utils/hooks: Set linux,stdout-path for primary console

If the boot_tty environment variable is set, determine which device path
to set in the linux,stdout-path property, which will instruct the next
kernel to use it as the primary console.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>

diff --git a/utils/hooks/30-add-offb.c b/utils/hooks/30-add-offb.c
index c635409f9708fc628409e01e8c7786c6833e752c..d711908cf9efdf23fd3a9428b4235fc5630c3432 100644 (file)
--- a/utils/hooks/30-add-offb.c
+++ b/utils/hooks/30-add-offb.c
@@ -9,6 +9,7 @@
 #include <string.h>
 #include <stdbool.h>
 #include <inttypes.h>
+#include <errno.h>
 
 #include <linux/fb.h>
 
@@ -441,6 +442,121 @@ static int populate_devicetree(struct offb_ctx *ctx)
        return 0;
 }
 
+/*
+ * Find the device tree path assoicated with a hvc device.
+ * On OPAL all hvc consoles have a 'serial@X' node under ibm,opal/consoles,
+ * so we make a simplifying assumption that a hvcX is associated with a
+ * serial@X node.
+ */
+static char *get_hvc_path(struct offb_ctx *ctx, unsigned int termno)
+{
+       char *serial;
+       int node;
+
+       serial = talloc_asprintf(ctx, "serial@%u", termno);
+       if (!serial)
+               return NULL;
+
+       node = fdt_subnode_offset(ctx->dtb, 0, "ibm,opal");
+       if (node <= 0) {
+               fprintf(stderr, "Couldn't find ibm,opal\n");
+               return NULL;
+       }
+       node = fdt_subnode_offset(ctx->dtb, node, "consoles");
+       if (node <= 0) {
+               fprintf(stderr, "Couldn't find ibm,opal/consoles\n");
+               return NULL;
+       }
+
+       node = fdt_subnode_offset(ctx->dtb, node, serial);
+       if (node <= 0) {
+               fprintf(stderr, "Could not locate hvc%u\n", termno);
+               return NULL;
+       }
+
+       return talloc_asprintf(ctx, "ibm,opal/consoles/%s", serial);
+}
+
+/*
+ * Find the device tree path of the vga device. On OPAL we assume there is only
+ * one of these that represents any 'tty' console.
+ */
+static char *get_vga_path(struct offb_ctx *ctx)
+{
+       char *root, *vga_path;
+
+       root = strstr(ctx->path, "/pciex@");
+       if (!root) {
+               fprintf(stderr, "Can't find root path for vga device in below:\n");
+               fprintf(stderr, "%s\n", ctx->path);
+               return NULL;
+       }
+
+       vga_path = talloc_strdup(ctx, root);
+       fprintf(stderr, "VGA target at '%s'\n", vga_path);
+
+       return vga_path;
+}
+
+static int set_stdout(struct offb_ctx *ctx)
+{
+       const char *boot_tty, *ptr;
+       long unsigned int termno;
+       const fdt32_t *prop;
+       int node, prop_len;
+       char *stdout_path;
+
+       boot_tty = getenv("boot_tty");
+       if (!boot_tty) {
+               fprintf(stderr, "boot_tty not set, using default stdout for boot\n");
+               return 0;
+       }
+
+       if (strstr(boot_tty, "tty") != NULL) {
+               fprintf(stderr, "TTY recognised: %s\n", boot_tty);
+               stdout_path = get_vga_path(ctx);
+       } else {
+               ptr = strstr(boot_tty, "hvc");
+               if (!ptr || strlen(ptr) <= strlen("hvc")) {
+                       fprintf(stderr, "Unrecognised console: %s\n", boot_tty);
+                       return 0;
+               }
+               ptr += strlen("hvc");
+               errno = 0;
+               termno = strtoul(ptr, NULL, 0);
+               if (errno) {
+                       fprintf(stderr, "Couldn't parse termno from %s\n", boot_tty);
+                       return 0;
+               }
+               fprintf(stderr, "HVC recognised: %s\n", boot_tty);
+               stdout_path = get_hvc_path(ctx, termno);
+       }
+
+       if (!stdout_path) {
+               fprintf(stderr, "Couldn't parse %s into a path\n", boot_tty);
+               return -1;
+       }
+
+       fprintf(stderr, "stdout-path: %s\n", stdout_path);
+
+       node = fdt_subnode_offset(ctx->dtb, 0, "chosen");
+       if (node <= 0) {
+               fprintf(stderr, "Failed to find chosen\n");
+               return -1;
+       }
+
+       prop = fdt_getprop(ctx->dtb, node, "linux,stdout-path", &prop_len);
+       if (!prop) {
+               fprintf(stderr, "Failed to find linux,stdout-path\n");
+               return -1;
+       }
+
+       fdt_set_check(ctx->dtb, node, fdt_setprop_string, "linux,stdout-path",
+                       stdout_path);
+
+       return 0;
+}
+
 static int write_devicetree(struct offb_ctx *ctx)
 {
        int rc;
@@ -484,6 +600,10 @@ int main(void)
        if (rc)
                goto out;
 
+       rc = set_stdout(ctx);
+       if (rc)
+               goto out;
+
        rc = write_devicetree(ctx);
 
 out: