
+			size_t len, size_t *retlen, const u_char *buf);
+	/* read */
+	int (*read)(struct spi_nor *nor, loff_t from,
+			size_t len, size_t *retlen, u_char *buf);
+	/* erase */
+	int (*erase)(struct spi_nor *nor, loff_t offs);

How do you specify what to erase (sub-sector, sector, whole chip)
here ?

I use a write_reg(OPCODE_ERASE_CHIP) to erase the whole chip.
Please read the patch 3.

This hook is used to erase a sector.

I suspect we might need a much better documentation for this structure,
it is hardly clear which function does what ;-)

sorry, i will add more comment in the next version.

Thanks ;-)

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Btw, what is the sub-sector mean? which opcodes for the sub-sector?

On large chips with for example 64K big sectors, you can erase a
sub-sector area, usually a 4K one. This reduces the wear of the chip.
See these defines in

m25p80.c :
  46 #define OPCODE_BE_4K            0x20    /* Erase 4KiB block */
  48 #define OPCODE_BE_32K           0x52    /* Erase 32KiB block */
  49 #define OPCODE_CHIP_ERASE       0xc7    /* Erase whole flash chip */

ok.

the @erase hook can be used for sub-sector too.

I don't quite get how, but maybe you can elaborate on that one more in the next 
version of the patches :)

Best regards,
Marek Vasut