[PATCH] powerpc: Unify udbg (#2)

This patch unifies udbg for both ppc32 and ppc64 when building the
merged achitecture. xmon now has a single "back end". The powermac udbg
stuff gets enriched with some ADB capabilities and btext output. In
addition, the early_init callback is now called on ppc32 as well,
approx. in the same order as ppc64 regarding device-tree manipulations.
The init sequences of ppc32 and ppc64 are getting closer, I'll unify
them in a later patch.

For now, you can force udbg to the scc using "sccdbg" or to btext using
"btextdbg" on powermacs. I'll implement a cleaner way of forcing udbg
output to something else than the autodetected OF output device in a
later patch.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

7 files changed, 470 insertions, 63 deletions

diff --git a/arch/powerpc/platforms/powermac/Makefile b/arch/powerpc/platforms/powermac/Makefile
index c9df44fcf571..3e5370eeb1b7 100644
--- a/arch/powerpc/platforms/powermac/Makefile
+++ b/arch/powerpc/platforms/powermac/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_NVRAM)		+= nvram.o
 # ppc64 pmac doesn't define CONFIG_NVRAM but needs nvram stuff
 obj-$(CONFIG_PPC64)             += nvram.o
 obj-$(CONFIG_SMP)               += smp.o
+obj-$(CONFIG_PPC_MERGE)         += udbg_scc.o udbg_adb.o
diff --git a/arch/powerpc/platforms/powermac/feature.c b/arch/powerpc/platforms/powermac/feature.c
index f6e22da2a5da..52a9d0c1b8b8 100644
--- a/arch/powerpc/platforms/powermac/feature.c
+++ b/arch/powerpc/platforms/powermac/feature.c
@@ -2607,6 +2607,8 @@ found:
  */
 static void __init probe_uninorth(void)
 {
+        u32 *addrp;
+        phys_addr_t address;
         unsigned long actrl;
 
         /* Locate core99 Uni-N */
@@ -2616,20 +2618,23 @@ static void __init probe_uninorth(void)
                 uninorth_node = of_find_node_by_name(NULL, "u3");
                 uninorth_u3 = 1;
         }
-        if (uninorth_node && uninorth_node->n_addrs > 0) {
-                unsigned long address = uninorth_node->addrs[0].address;
-                uninorth_base = ioremap(address, 0x40000);
-                uninorth_rev = in_be32(UN_REG(UNI_N_VERSION));
-                if (uninorth_u3)
-                        u3_ht = ioremap(address + U3_HT_CONFIG_BASE, 0x1000);
-        } else
-                uninorth_node = NULL;
-
-        if (!uninorth_node)
+        if (uninorth_node == NULL)
                 return;
 
-        printk(KERN_INFO "Found %s memory controller & host bridge, revision: %d\n",
-               uninorth_u3 ? "U3" : "UniNorth", uninorth_rev);
+        addrp = (u32 *)get_property(uninorth_node, "reg", NULL);
+        if (addrp == NULL)
+                return;
+        address = of_translate_address(uninorth_node, addrp);
+        if (address == 0)
+                return;
+        uninorth_base = ioremap(address, 0x40000);
+        uninorth_rev = in_be32(UN_REG(UNI_N_VERSION));
+        if (uninorth_u3)
+                u3_ht = ioremap(address + U3_HT_CONFIG_BASE, 0x1000);
+
+        printk(KERN_INFO "Found %s memory controller & host bridge,"
+               " revision: %d\n", uninorth_u3 ? "U3" : "UniNorth",
+               uninorth_rev);
         printk(KERN_INFO "Mapped at 0x%08lx\n", (unsigned long)uninorth_base);
 
         /* Set the arbitrer QAck delay according to what Apple does
@@ -2653,18 +2658,17 @@ static void __init probe_one_macio(const char *name, const char *compat, int typ
 {
         struct device_node*     node;
         int                     i;
-        volatile u32 __iomem *  base;
-        u32*                    revp;
+        volatile u32 __iomem    *base;
+        u32                     *addrp, *revp;
+        phys_addr_t             addr;
+        u64                     size;
 
