Release 4.16 drivers/tty/serial/8250/8250_early.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Early serial console for 8250/16550 devices
 *
 * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
 *      Bjorn Helgaas <bjorn.helgaas@hp.com>
 *
 * Based on the 8250.c serial driver, Copyright (C) 2001 Russell King,
 * and on early_printk.c by Andi Kleen.
 *
 * This is for use before the serial driver has initialized, in
 * particular, before the UARTs have been discovered and named.
 * Instead of specifying the console device as, e.g., "ttyS0",
 * we locate the device directly by its MMIO or I/O port address.
 *
 * The user can specify the device directly, e.g.,
 *      earlycon=uart8250,io,0x3f8,9600n8
 *      earlycon=uart8250,mmio,0xff5e0000,115200n8
 *      earlycon=uart8250,mmio32,0xff5e0000,115200n8
 * or
 *      console=uart8250,io,0x3f8,9600n8
 *      console=uart8250,mmio,0xff5e0000,115200n8
 *      console=uart8250,mmio32,0xff5e0000,115200n8
 */

#include <linux/tty.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/serial_reg.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <asm/io.h>
#include <asm/serial.h>



static unsigned int serial8250_early_in(struct uart_port *port, int offset)
{
	int reg_offset = offset;
	offset <<= port->regshift;

	switch (port->iotype) {
	case UPIO_MEM:
		return readb(port->membase + offset);
	case UPIO_MEM16:
		return readw(port->membase + offset);
	case UPIO_MEM32:
		return readl(port->membase + offset);
	case UPIO_MEM32BE:
		return ioread32be(port->membase + offset);
	case UPIO_PORT:
		return inb(port->iobase + offset);
	case UPIO_AU:
		return port->serial_in(port, reg_offset);
	default:
		return 0;
	}
}

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Björn Helgaas
38
32.76%
1
12.50%
Samium Gromoff
26
22.41%
1
12.50%
Marc Gonzalez
18
15.52%
1
12.50%
Kevin Cernekee
13
11.21%
1
12.50%
Masahiro Yamada
13
11.21%
1
12.50%
Peter Hurley
6
5.17%
1
12.50%
Noam Camus
1
0.86%
1
12.50%
Vineet Gupta
1
0.86%
1
12.50%
Total
116
100.00%
8
100.00%



static void serial8250_early_out(struct uart_port *port, int offset, int value)
{
	int reg_offset = offset;
	offset <<= port->regshift;

	switch (port->iotype) {
	case UPIO_MEM:
		writeb(value, port->membase + offset);
		break;
	case UPIO_MEM16:
		writew(value, port->membase + offset);
		break;
	case UPIO_MEM32:
		writel(value, port->membase + offset);
		break;
	case UPIO_MEM32BE:
		iowrite32be(value, port->membase + offset);
		break;
	case UPIO_PORT:
		outb(value, port->iobase + offset);
		break;
	case UPIO_AU:
		port->serial_out(port, reg_offset, value);
		break;
	}
}

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Björn Helgaas
42
33.33%
1
12.50%
Samium Gromoff
30
23.81%
1
12.50%
Marc Gonzalez
20
15.87%
1
12.50%
Masahiro Yamada
15
11.90%
1
12.50%
Kevin Cernekee
11
8.73%
1
12.50%
Peter Hurley
6
4.76%
1
12.50%
Noam Camus
1
0.79%
1
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Vineet Gupta
1
0.79%
1
12.50%
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126
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8
100.00%


#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)



static void serial_putc(struct uart_port *port, int c)
{
	unsigned int status;

	serial8250_early_out(port, UART_TX, c);

	for (;;) {
		status = serial8250_early_in(port, UART_LSR);
		if ((status & BOTH_EMPTY) == BOTH_EMPTY)
			break;
		cpu_relax();
	}
}

