linux-kernel - Re: [PATCH v1 1/1] mtd: mtk-nor: set controller's address width according to nor flash

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Message-ID: <e9eafca3-41a0-7e88-996b-9d1c51f0c132@wedev4u.fr>
Date:   Wed, 12 Apr 2017 22:57:27 +0200
From:   Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>
To:     Guochun Mao <guochun.mao@...iatek.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>
Cc:     Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
        Richard Weinberger <richard@....at>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        linux-mtd@...ts.infradead.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mediatek@...ts.infradead.org,
        David Woodhouse <dwmw2@...radead.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v1 1/1] mtd: mtk-nor: set controller's address width
 according to nor flash

Hi Guochun,

Le 05/04/2017 à 10:37, Guochun Mao a écrit :
> When nor's size larger than 16MByte, nor's address width maybe
> set to 3 or 4, and controller should change address width according
> to nor's setting.
> 
> Signed-off-by: Guochun Mao <guochun.mao@...iatek.com>
> ---
>  drivers/mtd/spi-nor/mtk-quadspi.c |   27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/mtk-quadspi.c b/drivers/mtd/spi-nor/mtk-quadspi.c
> index e661877..b637770 100644
> --- a/drivers/mtd/spi-nor/mtk-quadspi.c
> +++ b/drivers/mtd/spi-nor/mtk-quadspi.c
> @@ -104,6 +104,8 @@
>  #define MTK_NOR_MAX_RX_TX_SHIFT		6
>  /* can shift up to 56 bits (7 bytes) transfer by MTK_NOR_PRG_CMD */
>  #define MTK_NOR_MAX_SHIFT		7
> +/* nor controller 4-byte address mode enable bit */
> +#define MTK_NOR_4B_ADDR_EN		BIT(4)
>  
>  /* Helpers for accessing the program data / shift data registers */
>  #define MTK_NOR_PRG_REG(n)		(MTK_NOR_PRGDATA0_REG + 4 * (n))
> @@ -230,10 +232,35 @@ static int mt8173_nor_write_buffer_disable(struct mt8173_nor *mt8173_nor)
>  				  10000);
>  }
>  
> +static void mt8173_nor_set_addr_width(struct mt8173_nor *mt8173_nor)
> +{
> +	u8 val;
> +	struct spi_nor *nor = &mt8173_nor->nor;
> +
> +	val = readb(mt8173_nor->base + MTK_NOR_DUAL_REG);
> +
> +	switch (nor->addr_width) {
> +	case 3:
> +		val &= ~MTK_NOR_4B_ADDR_EN;
> +		break;
> +	case 4:
> +		val |= MTK_NOR_4B_ADDR_EN;
> +		break;
> +	default:
> +		dev_warn(mt8173_nor->dev, "Unexpected address width %u.\n",
> +			 nor->addr_width);
> +		break;
> +	}
> +
> +	writeb(val, mt8173_nor->base + MTK_NOR_DUAL_REG);
> +}
> +
>  static void mt8173_nor_set_addr(struct mt8173_nor *mt8173_nor, u32 addr)
>  {
>  	int i;
>  
> +	mt8173_nor_set_addr_width(mt8173_nor);
> +
>  	for (i = 0; i < 3; i++) {

Should it be 'i < nor->addr_width' instead of 'i < 3' ?
Does it work when accessing data after 128Mbit ?

Best regards,

Cyrille

>  		writeb(addr & 0xff, mt8173_nor->base + MTK_NOR_RADR0_REG + i * 4);
>  		addr >>= 8;
>