-        node = find_devices(name);
-        if (!node || !node->n_addrs)
-                return;
-        if (compat)
-                do {
-                        if (device_is_compatible(node, compat))
-                                break;
-                        node = node->next;
-                } while (node);
+        for (node = NULL; (node = of_find_node_by_name(node, name)) != NULL;) {
+                if (!compat)
+                        break;
+                if (device_is_compatible(node, compat))
+                        break;
+        }
         if (!node)
                 return;
         for(i=0; i<MAX_MACIO_CHIPS; i++) {
@@ -2673,14 +2677,28 @@ static void __init probe_one_macio(const char *name, const char *compat, int typ
                 if (macio_chips[i].of_node == node)
                         return;
         }
+
         if (i >= MAX_MACIO_CHIPS) {
                 printk(KERN_ERR "pmac_feature: Please increase MAX_MACIO_CHIPS !\n");
                 printk(KERN_ERR "pmac_feature: %s skipped\n", node->full_name);
                 return;
         }
-        base = ioremap(node->addrs[0].address, node->addrs[0].size);
+        addrp = of_get_pci_address(node, 0, &size);
+        if (addrp == NULL) {
+                printk(KERN_ERR "pmac_feature: %s: can't find base !\n",
+                       node->full_name);
+                return;
+        }
+        addr = of_translate_address(node, addrp);
+        if (addr == 0) {
+                printk(KERN_ERR "pmac_feature: %s, can't translate base !\n",
+                       node->full_name);
+                return;
+        }
+        base = ioremap(addr, (unsigned long)size);
         if (!base) {
-                printk(KERN_ERR "pmac_feature: Can't map mac-io chip !\n");
+                printk(KERN_ERR "pmac_feature: %s, can't map mac-io chip !\n",
+                       node->full_name);
                 return;
         }
         if (type == macio_keylargo) {
diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
index f3f39e8e337a..606e0ed13731 100644
--- a/arch/powerpc/platforms/powermac/low_i2c.c
+++ b/arch/powerpc/platforms/powermac/low_i2c.c
@@ -36,7 +36,7 @@
 
 #ifdef DEBUG
 #define DBG(x...) do {\
-                printk(KERN_DEBUG "KW:" x);     \
+                printk(KERN_DEBUG "low_i2c:" x);        \
         } while(0)
 #else
 #define DBG(x...)
@@ -342,7 +342,7 @@ static int keywest_low_i2c_func(struct low_i2c_host *host, u8 addr, u8 subaddr,
 static void keywest_low_i2c_add(struct device_node *np)
 {
         struct low_i2c_host     *host = find_low_i2c_host(NULL);
-        u32                     *psteps, *prate, steps, aoffset = 0;
+        u32                     *psteps, *prate, *addrp, steps;
         struct device_node      *parent;
 
         if (host == NULL) {
@@ -352,6 +352,16 @@ static void keywest_low_i2c_add(struct device_node *np)
         }
         memset(host, 0, sizeof(*host));
 
+        /* Apple is kind enough to provide a valid AAPL,address property
+         * on all i2c keywest nodes so far ... we would have to fallback
+         * to macio parsing if that wasn't the case
+         */
+        addrp = (u32 *)get_property(np, "AAPL,address", NULL);
+        if (addrp == NULL) {
+                printk(KERN_ERR "low_i2c: Can't find address for %s\n",
+                       np->full_name);
+                return;
+        }
         init_MUTEX(&host->mutex);
         host->np = of_node_get(np);     
         psteps = (u32 *)get_property(np, "AAPL,address-step", NULL);
@@ -360,12 +370,10 @@ static void keywest_low_i2c_add(struct device_node *np)
                 steps >>= 1;
         parent = of_get_parent(np);
         host->num_channels = 1;
-        if (parent && parent->name[0] == 'u') {
+        if (parent && parent->name[0] == 'u')
                 host->num_channels = 2;
-                aoffset = 3;
-        }
         /* Select interface rate */
-        host->speed = KW_I2C_MODE_100KHZ;
+        host->speed = KW_I2C_MODE_25KHZ;
         prate = (u32 *)get_property(np, "AAPL,i2c-rate", NULL);
         if (prate) switch(*prate) {
         case 100:
@@ -379,9 +387,12 @@ static void keywest_low_i2c_add(struct device_node *np)
                 break;
         }       
 
