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Message-ID: <84ff11bd-1d11-4d66-a56b-84bf915af346@kernel.org>
Date: Sun, 4 Aug 2024 17:33:14 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: zhenghaowei@...ngson.cn, gregkh@...uxfoundation.org,
jirislaby@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
conor+dt@...nel.org, chenhuacai@...nel.org, kernel@...0n.name,
p.zabel@...gutronix.de
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, loongarch@...ts.linux.dev
Subject: Re: [PATCH v2 2/3] tty: serial: 8250: Add loongson uart driver
support
On 04/08/2024 08:38, zhenghaowei@...ngson.cn wrote:
> From: Haowei Zheng <zhenghaowei@...ngson.cn>
>
> 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@...ngson.cn>
> ---
> 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@...ngson.cn>");
> +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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