1 /*
2 * Early printk support for Microblaze.
3 *
4 * Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
5 * Copyright (C) 2007-2009 PetaLogix
6 * Copyright (C) 2003-2006 Yasushi SHOJI <yashi@atmark-techno.com>
7 *
8 * This file is subject to the terms and conditions of the GNU General Public
9 * License. See the file "COPYING" in the main directory of this archive
10 * for more details.
11 */
12
13 #include <linux/console.h>
14 #include <linux/kernel.h>
15 #include <linux/init.h>
16 #include <linux/string.h>
17 #include <linux/tty.h>
18 #include <linux/io.h>
19 #include <asm/processor.h>
20 #include <linux/fcntl.h>
21 #include <asm/setup.h>
22 #include <asm/prom.h>
23
24 static u32 early_console_initialized;
25 static u32 base_addr;
26
27 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
early_printk_uartlite_putc(char c)28 static void early_printk_uartlite_putc(char c)
29 {
30 /*
31 * Limit how many times we'll spin waiting for TX FIFO status.
32 * This will prevent lockups if the base address is incorrectly
33 * set, or any other issue on the UARTLITE.
34 * This limit is pretty arbitrary, unless we are at about 10 baud
35 * we'll never timeout on a working UART.
36 */
37
38 unsigned retries = 1000000;
39 /* read status bit - 0x8 offset */
40 while (--retries && (in_be32(base_addr + 8) & (1 << 3)))
41 ;
42
43 /* Only attempt the iowrite if we didn't timeout */
44 /* write to TX_FIFO - 0x4 offset */
45 if (retries)
46 out_be32(base_addr + 4, c & 0xff);
47 }
48
early_printk_uartlite_write(struct console * unused,const char * s,unsigned n)49 static void early_printk_uartlite_write(struct console *unused,
50 const char *s, unsigned n)
51 {
52 while (*s && n-- > 0) {
53 if (*s == '\n')
54 early_printk_uartlite_putc('\r');
55 early_printk_uartlite_putc(*s);
56 s++;
57 }
58 }
59
60 static struct console early_serial_uartlite_console = {
61 .name = "earlyser",
62 .write = early_printk_uartlite_write,
63 .flags = CON_PRINTBUFFER | CON_BOOT,
64 .index = -1,
65 };
66 #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
67
68 #ifdef CONFIG_SERIAL_8250_CONSOLE
early_printk_uart16550_putc(char c)69 static void early_printk_uart16550_putc(char c)
70 {
71 /*
72 * Limit how many times we'll spin waiting for TX FIFO status.
73 * This will prevent lockups if the base address is incorrectly
74 * set, or any other issue on the UARTLITE.
75 * This limit is pretty arbitrary, unless we are at about 10 baud
76 * we'll never timeout on a working UART.
77 */
78
79 #define UART_LSR_TEMT 0x40 /* Transmitter empty */
80 #define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
81 #define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
82
83 unsigned retries = 10000;
84
85 while (--retries &&
86 !((in_be32(base_addr + 0x14) & BOTH_EMPTY) == BOTH_EMPTY))
87 ;
88
89 if (retries)
90 out_be32(base_addr, c & 0xff);
91 }
92
early_printk_uart16550_write(struct console * unused,const char * s,unsigned n)93 static void early_printk_uart16550_write(struct console *unused,
94 const char *s, unsigned n)
95 {
96 while (*s && n-- > 0) {
97 if (*s == '\n')
98 early_printk_uart16550_putc('\r');
99 early_printk_uart16550_putc(*s);
100 s++;
101 }
102 }
103
104 static struct console early_serial_uart16550_console = {
105 .name = "earlyser",
106 .write = early_printk_uart16550_write,
107 .flags = CON_PRINTBUFFER | CON_BOOT,
108 .index = -1,
109 };
110 #endif /* CONFIG_SERIAL_8250_CONSOLE */
111
112 static struct console *early_console;
113
early_printk(const char * fmt,...)114 void early_printk(const char *fmt, ...)
115 {
116 char buf[512];
117 int n;
118 va_list ap;
119
120 if (early_console_initialized) {
121 va_start(ap, fmt);
122 n = vscnprintf(buf, 512, fmt, ap);
123 early_console->write(early_console, buf, n);
124 va_end(ap);
125 }
126 }
127
setup_early_printk(char * opt)128 int __init setup_early_printk(char *opt)
129 {
130 int version = 0;
131
132 if (early_console_initialized)
133 return 1;
134
135 base_addr = of_early_console(&version);
136 if (base_addr) {
137 #ifdef CONFIG_MMU
138 early_console_reg_tlb_alloc(base_addr);
139 #endif
140 switch (version) {
141 #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
142 case UARTLITE:
143 printk(KERN_INFO "Early console on uartlite "
144 "at 0x%08x\n", base_addr);
145 early_console = &early_serial_uartlite_console;
146 break;
147 #endif
148 #ifdef CONFIG_SERIAL_8250_CONSOLE
149 case UART16550:
150 printk(KERN_INFO "Early console on uart16650 "
151 "at 0x%08x\n", base_addr);
152 early_console = &early_serial_uart16550_console;
153 break;
154 #endif
155 default:
156 printk(KERN_INFO "Unsupported early console %d\n",
157 version);
158 return 1;
159 }
160
161 register_console(early_console);
162 early_console_initialized = 1;
163 return 0;
164 }
165 return 1;
166 }
167
168 /* Remap early console to virtual address and do not allocate one TLB
169 * only for early console because of performance degression */
remap_early_printk(void)170 void __init remap_early_printk(void)
171 {
172 if (!early_console_initialized || !early_console)
173 return;
174 printk(KERN_INFO "early_printk_console remapping from 0x%x to ",
175 base_addr);
176 base_addr = (u32) ioremap(base_addr, PAGE_SIZE);
177 printk(KERN_CONT "0x%x\n", base_addr);
178
179 #ifdef CONFIG_MMU
180 /*
181 * Early console is on the top of skipped TLB entries
182 * decrease tlb_skip size ensure that hardcoded TLB entry will be
183 * used by generic algorithm
184 * FIXME check if early console mapping is on the top by rereading
185 * TLB entry and compare baseaddr
186 * mts rtlbx, (tlb_skip - 1)
187 * nop
188 * mfs rX, rtlblo
189 * nop
190 * cmp rX, orig_base_addr
191 */
192 tlb_skip -= 1;
193 #endif
194 }
195
disable_early_printk(void)196 void __init disable_early_printk(void)
197 {
198 if (!early_console_initialized || !early_console)
199 return;
200 printk(KERN_WARNING "disabling early console\n");
201 unregister_console(early_console);
202 early_console_initialized = 0;
203 }
204