+        printk(KERN_INFO "low_i2c: Bus %s found at 0x%08x, %d channels,"
+               " speed = %d KHz\n",
+               np->full_name, *addrp, host->num_channels, prate ? *prate : 25);
+
         host->mode = pmac_low_i2c_mode_std;
-        host->base = ioremap(np->addrs[0].address + aoffset,
-                                                np->addrs[0].size);
+        host->base = ioremap((*addrp), 0x1000);
         host->func = keywest_low_i2c_func;
 }
 
diff --git a/arch/powerpc/platforms/powermac/pic.c b/arch/powerpc/platforms/powermac/pic.c
index 90040c49494d..ff78eeac10f2 100644
--- a/arch/powerpc/platforms/powermac/pic.c
+++ b/arch/powerpc/platforms/powermac/pic.c
@@ -459,7 +459,7 @@ void __init pmac_pic_init(void)
                         mpic_setup_cascade(irqctrler2->intrs[0].line,
                                            pmac_u3_cascade, mpic2);
                 }
-#if defined(CONFIG_XMON) && defined(CONFIG_PPC32)
+#ifdef CONFIG_XMON
                 {
                         struct device_node* pswitch;
                         int nmi_irq;
diff --git a/arch/powerpc/platforms/powermac/setup.c b/arch/powerpc/platforms/powermac/setup.c
index 3b7a492d9b68..6ee620fe5195 100644
--- a/arch/powerpc/platforms/powermac/setup.c
+++ b/arch/powerpc/platforms/powermac/setup.c
@@ -77,6 +77,7 @@
 #include <asm/pmc.h>
 #include <asm/mpic.h>
 #include <asm/lmb.h>
+#include <asm/udbg.h>
 
 #include "pmac.h"
 
@@ -322,16 +323,6 @@ void __init pmac_setup_arch(void)
         l2cr_init();
 #endif /* CONFIG_PPC32 */
 
-#ifdef CONFIG_PPC64
-        /* Probe motherboard chipset */
-        /* this is done earlier in setup_arch for 32-bit */
-        pmac_feature_init();
-
-        /* We can NAP */
-        powersave_nap = 1;
-        printk(KERN_INFO "Using native/NAP idle loop\n");
-#endif
-
 #ifdef CONFIG_KGDB
         zs_kgdb_hook(0);
 #endif
@@ -622,13 +613,26 @@ static void __init pmac_init_early(void)
          * and call ioremap
          */
         hpte_init_native();
+#endif
 
-        /* Init SCC */
-        if (strstr(cmd_line, "sccdbg")) {
-                sccdbg = 1;
-                udbg_init_scc(NULL);
+        /* Enable early btext debug if requested */
+        if (strstr(cmd_line, "btextdbg")) {
+                udbg_adb_init_early();
+                register_early_udbg_console();
         }
 
+        /* Probe motherboard chipset */
+        pmac_feature_init();
+
+        /* We can NAP */
+        powersave_nap = 1;
+        printk(KERN_INFO "Using native/NAP idle loop\n");
+
+        /* Initialize debug stuff */
+        udbg_scc_init(!!strstr(cmd_line, "sccdbg"));
+        udbg_adb_init(!!strstr(cmd_line, "btextdbg"));
+
+#ifdef CONFIG_PPC64
         /* Setup interrupt mapping options */
         ppc64_interrupt_controller = IC_OPEN_PIC;
 
