linux-kernel - Re: [PATCH v5 17/17] serial: 8250: Add 8250

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Date: Sat, 4 May 2024 17:53:38 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Sunil V L <sunilvl@...tanamicro.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-serial@...r.kernel.org,
	acpica-devel@...ts.linux.dev,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
	Anup Patel <anup@...infault.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Samuel Holland <samuel.holland@...ive.com>,
	Jiri Slaby <jirislaby@...nel.org>,
	Robert Moore <robert.moore@...el.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Andrew Jones <ajones@...tanamicro.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Marc Zyngier <maz@...nel.org>,
	Atish Kumar Patra <atishp@...osinc.com>,
	Andrei Warkentin <andrei.warkentin@...el.com>,
	Haibo1 Xu <haibo1.xu@...el.com>,
	Björn Töpel <bjorn@...nel.org>
Subject: Re: [PATCH v5 17/17] serial: 8250: Add 8250_acpi driver

On Wed, May 01, 2024 at 05:47:42PM +0530, Sunil V L wrote:
> RISC-V has non-PNP generic 16550A compatible UART which needs to be
> enumerated as ACPI platform device. Add driver support for such devices
> similar to 8250_of.
> 
> The driver is enabled when the CONFIG_SERIAL_ACPI_PLATFORM option is
> enabled. Enable this option for RISC-V.
> 
> Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> ---
>  arch/riscv/configs/defconfig        |  1 +
>  drivers/tty/serial/8250/8250_acpi.c | 96 +++++++++++++++++++++++++++++
>  drivers/tty/serial/8250/Kconfig     |  8 +++
>  drivers/tty/serial/8250/Makefile    |  1 +
>  4 files changed, 106 insertions(+)
>  create mode 100644 drivers/tty/serial/8250/8250_acpi.c
> 
> diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
> index 3cae018f9315..bea8241f52eb 100644
> --- a/arch/riscv/configs/defconfig
> +++ b/arch/riscv/configs/defconfig
> @@ -150,6 +150,7 @@ CONFIG_SERIAL_8250=y
>  CONFIG_SERIAL_8250_CONSOLE=y
>  CONFIG_SERIAL_8250_DW=y
>  CONFIG_SERIAL_OF_PLATFORM=y
> +CONFIG_SERIAL_ACPI_PLATFORM=y
>  CONFIG_SERIAL_SH_SCI=y
>  CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
>  CONFIG_VIRTIO_CONSOLE=y
> diff --git a/drivers/tty/serial/8250/8250_acpi.c b/drivers/tty/serial/8250/8250_acpi.c
> new file mode 100644
> index 000000000000..3682443bb69c
> --- /dev/null
> +++ b/drivers/tty/serial/8250/8250_acpi.c
> @@ -0,0 +1,96 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Serial Port driver for ACPI platform devices
> + *
> + * This driver is for generic 16550 compatible UART enumerated via ACPI
> + * platform bus instead of PNP bus like PNP0501. This is not a full
> + * driver but mostly provides the ACPI wrapper and uses generic
> + * 8250 framework for rest of the functionality.

No copyright line?  Odd, but ok, I'll take it, glad to see your company
finally realizes the lack of needing them :)


And as Andy said, please use the existing driver and extend what you
need, don't write a new one, we really don't need a new one.

> +static int acpi_platform_serial_probe(struct platform_device *pdev)
> +{
> +	struct acpi_serial_info *data;
> +	struct uart_8250_port port8250;
> +	struct device *dev = &pdev->dev;
> +	struct resource *regs;
> +
> +	int ret, irq;
> +
> +	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!regs) {
> +		dev_err(dev, "no registers defined\n");
> +		return -EINVAL;
> +	}
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +
> +	memset(&port8250, 0, sizeof(port8250));
> +
> +	spin_lock_init(&port8250.port.lock);

Are you sure this works?

thanks,

greg k-h