linux-kernel - Re: [PATCH 9/9] spi: atmel-quadspi: add support for sam9x60 qspi controller

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Message-ID: <5a91b6b2-0fed-f411-6e96-568e610f15fa@microchip.com>
Date:   Thu, 31 Jan 2019 12:40:04 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <bbrezillon@...nel.org>
CC:     <alexandre.belloni@...tlin.com>, <linux-kernel@...r.kernel.org>,
        <Ludovic.Desroches@...rochip.com>, <broonie@...nel.org>,
        <linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 9/9] spi: atmel-quadspi: add support for sam9x60 qspi
 controller

On 01/31/2019 01:55 PM, Boris Brezillon wrote:
> On Wed, 30 Jan 2019 15:08:47 +0000
> <Tudor.Ambarus@...rochip.com> wrote:
> 
>> +
>> +static int atmel_sam9x60_qspi_set_cfg(struct atmel_qspi *aq,
>> +				      const struct spi_mem_op *op,
>> +				      struct atmel_qspi_cfg *cfg)
>> +{
>> +	int ret = atmel_qspi_set_mode(cfg, op);
>> +
>> +	if (ret)
>> +		return ret;
>> +
>> +	cfg->icr = QSPI_ICR_INST(op->cmd.opcode);
>> +
>> +	if (!op->addr.nbytes) {
>> +		cfg->ifr |= QSPI_IFR_TFRTYP_TRSFR_REG;
>> +		if (op->data.dir == SPI_MEM_DATA_OUT)
>> +			cfg->ifr |= QSPI_IFR_APBTFRTYP_WRITE;
>> +		else
>> +			cfg->ifr |= QSPI_IFR_APBTFRTYP_READ;
>> +	} else {
>> +		cfg->ifr |= QSPI_IFR_TFRTYP_TRSFR_MEM;
> 
> Why do you use a MEM transfer here? What's the difference with a
> regular transfer?

QSPI_IFR_TFRTYP_TRSFR_MEM must be set when one wants to read/write in the serial
memory, and particularly a memory data.

QSPI_IFR_TFRTYP_TRSFR_REG must be set when one wants to read or write to serial
memory, but not a memory data.
Read examples: JEDEC_ID or QSPI_SR
Write examples: writing the configuration or the QSPI_SR.

Does this answers your question?

> 
>> +	}
>> +
>> +	/* Set data enable */
>> +	if (op->data.nbytes)
>> +		cfg->ifr |= QSPI_IFR_DATAEN;
>> +
>> +	ret = atmel_qspi_set_address_mode(cfg, op);
>> +	if (ret)
>> +		return ret;
>>  
>>  	/* Clear pending interrupts */
>>  	(void)atmel_qspi_readl(aq, QSPI_SR);
>>  
>>  	/* Set QSPI Instruction Frame registers */
>> -	atmel_qspi_writel(aq, QSPI_IAR, iar);
>> -	atmel_qspi_writel(aq, QSPI_ICR, icr);
>> -	atmel_qspi_writel(aq, QSPI_IFR, ifr);
>> +	atmel_qspi_writel(aq, QSPI_IAR, cfg->iar);
>> +	if (op->data.dir == SPI_MEM_DATA_OUT)
>> +		atmel_qspi_writel(aq, QSPI_ICR, cfg->icr);
>> +	else
>> +		atmel_qspi_writel(aq, QSPI_RICR, cfg->icr);
>> +	atmel_qspi_writel(aq, QSPI_IFR, cfg->ifr);
>> +
>> +	return 0;
>> +}
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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