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1da177e4 LT |
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., | |
18a8bd94 YL |
20 | * earlycon=uart8250,io,0x3f8,9600n8 |
21 | * earlycon=uart8250,mmio,0xff5e0000,115200n8 | |
22 | * or | |
23 | * console=uart8250,io,0x3f8,9600n8 | |
24 | * console=uart8250,mmio,0xff5e0000,115200n8 | |
1da177e4 LT |
25 | */ |
26 | ||
27 | #include <linux/tty.h> | |
28 | #include <linux/init.h> | |
29 | #include <linux/console.h> | |
30 | #include <linux/serial_core.h> | |
31 | #include <linux/serial_reg.h> | |
32 | #include <linux/serial.h> | |
18a8bd94 | 33 | #include <linux/serial_8250.h> |
1da177e4 LT |
34 | #include <asm/io.h> |
35 | #include <asm/serial.h> | |
18a8bd94 YL |
36 | #ifdef CONFIG_FIX_EARLYCON_MEM |
37 | #include <asm/pgtable.h> | |
38 | #include <asm/fixmap.h> | |
39 | #endif | |
1da177e4 | 40 | |
18a8bd94 | 41 | struct early_serial8250_device { |
1da177e4 LT |
42 | struct uart_port port; |
43 | char options[16]; /* e.g., 115200n8 */ | |
44 | unsigned int baud; | |
45 | }; | |
46 | ||
18a8bd94 | 47 | static struct early_serial8250_device early_device; |
1da177e4 LT |
48 | |
49 | static unsigned int __init serial_in(struct uart_port *port, int offset) | |
50 | { | |
51 | if (port->iotype == UPIO_MEM) | |
52 | return readb(port->membase + offset); | |
53 | else | |
54 | return inb(port->iobase + offset); | |
55 | } | |
56 | ||
57 | static void __init serial_out(struct uart_port *port, int offset, int value) | |
58 | { | |
59 | if (port->iotype == UPIO_MEM) | |
60 | writeb(value, port->membase + offset); | |
61 | else | |
62 | outb(value, port->iobase + offset); | |
63 | } | |
64 | ||
65 | #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE) | |
66 | ||
67 | static void __init wait_for_xmitr(struct uart_port *port) | |
68 | { | |
69 | unsigned int status; | |
70 | ||
71 | for (;;) { | |
72 | status = serial_in(port, UART_LSR); | |
73 | if ((status & BOTH_EMPTY) == BOTH_EMPTY) | |
74 | return; | |
75 | cpu_relax(); | |
76 | } | |
77 | } | |
78 | ||
bf2cdef3 | 79 | static void __init serial_putc(struct uart_port *port, int c) |
1da177e4 LT |
80 | { |
81 | wait_for_xmitr(port); | |
82 | serial_out(port, UART_TX, c); | |
83 | } | |
84 | ||
ce2e204f AC |
85 | static void __init early_serial8250_write(struct console *console, |
86 | const char *s, unsigned int count) | |
1da177e4 LT |
87 | { |
88 | struct uart_port *port = &early_device.port; | |
89 | unsigned int ier; | |
90 | ||
91 | /* Save the IER and disable interrupts */ | |
92 | ier = serial_in(port, UART_IER); | |
93 | serial_out(port, UART_IER, 0); | |
94 | ||
bf2cdef3 | 95 | uart_console_write(port, s, count, serial_putc); |
1da177e4 LT |
96 | |
97 | /* Wait for transmitter to become empty and restore the IER */ | |
98 | wait_for_xmitr(port); | |
99 | serial_out(port, UART_IER, ier); | |
100 | } | |
101 | ||
102 | static unsigned int __init probe_baud(struct uart_port *port) | |
103 | { | |
104 | unsigned char lcr, dll, dlm; | |
105 | unsigned int quot; | |
106 | ||
107 | lcr = serial_in(port, UART_LCR); | |
108 | serial_out(port, UART_LCR, lcr | UART_LCR_DLAB); | |
109 | dll = serial_in(port, UART_DLL); | |
110 | dlm = serial_in(port, UART_DLM); | |
111 | serial_out(port, UART_LCR, lcr); | |
112 | ||
113 | quot = (dlm << 8) | dll; | |
114 | return (port->uartclk / 16) / quot; | |
115 | } | |
116 | ||
18a8bd94 | 117 | static void __init init_port(struct early_serial8250_device *device) |
1da177e4 LT |
118 | { |
119 | struct uart_port *port = &device->port; | |
120 | unsigned int divisor; | |
121 | unsigned char c; | |
122 | ||
123 | serial_out(port, UART_LCR, 0x3); /* 8n1 */ | |
124 | serial_out(port, UART_IER, 0); /* no interrupt */ | |
125 | serial_out(port, UART_FCR, 0); /* no fifo */ | |
126 | serial_out(port, UART_MCR, 0x3); /* DTR + RTS */ | |
127 | ||
128 | divisor = port->uartclk / (16 * device->baud); | |
129 | c = serial_in(port, UART_LCR); | |
130 | serial_out(port, UART_LCR, c | UART_LCR_DLAB); | |
131 | serial_out(port, UART_DLL, divisor & 0xff); | |
132 | serial_out(port, UART_DLM, (divisor >> 8) & 0xff); | |
133 | serial_out(port, UART_LCR, c & ~UART_LCR_DLAB); | |
134 | } | |
135 | ||
ce2e204f AC |
136 | static int __init parse_options(struct early_serial8250_device *device, |
137 | char *options) | |
1da177e4 LT |
138 | { |
139 | struct uart_port *port = &device->port; | |
