linux-kernel - Re: [PATCH 04/10] spi: aspeed: Add support for direct mapping

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Date:   Fri, 25 Feb 2022 14:42:19 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Cédric Le Goater <clg@...d.org>
CC:     <linux-spi@...r.kernel.org>, <linux-mtd@...ts.infradead.org>,
        Mark Brown <broonie@...nel.org>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-aspeed@...ts.ozlabs.org>, Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>,
        Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>,
        <devicetree@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/10] spi: aspeed: Add support for direct mapping

On 14/02/22 10:42AM, Cédric Le Goater wrote:
> Use direct mapping to read the flash device contents. This operation
> mode is called "Command mode" on Aspeed SoC SMC controllers. It uses a
> Control Register for the settings to apply when a memory operation is
> performed on the flash device mapping window.
> 
> If the window is not big enough, fall back to the "User mode" to
> perform the read.
> 
> Direct mapping for writes will come later when validated.
> 
> Signed-off-by: Cédric Le Goater <clg@...d.org>
> ---
>  drivers/spi/spi-aspeed-smc.c | 67 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 65 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/spi/spi-aspeed-smc.c b/drivers/spi/spi-aspeed-smc.c
> index 0aeff6f468af..8d33fcb7736a 100644
> --- a/drivers/spi/spi-aspeed-smc.c
> +++ b/drivers/spi/spi-aspeed-smc.c
> @@ -345,8 +345,8 @@ static int do_aspeed_spi_exec_op(struct spi_mem *mem, const struct spi_mem_op *o
>  		if (!op->addr.nbytes)
>  			ret = aspeed_spi_read_reg(chip, op);
>  		else
> -			ret = aspeed_spi_read_user(chip, op, op->addr.val,
> -						   op->data.nbytes, op->data.buf.in);
> +			memcpy_fromio(op->data.buf.in, chip->ahb_base + op->addr.val,
> +				      op->data.nbytes);

Why change this? exec_op should be independent from dirmap APIs. And you 
don't even do the ahb_window_size checks here.

>  	} else {
>  		if (!op->addr.nbytes)
>  			ret = aspeed_spi_write_reg(chip, op);
> @@ -426,10 +426,73 @@ static int aspeed_spi_chip_set_default_window(struct aspeed_spi_chip *chip)
>  	return chip->ahb_window_size ? 0 : -1;
>  }
>  
> +static int aspeed_spi_dirmap_create(struct spi_mem_dirmap_desc *desc)
> +{
> +	struct aspeed_spi *aspi = spi_controller_get_devdata(desc->mem->spi->master);
> +	struct aspeed_spi_chip *chip = &aspi->chips[desc->mem->spi->chip_select];
> +	struct spi_mem_op *op = &desc->info.op_tmpl;
> +	u32 ctl_val;
> +	int ret = 0;
> +
> +	chip->clk_freq = desc->mem->spi->max_speed_hz;
> +
> +	/* Only for reads */
> +	if (op->data.dir != SPI_MEM_DATA_IN)
> +		return -EOPNOTSUPP;
> +
> +	if (desc->info.length > chip->ahb_window_size)
> +		dev_warn(aspi->dev, "CE%d window (%dMB) too small for mapping",
> +			 chip->cs, chip->ahb_window_size >> 20);
> +
> +	/* Define the default IO read settings */
> +	ctl_val = readl(chip->ctl) & ~CTRL_IO_CMD_MASK;
> +	ctl_val |= aspeed_spi_get_io_mode(op) |
> +		op->cmd.opcode << CTRL_COMMAND_SHIFT |
> +		CTRL_IO_DUMMY_SET(op->dummy.nbytes / op->dummy.buswidth) |
> +		CTRL_IO_MODE_READ;
> +
> +	/* Tune 4BYTE address mode */
> +	if (op->addr.nbytes) {
> +		u32 addr_mode = readl(aspi->regs + CE_CTRL_REG);
> +
> +		if (op->addr.nbytes == 4)
> +			addr_mode |= (0x11 << chip->cs);
> +		else
> +			addr_mode &= ~(0x11 << chip->cs);
> +		writel(addr_mode, aspi->regs + CE_CTRL_REG);
> +	}
> +
> +	/* READ mode is the controller default setting */
> +	chip->ctl_val[ASPEED_SPI_READ] = ctl_val;
> +	writel(chip->ctl_val[ASPEED_SPI_READ], chip->ctl);
> +
> +	dev_info(aspi->dev, "CE%d read buswidth:%d [0x%08x]\n",
> +		 chip->cs, op->data.buswidth, chip->ctl_val[ASPEED_SPI_READ]);
> +
> +	return ret;
> +}
> +
> +static int aspeed_spi_dirmap_read(struct spi_mem_dirmap_desc *desc,
> +				  u64 offset, size_t len, void *buf)
> +{
> +	struct aspeed_spi *aspi = spi_controller_get_devdata(desc->mem->spi->master);
> +	struct aspeed_spi_chip *chip = &aspi->chips[desc->mem->spi->chip_select];
> +
> +	/* Switch to USER command mode if mapping window is too small */
> +	if (chip->ahb_window_size < offset + len)
> +		aspeed_spi_read_user(chip, &desc->info.op_tmpl, offset, len, buf);
> +	else
> +		memcpy_fromio(buf, chip->ahb_base + offset, len);
> +
> +	return len;
> +}
> +
>  static const struct spi_controller_mem_ops aspeed_spi_mem_ops = {
>  	.supports_op = aspeed_spi_supports_op,
>  	.exec_op = aspeed_spi_exec_op,
>  	.get_name = aspeed_spi_get_name,
> +	.dirmap_create = aspeed_spi_dirmap_create,
> +	.dirmap_read = aspeed_spi_dirmap_read,
>  };
>  
>  static void aspeed_spi_chip_set_type(struct aspeed_spi_chip *chip, int type)
> -- 
> 2.34.1
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.