linux-kernel - Re: [PATCH v2 6/9] spi: fsl-qspi: allot 1KB per chip

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Message-ID: <aa306536-f09b-414c-9e6d-0b69d69040a4@riscstar.com>
Date: Thu, 23 Oct 2025 19:04:14 -0500
From: Alex Elder <elder@...cstar.com>
To: Frank Li <Frank.li@....com>
Cc: han.xu@....com, broonie@...nel.org, dlan@...too.org,
 guodong@...cstar.com, linux-spi@...r.kernel.org, imx@...ts.linux.dev,
 spacemit@...ts.linux.dev, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/9] spi: fsl-qspi: allot 1KB per chip

On 10/23/25 6:38 PM, Frank Li wrote:
> On Thu, Oct 23, 2025 at 12:59:18PM -0500, Alex Elder wrote:
>> In fsl_qspi_default_setup(), four registers define the size of blocks of
>> data to written to each of four chips that comprise SPI NOR flash storage.
>> They are currently defined to be the same as the AHB buffer size (which is
>> always 1KB).
>>
>> The SpacemiT QSPI has an AHB buffer size of 512 bytes, but requires these
>> four sizes to be multiples of 1024 bytes.
>>
>> Define a new field sfa_size in the fsl_qspi_devtype_data structure that, if
>> non-zero, will be used instead of the AHB buffer size to define the size of
>> these chip regions.
>>
>> Signed-off-by: Alex Elder <elder@...cstar.com>
>> ---
>> v2: - New field fsl_qspi_devtype_data->sfa_size now defines the size of
>>         the serial flash regions if it's non-zero
>>
>>   drivers/spi/spi-fsl-qspi.c | 22 ++++++++++++----------
>>   1 file changed, 12 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/spi/spi-fsl-qspi.c b/drivers/spi/spi-fsl-qspi.c
>> index c21e3804cb032..a474d1b341b6a 100644
>> --- a/drivers/spi/spi-fsl-qspi.c
>> +++ b/drivers/spi/spi-fsl-qspi.c
>> @@ -207,6 +207,7 @@ struct fsl_qspi_devtype_data {
>>   	unsigned int txfifo;
>>   	int invalid_mstrid;
>>   	unsigned int ahb_buf_size;
>> +	unsigned int sfa_size;
>>   	unsigned int quirks;
>>   	bool little_endian;
>>   };
>> @@ -737,6 +738,7 @@ static int fsl_qspi_default_setup(struct fsl_qspi *q)
>>   {
>>   	void __iomem *base = q->iobase;
>>   	u32 reg, addr_offset = 0;
>> +	u32 size;
> 
> I think use 'sfa_size' is better to read code.

OK I'll rename in the next version.  Thanks.	-Alex

> Reviewed-by: Frank Li <Frank.Li@....com>
>>   	int ret;
>>
>>   	/* disable and unprepare clock to avoid glitch pass to controller */
>> @@ -795,17 +797,17 @@ static int fsl_qspi_default_setup(struct fsl_qspi *q)
>>   	 * In HW there can be a maximum of four chips on two buses with
>>   	 * two chip selects on each bus. We use four chip selects in SW
>>   	 * to differentiate between the four chips.
>> -	 * We use ahb_buf_size for each chip and set SFA1AD, SFA2AD, SFB1AD,
>> -	 * SFB2AD accordingly.
>> +	 *
>> +	 * By default we write the AHB buffer size to each chip, but
>> +	 * a different size can be specified with devtype_data->sfa_size.
>> +	 * The SFA1AD, SFA2AD, SFB1AD, and SFB2AD registers define the
>> +	 * top (end) of these four regions.
>>   	 */
>> -	qspi_writel(q, q->devtype_data->ahb_buf_size + addr_offset,
>> -		    base + QUADSPI_SFA1AD);
>> -	qspi_writel(q, q->devtype_data->ahb_buf_size * 2 + addr_offset,
>> -		    base + QUADSPI_SFA2AD);
>> -	qspi_writel(q, q->devtype_data->ahb_buf_size * 3 + addr_offset,
>> -		    base + QUADSPI_SFB1AD);
>> -	qspi_writel(q, q->devtype_data->ahb_buf_size * 4 + addr_offset,
>> -		    base + QUADSPI_SFB2AD);
>> +	size = q->devtype_data->sfa_size ? : q->devtype_data->ahb_buf_size;
>> +	qspi_writel(q, addr_offset + 1 * size, base + QUADSPI_SFA1AD);
>> +	qspi_writel(q, addr_offset + 2 * size, base + QUADSPI_SFA2AD);
>> +	qspi_writel(q, addr_offset + 3 * size, base + QUADSPI_SFB1AD);
>> +	qspi_writel(q, addr_offset + 4 * size, base + QUADSPI_SFB2AD);
>>
>>   	q->selected = -1;
>>
>> --
>> 2.43.0
>>