Commit 11361610 authored by kuldip dwivedi's avatar kuldip dwivedi Committed by Greg Kroah-Hartman
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serial: 8250_fsl: Add ACPI support 



This adds support for ACPI enumerated FSL 16550 UARTs.
For supporting ACPI, I added a wrapper so that this driver
can be used if firmware has exposed the HID "NXP0018" in
DSDT table.

This will be built as object file if config "SERIAL_8250_FSL"
is enabled which depends on config "SERIAL_8250_CONSOLE".

Signed-off-by: default avatarkuldip dwivedi <kuldip.dwivedi@puresoftware.com>
Link: https://lore.kernel.org/r/20200903113402.12371-1-kuldip.dwivedi@puresoftware.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad0c2748

drivers/tty/serial/8250/8250_fsl.c

+101 −7
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/serial_reg.h>

#include <linux/serial_8250.h>



#include "8250.h"



/*

 * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker.

 * Copyright 2020 NXP

 * Copyright 2020 Puresoftware Ltd.

 *

 * This isn't a full driver; it just provides an alternate IRQ

 * handler to deal with an errata.  Everything else is just

 * using the bog standard 8250 support.

 * handler to deal with an errata and provide ACPI wrapper.

 * Everything else is just using the bog standard 8250 support.

 *

 * We follow code flow of serial8250_default_handle_irq() but add

 * a check for a break and insert a dummy read on the Rx for the
@@ -20,6 +17,16 @@ 
 * IRQ event to the next one.

 */



#include <linux/acpi.h>

#include <linux/serial_reg.h>

#include <linux/serial_8250.h>



#include "8250.h"



struct fsl8250_data {

	int	line;

};



int fsl8250_handle_irq(struct uart_port *port)

{

	unsigned char lsr, orig_lsr;
@@ -79,3 +86,90 @@ int fsl8250_handle_irq(struct uart_port *port) 
	return 1;

}

EXPORT_SYMBOL_GPL(fsl8250_handle_irq);



#ifdef CONFIG_ACPI

static int fsl8250_acpi_probe(struct platform_device *pdev)

{

	struct fsl8250_data *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) {

		if (irq != -EPROBE_DEFER)

			dev_err(dev, "cannot get irq\n");

		return irq;

	}



	memset(&port8250, 0, sizeof(port8250));



	ret = device_property_read_u32(dev, "clock-frequency",

					&port8250.port.uartclk);

	if (ret)

		return ret;



	spin_lock_init(&port8250.port.lock);



	port8250.port.mapbase           = regs->start;

	port8250.port.irq               = irq;

	port8250.port.handle_irq        = fsl8250_handle_irq;

	port8250.port.type              = PORT_16550A;

	port8250.port.flags             = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF

						| UPF_FIXED_PORT | UPF_IOREMAP

						| UPF_FIXED_TYPE;

	port8250.port.dev               = dev;

	port8250.port.mapsize           = resource_size(regs);

	port8250.port.iotype            = UPIO_MEM;

	port8250.port.irqflags          = IRQF_SHARED;



	port8250.port.membase = devm_ioremap(dev,  port8250.port.mapbase,

							port8250.port.mapsize);

	if (!port8250.port.membase)

		return -ENOMEM;



	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;



	data->line = serial8250_register_8250_port(&port8250);

	if (data->line < 0)

		return data->line;



	platform_set_drvdata(pdev, data);

	return 0;

}



static int fsl8250_acpi_remove(struct platform_device *pdev)

{

	struct fsl8250_data *data = platform_get_drvdata(pdev);



	serial8250_unregister_port(data->line);

	return 0;

}



static const struct acpi_device_id fsl_8250_acpi_id[] = {

	{ "NXP0018", 0 },

	{ },

};

MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id);



static struct platform_driver fsl8250_platform_driver = {

	.driver = {

		.name			= "fsl-16550-uart",

		.acpi_match_table	= ACPI_PTR(fsl_8250_acpi_id),

	},

	.probe			= fsl8250_acpi_probe,

	.remove			= fsl8250_acpi_remove,

};



module_platform_driver(fsl8250_platform_driver);

#endif