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

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Dear Jiri,


On 2023/5/24 下午 04:34, Jacky Huang wrote:
Dear Jiri,

Thanks for your advice.

On 2023/5/24 下午 03:42, Jiri Slaby wrote:
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?

It's not actually 8250 or 16550A.
Can we add the following definition to 'include/uapi/linux/serial_core.h' and use PORT_MA35 instead?

#define PORT_MA35    124


+}
+
+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?


I will add the following check before np = "ma35d1serial_uart_nodes[co->index]".

if (co->index < 0 || co->index >= MA35_UART_NR)
    return -EINVAL;


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

The code below doesn't match this comment.

Yes, I will remove the above 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?


Will be fixed.

+        return -EINVAL;

One \n here please.


Okay, I will add it.

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

What if this fails?


I will add a check for the return value.

+    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.


I will remove port variable and use p->port only.

+
+    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?


I will remove it.


I removed the " .data    = &ma35d1serial_reg", but kernel crashed in 'drivers/tty/serial/serial_core.c'.

The variable 'p' of  uart_console_device() refer to a NULL, because co->data is NULL.
As a result, kernel crashed at 'p->tty_driver'.

struct tty_driver *uart_console_device(struct console *co, int *index)
{
    struct uart_driver *p = co->data;
    *index = co->index;
    return p->tty_driver;
}

We seem to be unable to remove it.
If there are no other considerations, I will keep it in the next version.

+};
...
+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.


Okay, sure.

+    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,

Best regards,
Jacky Huang


Best regards,
Jacky Huang




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