@@ -128,6 +128,7 @@ In addition, the following text indicates that the option:
BUGS= Relates to possible processor bugs on the said processor.
KNL Is a kernel start-up parameter.
BOOT Is a boot loader parameter.
+ FDT Is a flattened device tree paramter.
Parameters denoted with BOOT are actually interpreted by the boot
loader, and have no meaning to the kernel directly.
@@ -895,6 +896,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
General fault injection mechanism.
Format: <interval>,<probability>,<space>,<times>
See also Documentation/fault-injection/.
+ fdt.enable=
+ fdt.disable=
+ [KNL,FDT]
+ update device tree node status before populating devices
+ Format: fdt.<enable|disable>=<path>[,<path>]
+ enable := update the device node to a enabled state
+ disable := update the device node to a disabled state
+ <path> := node path or node full name in device tree
floppy= [HW]
See Documentation/blockdev/floppy.txt.
@@ -25,6 +25,11 @@
#include <asm/page.h>
+static char *enable;
+module_param(enable, charp, 0444);
+static char *disable;
+module_param(disable, charp, 0444);
+
char *of_fdt_get_string(struct boot_param_header *blob, u32 offset)
{
return ((char *)blob) +
@@ -713,4 +718,68 @@ void __init unflatten_device_tree(void)
of_alias_scan(early_init_dt_alloc_memory_arch);
}
+/*
+ * The format for the command line is as follows:
+ *
+ * fdt.<enable|disable>=<path>[,<path>]
+ * enable := update the device node to a enabled state
+ * disable := update the device node to a disabled state
+ * <path> := node path or node full name in device tree
+ *
+ * e.g:
+ * fdt.enable=/soc/aips-bus@02100000/i2c@021a8000,/soc/aips-bus@02100000/weim@021b8000
+ * fdt.disable=/soc/aips-bus@02100000/weim@021b8000
+ */
+static int __init __of_flat_parse_param(char *s, bool enable)
+{
+ char path[256], *p;
+
+ if (!s)
+ return 0;
+
+ p = s;
+ while (*s != '\0') {
+ p = strchr(s, ',');
+ if (p != NULL) {
+ BUG_ON((p - s) >= 256);
+ strncpy(path, s, p - s);
+ path[p - s] = '\0';
+ if (enable)
+ of_node_status_enable_by_path(path);
+ else
+ of_node_status_disable_by_path(path);
+ /* search for next node */
+ s = p + 1;
+ } else {
+ /* last node */
+ if (enable)
+ of_node_status_enable_by_path(s);
+ else
+ of_node_status_disable_by_path(s);
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static inline void __init of_flat_parse_param(void)
+{
+ __of_flat_parse_param(enable, 1);
+ __of_flat_parse_param(disable, 0);
+}
+
+/*
+ * handle device node status update
+ */
+static int __init of_flat_late_init(void)
+{
+ of_flat_parse_param();
+
+ return 0;
+}
+
+/* we use postcore_init to run before mach code populate platform devices */
+postcore_initcall(of_flat_late_init);
+
#endif /* CONFIG_OF_EARLY_FLATTREE */
Some boards may have a lot of pin conflicts between different devices, only one of them can be enabled to run at one time. Instead of changing dts manually or adding a lot dts files according to different device availability, we provide feature to dynamically update the device node status via command line, then those devices involved with pin conflict can be enabled or disabled dynamically. Signed-off-by: Dong Aisheng <b29396@freescale.com> --- Documentation/kernel-parameters.txt | 9 +++++ drivers/of/fdt.c | 69 +++++++++++++++++++++++++++++++++++ 2 files changed, 78 insertions(+), 0 deletions(-)