Patchwork [U-Boot,v3,2/2] mtd: nand: mxc_nand: Fix is_16bit_nand()

From: Fabio Estevam <fabio.estevam@freescale.com>

Currently is_16bit_nand() is a per SoC function and it decides the bus nand 
width by reading some boot related registers.

This method works when NAND is the boot medium, but does not work if another
boot medium is used. For example: booting from a SD card and then using NAND
to store the environment variables, would lead to the following error:

NAND bus width 16 instead 8 bit
No NAND device found!!!
0 MiB

Use CONFIG_SYS_NAND_BUSWIDTH_16BIT symbol to decide the bus width.

If it is defined in the board file, then consider 16-bit NAND bus-width, 
otherwise assume 8-bit NAND is used.

This also aligns with Documentation/devicetree/bindings/mtd/nand.txt, which
states:

nand-bus-width : 8 or 16 bus width if not present 8

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
Changes since v2:
- Fix typo "if not present 82"
Changes since v1:
- Add an entry into README
 README                      |    3 ++-
 drivers/mtd/nand/mxc_nand.c |   37 +++----------------------------------
 2 files changed, 5 insertions(+), 35 deletions(-)

Hi Fabio,

On Tuesday, February 26, 2013 11:37:45 PM, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> Currently is_16bit_nand() is a per SoC function and it decides the bus nand
> width by reading some boot related registers.
> 
> This method works when NAND is the boot medium, but does not work if another
> boot medium is used. For example: booting from a SD card and then using NAND
> to store the environment variables, would lead to the following error:
> 
> NAND bus width 16 instead 8 bit
> No NAND device found!!!
> 0 MiB
> 
> Use CONFIG_SYS_NAND_BUSWIDTH_16BIT symbol to decide the bus width.
> 
> If it is defined in the board file, then consider 16-bit NAND bus-width,
> otherwise assume 8-bit NAND is used.
> 
> This also aligns with Documentation/devicetree/bindings/mtd/nand.txt, which
> states:
> 
> nand-bus-width : 8 or 16 bus width if not present 8
> 
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
> ---
> Changes since v2:
> - Fix typo "if not present 82"
> Changes since v1:
> - Add an entry into README
>  README                      |    3 ++-
>  drivers/mtd/nand/mxc_nand.c |   37 +++----------------------------------
>  2 files changed, 5 insertions(+), 35 deletions(-)
> 
> diff --git a/README b/README
> index bdd2c81..1a6a7a5 100644
> --- a/README
> +++ b/README
> @@ -3717,8 +3717,9 @@ Low Level (hardware related) configuration options:
>  		Defined to tell the NAND controller that the NAND chip is using
>   		a 16 bit bus.
>  		Not all NAND drivers use this symbol.
> -		Example of driver that uses it:
> +		Example of drivers that use it:
>  		- drivers/mtd/nand/ndfc.c
> +		- drivers/mtd/nand/mxc_nand.c
>  
>  - CONFIG_SYS_NDFC_EBC0_CFG
>  		Sets the EBC0_CFG register for the NDFC. If not defined
> diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> index d0ded48..bb475f2 100644
> --- a/drivers/mtd/nand/mxc_nand.c
> +++ b/drivers/mtd/nand/mxc_nand.c
> @@ -98,45 +98,14 @@ static struct nand_ecclayout nand_hw_eccoob2k = {
>  #endif
>  #endif
>  
> -#ifdef CONFIG_MX27
>  static int is_16bit_nand(void)
>  {
> -	struct system_control_regs *sc_regs =
> -		(struct system_control_regs *)IMX_SYSTEM_CTL_BASE;
> -
> -	if (readl(&sc_regs->fmcr) & NF_16BIT_SEL)
> -		return 1;
> -	else
> -		return 0;
> -}
> -#elif defined(CONFIG_MX31)
> -static int is_16bit_nand(void)
> -{
> -	struct clock_control_regs *sc_regs =
> -		(struct clock_control_regs *)CCM_BASE;
> -
> -	if (readl(&sc_regs->rcsr) & CCM_RCSR_NF16B)
> -		return 1;
> -	else
> -		return 0;
> -}
> -#elif defined(CONFIG_MX25) || defined(CONFIG_MX35)
> -static int is_16bit_nand(void)
> -{
> -	struct ccm_regs *ccm = (struct ccm_regs *)IMX_CCM_BASE;
> -
> -	if (readl(&ccm->rcsr) & CCM_RCSR_NF_16BIT_SEL)
> -		return 1;
> -	else
> -		return 0;
> -}
> +#if defined(CONFIG_SYS_NAND_BUSWIDTH_16BIT)
> +	return 1;
>  #else
> -#warning "8/16 bit NAND autodetection not supported"
> -static int is_16bit_nand(void)
> -{
>  	return 0;
> -}
>  #endif
> +}
>  
>  static uint32_t *mxc_nand_memcpy32(uint32_t *dest, uint32_t *source, size_t
>  size)
>  {
> --
> 1.7.9.5

For this series:
Reviewed-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

I will integrate it as is at the beginning of the v8 of my series as planned,
unless it is applied before. I hope to post my v8 before the end of the week.

Best regards,
Benoît