1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * udbg for zilog scc ports as found on Apple PowerMacs
4 *
5 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
6 */
7 #include <linux/types.h>
8 #include <asm/udbg.h>
9 #include <asm/processor.h>
10 #include <asm/io.h>
11 #include <asm/prom.h>
12 #include <asm/pmac_feature.h>
13
14 extern u8 real_readb(volatile u8 __iomem *addr);
15 extern void real_writeb(u8 data, volatile u8 __iomem *addr);
16
17 #define SCC_TXRDY 4
18 #define SCC_RXRDY 1
19
20 static volatile u8 __iomem *sccc;
21 static volatile u8 __iomem *sccd;
22
udbg_scc_putc(char c)23 static void udbg_scc_putc(char c)
24 {
25 if (sccc) {
26 while ((in_8(sccc) & SCC_TXRDY) == 0)
27 ;
28 out_8(sccd, c);
29 if (c == '\n')
30 udbg_scc_putc('\r');
31 }
32 }
33
udbg_scc_getc_poll(void)34 static int udbg_scc_getc_poll(void)
35 {
36 if (sccc) {
37 if ((in_8(sccc) & SCC_RXRDY) != 0)
38 return in_8(sccd);
39 else
40 return -1;
41 }
42 return -1;
43 }
44
udbg_scc_getc(void)45 static int udbg_scc_getc(void)
46 {
47 if (sccc) {
48 while ((in_8(sccc) & SCC_RXRDY) == 0)
49 ;
50 return in_8(sccd);
51 }
52 return -1;
53 }
54
55 static unsigned char scc_inittab[] = {
56 13, 0, /* set baud rate divisor */
57 12, 0,
58 14, 1, /* baud rate gen enable, src=rtxc */
59 11, 0x50, /* clocks = br gen */
60 5, 0xea, /* tx 8 bits, assert DTR & RTS */
61 4, 0x46, /* x16 clock, 1 stop */
62 3, 0xc1, /* rx enable, 8 bits */
63 };
64
udbg_scc_init(int force_scc)65 void udbg_scc_init(int force_scc)
66 {
67 const u32 *reg;
68 unsigned long addr;
69 struct device_node *stdout = NULL, *escc = NULL, *macio = NULL;
70 struct device_node *ch, *ch_def = NULL, *ch_a = NULL;
71 const char *path;
72 int i;
73
74 escc = of_find_node_by_name(NULL, "escc");
75 if (escc == NULL)
76 goto bail;
77 macio = of_get_parent(escc);
78 if (macio == NULL)
79 goto bail;
80 path = of_get_property(of_chosen, "linux,stdout-path", NULL);
81 if (path != NULL)
82 stdout = of_find_node_by_path(path);
83 for_each_child_of_node(escc, ch) {
84 if (ch == stdout)
85 ch_def = of_node_get(ch);
86 if (of_node_name_eq(ch, "ch-a"))
87 ch_a = of_node_get(ch);
88 }
89 if (ch_def == NULL && !force_scc)
90 goto bail;
91
92 ch = ch_def ? ch_def : ch_a;
93
94 /* Get address within mac-io ASIC */
95 reg = of_get_property(escc, "reg", NULL);
96 if (reg == NULL)
97 goto bail;
98 addr = reg[0];
99
100 /* Get address of mac-io PCI itself */
101 reg = of_get_property(macio, "assigned-addresses", NULL);
102 if (reg == NULL)
103 goto bail;
104 addr += reg[2];
105
106 /* Lock the serial port */
107 pmac_call_feature(PMAC_FTR_SCC_ENABLE, ch,
108 PMAC_SCC_ASYNC | PMAC_SCC_FLAG_XMON, 1);
109
110 if (ch == ch_a)
111 addr += 0x20;
112 sccc = ioremap(addr & PAGE_MASK, PAGE_SIZE) ;
113 sccc += addr & ~PAGE_MASK;
114 sccd = sccc + 0x10;
115
116 mb();
117
118 for (i = 20000; i != 0; --i)
119 in_8(sccc);
120 out_8(sccc, 0x09); /* reset A or B side */
121 out_8(sccc, 0xc0);
122
123 /* If SCC was the OF output port, read the BRG value, else
124 * Setup for 38400 or 57600 8N1 depending on the machine
125 */
126 if (ch_def != NULL) {
127 out_8(sccc, 13);
128 scc_inittab[1] = in_8(sccc);
129 out_8(sccc, 12);
130 scc_inittab[3] = in_8(sccc);
131 } else if (of_machine_is_compatible("RackMac1,1")
132 || of_machine_is_compatible("RackMac1,2")
133 || of_machine_is_compatible("MacRISC4")) {
134 /* Xserves and G5s default to 57600 */
135 scc_inittab[1] = 0;
136 scc_inittab[3] = 0;
137 } else {
138 /* Others default to 38400 */
139 scc_inittab[1] = 0;
140 scc_inittab[3] = 1;
141 }
142
143 for (i = 0; i < sizeof(scc_inittab); ++i)
144 out_8(sccc, scc_inittab[i]);
145
146
147 udbg_putc = udbg_scc_putc;
148 udbg_getc = udbg_scc_getc;
149 udbg_getc_poll = udbg_scc_getc_poll;
150
151 udbg_puts("Hello World !\n");
152
153 bail:
154 of_node_put(macio);
155 of_node_put(escc);
156 of_node_put(stdout);
157 of_node_put(ch_def);
158 of_node_put(ch_a);
159 }
160
161 #ifdef CONFIG_PPC64
udbg_real_scc_putc(char c)162 static void udbg_real_scc_putc(char c)
163 {
164 while ((real_readb(sccc) & SCC_TXRDY) == 0)
165 ;
166 real_writeb(c, sccd);
167 if (c == '\n')
168 udbg_real_scc_putc('\r');
169 }
170
udbg_init_pmac_realmode(void)171 void __init udbg_init_pmac_realmode(void)
172 {
173 sccc = (volatile u8 __iomem *)0x80013020ul;
174 sccd = (volatile u8 __iomem *)0x80013030ul;
175
176 udbg_putc = udbg_real_scc_putc;
177 udbg_getc = NULL;
178 udbg_getc_poll = NULL;
179 }
180 #endif /* CONFIG_PPC64 */
181