@@ -638,19 +642,8 @@ static void __init pmac_init_early(void)
 
 static void __init pmac_progress(char *s, unsigned short hex)
 {
-#ifdef CONFIG_PPC64
-        if (sccdbg) {
-                udbg_puts(s);
-                udbg_puts("\n");
-                return;
-        }
-#endif
-#ifdef CONFIG_BOOTX_TEXT
-        if (boot_text_mapped) {
-                btext_drawstring(s);
-                btext_drawchar('\n');
-        }
-#endif /* CONFIG_BOOTX_TEXT */
+        udbg_puts(s);
+        udbg_puts("\n");
 }
 
 /*
@@ -735,7 +728,8 @@ static int __init pmac_probe(int platform)
 }
 
 #ifdef CONFIG_PPC64
-static int pmac_probe_mode(struct pci_bus *bus)
+/* Move that to pci.c */
+static int pmac_pci_probe_mode(struct pci_bus *bus)
 {
         struct device_node *node = bus->sysdata;
 
@@ -771,7 +765,7 @@ struct machdep_calls __initdata pmac_md = {
         .check_legacy_ioport    = pmac_check_legacy_ioport,
         .progress               = pmac_progress,
 #ifdef CONFIG_PPC64
-        .pci_probe_mode         = pmac_probe_mode,
+        .pci_probe_mode         = pmac_pci_probe_mode,
         .idle_loop              = native_idle,
         .enable_pmcs            = power4_enable_pmcs,
 #ifdef CONFIG_KEXEC
diff --git a/arch/powerpc/platforms/powermac/udbg_adb.c b/arch/powerpc/platforms/powermac/udbg_adb.c
new file mode 100644
index 000000000000..e51de55b2d6e
--- /dev/null
+++ b/arch/powerpc/platforms/powermac/udbg_adb.c
@@ -0,0 +1,218 @@
+#include <linux/config.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/bitops.h>
+#include <linux/ptrace.h>
+#include <linux/adb.h>
+#include <linux/pmu.h>
+#include <linux/cuda.h>
+#include <asm/machdep.h>
+#include <asm/io.h>
+#include <asm/page.h>
+#include <asm/xmon.h>
+#include <asm/prom.h>
+#include <asm/bootx.h>
+#include <asm/machdep.h>
+#include <asm/errno.h>
+#include <asm/pmac_feature.h>
+#include <asm/processor.h>
+#include <asm/delay.h>
+#include <asm/btext.h>
+#include <asm/time.h>
+#include <asm/udbg.h>
+
+/*
+ * This implementation is "special", it can "patch" the current
+ * udbg implementation and work on top of it. It must thus be
+ * initialized last
+ */
+
+static void (*udbg_adb_old_putc)(char c);
+static char (*udbg_adb_old_getc)(void);
+static int (*udbg_adb_old_getc_poll)(void);
+
+static enum {
+        input_adb_none,
+        input_adb_pmu,
+        input_adb_cuda,
+} input_type = input_adb_none;
+
+static int udbg_adb_use_btext;
+
+int xmon_wants_key, xmon_adb_keycode;
+
+static inline void udbg_adb_poll(void)
+{
+#ifdef CONFIG_ADB_PMU
+        if (input_type == input_adb_pmu)
+                pmu_poll_adb();
+#endif /* CONFIG_ADB_PMU */
+#ifdef CONFIG_ADB_CUDA
+        if (input_type == input_adb_cuda)
+                cuda_poll();
+#endif /* CONFIG_ADB_CUDA */
+}
+
+#ifdef CONFIG_BOOTX_TEXT
+static int xmon_adb_shiftstate;
+
+static unsigned char xmon_keytab[128] =
+        "asdfhgzxcv\000bqwer"                           /* 0x00 - 0x0f */
+        "yt123465=97-80]o"                              /* 0x10 - 0x1f */
+        "u[ip\rlj'k;\\,/nm."                            /* 0x20 - 0x2f */
+        "\t `\177\0\033\0\0\0\0\0\0\0\0\0\0"            /* 0x30 - 0x3f */
+        "\0.\0*\0+\0\0\0\0\0/\r\0-\0"                   /* 0x40 - 0x4f */
