arch/powerpc/platforms/powermac/udbg_scc.c

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