[U-Boot] [RFC PATCH v1] kirkwood_nand: claim MPP pins on the fly

[Scott Wood <oss@buserror.net>]

On Fri, 2016-01-15 at 17:22 +1300, Chris Packham wrote:
> Claim the MPP pins for the NAND flash controller only when it's actually
> being used. This allows the pins to be shared with the SPI interface
> which already supports an equivalent on-access MPP reconfiguration.
> 
> Reviewed-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
> Signed-off-by: Chris Packham <judge.packham@gmail.com>
> ---
> I haven't wrapped this with a configuration option because I think it
> should be safe to enable by default. It will either re-apply the same
> MPP configuration that has already been done in the board init or put
> the MPP pins into the correct mode to access NAND.
> 
> I've only got access to one kirkwood based board with NAND flash so I'd
> appreciate some feedback from someone with access to a few different
> boards.
> 
> From the datasheets I have access to it looks like there is only one
> possible MPP configuration for NF_IO[0-7] so that is what I've
> implemented. I'm not aware of anything using this driver that needs a
> different MPP config.
> 
>  drivers/mtd/nand/kirkwood_nand.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/mtd/nand/kirkwood_nand.c
> b/drivers/mtd/nand/kirkwood_nand.c
> index 4fc34d6..ff81212 100644
> --- a/drivers/mtd/nand/kirkwood_nand.c
> +++ b/drivers/mtd/nand/kirkwood_nand.c
> @@ -9,6 +9,7 @@
>  #include <common.h>
>  #include <asm/io.h>
>  #include <asm/arch/soc.h>
> +#include <asm/arch/mpp.h>
>  #include <nand.h>
>  
>  /* NAND Flash Soc registers */
> @@ -22,6 +23,8 @@ struct kwnandf_registers {
>  static struct kwnandf_registers *nf_reg =
>  	(struct kwnandf_registers *)KW_NANDF_BASE;
>  
> +static u32 nand_mpp_backup[9] = { 0 };

There's a non-static nand_mpp_backup[] in drivers/spi/kirkwood_spi.c, with a
different length.  And the length assumed by kirkwood_mpp_conf seems to be
different still (and larger than the spi array).

> +
>  /*
>   * hardware specific access to control-lines/bits
>   */
> @@ -49,6 +52,22 @@ static void kw_nand_hwcontrol(struct mtd_info *mtd, int
> cmd,
>  void kw_nand_select_chip(struct mtd_info *mtd, int chip)
>  {
>  	u32 data;
> +	u32 nand_config[] = {
> +		MPP0_NF_IO2,
> +		MPP1_NF_IO3,
> +		MPP2_NF_IO4,
> +		MPP3_NF_IO5,
> +		MPP4_NF_IO6,
> +		MPP5_NF_IO7,
> +		MPP18_NF_IO0,
> +		MPP19_NF_IO1,
> +		0
> +	};

If you make this static const the compiler won't need to create the table at
runtime.

-Scott