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 <linux/of.h> 9 #include <asm/udbg.h> 10 #include <asm/processor.h> 11 #include <asm/io.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 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 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 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 65 void __init 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 of_node_put(ch_def); 86 ch_def = of_node_get(ch); 87 } 88 if (of_node_name_eq(ch, "ch-a")) { 89 of_node_put(ch_a); 90 ch_a = of_node_get(ch); 91 } 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 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