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: <e78dba15-80d0-f2c3-c963-a7eb033af58d@wedev4u.fr>
Date:   Sun, 16 Apr 2017 19:18:18 +0200
From:   Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>
To:     Guochun Mao <guochun.mao@...iatek.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,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        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

Le 13/04/2017 à 10:24, Cyrille Pitchen a écrit :
> Hi Guochun,
> 
> Le 13/04/2017 à 04:40, Guochun Mao a écrit :
>> Hi Cyrille,
>>
>> On Wed, 2017-04-12 at 22:57 +0200, Cyrille Pitchen wrote:
>>> 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>st
> 
> Acked-by: Cyrille Pitchen <cyrille.pitchen@...el.com>
> 

Applied to github/spi-nor

Thanks!

>>>> ---
>>>>  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 ?
>>
>> Yes, it can work.
>>
>> Let's see the whole function,
>>
>> 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++) {
>>                 writeb(addr & 0xff, mt8173_nor->base + MTK_NOR_RADR0_REG
>> + i * 4);
>>                 addr >>= 8;
>>         }
>>         /* Last register is non-contiguous */
>>         writeb(addr & 0xff, mt8173_nor->base + MTK_NOR_RADR3_REG);
>> }
>>
>> The nor controller has 4 registers for address.
>> This '3' indicates the number of contiguous address' registers
>> base + MTK_NOR_RADR0_REG(0x10)
>> base + MTK_NOR_RADR1_REG(0x14)
>> base + MTK_NOR_RADR2_REG(0x18),
>> but the last address register is non-contiguous,
>> it's base + MTK_NOR_RADR3_REG(0xc8)
>>
>> mt8173_nor_set_addr will set addr into these 4 registers by Byte.
>> The bit MTK_NOR_4B_ADDR_EN will decide whether 3-byte(0x10,0x14,0x18)
>> or 4-byte(0x10,0x14,x018,0xc8) been sent to nor device.
>> and, it can access data after 128Mbit when sent 4-byte address.
> 
> Indeed, you're right. Sorry for the noise!
> 
>>
>> Best regards,
>>
>> Guochun
>>
>>>
>>> Best regards,
>>>
>>> Cyrille
>>>
>>>>  		writeb(addr & 0xff, mt8173_nor->base + MTK_NOR_RADR0_REG + i * 4);
>>>>  		addr >>= 8;
>>>>
>>>
>>
>>
>>
> 
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
> 

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