cregit-Linux how code gets into the kernel

Release 4.7 drivers/tty/serial/8250/8250_early.c

Directory: drivers/tty/serial/8250
/*
 * Early serial console for 8250/16550 devices
 *
 * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
 *      Bjorn Helgaas <bjorn.helgaas@hp.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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 __init serial8250_early_in(struct uart_port *port, int 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);
	default:
		return 0;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas3939.39%114.29%


samium gromoffsamium gromoff2626.26%114.29%


kevin cernekeekevin cernekee1313.13%114.29%


masahiro yamadamasahiro yamada1313.13%114.29%


peter hurleypeter hurley66.06%114.29%


noam camusnoam camus11.01%114.29%


vineet guptavineet gupta11.01%114.29%


Total99100.00%7100.00%






static void __init serial8250_early_out(struct uart_port *port, int offset, int value)
{
	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;
	}
}


Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas4340.19%114.29%


samium gromoffsamium gromoff3229.91%114.29%


masahiro yamadamasahiro yamada1514.02%114.29%


kevin cernekeekevin cernekee98.41%114.29%


peter hurleypeter hurley65.61%114.29%


noam camusnoam camus10.93%114.29%


vineet guptavineet gupta10.93%114.29%


Total107100.00%7100.00%




#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)




static void __init 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();
	}
}


Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas4374.14%133.33%


masahiro yamadamasahiro yamada1424.14%133.33%


noam camusnoam camus11.72%133.33%


Total58100.00%3100.00%






static void __init 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);
}


Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas3568.63%116.67%


peter hurleypeter hurley1019.61%116.67%


russell kingrussell king35.88%116.67%


yinghai luyinghai lu23.92%233.33%


rob herringrob herring11.96%116.67%


Total51100.00%6100.00%






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 */

	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);
}


Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas12881.01%120.00%


rob herringrob herring1710.76%240.00%


noam camusnoam camus95.70%120.00%


alexey brodkinalexey brodkin42.53%120.00%


Total158100.00%5100.00%






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;
}

Contributors
PersonTokensPropCommitsCommitProp
peter hurleypeter hurley3838.78%222.22%


bjorn helgaasbjorn helgaas3737.76%111.11%


rob herringrob herring1717.35%222.22%


yinghai luyinghai lu22.04%111.11%


alan coxalan cox22.04%111.11%


samium gromoffsamium gromoff11.02%111.11%


josh boyerjosh boyer11.02%111.11%


Total98100.00%9100.00%



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);

#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;
}


Contributors
PersonTokensPropCommitsCommitProp
peter hurleypeter hurley65100.00%1100.00%


Total65100.00%1100.00%



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

Overall Contributors
PersonTokensPropCommitsCommitProp
bjorn helgaasbjorn helgaas35447.58%14.35%


peter hurleypeter hurley15721.10%521.74%


samium gromoffsamium gromoff608.06%14.35%


masahiro yamadamasahiro yamada425.65%28.70%


rob herringrob herring405.38%313.04%


scott woodscott wood243.23%14.35%


kevin cernekeekevin cernekee222.96%14.35%


yinghai luyinghai lu121.61%28.70%


noam camusnoam camus121.61%14.35%


jon hunterjon hunter91.21%14.35%


alexey brodkinalexey brodkin40.54%14.35%


russell kingrussell king30.40%14.35%


alan coxalan cox20.27%14.35%


vineet guptavineet gupta20.27%14.35%


josh boyerjosh boyer10.13%14.35%


Total744100.00%23100.00%

  
Directory: drivers/tty/serial/8250



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