+        "\0\0000123456789\0\0\0";                       /* 0x50 - 0x5f */
+
+static unsigned char xmon_shift_keytab[128] =
+        "ASDFHGZXCV\000BQWER"                           /* 0x00 - 0x0f */
+        "YT!@#$^%+(&_*)}O"                              /* 0x10 - 0x1f */
+        "U{IP\rLJ\"K:|<?NM>"                            /* 0x20 - 0x2f */
+        "\t ~\177\0\033\0\0\0\0\0\0\0\0\0\0"            /* 0x30 - 0x3f */
+        "\0.\0*\0+\0\0\0\0\0/\r\0-\0"                   /* 0x40 - 0x4f */
+        "\0\0000123456789\0\0\0";                       /* 0x50 - 0x5f */
+
+static char udbg_adb_local_getc(void)
+{
+        int k, t, on;
+
+        xmon_wants_key = 1;
+        for (;;) {
+                xmon_adb_keycode = -1;
+                t = 0;
+                on = 0;
+                k = -1;
+                do {
+                        if (--t < 0) {
+                                on = 1 - on;
+                                btext_drawchar(on? 0xdb: 0x20);
+                                btext_drawchar('\b');
+                                t = 200000;
+                        }
+                        udbg_adb_poll();
+                        if (udbg_adb_old_getc_poll)
+                                k = udbg_adb_old_getc_poll();
+                } while (k == -1 && xmon_adb_keycode == -1);
+                if (on)
+                        btext_drawstring(" \b");
+                if (k != -1)
+                        return k;
+                k = xmon_adb_keycode;
+
+                /* test for shift keys */
+                if ((k & 0x7f) == 0x38 || (k & 0x7f) == 0x7b) {
+                        xmon_adb_shiftstate = (k & 0x80) == 0;
+                        continue;
+                }
+                if (k >= 0x80)
+                        continue;       /* ignore up transitions */
+                k = (xmon_adb_shiftstate? xmon_shift_keytab: xmon_keytab)[k];
+                if (k != 0)
+                        break;
+        }
+        xmon_wants_key = 0;
+        return k;
+}
+#endif /* CONFIG_BOOTX_TEXT */
+
+static char udbg_adb_getc(void)
+{
+#ifdef CONFIG_BOOTX_TEXT
+        if (udbg_adb_use_btext && input_type != input_adb_none)
+                return udbg_adb_local_getc();
+#endif
+        if (udbg_adb_old_getc)
+                return udbg_adb_old_getc();
+        return -1;
+}
+
+/* getc_poll() is not really used, unless you have the xmon-over modem
+ * hack that doesn't quite concern us here, thus we just poll the low level
+ * ADB driver to prevent it from timing out and call back the original poll
+ * routine.
+ */
+static int udbg_adb_getc_poll(void)
+{
+        udbg_adb_poll();
+
+        if (udbg_adb_old_getc_poll)
+                return udbg_adb_old_getc_poll();
+        return -1;
+}
+
+static void udbg_adb_putc(char c)
+{
+#ifdef CONFIG_BOOTX_TEXT
+        if (udbg_adb_use_btext)
+                btext_drawchar(c);
+#endif
+        if (udbg_adb_old_putc)
+                return udbg_adb_old_putc(c);
+}
+
+void udbg_adb_init_early(void)
+{
+#ifdef CONFIG_BOOTX_TEXT
+        if (btext_find_display(1) == 0) {
+                udbg_adb_use_btext = 1;
+                udbg_putc = udbg_adb_putc;
+        }
+#endif
+}
+
+int udbg_adb_init(int force_btext)
+{
+        struct device_node *np;
+
+        /* Capture existing callbacks */
+        udbg_adb_old_putc = udbg_putc;
+        udbg_adb_old_getc = udbg_getc;
+        udbg_adb_old_getc_poll = udbg_getc_poll;
+
+        /* Check if our early init was already called */
+        if (udbg_adb_old_putc == udbg_adb_putc ||
+            udbg_adb_old_putc == btext_drawchar)
+                udbg_adb_old_putc = NULL;
+
+        /* Set ours as output */
+        udbg_putc = udbg_adb_putc;
+        udbg_getc = udbg_adb_getc;
+        udbg_getc_poll = udbg_adb_getc_poll;
+
+#ifdef CONFIG_BOOTX_TEXT
+        /* Check if we should use btext output */
+        if (btext_find_display(force_btext) == 0)
+                udbg_adb_use_btext = 1;
+#endif
+
+        /* See if there is a keyboard in the device tree with a parent
+         * of type "adb". If not, we return a failure, but we keep the
+         * bext output set for now
+         */
+        for (np = NULL; (np = of_find_node_by_name(np, "keyboard")) != NULL;) {
+                struct device_node *parent = of_get_parent(np);
+                int found = (parent && !strcmp(parent->type, "adb") == 0);
+                of_node_put(parent);
+                if (found)
+                        break;
+        }
+        if (np == NULL)
+                return -ENODEV;
+        of_node_put(np);
+
+#ifdef CONFIG_ADB_PMU
+        if (find_via_pmu())
+                input_type = input_adb_pmu;
+#endif
+#ifdef CONFIG_ADB_CUDA
+        if (find_via_cuda())
+                input_type = input_adb_cuda;
+#endif
+
+        /* Same as above: nothing found, keep btext set for output */
+        if (input_type == input_adb_none)
+                return -ENODEV;
+
+        return 0;
+}
diff --git a/arch/powerpc/platforms/powermac/udbg_scc.c b/arch/powerpc/platforms/powermac/udbg_scc.c
new file mode 100644
index 000000000000..df6dec49c4c7
--- /dev/null
+++ b/arch/powerpc/platforms/powermac/udbg_scc.c
@@ -0,0 +1,165 @@
+/*
+ * udbg for for zilog scc ports as found on Apple PowerMacs
+ *
+ * Copyright (C) 2001-2005 PPC 64 Team, IBM Corp
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+#include <linux/config.h>
+#include <linux/types.h>
+#include <asm/udbg.h>
+#include <asm/processor.h>
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/pmac_feature.h>
+
+extern u8 real_readb(volatile u8 __iomem  *addr);
+extern void real_writeb(u8 data, volatile u8 __iomem *addr);
+
+#define SCC_TXRDY       4
+#define SCC_RXRDY       1
+
+static volatile u8 __iomem *sccc;
+static volatile u8 __iomem *sccd;
+
+static void udbg_scc_putc(char c)
+{
+        if (sccc) {
+                while ((in_8(sccc) & SCC_TXRDY) == 0)
+                        ;
+                out_8(sccd,  c);
+                if (c == '\n')
+                        udbg_scc_putc('\r');
+        }
+}
+
+static int udbg_scc_getc_poll(void)
+{
+        if (sccc) {
+                if ((in_8(sccc) & SCC_RXRDY) != 0)
+                        return in_8(sccd);
+                else
+                        return -1;
+        }
+        return -1;
+}
+
+static char udbg_scc_getc(void)
+{
+        if (sccc) {
+                while ((in_8(sccc) & SCC_RXRDY) == 0)
+                        ;
+                return in_8(sccd);
+        }
+        return 0;
+}
+
