Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Early serial console for 8250/16550 devices |
| 3 | * |
| 4 | * (c) Copyright 2004 Hewlett-Packard Development Company, L.P. |
| 5 | * Bjorn Helgaas <bjorn.helgaas@hp.com> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | * |
| 11 | * Based on the 8250.c serial driver, Copyright (C) 2001 Russell King, |
| 12 | * and on early_printk.c by Andi Kleen. |
| 13 | * |
| 14 | * This is for use before the serial driver has initialized, in |
| 15 | * particular, before the UARTs have been discovered and named. |
| 16 | * Instead of specifying the console device as, e.g., "ttyS0", |
| 17 | * we locate the device directly by its MMIO or I/O port address. |
| 18 | * |
| 19 | * The user can specify the device directly, e.g., |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 20 | * earlycon=uart8250,io,0x3f8,9600n8 |
| 21 | * earlycon=uart8250,mmio,0xff5e0000,115200n8 |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 22 | * earlycon=uart8250,mmio32,0xff5e0000,115200n8 |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 23 | * or |
| 24 | * console=uart8250,io,0x3f8,9600n8 |
| 25 | * console=uart8250,mmio,0xff5e0000,115200n8 |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 26 | * console=uart8250,mmio32,0xff5e0000,115200n8 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 27 | */ |
| 28 | |
| 29 | #include <linux/tty.h> |
| 30 | #include <linux/init.h> |
| 31 | #include <linux/console.h> |
| 32 | #include <linux/serial_core.h> |
| 33 | #include <linux/serial_reg.h> |
| 34 | #include <linux/serial.h> |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 35 | #include <linux/serial_8250.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | #include <asm/io.h> |
| 37 | #include <asm/serial.h> |
| 38 | |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 39 | static struct earlycon_device *early_device; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 40 | |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 41 | unsigned int __weak __init serial8250_early_in(struct uart_port *port, int offset) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | { |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 43 | switch (port->iotype) { |
| 44 | case UPIO_MEM: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | return readb(port->membase + offset); |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 46 | case UPIO_MEM32: |
| 47 | return readl(port->membase + (offset << 2)); |
| 48 | case UPIO_PORT: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | return inb(port->iobase + offset); |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 50 | default: |
| 51 | return 0; |
| 52 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | } |
| 54 | |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 55 | void __weak __init serial8250_early_out(struct uart_port *port, int offset, int value) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | { |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 57 | switch (port->iotype) { |
| 58 | case UPIO_MEM: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | writeb(value, port->membase + offset); |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 60 | break; |
| 61 | case UPIO_MEM32: |
| 62 | writel(value, port->membase + (offset << 2)); |
| 63 | break; |
| 64 | case UPIO_PORT: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 65 | outb(value, port->iobase + offset); |
Samium Gromoff | 1917ac7 | 2010-07-20 15:26:51 -0700 | [diff] [blame] | 66 | break; |
| 67 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | } |
| 69 | |
| 70 | #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) |
| 71 | |
| 72 | static void __init wait_for_xmitr(struct uart_port *port) |
| 73 | { |
| 74 | unsigned int status; |
| 75 | |
| 76 | for (;;) { |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 77 | status = serial8250_early_in(port, UART_LSR); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | if ((status & BOTH_EMPTY) == BOTH_EMPTY) |
| 79 | return; |
| 80 | cpu_relax(); |
| 81 | } |
| 82 | } |
| 83 | |
Yinghai Lu | bf2cdef | 2007-11-05 14:50:53 -0800 | [diff] [blame] | 84 | static void __init serial_putc(struct uart_port *port, int c) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | { |
| 86 | wait_for_xmitr(port); |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 87 | serial8250_early_out(port, UART_TX, c); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | } |
| 89 | |
Alan Cox | ce2e204 | 2008-02-08 04:18:49 -0800 | [diff] [blame] | 90 | static void __init early_serial8250_write(struct console *console, |
| 91 | const char *s, unsigned int count) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 92 | { |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 93 | struct uart_port *port = &early_device->port; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 94 | unsigned int ier; |
| 95 | |
| 96 | /* Save the IER and disable interrupts */ |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 97 | ier = serial8250_early_in(port, UART_IER); |
