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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

arch/arm/include/asm/mach/arch.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

arch/arm/include/asm/prom.h

+12 −0
Original line number Diff line number Diff line
@@ -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 */

arch/arm/include/asm/setup.h

+2 −0
Original line number Diff line number Diff line
@@ -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__  */

arch/arm/kernel/devtree.c

+98 −0
Original line number Diff line number Diff line
@@ -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#

 *

arch/arm/kernel/setup.c

+19 −4
Original line number Diff line number Diff line
@@ -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);
@@ -864,6 +875,8 @@ void __init setup_arch(char **cmdline_p) 
	unwind_init();



	setup_processor();

	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();