From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Subject: Re: [PATCH V2 2/4] mtd: spi-nor: add the basic data structures Date: Wed, 11 Dec 2013 15:36:31 +0100 Message-ID: <201312111536.32091.marex@denx.de> References: <1386318764-15882-1-git-send-email-b32955@freescale.com> <201312111102.18554.marex@denx.de> <20131211143356.GA1719@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Huang Shijie , angus.clark-qxv4g6HH51o@public.gmane.org, broonie-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, pekon-l0cyMroinI0@public.gmane.org, sourav.poddar-l0cyMroinI0@public.gmane.org, computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Huang Shijie Return-path: In-Reply-To: <20131211143356.GA1719-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 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: > > > > > + > > > > > + /* 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, > > > > > 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 > > > > > + 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 ;-) > > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html