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linux-sg2042/drivers/tty/serial/8250/8250_mtk.c

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/*
* Mediatek 8250 driver.
*
* Copyright (c) 2014 MundoReader S.L.
* Author: Matthias Brugger <matthias.bgg@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/serial_8250.h>
#include <linux/serial_reg.h>
#include "8250.h"
#define UART_MTK_HIGHS 0x09 /* Highspeed register */
#define UART_MTK_SAMPLE_COUNT 0x0a /* Sample count register */
#define UART_MTK_SAMPLE_POINT 0x0b /* Sample point register */
#define MTK_UART_RATE_FIX 0x0d /* UART Rate Fix Register */
struct mtk8250_data {
int line;
struct clk *uart_clk;
struct clk *bus_clk;
};
static void
mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
struct uart_8250_port *up = up_to_u8250p(port);
unsigned long flags;
unsigned int baud, quot;
serial8250_do_set_termios(port, termios, old);
/*
* Mediatek UARTs use an extra highspeed register (UART_MTK_HIGHS)
*
* We need to recalcualte the quot register, as the claculation depends
* on the vaule in the highspeed register.
*
* Some baudrates are not supported by the chip, so we use the next
* lower rate supported and update termios c_flag.
*
* If highspeed register is set to 3, we need to specify sample count
* and sample point to increase accuracy. If not, we reset the
* registers to their default values.
*/
baud = uart_get_baud_rate(port, termios, old,
port->uartclk / 16 / 0xffff,
port->uartclk);
if (baud <= 115200) {
serial_port_out(port, UART_MTK_HIGHS, 0x0);
quot = uart_get_divisor(port, baud);
} else if (baud <= 576000) {
serial_port_out(port, UART_MTK_HIGHS, 0x2);
/* Set to next lower baudrate supported */
if ((baud == 500000) || (baud == 576000))
baud = 460800;
quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
} else {
serial_port_out(port, UART_MTK_HIGHS, 0x3);
quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
}
/*
* Ok, we're now changing the port state. Do it with
* interrupts disabled.
*/
spin_lock_irqsave(&port->lock, flags);
/* set DLAB we have cval saved in up->lcr from the call to the core */
serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB);
serial_dl_write(up, quot);
/* reset DLAB */
serial_port_out(port, UART_LCR, up->lcr);
if (baud > 460800) {
unsigned int tmp;
tmp = DIV_ROUND_CLOSEST(port->uartclk, quot * baud);
serial_port_out(port, UART_MTK_SAMPLE_COUNT, tmp - 1);
serial_port_out(port, UART_MTK_SAMPLE_POINT,
(tmp - 2) >> 1);
} else {
serial_port_out(port, UART_MTK_SAMPLE_COUNT, 0x00);
serial_port_out(port, UART_MTK_SAMPLE_POINT, 0xff);
}
spin_unlock_irqrestore(&port->lock, flags);
/* Don't rewrite B0 */
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
}
static int __maybe_unused mtk8250_runtime_suspend(struct device *dev)
{
struct mtk8250_data *data = dev_get_drvdata(dev);
clk_disable_unprepare(data->uart_clk);
clk_disable_unprepare(data->bus_clk);
return 0;
}
static int __maybe_unused mtk8250_runtime_resume(struct device *dev)
{
struct mtk8250_data *data = dev_get_drvdata(dev);
int err;
err = clk_prepare_enable(data->uart_clk);
if (err) {
dev_warn(dev, "Can't enable clock\n");
return err;
}
err = clk_prepare_enable(data->bus_clk);
if (err) {
dev_warn(dev, "Can't enable bus clock\n");
return err;
}
return 0;
}
static void
mtk8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old)
{
if (!state)
pm_runtime_get_sync(port->dev);
serial8250_do_pm(port, state, old);
if (state)
pm_runtime_put_sync_suspend(port->dev);
}
static int mtk8250_probe_of(struct platform_device *pdev, struct uart_port *p,
struct mtk8250_data *data)
{
data->uart_clk = devm_clk_get(&pdev->dev, "baud");
if (IS_ERR(data->uart_clk)) {
/*
* For compatibility with older device trees try unnamed
* clk when no baud clk can be found.
