linux-kernel - Re: [PATCH 03/10] spi: spi-mem: Add driver for Aspeed SMC controllers

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Message-ID: <20220225075007.73xypamm3zbjnkg6@ti.com>
Date:   Fri, 25 Feb 2022 13:20:07 +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 03/10] spi: spi-mem: Add driver for Aspeed SMC controllers

On 14/02/22 10:42AM, Cédric Le Goater wrote:
> This SPI driver adds support for the Aspeed static memory controllers
> of the AST2600, AST2500 and AST2400 SoCs using the spi-mem interface.
> 
>  * AST2600 Firmware SPI Memory Controller (FMC)
>    . BMC firmware
>    . 3 chip select pins (CE0 ~ CE2)
>    . Only supports SPI type flash memory
>    . different segment register interface
>    . single, dual and quad mode.
> 
>  * AST2600 SPI Flash Controller (SPI1 and SPI2)
>    . host firmware
>    . 2 chip select pins (CE0 ~ CE1)
>    . different segment register interface
>    . single, dual and quad mode.
> 
>  * AST2500 Firmware SPI Memory Controller (FMC)
>    . BMC firmware
>    . 3 chip select pins (CE0 ~ CE2)
>    . supports SPI type flash memory (CE0-CE1)
>    . CE2 can be of NOR type flash but this is not supported by the driver
>    . single, dual mode.
> 
>  * AST2500 SPI Flash Controller (SPI1 and SPI2)
>    . host firmware
>    . 2 chip select pins (CE0 ~ CE1)
>    . single, dual mode.
> 
>  * AST2400 New Static Memory Controller (also referred as FMC)
>    . BMC firmware
>    . New register set
>    . 5 chip select pins (CE0 ∼ CE4)
>    . supports NOR flash, NAND flash and SPI flash memory.
>    . single, dual and quad mode.
> 
> Each controller has a memory range on which flash devices contents are
> mapped. Each device is assigned a window that can be changed at bootime
> with the Segment Address Registers.
> 
> Each SPI flash device can then be accessed in two modes: Command and
> User. When in User mode, SPI transfers are initiated with accesses to
> the memory segment of a device. When in Command mode, memory
> operations on the memory segment of a device generate SPI commands
> automatically using a Control Register for the settings.
> 
> This initial patch adds support for User mode. Command mode needs a little
> more work to check that the memory window on the AHB bus fits the device
> size. It will come later when support for direct mapping is added.
> 
> Single and dual mode RX transfers are supported. Other types than SPI
> are not supported.
> 
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@...eedtech.com>
> Signed-off-by: Cédric Le Goater <clg@...d.org>
> ---
>  drivers/spi/spi-aspeed-smc.c            | 766 ++++++++++++++++++++++++
>  drivers/mtd/spi-nor/controllers/Kconfig |   2 +-
>  drivers/spi/Kconfig                     |  11 +
>  drivers/spi/Makefile                    |   1 +
>  4 files changed, 779 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/spi/spi-aspeed-smc.c
> 
[...]
> +
> +/* support for 1-1-1, 1-1-2 or 1-1-4 */
> +static bool aspeed_spi_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
> +{
> +	if (op->cmd.buswidth > 1)
> +		return false;
> +
> +	if (op->addr.nbytes != 0) {
> +		if (op->addr.buswidth > 1 || op->addr.nbytes > 4)
> +			return false;
> +	}
> +
> +	if (op->dummy.nbytes != 0) {
> +		if (op->dummy.buswidth > 1 || op->dummy.nbytes > 7)
> +			return false;
> +	}
> +
> +	if (op->data.nbytes != 0 && op->data.buswidth > 4)
> +		return false;
> +
> +	if (!spi_mem_default_supports_op(mem, op))
> +		return false;
> +
> +	return true;

Nitpick: You can just do return spi_mem_default_supports_op(mem, op);

> +}
> +
[...]
> +
> +static int aspeed_spi_init_devices(struct platform_device *pdev, struct aspeed_spi *aspi)
> +{
> +	struct device_node *np;
> +	unsigned int cs;
> +	int ret;
> +
> +	for_each_available_child_of_node(aspi->dev->of_node, np) {
> +		struct aspeed_spi_chip *chip;
> +
> +		if (!of_device_is_compatible(np, "jedec,spi-nor"))
> +			continue;
> +
> +		ret = of_property_read_u32(np, "reg", &cs);
> +		if (ret) {
> +			dev_err(aspi->dev, "Couldn't not read chip select.\n");
> +			of_node_put(np);
> +			return ret;
> +		}
> +
> +		if (cs > aspi->data->max_cs) {
> +			dev_err(aspi->dev, "Chip select %d out of range.\n", cs);
> +			of_node_put(np);
> +			return -ERANGE;
> +		}
> +
> +		chip = &aspi->chips[cs];
> +		chip->aspi = aspi;
> +		chip->cs = cs;
> +
> +		ret = aspeed_spi_chip_init(chip);
> +		if (ret) {
> +			of_node_put(np);
> +			return ret;
> +		}
> +
> +		if (of_property_read_u32(np, "spi-max-frequency", &chip->clk_freq))
> +			chip->clk_freq = ASPEED_SPI_DEFAULT_FREQ;
> +
> +		aspi->num_cs++;
> +	}

SPI MEM already gives you all this information. Get it from there, don't 
parse it yourself.

You can get Chip Select via spi_mem->spi->chip_select.
You can get clock frequency via spi_mem->spi->max_speed_hz.

With these comments fixed,

Acked-by: Pratyush Yadav <p.yadav@...com>

> +
> +	return 0;
> +}
> +
[...]

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.