1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * udbg for zilog scc ports as found on Apple PowerMacs
5 * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
7 #include <linux/types.h>
10 #include <asm/processor.h>
12 #include <asm/pmac_feature.h>
14 extern u8 real_readb(volatile u8 __iomem *addr);
15 extern void real_writeb(u8 data, volatile u8 __iomem *addr);
20 static volatile u8 __iomem *sccc;
21 static volatile u8 __iomem *sccd;
23 static void udbg_scc_putc(char c)
26 while ((in_8(sccc) & SCC_TXRDY) == 0)
34 static int udbg_scc_getc_poll(void)
37 if ((in_8(sccc) & SCC_RXRDY) != 0)
45 static int udbg_scc_getc(void)
48 while ((in_8(sccc) & SCC_RXRDY) == 0)
55 static unsigned char scc_inittab[] = {
56 13, 0, /* set baud rate divisor */
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 */
65 void __init udbg_scc_init(int force_scc)
69 struct device_node *stdout = NULL, *escc = NULL, *macio = NULL;
70 struct device_node *ch, *ch_def = NULL, *ch_a = NULL;
74 escc = of_find_node_by_name(NULL, "escc");
77 macio = of_get_parent(escc);
80 path = of_get_property(of_chosen, "linux,stdout-path", NULL);
82 stdout = of_find_node_by_path(path);
83 for_each_child_of_node(escc, ch) {
86 ch_def = of_node_get(ch);
88 if (of_node_name_eq(ch, "ch-a")) {
90 ch_a = of_node_get(ch);
93 if (ch_def == NULL && !force_scc)
96 ch = ch_def ? ch_def : ch_a;
98 /* Get address within mac-io ASIC */
99 reg = of_get_property(escc, "reg", NULL);
104 /* Get address of mac-io PCI itself */
105 reg = of_get_property(macio, "assigned-addresses", NULL);
110 /* Lock the serial port */
111 pmac_call_feature(PMAC_FTR_SCC_ENABLE, ch,
112 PMAC_SCC_ASYNC | PMAC_SCC_FLAG_XMON, 1);
116 sccc = ioremap(addr & PAGE_MASK, PAGE_SIZE) ;
117 sccc += addr & ~PAGE_MASK;
122 for (i = 20000; i != 0; --i)
124 out_8(sccc, 0x09); /* reset A or B side */
127 /* If SCC was the OF output port, read the BRG value, else
128 * Setup for 38400 or 57600 8N1 depending on the machine
130 if (ch_def != NULL) {
132 scc_inittab[1] = in_8(sccc);
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 */
142 /* Others default to 38400 */
147 for (i = 0; i < sizeof(scc_inittab); ++i)
148 out_8(sccc, scc_inittab[i]);
151 udbg_putc = udbg_scc_putc;
152 udbg_getc = udbg_scc_getc;
153 udbg_getc_poll = udbg_scc_getc_poll;
155 udbg_puts("Hello World !\n");
166 static void udbg_real_scc_putc(char c)
168 while ((real_readb(sccc) & SCC_TXRDY) == 0)
170 real_writeb(c, sccd);
172 udbg_real_scc_putc('\r');
175 void __init udbg_init_pmac_realmode(void)
177 sccc = (volatile u8 __iomem *)0x80013020ul;
178 sccd = (volatile u8 __iomem *)0x80013030ul;
180 udbg_putc = udbg_real_scc_putc;
182 udbg_getc_poll = NULL;
184 #endif /* CONFIG_PPC64 */