*/
data->uart_clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(data->uart_clk)) {
dev_warn(&pdev->dev, "Can't get uart clock\n");
return PTR_ERR(data->uart_clk);
}
return 0;
}
data->bus_clk = devm_clk_get(&pdev->dev, "bus");
if (IS_ERR(data->bus_clk))
return PTR_ERR(data->bus_clk);
return 0;
}
static int mtk8250_probe(struct platform_device *pdev)
{
struct uart_8250_port uart = {};
struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
struct mtk8250_data *data;
int err;
if (!regs || !irq) {
dev_err(&pdev->dev, "no registers/irq defined\n");
return -EINVAL;
}
uart.port.membase = devm_ioremap(&pdev->dev, regs->start,
resource_size(regs));
if (!uart.port.membase)
return -ENOMEM;
data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
if (pdev->dev.of_node) {
err = mtk8250_probe_of(pdev, &uart.port, data);
if (err)
return err;
} else
return -ENODEV;
spin_lock_init(&uart.port.lock);
uart.port.mapbase = regs->start;
uart.port.irq = irq->start;
uart.port.pm = mtk8250_do_pm;
uart.port.type = PORT_16550;
uart.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT;
uart.port.dev = &pdev->dev;
uart.port.iotype = UPIO_MEM32;
uart.port.regshift = 2;
uart.port.private_data = data;
uart.port.set_termios = mtk8250_set_termios;
uart.port.uartclk = clk_get_rate(data->uart_clk);
/* Disable Rate Fix function */
writel(0x0, uart.port.membase +
(MTK_UART_RATE_FIX << uart.port.regshift));
platform_set_drvdata(pdev, data);
pm_runtime_enable(&pdev->dev);
if (!pm_runtime_enabled(&pdev->dev)) {
err = mtk8250_runtime_resume(&pdev->dev);
if (err)
return err;
}
data->line = serial8250_register_8250_port(&uart);
if (data->line < 0)
return data->line;
return 0;
}
static int mtk8250_remove(struct platform_device *pdev)
{
struct mtk8250_data *data = platform_get_drvdata(pdev);
pm_runtime_get_sync(&pdev->dev);
serial8250_unregister_port(data->line);
pm_runtime_disable(&pdev->dev);
pm_runtime_put_noidle(&pdev->dev);
if (!pm_runtime_status_suspended(&pdev->dev))
mtk8250_runtime_suspend(&pdev->dev);
return 0;
}
static int __maybe_unused mtk8250_suspend(struct device *dev)
{
struct mtk8250_data *data = dev_get_drvdata(dev);
serial8250_suspend_port(data->line);
return 0;
}
static int __maybe_unused mtk8250_resume(struct device *dev)
{
struct mtk8250_data *data = dev_get_drvdata(dev);
serial8250_resume_port(data->line);
return 0;
}
static const struct dev_pm_ops mtk8250_pm_ops = {
SET_SYSTEM_SLEEP_PM_OPS(mtk8250_suspend, mtk8250_resume)
SET_RUNTIME_PM_OPS(mtk8250_runtime_suspend, mtk8250_runtime_resume,
NULL)
};
static const struct of_device_id mtk8250_of_match[] = {
{ .compatible = "mediatek,mt6577-uart" },
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, mtk8250_of_match);
static struct platform_driver mtk8250_platform_driver = {
.driver = {
.name = "mt6577-uart",
.pm = &mtk8250_pm_ops,
.of_match_table = mtk8250_of_match,
},
.probe = mtk8250_probe,
.remove = mtk8250_remove,
};
module_platform_driver(mtk8250_platform_driver);
#ifdef CONFIG_SERIAL_8250_CONSOLE
static int __init early_mtk8250_setup(struct earlycon_device *device,
const char *options)
{
if (!device->port.membase)
return -ENODEV;
device->port.iotype = UPIO_MEM32;
return early_serial8250_setup(device, NULL);
}
OF_EARLYCON_DECLARE(mtk8250, "mediatek,mt6577-uart", early_mtk8250_setup);
#endif
MODULE_AUTHOR("Matthias Brugger");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Mediatek 8250 serial port driver");
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