linux-kernel - Re: [PATCH 2/2] serial: tegra-utc: Add driver for Tegra UART Trace Controller (UTC)

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Message-ID: <Z5nTm9UniwCgGNOY@smile.fi.intel.com>
Date: Wed, 29 Jan 2025 09:07:07 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Kartik Rajput <kkartik@...dia.com>
Cc: gregkh@...uxfoundation.org, jirislaby@...nel.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, thierry.reding@...il.com,
	jonathanh@...dia.com, hvilleneuve@...onoff.com, arnd@...nel.org,
	geert+renesas@...der.be, robert.marko@...tura.hr,
	schnelle@...ux.ibm.com, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org, devicetree@...r.kernel.org,
	linux-tegra@...r.kernel.org
Subject: Re: [PATCH 2/2] serial: tegra-utc: Add driver for Tegra UART Trace
 Controller (UTC)

On Tue, Jan 28, 2025 at 12:16:33PM +0530, Kartik Rajput wrote:
> The Tegra264 SoC supports the UART Trace Controller (UTC), which allows
> multiple firmware clients (up to 16) to share a single physical UART.
> Each client is provided with its own interrupt and has access to a
> 128-character wide FIFO for both transmit (TX) and receive (RX)
> operations.
> 
> Add tegra-utc driver to support Tegra UART Trace Controller (UTC)
> client.

...

> +static int tegra_utc_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct tegra_utc_port *tup;
> +	int index;
> +	int ret;
> +
> +	index = of_alias_get_id(np, "serial");
> +	if (index < 0) {
> +		dev_err(&pdev->dev, "failed to get alias id, err %d\n", index);
> +		return index;
> +	}

Can we please use uart_read_port_properties() instead of open-coding everything
again and again?

> +	tup = devm_kzalloc(&pdev->dev, sizeof(struct tegra_utc_port), GFP_KERNEL);
> +	if (!tup)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u32(np, "current-speed", &tup->baudrate);

Why not clock-frequency? But if needed, add this to the above mentioned API as
I know more than one driver may utilise this.


> +	if (ret) {
> +		dev_err(&pdev->dev, "missing current-speed device-tree property\n");

With

	struct device *dev = &pdev-dev;

this and other lines will be neater.

> +		return ret;

		return dev_err_probe(...);

> +	}
> +
> +	ret = of_property_read_u32(np, "nvidia,utc-fifo-threshold", &tup->fifo_threshold);
> +	if (ret) {
> +		dev_err(&pdev->dev, "missing nvidia,fifo-threshold device-tree property\n");
> +		return ret;
> +	}
> +
> +	tup->irq = platform_get_irq(pdev, 0);
> +	if (tup->irq < 0) {

> +		dev_err(&pdev->dev, "failed to get interrupt\n");

Dup. This error report is done by the above API.

> +		return tup->irq;
> +	}

> +	tup->soc = of_device_get_match_data(&pdev->dev);

> +	tup->tx_base = devm_platform_ioremap_resource_byname(pdev, "tx");
> +	if (IS_ERR(tup->tx_base))
> +		return PTR_ERR(tup->tx_base);
> +
> +	tup->rx_base = devm_platform_ioremap_resource_byname(pdev, "rx");
> +	if (IS_ERR(tup->rx_base))
> +		return PTR_ERR(tup->rx_base);
> +
> +	tegra_utc_setup_port(&pdev->dev, tup, index);
> +	platform_set_drvdata(pdev, tup);
> +
> +	return tegra_utc_register_port(tup);
> +}

...

> +static const struct of_device_id tegra_utc_of_match[] = {
> +	{ .compatible = "nvidia,tegra264-utc", .data = &tegra264_utc_soc },
> +	{},

No comma for the terminator line.

> +};

-- 
With Best Regards,
Andy Shevchenko