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217 lines
5.8 KiB
217 lines
5.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Early serial console for 8250/16550 devices |
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* |
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* (c) Copyright 2004 Hewlett-Packard Development Company, L.P. |
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* Bjorn Helgaas <[email protected]> |
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* |
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* Based on the 8250.c serial driver, Copyright (C) 2001 Russell King, |
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* and on early_printk.c by Andi Kleen. |
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* |
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* This is for use before the serial driver has initialized, in |
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* particular, before the UARTs have been discovered and named. |
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* Instead of specifying the console device as, e.g., "ttyS0", |
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* we locate the device directly by its MMIO or I/O port address. |
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* |
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* The user can specify the device directly, e.g., |
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* earlycon=uart8250,io,0x3f8,9600n8 |
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* earlycon=uart8250,mmio,0xff5e0000,115200n8 |
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* earlycon=uart8250,mmio32,0xff5e0000,115200n8 |
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* or |
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* console=uart8250,io,0x3f8,9600n8 |
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* console=uart8250,mmio,0xff5e0000,115200n8 |
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* console=uart8250,mmio32,0xff5e0000,115200n8 |
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*/ |
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#include <linux/tty.h> |
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#include <linux/init.h> |
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#include <linux/console.h> |
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#include <linux/of.h> |
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#include <linux/of_device.h> |
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#include <linux/serial_reg.h> |
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#include <linux/serial.h> |
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#include <linux/serial_8250.h> |
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#include <asm/io.h> |
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#include <asm/serial.h> |
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static unsigned int serial8250_early_in(struct uart_port *port, int offset) |
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{ |
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int reg_offset = offset; |
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offset <<= port->regshift; |
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switch (port->iotype) { |
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case UPIO_MEM: |
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return readb(port->membase + offset); |
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case UPIO_MEM16: |
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return readw(port->membase + offset); |
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case UPIO_MEM32: |
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return readl(port->membase + offset); |
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case UPIO_MEM32BE: |
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return ioread32be(port->membase + offset); |
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case UPIO_PORT: |
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return inb(port->iobase + offset); |
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case UPIO_AU: |
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return port->serial_in(port, reg_offset); |
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default: |
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return 0; |
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} |
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} |
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static void serial8250_early_out(struct uart_port *port, int offset, int value) |
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{ |
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int reg_offset = offset; |
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offset <<= port->regshift; |
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switch (port->iotype) { |
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case UPIO_MEM: |
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writeb(value, port->membase + offset); |
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break; |
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case UPIO_MEM16: |
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writew(value, port->membase + offset); |
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break; |
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case UPIO_MEM32: |
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writel(value, port->membase + offset); |
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break; |
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case UPIO_MEM32BE: |
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iowrite32be(value, port->membase + offset); |
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break; |
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case UPIO_PORT: |
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outb(value, port->iobase + offset); |
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break; |
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case UPIO_AU: |
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port->serial_out(port, reg_offset, value); |
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break; |
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} |
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} |
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#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) |
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static void serial_putc(struct uart_port *port, int c) |
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{ |
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unsigned int status; |
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serial8250_early_out(port, UART_TX, c); |
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for (;;) { |
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status = serial8250_early_in(port, UART_LSR); |
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if ((status & BOTH_EMPTY) == BOTH_EMPTY) |
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break; |
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cpu_relax(); |
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} |
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} |
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static void early_serial8250_write(struct console *console, |
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const char *s, unsigned int count) |
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{ |
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struct earlycon_device *device = console->data; |
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struct uart_port *port = &device->port; |
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uart_console_write(port, s, count, serial_putc); |
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} |
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#ifdef CONFIG_CONSOLE_POLL |
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static int early_serial8250_read(struct console *console, |
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char *s, unsigned int count) |
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{ |
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struct earlycon_device *device = console->data; |
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struct uart_port *port = &device->port; |
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unsigned int status; |
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int num_read = 0; |
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while (num_read < count) { |
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status = serial8250_early_in(port, UART_LSR); |
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if (!(status & UART_LSR_DR)) |
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break; |
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s[num_read++] = serial8250_early_in(port, UART_RX); |
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} |
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return num_read; |
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} |
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#else |
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#define early_serial8250_read NULL |
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#endif |
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static void __init init_port(struct earlycon_device *device) |
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{ |
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struct uart_port *port = &device->port; |
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unsigned int divisor; |
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unsigned char c; |
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unsigned int ier; |
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serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */ |
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ier = serial8250_early_in(port, UART_IER); |
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serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */ |
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serial8250_early_out(port, UART_FCR, 0); /* no fifo */ |
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serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */ |
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if (port->uartclk) { |
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divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud); |
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c = serial8250_early_in(port, UART_LCR); |
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serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB); |
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serial8250_early_out(port, UART_DLL, divisor & 0xff); |
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serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff); |
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serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB); |
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} |
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} |
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int __init early_serial8250_setup(struct earlycon_device *device, |
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const char *options) |
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{ |
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if (!(device->port.membase || device->port.iobase)) |
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return -ENODEV; |
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if (!device->baud) { |
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struct uart_port *port = &device->port; |
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unsigned int ier; |
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/* assume the device was initialized, only mask interrupts */ |
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ier = serial8250_early_in(port, UART_IER); |
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serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); |
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} else |
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init_port(device); |
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device->con->write = early_serial8250_write; |
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device->con->read = early_serial8250_read; |
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return 0; |
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} |
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EARLYCON_DECLARE(uart8250, early_serial8250_setup); |
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EARLYCON_DECLARE(uart, early_serial8250_setup); |
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OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup); |
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OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup); |
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OF_EARLYCON_DECLARE(uart, "nvidia,tegra20-uart", early_serial8250_setup); |
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OF_EARLYCON_DECLARE(uart, "snps,dw-apb-uart", early_serial8250_setup); |
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#ifdef CONFIG_SERIAL_8250_OMAP |
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static int __init early_omap8250_setup(struct earlycon_device *device, |
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const char *options) |
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{ |
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struct uart_port *port = &device->port; |
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if (!(device->port.membase || device->port.iobase)) |
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return -ENODEV; |
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port->regshift = 2; |
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device->con->write = early_serial8250_write; |
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return 0; |
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} |
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OF_EARLYCON_DECLARE(omap8250, "ti,omap2-uart", early_omap8250_setup); |
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OF_EARLYCON_DECLARE(omap8250, "ti,omap3-uart", early_omap8250_setup); |
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OF_EARLYCON_DECLARE(omap8250, "ti,omap4-uart", early_omap8250_setup); |
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#endif |
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#ifdef CONFIG_SERIAL_8250_RT288X |
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static int __init early_au_setup(struct earlycon_device *dev, const char *opt) |
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{ |
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dev->port.serial_in = au_serial_in; |
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dev->port.serial_out = au_serial_out; |
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dev->port.iotype = UPIO_AU; |
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dev->con->write = early_serial8250_write; |
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return 0; |
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} |
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OF_EARLYCON_DECLARE(palmchip, "ralink,rt2880-uart", early_au_setup); |
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#endif
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