1 /*
2  * udbg for zilog scc ports as found on Apple PowerMacs
3  *
4  * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
5  *
6  *      This program is free software; you can redistribute it and/or
7  *      modify it under the terms of the GNU General Public License
8  *      as published by the Free Software Foundation; either version
9  *      2 of the License, or (at your option) any later version.
10  */
11 #include <linux/types.h>
12 #include <asm/udbg.h>
13 #include <asm/processor.h>
14 #include <asm/io.h>
15 #include <asm/prom.h>
16 #include <asm/pmac_feature.h>
17 
18 extern u8 real_readb(volatile u8 __iomem  *addr);
19 extern void real_writeb(u8 data, volatile u8 __iomem *addr);
20 
21 #define	SCC_TXRDY	4
22 #define SCC_RXRDY	1
23 
24 static volatile u8 __iomem *sccc;
25 static volatile u8 __iomem *sccd;
26 
27 static void udbg_scc_putc(char c)
28 {
29 	if (sccc) {
30 		while ((in_8(sccc) & SCC_TXRDY) == 0)
31 			;
32 		out_8(sccd,  c);
33 		if (c == '\n')
34 			udbg_scc_putc('\r');
35 	}
36 }
37 
38 static int udbg_scc_getc_poll(void)
39 {
40 	if (sccc) {
41 		if ((in_8(sccc) & SCC_RXRDY) != 0)
42 			return in_8(sccd);
43 		else
44 			return -1;
45 	}
46 	return -1;
47 }
48 
49 static int udbg_scc_getc(void)
50 {
51 	if (sccc) {
52 		while ((in_8(sccc) & SCC_RXRDY) == 0)
53 			;
54 		return in_8(sccd);
55 	}
56 	return -1;
57 }
58 
59 static unsigned char scc_inittab[] = {
60     13, 0,		/* set baud rate divisor */
61     12, 0,
62     14, 1,		/* baud rate gen enable, src=rtxc */
63     11, 0x50,		/* clocks = br gen */
64     5,  0xea,		/* tx 8 bits, assert DTR & RTS */
65     4,  0x46,		/* x16 clock, 1 stop */
66     3,  0xc1,		/* rx enable, 8 bits */
67 };
68 
69 void udbg_scc_init(int force_scc)
70 {
71 	const u32 *reg;
72 	unsigned long addr;
73 	struct device_node *stdout = NULL, *escc = NULL, *macio = NULL;
74 	struct device_node *ch, *ch_def = NULL, *ch_a = NULL;
75 	const char *path;
76 	int i, x;
77 
78 	escc = of_find_node_by_name(NULL, "escc");
79 	if (escc == NULL)
80 		goto bail;
81 	macio = of_get_parent(escc);
82 	if (macio == NULL)
83 		goto bail;
84 	path = of_get_property(of_chosen, "linux,stdout-path", NULL);
85 	if (path != NULL)
86 		stdout = of_find_node_by_path(path);
87 	for (ch = NULL; (ch = of_get_next_child(escc, ch)) != NULL;) {
88 		if (ch == stdout)
89 			ch_def = of_node_get(ch);
90 		if (strcmp(ch->name, "ch-a") == 0)
91 			ch_a = of_node_get(ch);
92 	}
93 	if (ch_def == NULL && !force_scc)
94 		goto bail;
95 
96 	ch = ch_def ? ch_def : ch_a;
97 
98 	/* Get address within mac-io ASIC */
99 	reg = of_get_property(escc, "reg", NULL);
100 	if (reg == NULL)
101 		goto bail;
102 	addr = reg[0];
103 
104 	/* Get address of mac-io PCI itself */
105 	reg = of_get_property(macio, "assigned-addresses", NULL);
106 	if (reg == NULL)
107 		goto bail;
108 	addr += reg[2];
109 
110 	/* Lock the serial port */
111 	pmac_call_feature(PMAC_FTR_SCC_ENABLE, ch,
112 			  PMAC_SCC_ASYNC | PMAC_SCC_FLAG_XMON, 1);
113 
114 	if (ch == ch_a)
115 		addr += 0x20;
116 	sccc = ioremap(addr & PAGE_MASK, PAGE_SIZE) ;
117 	sccc += addr & ~PAGE_MASK;
118 	sccd = sccc + 0x10;
119 
120 	mb();
121 
122 	for (i = 20000; i != 0; --i)
123 		x = in_8(sccc);
124 	out_8(sccc, 0x09);		/* reset A or B side */
125 	out_8(sccc, 0xc0);
126 
127 	/* If SCC was the OF output port, read the BRG value, else
128 	 * Setup for 38400 or 57600 8N1 depending on the machine
129 	 */
130 	if (ch_def != NULL) {
131 		out_8(sccc, 13);
132 		scc_inittab[1] = in_8(sccc);
133 		out_8(sccc, 12);
134 		scc_inittab[3] = in_8(sccc);
135 	} else if (of_machine_is_compatible("RackMac1,1")
136 		   || of_machine_is_compatible("RackMac1,2")
137 		   || of_machine_is_compatible("MacRISC4")) {
138 		/* Xserves and G5s default to 57600 */
139 		scc_inittab[1] = 0;
140 		scc_inittab[3] = 0;
141 	} else {
142 		/* Others default to 38400 */
143 		scc_inittab[1] = 0;
144 		scc_inittab[3] = 1;
145 	}
146 
147 	for (i = 0; i < sizeof(scc_inittab); ++i)
148 		out_8(sccc, scc_inittab[i]);
149 
150 
151 	udbg_putc = udbg_scc_putc;
152 	udbg_getc = udbg_scc_getc;
153 	udbg_getc_poll = udbg_scc_getc_poll;
154 
155 	udbg_puts("Hello World !\n");
156 
157  bail:
158 	of_node_put(macio);
159 	of_node_put(escc);
160 	of_node_put(stdout);
161 	of_node_put(ch_def);
162 	of_node_put(ch_a);
163 }
164 
165 #ifdef CONFIG_PPC64
166 static void udbg_real_scc_putc(char c)
167 {
168 	while ((real_readb(sccc) & SCC_TXRDY) == 0)
169 		;
170 	real_writeb(c, sccd);
171 	if (c == '\n')
172 		udbg_real_scc_putc('\r');
173 }
174 
175 void __init udbg_init_pmac_realmode(void)
176 {
177 	sccc = (volatile u8 __iomem *)0x80013020ul;
178 	sccd = (volatile u8 __iomem *)0x80013030ul;
179 
180 	udbg_putc = udbg_real_scc_putc;
181 	udbg_getc = NULL;
182 	udbg_getc_poll = NULL;
183 }
184 #endif /* CONFIG_PPC64 */
185