arm/dt: probe for platforms via the device tree
If a dtb is passed to the kernel then the kernel needs to iterate
through compiled-in mdescs looking for one that matches and move the
dtb data to a safe location before it gets accidentally overwritten by
the kernel.
This patch creates a new function, setup_machine_fdt() which is
analogous to the setup_machine_atags() created in the previous patch.
It does all the early setup needed to use a device tree machine
description.
v5: - Print warning with neither dtb nor atags are passed to the kernel
- Fix bug in setting of __machine_arch_type to the selected machine,
not just the last machine in the list.
Reported-by: Tixy <tixy@yxit.co.uk>
- Copy command line directly into boot_command_line instead of cmd_line
v4: - Dump some output when a matching machine_desc cannot be found
v3: - Added processing of reserved list.
- Backed out the v2 change that copied instead of reserved the
dtb. dtb is reserved again and the real problem was fixed by
using alloc_bootmem_align() for early allocation of RAM for
unflattening the tree.
- Moved cmd_line and initrd changes to earlier patch to make series
bisectable.
v2: Changed to save the dtb by copying into an allocated buffer.
- Since the dtb will very likely be passed in the first 16k of ram
where the interrupt vectors live, memblock_reserve() is
insufficient to protect the dtb data.
[based on work originally written by Jeremy Kerr <jeremy.kerr@canonical.com>]
Tested-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index 75e3df8..a701e42 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -21,6 +21,8 @@
#include <asm/setup.h>
#include <asm/page.h>
+#include <asm/mach/arch.h>
+#include <asm/mach-types.h>
void __init early_init_dt_add_memory_arch(u64 base, u64 size)
{
@@ -32,6 +34,102 @@
return alloc_bootmem_align(size, align);
}
+void __init arm_dt_memblock_reserve(void)
+{
+ u64 *reserve_map, base, size;
+
+ if (!initial_boot_params)
+ return;
+
+ /* Reserve the dtb region */
+ memblock_reserve(virt_to_phys(initial_boot_params),
+ be32_to_cpu(initial_boot_params->totalsize));
+
+ /*
+ * Process the reserve map. This will probably overlap the initrd
+ * and dtb locations which are already reserved, but overlaping
+ * doesn't hurt anything
+ */
+ reserve_map = ((void*)initial_boot_params) +
+ be32_to_cpu(initial_boot_params->off_mem_rsvmap);
+ while (1) {
+ base = be64_to_cpup(reserve_map++);
+ size = be64_to_cpup(reserve_map++);
+ if (!size)
+ break;
+ memblock_reserve(base, size);
+ }
+}
+
+/**
+ * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
+ * @dt_phys: physical address of dt blob
+ *
+ * If a dtb was passed to the kernel in r2, then use it to choose the
+ * correct machine_desc and to setup the system.
+ */
+struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)
+{
+ struct boot_param_header *devtree;
+ struct machine_desc *mdesc, *mdesc_best = NULL;
+ unsigned int score, mdesc_score = ~1;
+ unsigned long dt_root;
+ const char *model;
+
+ devtree = phys_to_virt(dt_phys);
+
+ /* check device tree validity */
+ if (be32_to_cpu(devtree->magic) != OF_DT_HEADER)
+ return NULL;
+
+ /* Search the mdescs for the 'best' compatible value match */
+ initial_boot_params = devtree;
+ dt_root = of_get_flat_dt_root();
+ for_each_machine_desc(mdesc) {
+ score = of_flat_dt_match(dt_root, mdesc->dt_compat);
+ if (score > 0 && score < mdesc_score) {
+ mdesc_best = mdesc;
+ mdesc_score = score;
+ }
+ }
+ if (!mdesc_best) {
+ const char *prop;
+ long size;
+
+ early_print("\nError: unrecognized/unsupported "
+ "device tree compatible list:\n[ ");
+
+ prop = of_get_flat_dt_prop(dt_root, "compatible", &size);
+ while (size > 0) {
+ early_print("'%s' ", prop);
+ size -= strlen(prop) + 1;
+ prop += strlen(prop) + 1;
+ }
+ early_print("]\n\n");
+
+ dump_machine_table(); /* does not return */
+ }
+
+ model = of_get_flat_dt_prop(dt_root, "model", NULL);
+ if (!model)
+ model = of_get_flat_dt_prop(dt_root, "compatible", NULL);
+ if (!model)
+ model = "<unknown>";
+ pr_info("Machine: %s, model: %s\n", mdesc_best->name, model);
+
+ /* Retrieve various information from the /chosen node */
+ of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
+ /* Initialize {size,address}-cells info */
+ of_scan_flat_dt(early_init_dt_scan_root, NULL);
+ /* Setup memory, calling early_init_dt_add_memory_arch */
+ of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+
+ /* Change machine number to match the mdesc we're using */
+ __machine_arch_type = mdesc_best->nr;
+
+ return mdesc_best;
+}
+
/**
* irq_create_of_mapping - Hook to resolve OF irq specifier into a Linux irq#
*