| 98 | serial8250_early_out(port, UART_IER, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | |
Yinghai Lu | bf2cdef | 2007-11-05 14:50:53 -0800 | [diff] [blame] | 100 | uart_console_write(port, s, count, serial_putc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | |
| 102 | /* Wait for transmitter to become empty and restore the IER */ |
| 103 | wait_for_xmitr(port); |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 104 | serial8250_early_out(port, UART_IER, ier); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | } |
| 106 | |
| 107 | static unsigned int __init probe_baud(struct uart_port *port) |
| 108 | { |
| 109 | unsigned char lcr, dll, dlm; |
| 110 | unsigned int quot; |
| 111 | |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 112 | lcr = serial8250_early_in(port, UART_LCR); |
| 113 | serial8250_early_out(port, UART_LCR, lcr | UART_LCR_DLAB); |
| 114 | dll = serial8250_early_in(port, UART_DLL); |
| 115 | dlm = serial8250_early_in(port, UART_DLM); |
| 116 | serial8250_early_out(port, UART_LCR, lcr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 117 | |
| 118 | quot = (dlm << 8) | dll; |
| 119 | return (port->uartclk / 16) / quot; |
| 120 | } |
| 121 | |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 122 | static void __init init_port(struct earlycon_device *device) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | { |
| 124 | struct uart_port *port = &device->port; |
| 125 | unsigned int divisor; |
| 126 | unsigned char c; |
| 127 | |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 128 | serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */ |
| 129 | serial8250_early_out(port, UART_IER, 0); /* no interrupt */ |
| 130 | serial8250_early_out(port, UART_FCR, 0); /* no fifo */ |
| 131 | serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | |
Alexey Brodkin | b15d538 | 2012-10-03 16:27:43 +0400 | [diff] [blame] | 133 | divisor = DIV_ROUND_CLOSEST(port->uartclk, 16 * device->baud); |
Noam Camus | ed71871 | 2012-11-16 07:03:05 +0200 | [diff] [blame] | 134 | c = serial8250_early_in(port, UART_LCR); |
| 135 | serial8250_early_out(port, UART_LCR, c | UART_LCR_DLAB); |
| 136 | serial8250_early_out(port, UART_DLL, divisor & 0xff); |
| 137 | serial8250_early_out(port, UART_DLM, (divisor >> 8) & 0xff); |
| 138 | serial8250_early_out(port, UART_LCR, c & ~UART_LCR_DLAB); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 139 | } |
| 140 | |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 141 | static int __init early_serial8250_setup(struct earlycon_device *device, |
| 142 | const char *options) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | { |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 144 | if (!(device->port.membase || device->port.iobase)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 145 | return 0; |
| 146 | |
Rob Herring | 60efcf0 | 2014-06-12 12:52:44 -0500 | [diff] [blame] | 147 | if (!device->baud) { |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 148 | device->baud = probe_baud(&device->port); |
Rob Herring | 60efcf0 | 2014-06-12 12:52:44 -0500 | [diff] [blame] | 149 | snprintf(device->options, sizeof(device->options), "%u", |
| 150 | device->baud); |
| 151 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | |
| 153 | init_port(device); |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 154 | |
| 155 | early_device = device; |
| 156 | device->con->write = early_serial8250_write; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 157 | return 0; |
| 158 | } |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 159 | EARLYCON_DECLARE(uart8250, early_serial8250_setup); |
| 160 | EARLYCON_DECLARE(uart, early_serial8250_setup); |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 161 | |
Rob Herring | fe1cf8a | 2014-04-30 19:48:28 -0500 | [diff] [blame] | 162 | int __init setup_early_serial8250_console(char *cmdline) |
| 163 | { |
| 164 | char match[] = "uart8250"; |
| 165 | |
| 166 | if (cmdline && cmdline[4] == ',') |
| 167 | match[4] = '\0'; |
| 168 | |
| 169 | return setup_earlycon(cmdline, match, early_serial8250_setup); |
| 170 | } |
| 171 | |
Daniel Ritz | b6b1d87 | 2007-08-03 16:07:43 +0200 | [diff] [blame] | 172 | int serial8250_find_port_for_earlycon(void) |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 173 | { |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 174 | struct earlycon_device *device = early_device; |
| 175 | struct uart_port *port = device ? &device->port : NULL; |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 176 | int line; |
| 177 | int ret; |
| 178 | |
Rob Herring | d2fd681 | 2014-04-18 17:19:56 -0500 | [diff] [blame] | 179 | if (!port || (!port->membase && !port->iobase)) |
Yinghai Lu | 18a8bd9 | 2007-07-15 23:37:59 -0700 | [diff] [blame] | 180 | return -ENODEV; |
| 181 | |
| 182 | line = serial8250_find_port(port); |
| 183 | if (line < 0) |
| 184 | return -ENODEV; |
| 185 | |
| 186 | ret = update_console_cmdline("uart", 8250, |
| 187 | "ttyS", line, device->options); |
| 188 | if (ret < 0) |
| 189 | ret = update_console_cmdline("uart", 0, |
| 190 | "ttyS", line, device->options); |
| 191 | |
| 192 | return ret; |
| 193 | } |