Re: [PATCH 4/6] spi: Add SPIBSC driver

[Mark Brown <broonie@kernel.org>]

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On Mon, Dec 02, 2019 at 10:45:17PM -0500, Chris Brandt wrote:

> +config SPI_SPIBSC
> +	tristate "Renesas SPI Multi I/O Bus Controller"
> +	depends on ARCH_R7S72100 || ARCH_R7S9210

I'm not seeing any build dependency here, please add an ||
COMPILE_TEST for build coverage.

> +++ b/drivers/spi/spi-spibsc.c
> @@ -0,0 +1,609 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * SPI Bus Space Controller (SPIBSC) bus driver

Please make the entire comment block here a C++ one so things
look more intentional.

> +static void spibsc_write(struct spibsc_priv *sbsc, int reg, u32 val)
> +{
> +	iowrite32(val, sbsc->base + reg);
> +}
> +static void spibsc_write8(struct spibsc_priv *sbsc, int reg, u8 val)

Blank likes between functions, please see coding-style.rst.
Looking at a bunch of the stuff here it looks like you could
benefit from regmap, it's got lots of debug infrastructure.

> +	if (tx)
> +		pr_debug("spibsc: send data: ");
> +	else
> +		pr_debug("spibsc: recv data: ");

dev_dbg() if you're going to do tis.

> +
> +	for (i = 0; i < len; ) {
> +		sprintf(line_buffer + line_index, " %02X", buf[i]);

snprintf()!

> +static int spibsc_transfer_one_message(struct spi_controller *master,
> +				       struct spi_message *msg)
> +{
> +	struct spibsc_priv *sbsc = spi_controller_get_devdata(master);
> +	struct spi_transfer *t, *t_last;
> +	u8 tx_data[MAX_CMD_LEN];
> +	int tx_only;
> +	u8 tx_len;
> +	int ret;
> +
> +	t_last = list_last_entry(&msg->transfers, struct spi_transfer,
> +				 transfer_list);
> +	/* defaults */
> +	ret = 0;
> +	sbsc->last_xfer = 0;
> +	tx_only = 1;
> +
> +	/* Analyze the messages */
> +	t = list_first_entry(&msg->transfers, struct spi_transfer,
> +			     transfer_list);
> +	if (t->rx_buf) {
> +		dev_dbg(sbsc->dev, "Cannot Rx without Tx first!\n");
> +		return -EIO;

These errors should probably be -EINVAL, you're failing on
validation here.

> +	}
> +	list_for_each_entry(t, &msg->transfers, transfer_list) {

Blank line here please as well.

> +	if (spi->bits_per_word != 8) {
> +		dev_err(sbsc->dev, "bits_per_word must be 8\n");
> +		return -EIO;
> +	}

The core will validate this for you.

> +	master->num_chipselect	= 1;
> +	master->mode_bits		= SPI_CPOL | SPI_CPHA;
> +	master->setup			= spibsc_setup;
> +	master->transfer_one_message	= spibsc_transfer_one_message;

Set bits_per_word_mask here.

> +	dev_info(&pdev->dev, "probed\n");
> +

Remove this, it's just noise.

> +static int spibsc_remove(struct platform_device *pdev)
> +{
> +	struct spibsc_priv *sbsc = dev_get_drvdata(&pdev->dev);
> +
> +	pm_runtime_put(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);

There seems to be no purpose in the runtime PM code in this
driver, there's no PM operations of any kind and the driver holds
a runtime PM reference for the entire lifetime of the device.

> +	spi_unregister_controller(sbsc->master);

You registered the controller with devm_, there's no need to
unregister it and if you do you need to use a matching devm_
unregiser.

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