[SPARC]: Fix serial console device detection.

The current scheme works on static interpretation of text names, which
is wrong.

The output-device setting, for example, must be resolved via an alias
or similar to a full path name to the console device.

Paths also contain an optional set of 'options', which starts with a
colon at the end of the path.  The option area is used to specify
which of two serial ports ('a' or 'b') the path refers to when a
device node drives multiple ports.  'a' is assumed if the option
specification is missing.

This was caught by the UltraSPARC-T1 simulator.  The 'output-device'
property was set to 'ttya' and we didn't pick upon the fact that this
is an OBP alias set to '/virtual-devices/console'.  Instead we saw it
as the first serial console device, instead of the hypervisor console.

The infrastructure is now there to take advantage of this to resolve
the console correctly even in multi-head situations in fbcon too.

Thanks to Greg Onufer for the bug report.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 131 insertions, 0 deletions

diff --git a/arch/sparc/kernel/prom.c b/arch/sparc/kernel/prom.c
index 012f98346bcd..e3a537650db1 100644
--- a/arch/sparc/kernel/prom.c
+++ b/arch/sparc/kernel/prom.c
@@ -397,6 +397,135 @@ static struct device_node * __init build_tree(struct device_node *parent, phandl
         return dp;
 }
 
+struct device_node *of_console_device;
+EXPORT_SYMBOL(of_console_device);
+
+char *of_console_path;
+EXPORT_SYMBOL(of_console_path);
+
+char *of_console_options;
+EXPORT_SYMBOL(of_console_options);
+
+extern void restore_current(void);
+
+static void __init of_console_init(void)
+{
+        char *msg = "OF stdout device is: %s\n";
+        struct device_node *dp;
+        unsigned long flags;
+        const char *type;
+        phandle node;
+        int skip, fd;
+
+        of_console_path = prom_early_alloc(256);
+
+        switch (prom_vers) {
+        case PROM_V0:
+        case PROM_SUN4:
+                skip = 0;
+                switch (*romvec->pv_stdout) {
+                case PROMDEV_SCREEN:
+                        type = "display";
+                        break;
+
+                case PROMDEV_TTYB:
+                        skip = 1;
+                        /* FALLTHRU */
+
+                case PROMDEV_TTYA:
+                        type = "serial";
+                        break;
+
+                default:
+                        prom_printf("Invalid PROM_V0 stdout value %u\n",
+                                    *romvec->pv_stdout);
+                        prom_halt();
+                }
+
+                for_each_node_by_type(dp, type) {
+                        if (!skip--)
+                                break;
+                }
+                if (!dp) {
+                        prom_printf("Cannot find PROM_V0 console node.\n");
+                        prom_halt();
+                }
+                of_console_device = dp;
+
+                strcpy(of_console_path, dp->full_name);
+                if (!strcmp(type, "serial")) {
+                        strcat(of_console_path,
+                               (skip ? ":b" : ":a"));
+                }
+                break;
+
+        default:
+        case PROM_V2:
+        case PROM_V3:
+                fd = *romvec->pv_v2bootargs.fd_stdout;
+
+                spin_lock_irqsave(&prom_lock, flags);
+                node = (*romvec->pv_v2devops.v2_inst2pkg)(fd);
+                restore_current();
+                spin_unlock_irqrestore(&prom_lock, flags);
+
+                if (!node) {
+                        prom_printf("Cannot resolve stdout node from "
+                                    "instance %08x.\n", fd);
+                        prom_halt();
+                }
+                dp = of_find_node_by_phandle(node);
+                type = of_get_property(dp, "device_type", NULL);
+
+                if (!type) {
+                        prom_printf("Console stdout lacks "
+                                    "device_type property.\n");
+                        prom_halt();
+                }
+
+                if (strcmp(type, "display") && strcmp(type, "serial")) {
+                        prom_printf("Console device_type is neither display "
+                                    "nor serial.\n");
+                        prom_halt();
+                }
+
+                of_console_device = dp;
+
+                if (prom_vers == PROM_V2) {
+                        strcpy(of_console_path, dp->full_name);
+                        switch (*romvec->pv_stdout) {
+                        case PROMDEV_TTYA:
+                                strcat(of_console_path, ":a");
+                                break;
+                        case PROMDEV_TTYB:
+                                strcat(of_console_path, ":b");
+                                break;
+                        }
+                } else {
+                        const char *path;
+
+                        dp = of_find_node_by_path("/");
+                        path = of_get_property(dp, "stdout-path", NULL);
+                        if (!path) {
+                                prom_printf("No stdout-path in root node.\n");
+                                prom_halt();
+                        }
+                        strcpy(of_console_path, path);
+                }
+                break;
+        }
+
+        of_console_options = strrchr(of_console_path, ':');
+        if (of_console_options) {
+                of_console_options++;
+                if (*of_console_options == '\0')
+                        of_console_options = NULL;
+        }
+
+        prom_printf(msg, of_console_path);
+        printk(msg, of_console_path);
+}
+
 void __init prom_build_devicetree(void)
 {
         struct device_node **nextp;
@@ -409,6 +538,8 @@ void __init prom_build_devicetree(void)
         allnodes->child = build_tree(allnodes,
                                      prom_getchild(allnodes->node),
                                      &nextp);
+        of_console_init();
+
         printk("PROM: Built device tree with %u bytes of memory.\n",
                prom_early_allocated);
 }