Re: [PATCH v2 2/3] tty: serial: 8250: Add loongson uart driver support

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On 04/08/2024 08:38, zhenghaowei@xxxxxxxxxxx wrote:
> From: Haowei Zheng <zhenghaowei@xxxxxxxxxxx>
> 
> Due to certain hardware design challenges, we have opted to
> utilize a dedicated UART driver to probe the UART interface.
> 
> Presently, we have defined four parameters — 'fractional-division',
> 'invert-rts', 'invert-dtr', 'invert-cts', and 'invert-dsr' — which
> will be employed as needed.
> 
> Signed-off-by: Haowei Zheng <zhenghaowei@xxxxxxxxxxx>
> ---
>  drivers/tty/serial/8250/8250_loongson.c | 208 ++++++++++++++++++++++++
>  drivers/tty/serial/8250/8250_port.c     |   8 +
>  drivers/tty/serial/8250/Kconfig         |   9 +
>  drivers/tty/serial/8250/Makefile        |   1 +
>  include/uapi/linux/serial_core.h        |   1 +
>  5 files changed, 227 insertions(+)
>  create mode 100644 drivers/tty/serial/8250/8250_loongson.c
> 
> diff --git a/drivers/tty/serial/8250/8250_loongson.c b/drivers/tty/serial/8250/8250_loongson.c
> new file mode 100644
> index 000000000000..eb16677f1dde
> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_loongson.c
> @@ -0,0 +1,208 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2020-2024 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/acpi.h>

How is this used?

> +#include <linux/clk.h>

And this?

> +#include <linux/console.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/reset.h>
> +
> +#include "8250.h"
> +
> +struct loongson_uart_data {
> +	struct reset_control *rst;
> +	int line;
> +	int mcr_invert;
> +	int msr_invert;
> +};

...

> +static int loongson_uart_probe(struct platform_device *pdev)
> +{
> +	struct uart_8250_port uart = {};
> +	struct loongson_uart_data *data;
> +	struct uart_port *port;
> +	struct resource *res;
> +	int ret;
> +
> +	port = &uart.port;
> +	spin_lock_init(&port->lock);
> +
> +	port->flags		= UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
> +	port->iotype		= UPIO_MEM;
> +	port->regshift		= 0;
> +	port->dev		= &pdev->dev;
> +	port->type		= (unsigned long)device_get_match_data(&pdev->dev);
> +	port->serial_in		= loongson_serial_in;
> +	port->serial_out	= loongson_serial_out;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENODEV;
> +
> +	port->membase = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!port->membase)
> +		return -ENOMEM;
> +

Use wrapper combining both calls.

> +	port->mapbase = res->start;
> +	port->mapsize = resource_size(res);
> +
> +	port->irq = platform_get_irq(pdev, 0);
> +	if (port->irq < 0)
> +		return -EINVAL;
> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	port->private_data = data;
> +
> +	if (device_property_read_bool(&pdev->dev, "fractional-division")) {
> +		port->get_divisor = loongson_frac_get_divisor;
> +		port->set_divisor = loongson_frac_set_divisor;
> +	}
> +
> +	if (device_property_read_bool(&pdev->dev, "rts-invert"))
> +		data->mcr_invert |= UART_MCR_RTS;
> +
> +	if (device_property_read_bool(&pdev->dev, "dtr-invert"))
> +		data->mcr_invert |= UART_MCR_DTR;
> +
> +	if (device_property_read_bool(&pdev->dev, "cts-invert"))
> +		data->msr_invert |= UART_MSR_CTS;
> +
> +	if (device_property_read_bool(&pdev->dev, "dsr-invert"))
> +		data->msr_invert |= UART_MSR_DSR;
> +
> +	data->rst = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> +	if (IS_ERR(data->rst))
> +		return PTR_ERR(data->rst);
> +
> +	device_property_read_u32(&pdev->dev, "clock-frequency", &port->uartclk);
> +
> +	ret = reset_control_deassert(data->rst);
> +	if (ret)
> +		goto err_unprepare;
> +
> +	ret = serial8250_register_8250_port(&uart);
> +	if (ret < 0)
> +		goto err_unprepare;
> +
> +	platform_set_drvdata(pdev, data);
> +	data->line = ret;
> +
> +	return 0;
> +
> +err_unprepare:
> +
> +	return ret;
> +}
> +
> +static void loongson_uart_remove(struct platform_device *pdev)
> +{
> +	struct loongson_uart_data *data = platform_get_drvdata(pdev);
> +
> +	serial8250_unregister_port(data->line);
> +	reset_control_assert(data->rst);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int loongson_uart_suspend(struct device *dev)
> +{
> +	struct loongson_uart_data *data = dev_get_drvdata(dev);
> +
> +	serial8250_suspend_port(data->line);
> +
> +	return 0;
> +}
> +
> +static int loongson_uart_resume(struct device *dev)
> +{
> +	struct loongson_uart_data *data = dev_get_drvdata(dev);
> +
> +	serial8250_resume_port(data->line);
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops loongson_uart_pm_ops = {
> +	SET_SYSTEM_SLEEP_PM_OPS(loongson_uart_suspend, loongson_uart_resume)
> +};
> +
> +static const struct of_device_id of_platform_serial_table[] = {
> +	{.compatible = "loongson,ls7a-uart", .data = (void *)PORT_LOONGSON},

Why do you need match data if there is no choice?

> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_platform_serial_table);
> +
> +static struct platform_driver loongson_uart_driver = {
> +	.probe = loongson_uart_probe,
> +	.remove = loongson_uart_remove,
> +	.driver = {
> +		.name = "ls7a-uart",
> +		.pm = &loongson_uart_pm_ops,
> +		.of_match_table = of_match_ptr(of_platform_serial_table),

Except that this does not build... drop of_match_ptr(), not needed and
causes warnings.

> +	},
> +};
> +
> +module_platform_driver(loongson_uart_driver);
> +
> +MODULE_DESCRIPTION("LOONGSON 8250 Driver");
> +MODULE_AUTHOR("Haowei Zheng <zhenghaowei@xxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 2786918aea98..60b72c785028 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -319,6 +319,14 @@ static const struct serial8250_config uart_config[] = {
>  		.rxtrig_bytes	= {1, 8, 16, 30},
>  		.flags		= UART_CAP_FIFO | UART_CAP_AFE,
>  	},
> +	[PORT_LOONGSON] = {
> +		.name		= "Loongson",
> +		.fifo_size	= 16,
> +		.tx_loadsz	= 16,
> +		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
> +		.rxtrig_bytes   = {1, 4, 8, 14},
> +		.flags		= UART_CAP_FIFO,
> +	},
>  };
>  
>  /* Uart divisor latch read */
> diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
> index 47ff50763c04..a696afc4f8a8 100644
> --- a/drivers/tty/serial/8250/Kconfig
> +++ b/drivers/tty/serial/8250/Kconfig
> @@ -568,6 +568,15 @@ config SERIAL_8250_BCM7271
>  	  including DMA support and high accuracy BAUD rates, say
>  	  Y to this option. If unsure, say N.
>  
> +config SERIAL_8250_LOONGSON
> +	tristate "Loongson 8250 serial port support"
> +	default SERIAL_8250
> +	depends on SERIAL_8250
> +	depends on LOONGARCH || MIPS

MIPS? Why?

You also miss COMPILE_TEST.



Best regards,
Krzysztof





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