Commit 93c02ab4 authored by Grant Likely's avatar Grant Likely
Browse files

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: default avatarTixy <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: default avatarTony Lindgren <tony@atomide.com>
Acked-by: default avatarNicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent 6291319d
......@@ -18,6 +18,8 @@ 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 */
......
......@@ -21,5 +21,17 @@ static inline void irq_dispose_mapping(unsigned int virq)
return;
}
extern struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
extern void arm_dt_memblock_reserve(void);
#else /* CONFIG_OF */
static inline struct machine_desc *setup_machine_fdt(unsigned int dt_phys)
{
return NULL;
}
static inline void arm_dt_memblock_reserve(void) { }
#endif /* CONFIG_OF */
#endif /* ASMARM_PROM_H */
......@@ -218,6 +218,8 @@ extern struct meminfo meminfo;
#define bank_phys_size(bank) (bank)->size
extern int arm_add_memory(phys_addr_t start, unsigned long size);
extern void early_print(const char *str, ...);
extern void dump_machine_table(void);
#endif /* __KERNEL__ */
......
......@@ -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 @@ void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
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#
*
......
......@@ -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>
......@@ -309,7 +311,7 @@ static void __init cacheid_init(void)
*/
extern struct proc_info_list *lookup_processor_type(unsigned int);
static void __init early_print(const char *str, ...)
void __init early_print(const char *str, ...)
{
extern void printascii(const char *);
char buf[256];
......@@ -439,7 +441,7 @@ void cpu_init(void)
: "r14");
}
static void __init dump_machine_table(void)
void __init dump_machine_table(void)
{
struct machine_desc *p;
......@@ -837,8 +839,17 @@ static struct machine_desc * __init setup_machine_tags(unsigned int nr)
if (tags->hdr.tag != ATAG_CORE)
convert_to_tag_list(tags);
#endif
if (tags->hdr.tag != ATAG_CORE)
if (tags->hdr.tag != ATAG_CORE) {
#if defined(CONFIG_OF)
/*
* If CONFIG_OF is set, then assume this is a reasonably
* modern system that should pass boot parameters
*/
early_print("Warning: Neither atags nor dtb found\n");
#endif
tags = (struct tag *)&init_tags;
}
if (mdesc->fixup)
mdesc->fixup(mdesc, tags, &from, &meminfo);
......@@ -864,7 +875,9 @@ 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;
......@@ -887,6 +900,8 @@ void __init setup_arch(char **cmdline_p)
paging_init(mdesc);
request_standard_resources(mdesc);
unflatten_device_tree();
#ifdef CONFIG_SMP
if (is_smp())
smp_init_cpus();
......
......@@ -22,6 +22,7 @@
#include <linux/sort.h>
#include <asm/mach-types.h>
#include <asm/prom.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/sizes.h>
......@@ -322,6 +323,7 @@ void __init arm_memblock_init(struct meminfo *mi, struct machine_desc *mdesc)
#endif
arm_mm_memblock_reserve();
arm_dt_memblock_reserve();
/* reserve any platform specific memblock areas */
if (mdesc->reserve)
......
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