[PATCH v2 4/6] arm/dt: probe for platforms via the device tree
Grant Likely
grant.likely at secretlab.ca
Mon Jan 31 16:04:11 EST 2011
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. It also creates arm_unflatten_device_tree() which copies
the dtb into an allocated buffer and unflattens it into the live-tree
representation.
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 at canonical.com>]
Signed-off-by: Grant Likely <grant.likely at secretlab.ca>
---
arch/arm/include/asm/mach/arch.h | 2 +
arch/arm/include/asm/prom.h | 11 +++++
arch/arm/include/asm/setup.h | 1
arch/arm/kernel/devtree.c | 87 ++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/setup.c | 10 +++-
arch/arm/mm/init.c | 8 +++
6 files changed, 117 insertions(+), 2 deletions(-)
diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index 3a0893a..2ed24e7 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -22,6 +22,8 @@ struct machine_desc {
unsigned int nr; /* architecture number */
const char *name; /* architecture name */
unsigned long boot_params; /* tagged list */
+ const char **dt_compat; /* array of device tree
+ * 'compatible' strings */
unsigned int nr_irqs; /* number of IRQs */
diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
index 8f1037f..6ba62a8 100644
--- a/arch/arm/include/asm/prom.h
+++ b/arch/arm/include/asm/prom.h
@@ -21,5 +21,16 @@ static inline void irq_dispose_mapping(unsigned int virq)
return;
}
+extern void arm_unflatten_device_tree(void);
+extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
+
+#else /* CONFIG_OF */
+
+static void arm_unflatten_device_tree(void) { }
+static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys)
+{
+ return NULL;
+}
+
#endif /* CONFIG_OF */
#endif /* ASMARM_PROM_H */
diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
index 06c4d0e..1cec82a 100644
--- a/arch/arm/include/asm/setup.h
+++ b/arch/arm/include/asm/setup.h
@@ -222,6 +222,7 @@ extern struct meminfo meminfo;
#define bank_phys_size(bank) (bank)->size
extern int arm_add_memory(unsigned long start, unsigned long size);
+extern char cmd_line[COMMAND_LINE_SIZE];
#endif /* __KERNEL__ */
diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index ac48da2..07b75bb 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c
@@ -21,6 +21,7 @@
#include <asm/setup.h>
#include <asm/page.h>
+#include <asm/mach/arch.h>
void __init early_init_dt_add_memory_arch(u64 base, u64 size)
{
@@ -45,3 +46,89 @@ unsigned int irq_create_of_mapping(struct device_node *controller,
return intspec[0];
}
EXPORT_SYMBOL_GPL(irq_create_of_mapping);
+
+extern struct machine_desc __arch_info_begin, __arch_info_end;
+
+/**
+ * arm_unflatten_device_tree - Copy dtb into a safe area and unflatten it.
+ *
+ * Copies the dtb out of initial memory and into an allocated block so that
+ * it doesn't get overwritten by the kernel and then unflatten it into the
+ * live tree representation.
+ */
+void __init arm_unflatten_device_tree(void)
+{
+ struct boot_param_header *devtree;
+ u32 dtb_size;
+
+ if (!initial_boot_params)
+ return;
+
+ /* Save the dtb to an allocated buffer */
+ dtb_size = be32_to_cpu(initial_boot_params->totalsize);
+ devtree = early_init_dt_alloc_memory_arch(dtb_size, SZ_4K);
+ if (!devtree) {
+ printk("Unable to allocate memory for device tree\n");
+ while(1);
+ }
+ pr_info("relocating device tree from 0x%p to 0x%p, length 0x%x\n",
+ initial_boot_params, devtree, dtb_size);
+ memmove(devtree, initial_boot_params, dtb_size);
+ initial_boot_params = devtree;
+
+ unflatten_device_tree();
+}
+
+/**
+ * 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 = phys_to_virt(dt_phys);
+ struct machine_desc *mdesc, *mdesc_best = NULL;
+ unsigned int score, mdesc_score = ~1;
+ unsigned long dt_root;
+ const char *model;
+
+ /* check device tree validity */
+ if (!dt_phys || 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 (mdesc = &__arch_info_begin; mdesc < &__arch_info_end; 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) {
+ printk("Machine not supported, unable to continue.\n");
+ while (1);
+ }
+
+ 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, NULL);
+ /* 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);
+ /* Save command line for /proc/cmdline */
+ strlcpy(boot_command_line, cmd_line, COMMAND_LINE_SIZE);
+
+ return mdesc_best;
+}
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index cbc1836..68e0204 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -20,6 +20,7 @@
#include <linux/screen_info.h>
#include <linux/init.h>
#include <linux/kexec.h>
+#include <linux/of_fdt.h>
#include <linux/crash_dump.h>
#include <linux/root_dev.h>
#include <linux/cpu.h>
@@ -42,6 +43,7 @@
#include <asm/cachetype.h>
#include <asm/tlbflush.h>
+#include <asm/prom.h>
#include <asm/mach/arch.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
@@ -125,7 +127,7 @@ EXPORT_SYMBOL(elf_platform);
static const char *cpu_name;
static const char *machine_name;
-static char __initdata cmd_line[COMMAND_LINE_SIZE];
+char cmd_line[COMMAND_LINE_SIZE];
struct machine_desc *machine_desc __initdata;
static char default_command_line[COMMAND_LINE_SIZE] __initdata = CONFIG_CMDLINE;
@@ -838,7 +840,9 @@ void __init setup_arch(char **cmdline_p)
unwind_init();
setup_processor();
- mdesc = setup_machine_tags(machine_arch_type);
+ mdesc = setup_machine_fdt(__atags_pointer);
+ if (!mdesc)
+ mdesc = setup_machine_tags(machine_arch_type);
machine_desc = mdesc;
machine_name = mdesc->name;
@@ -859,6 +863,8 @@ void __init setup_arch(char **cmdline_p)
paging_init(mdesc);
request_standard_resources(mdesc);
+ arm_unflatten_device_tree();
+
#ifdef CONFIG_SMP
if (is_smp())
smp_init_cpus();
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 5164069..62ff2e8 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -71,6 +71,14 @@ static int __init parse_tag_initrd2(const struct tag *tag)
__tagtable(ATAG_INITRD2, parse_tag_initrd2);
+#ifdef CONFIG_OF_FLATTREE
+void __init early_init_dt_setup_initrd_arch(unsigned long start, unsigned long end)
+{
+ phys_initrd_start = start;
+ phys_initrd_size = end - start + 1;
+}
+#endif /* CONFIG_OF_FLATTREE */
+
/*
* This keeps memory configuration data used by a couple memory
* initialization functions, as well as show_mem() for the skipping
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