linux-kernel - Re: [PATCH v2 1/2] mtd: spi-nor: intel-spi: support chips without software sequencer

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Message-ID: <32ab6570-c3b7-4eec-7a0b-69bc2f7f76dc@fortanix.com>
Date:   Sun, 15 Sep 2019 20:41:55 +0000
From:   Jethro Beekman <jethro@...tanix.com>
To:     Marek Vasut <marek.vasut@...il.com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     Jethro Beekman <jethro@...tanix.com>
Subject: Re: [PATCH v2 1/2] mtd: spi-nor: intel-spi: support chips without
 software sequencer

Could someone please review this?

On 2019-09-04 03:15, Jethro Beekman wrote:
> Some flash controllers don't have a software sequencer. Avoid
> configuring the register addresses for it, and double check
> everywhere that its not accidentally trying to be used.
> 
> Every use of `sregs` is now guarded by a check of `sregs` or
> `swseq_reg`. The check might be done in the calling function.
> 
> Signed-off-by: Jethro Beekman <jethro@...tanix.com>
> ---
>  drivers/mtd/spi-nor/intel-spi.c | 23 ++++++++++++++++-------
>  1 file changed, 16 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/intel-spi.c b/drivers/mtd/spi-nor/intel-spi.c
> index 1ccf23f..195cdca 100644
> --- a/drivers/mtd/spi-nor/intel-spi.c
> +++ b/drivers/mtd/spi-nor/intel-spi.c
> @@ -187,12 +187,16 @@ static void intel_spi_dump_regs(struct intel_spi *ispi)
>  		dev_dbg(ispi->dev, "PR(%d)=0x%08x\n", i,
>  			readl(ispi->pregs + PR(i)));
>  
> -	value = readl(ispi->sregs + SSFSTS_CTL);
> -	dev_dbg(ispi->dev, "SSFSTS_CTL=0x%08x\n", value);
> -	dev_dbg(ispi->dev, "PREOP_OPTYPE=0x%08x\n",
> -		readl(ispi->sregs + PREOP_OPTYPE));
> -	dev_dbg(ispi->dev, "OPMENU0=0x%08x\n", readl(ispi->sregs + OPMENU0));
> -	dev_dbg(ispi->dev, "OPMENU1=0x%08x\n", readl(ispi->sregs + OPMENU1));
> +	if (ispi->sregs) {
> +		value = readl(ispi->sregs + SSFSTS_CTL);
> +		dev_dbg(ispi->dev, "SSFSTS_CTL=0x%08x\n", value);
> +		dev_dbg(ispi->dev, "PREOP_OPTYPE=0x%08x\n",
> +			readl(ispi->sregs + PREOP_OPTYPE));
> +		dev_dbg(ispi->dev, "OPMENU0=0x%08x\n",
> +			readl(ispi->sregs + OPMENU0));
> +		dev_dbg(ispi->dev, "OPMENU1=0x%08x\n",
> +			readl(ispi->sregs + OPMENU1));
> +	}
>  
>  	if (ispi->info->type == INTEL_SPI_BYT)
>  		dev_dbg(ispi->dev, "BCR=0x%08x\n", readl(ispi->base + BYT_BCR));
> @@ -367,6 +371,11 @@ static int intel_spi_init(struct intel_spi *ispi)
>  		    !(uvscc & ERASE_64K_OPCODE_MASK))
>  			ispi->erase_64k = false;
>  
> +	if (ispi->sregs == NULL && (ispi->swseq_reg || ispi->swseq_erase)) {
> +		dev_err(ispi->dev, "software sequencer not supported, but required\n");
> +		return -EINVAL;
> +	}
> +
>  	/*
>  	 * Some controllers can only do basic operations using hardware
>  	 * sequencer. All other operations are supposed to be carried out
> @@ -383,7 +392,7 @@ static int intel_spi_init(struct intel_spi *ispi)
>  	val = readl(ispi->base + HSFSTS_CTL);
>  	ispi->locked = !!(val & HSFSTS_CTL_FLOCKDN);
>  
> -	if (ispi->locked) {
> +	if (ispi->locked && ispi->sregs) {
>  		/*
>  		 * BIOS programs allowed opcodes and then locks down the
>  		 * register. So read back what opcodes it decided to support.
>