of: Support CONFIG_CMDLINE_EXTEND config option

The old logic assumes CMDLINE_FROM_BOOTLOADER vs. CMDLINE_FORCE and
ignores CMDLINE_EXTEND.  Here's the old logic:

- CONFIG_CMDLINE_FORCE=true
    CONFIG_CMDLINE
- dt bootargs=non-empty:
    dt bootargs
- dt bootargs=empty, @data is non-empty string
    @data is left unchanged
- dt bootargs=empty, @data is empty string
    CONFIG_CMDLINE (or "" if that's not defined)

The new logic is now documented in of_fdt.h and is copied here for
reference:

- CONFIG_CMDLINE_FORCE=true
    CONFIG_CMDLINE
- CONFIG_CMDLINE_EXTEND=true, @data is non-empty string
    @data + dt bootargs (even if dt bootargs are empty)
- CONFIG_CMDLINE_EXTEND=true, @data is empty string
    CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
    dt bootargs
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
    @data is left unchanged
- CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
    CONFIG_CMDLINE (or "" if that's not defined)

Signed-off-by: Doug Anderson <dianders@chromium.org>
CC: devicetree-discuss@lists.ozlabs.org
CC: Grant Likely <grant.likely@secretlab.ca>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Rob Herring <rob.herring@calxeda.com>
Change-Id: I40ace250847f813358125dfcaa8998fd32cf7ea3
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 655f79db7899ffd0628714d51203847630a8075c..b832f5981df0b1bfd0a7a62c66a96e9d06e96890 100644 (file)
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -938,6 +938,29 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
        return 0;
 }
 
+/*
+ * Convert configs to something easy to use in C code
+ */
+#if defined(CONFIG_CMDLINE_FORCE)
+static const int overwrite_incoming_cmdline = 1;
+static const int read_dt_cmdline;
+static const int concat_cmdline;
+#elif defined(CONFIG_CMDLINE_EXTEND)
+static const int overwrite_incoming_cmdline;
+static const int read_dt_cmdline = 1;
+static const int concat_cmdline = 1;
+#else /* CMDLINE_FROM_BOOTLOADER */
+static const int overwrite_incoming_cmdline;
+static const int read_dt_cmdline = 1;
+static const int concat_cmdline;
+#endif
+
+#ifdef CONFIG_CMDLINE
+static const char *config_cmdline = CONFIG_CMDLINE;
+#else
+static const char *config_cmdline = "";
+#endif
+
 int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
                                     int depth, void *data)
 {
@@ -952,22 +975,23 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 
        early_init_dt_check_for_initrd(node);
 
-       /* Retrieve command line */
-       p = of_get_flat_dt_prop(node, "bootargs", &l);
-       if (p != NULL && l > 0)
-               strlcpy(data, p, min((int)l, COMMAND_LINE_SIZE));
-
-       /*
-        * CONFIG_CMDLINE is meant to be a default in case nothing else
-        * managed to set the command line, unless CONFIG_CMDLINE_FORCE
-        * is set in which case we override whatever was found earlier.
-        */
-#ifdef CONFIG_CMDLINE
-#ifndef CONFIG_CMDLINE_FORCE
-       if (!((char *)data)[0])
-#endif
-               strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
-#endif /* CONFIG_CMDLINE */
+       /* Put CONFIG_CMDLINE in if forced or if data had nothing in it to start */
+       if (overwrite_incoming_cmdline || !((char *)data)[0])
+               strlcpy(data, config_cmdline, COMMAND_LINE_SIZE);
+
+       /* Retrieve command line unless forcing */
+       if (read_dt_cmdline) {
+               p = of_get_flat_dt_prop(node, "bootargs", &l);
+               if (p != NULL && l > 0) {
+                       if (concat_cmdline) {
+                               strlcat(data, " ", COMMAND_LINE_SIZE);
+                               strlcat(data, p, min_t(int, (int)l,
+                                                      COMMAND_LINE_SIZE));
+                       } else
+                               strlcpy(data, p, min_t(int, (int)l,
+                                                      COMMAND_LINE_SIZE));
+               }
+       }
 
        pr_debug("Command line is: %s\n", (char*)data);
 

diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index df9ef380181285a5b196b18a925942346c836d63..fbbb89b690123c5bf61c10971c3f393d200b84e2 100644 (file)
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -59,6 +59,27 @@ extern int of_flat_dt_match(unsigned long node, const char *const *matches);
 extern unsigned long of_get_flat_dt_root(void);
 extern int of_get_flat_dt_size(void);
 
+/*
+ * early_init_dt_scan_chosen - scan the device tree for ramdisk and bootargs
+ *
+ * The boot arguments will be placed into the memory pointed to by @data.
+ * That memory should be COMMAND_LINE_SIZE big and initialized to be a valid
+ * (possibly empty) string.  Logic for what will be in @data after this
+ * function finishes:
+ *
+ * - CONFIG_CMDLINE_FORCE=true
+ *     CONFIG_CMDLINE
+ * - CONFIG_CMDLINE_EXTEND=true, @data is non-empty string
+ *     @data + dt bootargs (even if dt bootargs are empty)
+ * - CONFIG_CMDLINE_EXTEND=true, @data is empty string
+ *     CONFIG_CMDLINE + dt bootargs (even if dt bootargs are empty)
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=non-empty:
+ *     dt bootargs
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is non-empty string
+ *     @data is left unchanged
+ * - CMDLINE_FROM_BOOTLOADER=true, dt bootargs=empty, @data is empty string
+ *     CONFIG_CMDLINE (or "" if that's not defined)
+ */
 extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
                                     int depth, void *data);
 extern int early_init_dt_scan_memory(unsigned long node, const char *uname,