[U-Boot] [PATCH v2 2/6] sf: disable write protection for Macronix flash

[Prafulla Wadaskar]

> -----Original Message-----
> From: Simon Guinot [mailto:sguinot at lacie.com]
> Sent: Monday, May 02, 2011 2:40 AM
> To: Prafulla Wadaskar; Albert ARIBAUD; Wolfgang Denk
> Cc: u-boot at lists.denx.de; Simon Guinot
> Subject: [PATCH v2 2/6] sf: disable write protection for Macronix flash
> 
> Signed-off-by: Simon Guinot <sguinot at lacie.com>
> ---
>  drivers/mtd/spi/macronix.c |   87
> ++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 87 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/mtd/spi/macronix.c b/drivers/mtd/spi/macronix.c
> index 8e4d71c..b587ac9 100644
> --- a/drivers/mtd/spi/macronix.c
> +++ b/drivers/mtd/spi/macronix.c
> @@ -49,6 +49,10 @@
>  #define CMD_MX25XX_DP		0xb9	/* Deep Power-down */
>  #define CMD_MX25XX_RES		0xab	/* Release from DP, and Read Signature
> */
> 
> +/* Status registers */
> +#define MX25XX_SR_BP		(0xF << 2)	/* Block Protect */
> +#define MX25XX_SR_SRWP		(1 << 7)	/* Write Protect */
> +
>  struct macronix_spi_flash_params {
>  	u16 idcode;
>  	u16 page_size;
> @@ -120,6 +124,86 @@ static const struct macronix_spi_flash_params
> macronix_spi_flash_table[] = {
>  	},
>  };
> 
> +static int macronix_write_status(struct spi_flash *flash, u8 sr)
> +{
> +	u8 cmd[2];
> +	int ret;
> +
> +	ret = spi_flash_cmd(flash->spi, CMD_MX25XX_WREN, NULL, 0);
> +	if (ret < 0) {
> +		debug("SF: Enabling Write failed\n");
> +		return ret;
> +	}
> +
> +	cmd[0] = CMD_MX25XX_WRSR;
> +	cmd[1] = sr;
> +	ret = spi_xfer(flash->spi, 16, cmd, NULL, SPI_XFER_BEGIN);
> +	if (ret) {
> +		debug("SF: fail to write status register\n");
> +		return ret;
> +	}
> +
> +	spi_xfer(flash->spi, 0, NULL, NULL, SPI_XFER_END);
> +
> +	ret = spi_flash_cmd_wait_ready(flash, SPI_FLASH_PROG_TIMEOUT);
> +	if (ret < 0) {
> +		debug("SF: write status register timed out\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int macronix_read_status(struct spi_flash *flash, u8 *sr)
> +{
> +	u8 cmd = CMD_MX25XX_RDSR;
> +	int ret;
> +
> +	ret = spi_xfer(flash->spi, 8, &cmd, NULL, SPI_XFER_BEGIN);
> +	if (ret) {
> +		debug("SF: Failed to send command %02x: %d\n", cmd, ret);
> +		return ret;
> +	}
> +	ret = spi_xfer(flash->spi, 8, NULL, sr, 0);
> +	if (ret) {
> +		debug("SF: fail to read status register: %d\n", ret);
> +		return ret;
> +	}
> +
> +	spi_xfer(flash->spi, 0, NULL, NULL, SPI_XFER_END);
> +
> +	return 0;
> +}
> +
> +static int macronix_disable_protect(struct spi_flash *flash)
> +{
> +	int ret;
> +	u8 sr;
> +
> +	ret = macronix_read_status(flash, &sr);
> +	if (ret)
> +		return ret;
> +
> +	if ((sr & MX25XX_SR_BP) == 0)
> +		return ret;
> +
> +	/* Disable status register write protection. */
> +	sr &= ~MX25XX_SR_SRWP;
> +	ret = macronix_write_status(flash, sr);
> +	if (ret)
> +		return ret;
> +
> +	/* Disable block protection. */
> +	sr &= ~MX25XX_SR_BP;
> +	ret = macronix_write_status(flash, sr);
> +	if (ret)
> +		return ret;
> +
> +	printf("SF: disable write protection\n");
> +
> +	return 0;
> +}
> +
>  static int macronix_write(struct spi_flash *flash,
>  			  u32 offset, size_t len, const void *buf)
>  {
> @@ -223,5 +307,8 @@ struct spi_flash *spi_flash_probe_macronix(struct
> spi_slave *spi, u8 *idcode)
>  		* params->sectors_per_block;
>  	mcx->flash.size = mcx->flash.sector_size * params->nr_blocks;
> 
> +	if (macronix_disable_protect(&mcx->flash))
> +		printf("SF: disable write protection failed\n");
> +

This will forced disable the flash being written.
What if some one has purposely protected certain flash sectors?

This feature should be addressed through protect CLI

Regards..
Prafulla . .
   
>  	return &mcx->flash;
>  }
> --
> 1.6.3.1