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42
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Masahiro Yamada
14
24.56%
1
33.33%
Noam Camus
1
1.75%
1
33.33%
Total
57
100.00%
3
100.00%



static void early_serial8250_write(struct console *console,
					const char *s, unsigned int count)
{
	struct earlycon_device *device = console->data;
	struct uart_port *port = &device->port;

	uart_console_write(port, s, count, serial_putc);
}

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34
68.00%
1
16.67%
Peter Hurley
10
20.00%
1
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Russell King
3
6.00%
1
16.67%
Yinghai Lu
2
4.00%
2
33.33%
Rob Herring
1
2.00%
1
16.67%
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50
100.00%
6
100.00%



static void __init init_port(struct earlycon_device *device)
{
	struct uart_port *port = &device->port;
	unsigned int divisor;
	unsigned char c;
	unsigned int ier;

	serial8250_early_out(port, UART_LCR, 0x3);	/* 8n1 */
	ier = serial8250_early_in(port, UART_IER);
	serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */
	serial8250_early_out(port, UART_FCR, 0);	/* no fifo */
	serial8250_early_out(port, UART_MCR, 0x3);	/* DTR + RTS */

	if (port->uartclk && device->baud) {
		divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud);
		c = serial8250_early_in(port, UART_LCR);
		serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB);
		serial8250_early_out(port, UART_DLL, divisor & 0xff);
		serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff);
		serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB);
	}
}

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Björn Helgaas
128
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1
16.67%
Rob Herring
17
10.00%
2
33.33%
Matt Redfearn
12
7.06%
1
16.67%
Noam Camus
9
5.29%
1
16.67%
Alexey Brodkin
4
2.35%
1
16.67%
Total
170
100.00%
6
100.00%



int __init early_serial8250_setup(struct earlycon_device *device,
					 const char *options)
{
	if (!(device->port.membase || device->port.iobase))
		return -ENODEV;

	if (!device->baud) {
		struct uart_port *port = &device->port;
		unsigned int ier;

		/* assume the device was initialized, only mask interrupts */
		ier = serial8250_early_in(port, UART_IER);
		serial8250_early_out(port, UART_IER, ier & UART_IER_UUE);
	} else
		init_port(device);

	device->con->write = early_serial8250_write;
	return 0;
}
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2
22.22%
Björn Helgaas
37
37.76%
1
11.11%
Rob Herring
17
17.35%
2
22.22%
Alan Cox
2
2.04%
1
11.11%
Samium Gromoff
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2.04%
1
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Yinghai Lu
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Josh Boyer
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9
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EARLYCON_DECLARE(uart8250, early_serial8250_setup);
EARLYCON_DECLARE(uart, early_serial8250_setup);
OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup);
OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup);

#ifdef CONFIG_SERIAL_8250_OMAP



static int __init early_omap8250_setup(struct earlycon_device *device,
				       const char *options)
{
	struct uart_port *port = &device->port;

	if (!(device->port.membase || device->port.iobase))
		return -ENODEV;

	port->regshift = 2;
	device->con->write = early_serial8250_write;
	return 0;
}

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OF_EARLYCON_DECLARE(omap8250, "ti,omap2-uart", early_omap8250_setup);
OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup);
OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup);

#endif

#ifdef CONFIG_SERIAL_8250_RT288X

unsigned int au_serial_in(struct uart_port *p, int offset);
void au_serial_out(struct uart_port *p, int offset, int value);



static int __init early_au_setup(struct earlycon_device *dev, const char *opt)
{
	dev->port.serial_in = au_serial_in;
	dev->port.serial_out = au_serial_out;
	dev->port.iotype = UPIO_AU;
	dev->con->write = early_serial8250_write;
	return 0;
}
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OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup);

#endif
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5
17.86%
Marc Gonzalez
132
14.77%
1
3.57%
Samium Gromoff
58
6.49%
1
3.57%
Masahiro Yamada
42
4.70%
2
7.14%
Rob Herring
40
4.47%
3
10.71%
Kevin Cernekee
24
2.68%
1
3.57%
Scott Wood
24
2.68%
1
3.57%
Noam Camus
12
1.34%
1
3.57%
Matt Redfearn
12
1.34%
1
3.57%
Kefeng Wang
9
1.01%
1
3.57%
Jon Hunter
9
1.01%
1
3.57%
Yinghai Lu
9
1.01%
2
7.14%
Alexey Brodkin
4
0.45%
1
3.57%
Alan Cox
3
0.34%
1
3.57%
Russell King
3
0.34%
1
3.57%
Vineet Gupta
2
0.22%
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Greg Kroah-Hartman
2
0.22%
2
7.14%
Josh Boyer
1
0.11%
1
3.57%
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28
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Directory: drivers/tty/serial/8250

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