linux-kernel - Re: [PATCH v11 10/10] tty: serial: Add Nuvoton ma35d1 serial driver support

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Message-ID: <3d4acb20-c80e-fd39-c0d0-e9b1e0309d81@kernel.org>
Date:   Wed, 24 May 2023 09:42:50 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Jacky Huang <ychuang570808@...il.com>, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, lee@...nel.org,
        mturquette@...libre.com, sboyd@...nel.org, p.zabel@...gutronix.de,
        gregkh@...uxfoundation.org, tmaimon77@...il.com,
        catalin.marinas@....com, will@...nel.org
Cc:     devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-serial@...r.kernel.org, arnd@...db.de, soc@...nel.org,
        schung@...oton.com, mjchen@...oton.com,
        Jacky Huang <ychuang3@...oton.com>
Subject: Re: [PATCH v11 10/10] tty: serial: Add Nuvoton ma35d1 serial driver
 support

On 16. 05. 23, 9:52, Jacky Huang wrote:
> +static void ma35d1serial_config_port(struct uart_port *port, int flags)
> +{
> +	/*
> +	 * Driver core for serial ports forces a non-zero value for port type.
> +	 * Write an arbitrary value here to accommodate the serial core driver,
> +	 * as ID part of UAPI is redundant.
> +	 */
> +	port->type = 1;

So this 1 translates to PORT_8250. Why not to use it directly? Or 
something more saner like PORT_16550A?

> +}
> +
> +static int ma35d1serial_verify_port(struct uart_port *port, struct serial_struct *ser)
> +{
> +	if (port->type != PORT_UNKNOWN && ser->type != 1)
> +		return -EINVAL;
> +
> +	return 0;
> +}
...
> +static int __init ma35d1serial_console_setup(struct console *co, char *options)
> +{
> +	struct device_node *np = ma35d1serial_uart_nodes[co->index];
> +	struct uart_ma35d1_port *p = &ma35d1serial_ports[co->index];
> +	u32 val32[4];
> +	struct uart_port *port;
> +	int baud = 115200;
> +	int bits = 8;
> +	int parity = 'n';
> +	int flow = 'n';
> +
> +	/*
> +	 * Check whether an invalid uart number has been specified, and

You dereferenced ma35d1serial_uart_nodes already. Doesn't 
console=ttyNVT1000 (or something like that) crash the system?

> +	 * if so, search for the first available port that does have
> +	 * console support.

The code below doesn't match this comment.

> +	 */
> +	if ((co->index < 0) || (co->index >= MA35_UART_NR)) {
> +		pr_debug("Console Port%x out of range\n", co->index);
> +		return -EINVAL;
> +	}
> +
> +	if (of_property_read_u32_array(np, "reg", val32, 4) != 0)

Shouldn't that 4 be ARRAY_SIZE(val32) instead?

> +		return -EINVAL;

One \n here please.

> +	p->port.iobase = val32[1];
> +	p->port.membase = ioremap(p->port.iobase, MA35_UART_REG_SIZE);

What if this fails?

> +	p->port.ops = &ma35d1serial_ops;
> +	p->port.line = 0;
> +	p->port.uartclk = MA35_UART_CONSOLE_CLK;
> +
> +	port = &ma35d1serial_ports[co->index].port;

Isn't this:
   port = &p->port;
?

Either use port on all above lines or drop the "port" variable 
completely and use "p->port" below instead.

> +
> +	if (options)
> +		uart_parse_options(options, &baud, &parity, &bits, &flow);
> +
> +	return uart_set_options(port, co, baud, parity, bits, flow);
> +}
> +
> +static struct console ma35d1serial_console = {
> +	.name    = "ttyNVT",
> +	.write   = ma35d1serial_console_write,
> +	.device  = uart_console_device,
> +	.setup   = ma35d1serial_console_setup,
> +	.flags   = CON_PRINTBUFFER | CON_ENABLED,
> +	.index   = -1,
> +	.data    = &ma35d1serial_reg,

I don't see console->data used anywhere in the driver?

> +};
...
> +static int ma35d1serial_probe(struct platform_device *pdev)
> +{
> +	struct resource *res_mem;
> +	struct uart_ma35d1_port *up;
> +	int ret = 0;
> +
> +	if (pdev->dev.of_node) {
> +		ret = of_alias_get_id(pdev->dev.of_node, "serial");
> +		if (ret < 0) {
> +			dev_err(&pdev->dev, "failed to get alias/pdev id, errno %d\n", ret);
> +			return ret;
> +		}
> +	}
> +	up = &ma35d1serial_ports[ret];
> +	up->port.line = ret;
> +	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res_mem)
> +		return -ENODEV;
> +
> +	up->port.iobase = res_mem->start;
> +	up->port.membase = ioremap(up->port.iobase, MA35_UART_REG_SIZE);

Check this too.

> +	up->port.ops = &ma35d1serial_ops;
> +
> +	spin_lock_init(&up->port.lock);
> +
> +	up->clk = of_clk_get(pdev->dev.of_node, 0);
> +	if (IS_ERR(up->clk)) {
> +		ret = PTR_ERR(up->clk);
> +		dev_err(&pdev->dev, "failed to get core clk: %d\n", ret);
> +		goto err_iounmap;
> +	}
> +
> +	ret = clk_prepare_enable(up->clk);
> +	if (ret)
> +		goto err_iounmap;
> +
> +	if (up->port.line != 0)
> +		up->port.uartclk = clk_get_rate(up->clk);
> +
> +	ret = platform_get_irq(pdev, 0);
> +	if (ret < 0)
> +		goto err_clk_disable;
> +
> +	up->port.irq = ret;
> +	up->port.dev = &pdev->dev;
> +	up->port.flags = UPF_BOOT_AUTOCONF;
> +
> +	platform_set_drvdata(pdev, up);
> +
> +	ret = uart_add_one_port(&ma35d1serial_reg, &up->port);
> +	if (ret < 0)
> +		goto err_free_irq;
> +
> +	return 0;
> +
> +err_free_irq:
> +	free_irq(up->port.irq, &up->port);
> +
> +err_clk_disable:
> +	clk_disable_unprepare(up->clk);
> +
> +err_iounmap:
> +	iounmap(up->port.membase);
> +	return ret;
> +}

thanks,
-- 
js
suse labs