[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, 56 insertions, 0 deletions

diff --git a/arch/sparc64/kernel/prom.c b/arch/sparc64/kernel/prom.c
index 2b2017ce2267..f4e0a9ad9be3 100644
--- a/arch/sparc64/kernel/prom.c
+++ b/arch/sparc64/kernel/prom.c
@@ -1646,6 +1646,60 @@ static void __init of_fill_in_cpu_data(void)
         smp_fill_in_sib_core_maps();
 }
 
+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);
+
+static void __init of_console_init(void)
+{
+        char *msg = "OF stdout device is: %s\n";
+        struct device_node *dp;
+        const char *type;
+        phandle node;
+
+        of_console_path = prom_early_alloc(256);
+        if (prom_ihandle2path(prom_stdout, of_console_path, 256) < 0) {
+                prom_printf("Cannot obtain path of stdout.\n");
+                prom_halt();
+        }
+        of_console_options = strrchr(of_console_path, ':');
+        if (of_console_options) {
+                of_console_options++;
+                if (*of_console_options == '\0')
+                        of_console_options = NULL;
+        }
+
+        node = prom_inst2pkg(prom_stdout);
+        if (!node) {
+                prom_printf("Cannot resolve stdout node from "
+                            "instance %08x.\n", prom_stdout);
+                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;
+
+        prom_printf(msg, of_console_path);
+        printk(msg, of_console_path);
+}
+
 void __init prom_build_devicetree(void)
 {
         struct device_node **nextp;
@@ -1658,6 +1712,8 @@ 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);