1da177e4 LT |
140 | int mmio, length; |
141 | ||
142 | if (!options) | |
143 | return -ENODEV; | |
144 | ||
145 | port->uartclk = BASE_BAUD * 16; | |
146 | if (!strncmp(options, "mmio,", 5)) { | |
147 | port->iotype = UPIO_MEM; | |
148 | port->mapbase = simple_strtoul(options + 5, &options, 0); | |
18a8bd94 | 149 | #ifdef CONFIG_FIX_EARLYCON_MEM |
ce2e204f AC |
150 | set_fixmap_nocache(FIX_EARLYCON_MEM_BASE, |
151 | port->mapbase & PAGE_MASK); | |
152 | port->membase = | |
153 | (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE); | |
18a8bd94 YL |
154 | port->membase += port->mapbase & ~PAGE_MASK; |
155 | #else | |
6f441fe9 | 156 | port->membase = ioremap_nocache(port->mapbase, 64); |
1da177e4 | 157 | if (!port->membase) { |
4f640efb | 158 | printk(KERN_ERR "%s: Couldn't ioremap 0x%llx\n", |
71cc2c21 | 159 | __func__, |
4f640efb | 160 | (unsigned long long)port->mapbase); |
1da177e4 LT |
161 | return -ENOMEM; |
162 | } | |
18a8bd94 | 163 | #endif |
1da177e4 LT |
164 | mmio = 1; |
165 | } else if (!strncmp(options, "io,", 3)) { | |
166 | port->iotype = UPIO_PORT; | |
167 | port->iobase = simple_strtoul(options + 3, &options, 0); | |
168 | mmio = 0; | |
169 | } else | |
170 | return -EINVAL; | |
171 | ||
ce2e204f AC |
172 | options = strchr(options, ','); |
173 | if (options) { | |
1da177e4 | 174 | options++; |
b2281abf | 175 | device->baud = simple_strtoul(options, NULL, 0); |
1da177e4 LT |
176 | length = min(strcspn(options, " "), sizeof(device->options)); |
177 | strncpy(device->options, options, length); | |
178 | } else { | |
179 | device->baud = probe_baud(port); | |
180 | snprintf(device->options, sizeof(device->options), "%u", | |
181 | device->baud); | |
182 | } | |
183 | ||
4f640efb | 184 | printk(KERN_INFO "Early serial console at %s 0x%llx (options '%s')\n", |
1da177e4 | 185 | mmio ? "MMIO" : "I/O port", |
4f640efb | 186 | mmio ? (unsigned long long) port->mapbase |
ce2e204f | 187 | : (unsigned long long) port->iobase, |
1da177e4 LT |
188 | device->options); |
189 | return 0; | |
190 | } | |
191 | ||
18a8bd94 YL |
192 | static struct console early_serial8250_console __initdata = { |
193 | .name = "uart", | |
194 | .write = early_serial8250_write, | |
195 | .flags = CON_PRINTBUFFER | CON_BOOT, | |
196 | .index = -1, | |
197 | }; | |
198 | ||
199 | static int __init early_serial8250_setup(char *options) | |
1da177e4 | 200 | { |
18a8bd94 | 201 | struct early_serial8250_device *device = &early_device; |
1da177e4 LT |
202 | int err; |
203 | ||
204 | if (device->port.membase || device->port.iobase) | |
205 | return 0; | |
206 | ||
ce2e204f AC |
207 | err = parse_options(device, options); |
208 | if (err < 0) | |
1da177e4 LT |
209 | return err; |
210 | ||
211 | init_port(device); | |
212 | return 0; | |
213 | } | |
214 | ||
18a8bd94 | 215 | int __init setup_early_serial8250_console(char *cmdline) |
1da177e4 LT |
216 | { |
217 | char *options; | |
218 | int err; | |
219 | ||
18a8bd94 YL |
220 | options = strstr(cmdline, "uart8250,"); |
221 | if (!options) { | |
222 | options = strstr(cmdline, "uart,"); | |
223 | if (!options) | |
224 | return 0; | |
225 | } | |
1da177e4 LT |
226 | |
227 | options = strchr(cmdline, ',') + 1; | |
ce2e204f AC |
228 | err = early_serial8250_setup(options); |
229 | if (err < 0) | |
1da177e4 | 230 | return err; |
18a8bd94 YL |
231 | |
232 | register_console(&early_serial8250_console); | |
233 | ||
234 | return 0; | |
1da177e4 LT |
235 | } |
236 | ||
b6b1d877 | 237 | int serial8250_find_port_for_earlycon(void) |
1da177e4 | 238 | { |
18a8bd94 | 239 | struct early_serial8250_device *device = &early_device; |
1da177e4 | 240 | struct uart_port *port = &device->port; |
18a8bd94 YL |
241 | int line; |
242 | int ret; | |
1da177e4 | 243 | |
18a8bd94 YL |
244 | if (!device->port.membase && !device->port.iobase) |
245 | return -ENODEV; | |
1da177e4 | 246 | |
18a8bd94 | 247 | line = serial8250_find_port(port); |
1da177e4 | 248 | if (line < 0) |
18a8bd94 | 249 | return -ENODEV; |
1da177e4 | 250 | |
18a8bd94 YL |
251 | ret = update_console_cmdline("uart", 8250, |
252 | "ttyS", line, device->options); | |
253 | if (ret < 0) | |
254 | ret = update_console_cmdline("uart", 0, | |
255 | "ttyS", line, device->options); | |
1da177e4 | 256 | |
18a8bd94 | 257 | return ret; |
1da177e4 | 258 | } |
18a8bd94 YL |
259 | |
260 | early_param("earlycon", setup_early_serial8250_console); |