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// SPDX-License-Identifier: GPL-2.0
/*
* Serial port driver for BCM2835AUX UART
*
* Copyright (C) 2016 Martin Sperl <kernel@martin.sperl.org>
*
* Based on 8250_lpc18xx.c:
* Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include "8250.h"
/**
* struct bcm2835aux_data - driver private data of BCM2835 auxiliary UART
* @clk: clock producer of the port's uartclk
* @line: index of the port's serial8250_ports[] entry
*/
struct bcm2835aux_data {
struct clk *clk;
int line;
};
static int bcm2835aux_serial_probe(struct platform_device *pdev)
{
struct uart_8250_port up = { };
struct bcm2835aux_data *data;
struct resource *res;
int ret;
/* allocate the custom structure */
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
/* initialize data */
up.capabilities = UART_CAP_FIFO | UART_CAP_MINI;
up.port.dev = &pdev->dev;
up.port.regshift = 2;
up.port.type = PORT_16550;
up.port.iotype = UPIO_MEM;
up.port.fifosize = 8;
up.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE |
UPF_SKIP_TEST | UPF_IOREMAP;
/* get the clock - this also enables the HW */
data->clk = devm_clk_get(&pdev->dev, NULL);
ret = PTR_ERR_OR_ZERO(data->clk);
if (ret) {
if (ret != -EPROBE_DEFER)
dev_err(&pdev->dev, "could not get clk: %d\n", ret);
return ret;
}
/* get the interrupt */
ret = platform_get_irq(pdev, 0);
if (ret < 0)
return ret;
up.port.irq = ret;
/* map the main registers */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
dev_err(&pdev->dev, "memory resource not found");
return -EINVAL;
}
up.port.mapbase = res->start;
up.port.mapsize = resource_size(res);
/* Check for a fixed line number */
ret = of_alias_get_id(pdev->dev.of_node, "serial");
if (ret >= 0)
up.port.line = ret;
/* enable the clock as a last step */
ret = clk_prepare_enable(data->clk);
if (ret) {
dev_err(&pdev->dev, "unable to enable uart clock - %d\n",
ret);
return ret;
}
/* the HW-clock divider for bcm2835aux is 8,
* but 8250 expects a divider of 16,
* so we have to multiply the actual clock by 2
* to get identical baudrates.
*/
up.port.uartclk = clk_get_rate(data->clk) * 2;
/* register the port */
ret = serial8250_register_8250_port(&up);
if (ret < 0) {
if (ret != -EPROBE_DEFER)
dev_err(&pdev->dev,
"unable to register 8250 port - %d\n", ret);
goto dis_clk;
}
data->line = ret;
platform_set_drvdata(pdev, data);
return 0;
dis_clk:
clk_disable_unprepare(data->clk);
return ret;
}
static int bcm2835aux_serial_remove(struct platform_device *pdev)
{
struct bcm2835aux_data *data = platform_get_drvdata(pdev);
serial8250_unregister_port(data->line);
clk_disable_unprepare(data->clk);
return 0;
}
static const struct of_device_id bcm2835aux_serial_match[] = {
{ .compatible = "brcm,bcm2835-aux-uart" },
{ },
};
MODULE_DEVICE_TABLE(of, bcm2835aux_serial_match);
static struct platform_driver bcm2835aux_serial_driver = {
.driver = {
.name = "bcm2835-aux-uart",
.of_match_table = bcm2835aux_serial_match,
},
.probe = bcm2835aux_serial_probe,
.remove = bcm2835aux_serial_remove,
};
module_platform_driver(bcm2835aux_serial_driver);
MODULE_DESCRIPTION("BCM2835 auxiliar UART driver");
MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
MODULE_LICENSE("GPL v2");
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