+static unsigned char scc_inittab[] = {
+    13, 0,              /* set baud rate divisor */
+    12, 0,
+    14, 1,              /* baud rate gen enable, src=rtxc */
+    11, 0x50,           /* clocks = br gen */
+    5,  0xea,           /* tx 8 bits, assert DTR & RTS */
+    4,  0x46,           /* x16 clock, 1 stop */
+    3,  0xc1,           /* rx enable, 8 bits */
+};
+
+void udbg_scc_init(int force_scc)
+{
+        u32 *reg;
+        unsigned long addr;
+        struct device_node *stdout = NULL, *escc = NULL, *macio = NULL;
+        struct device_node *ch, *ch_def = NULL, *ch_a = NULL;
+        char *path;
+        int i, x;
+
+        escc = of_find_node_by_name(NULL, "escc");
+        if (escc == NULL)
+                goto bail;
+        macio = of_get_parent(escc);
+        if (macio == NULL)
+                goto bail;
+        path = (char *)get_property(of_chosen, "linux,stdout-path", NULL);
+        if (path != NULL)
+                stdout = of_find_node_by_path(path);
+        for (ch = NULL; (ch = of_get_next_child(escc, ch)) != NULL;) {
+                if (ch == stdout)
+                        ch_def = of_node_get(ch);
+                if (strcmp(ch->name, "ch-a") == 0)
+                        ch_a = of_node_get(ch);
+        }
+        if (ch_def == NULL && !force_scc)
+                goto bail;
+
+        ch = ch_def ? ch_def : ch_a;
+
+        /* Get address within mac-io ASIC */
+        reg = (u32 *)get_property(escc, "reg", NULL);
+        if (reg == NULL)
+                goto bail;
+        addr = reg[0];
+
+        /* Get address of mac-io PCI itself */
+        reg = (u32 *)get_property(macio, "assigned-addresses", NULL);
+        if (reg == NULL)
+                goto bail;
+        addr += reg[2];
+
+        /* Lock the serial port */
+        pmac_call_feature(PMAC_FTR_SCC_ENABLE, ch,
+                          PMAC_SCC_ASYNC | PMAC_SCC_FLAG_XMON, 1);
+
+
+        /* Setup for 57600 8N1 */
+        if (ch == ch_a)
+                addr += 0x20;
+        sccc = (volatile u8 * __iomem) ioremap(addr & PAGE_MASK, PAGE_SIZE) ;
+        sccc += addr & ~PAGE_MASK;
+        sccd = sccc + 0x10;
+
+        mb();
+
+        for (i = 20000; i != 0; --i)
+                x = in_8(sccc);
+        out_8(sccc, 0x09);              /* reset A or B side */
+        out_8(sccc, 0xc0);
+        for (i = 0; i < sizeof(scc_inittab); ++i)
+                out_8(sccc, scc_inittab[i]);
+
+        udbg_putc = udbg_scc_putc;
+        udbg_getc = udbg_scc_getc;
+        udbg_getc_poll = udbg_scc_getc_poll;
+
+        udbg_puts("Hello World !\n");
+
+ bail:
+        of_node_put(macio);
+        of_node_put(escc);
+        of_node_put(stdout);
+        of_node_put(ch_def);
+        of_node_put(ch_a);
+}
+
+#ifdef CONFIG_PPC64
+static void udbg_real_scc_putc(char c)
+{
+        while ((real_readb(sccc) & SCC_TXRDY) == 0)
+                ;
+        real_writeb(c, sccd);
+        if (c == '\n')
+                udbg_real_scc_putc('\r');
+}
+
+void udbg_init_pmac_realmode(void)
+{
+        sccc = (volatile u8 __iomem *)0x80013020ul;
+        sccd = (volatile u8 __iomem *)0x80013030ul;
+
+        udbg_putc = udbg_real_scc_putc;
+        udbg_getc = NULL;
+        udbg_getc_poll = NULL;
+}
+#endif /* CONFIG_PPC64 */