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linux/drivers/of/of_private.h
Oreoluwa Babatunde 8a6e02d0c0 of: reserved_mem: Restructure how the reserved memory regions are processed 
Reserved memory regions defined in the devicetree can be broken up into
two groups:
i) Statically-placed reserved memory regions
i.e. regions defined with a static start address and size using the
     "reg" property.
ii) Dynamically-placed reserved memory regions.
i.e. regions defined by specifying an address range where they can be
     placed in memory using the "alloc_ranges" and "size" properties.

These regions are processed and set aside at boot time.
This is done in two stages as seen below:

Stage 1:
At this stage, fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:

1) If the node represents a statically-placed reserved memory region,
   i.e. if it is defined using the "reg" property:
   - Call memblock_reserve() or memblock_mark_nomap() as needed.
   - Add the information for that region into the reserved_mem array
     using fdt_reserved_mem_save_node().
     i.e. fdt_reserved_mem_save_node(node, name, base, size).

2) If the node represents a dynamically-placed reserved memory region,
   i.e. if it is defined using "alloc-ranges" and "size" properties:
   - Add the information for that region to the reserved_mem array with
     the starting address and size set to 0.
     i.e. fdt_reserved_mem_save_node(node, name, 0, 0).
   Note: This region is saved to the array with a starting address of 0
   because a starting address is not yet allocated for it.

Stage 2:
After iterating through all the reserved memory nodes and storing their
relevant information in the reserved_mem array,fdt_init_reserved_mem() is
called and does the following:

1) For statically-placed reserved memory regions:
   - Call the region specific init function using
     __reserved_mem_init_node().
2) For dynamically-placed reserved memory regions:
   - Call __reserved_mem_alloc_size() which is used to allocate memory
     for each of these regions, and mark them as nomap if they have the
     nomap property specified in the DT.
   - Call the region specific init function.

The current size of the resvered_mem array is 64 as is defined by
MAX_RESERVED_REGIONS. This means that there is a limitation of 64 for
how many reserved memory regions can be specified on a system.
As systems continue to grow more and more complex, the number of
reserved memory regions needed are also growing and are starting to hit
this 64 count limit, hence the need to make the reserved_mem array
dynamically sized (i.e. dynamically allocating memory for the
reserved_mem array using membock_alloc_*).

On architectures such as arm64, memory allocated using memblock is
writable only after the page tables have been setup. This means that if
the reserved_mem array is going to be dynamically allocated, it needs to
happen after the page tables have been setup, not before.

Since the reserved memory regions are currently being processed and
added to the array before the page tables are setup, there is a need to
change the order in which some of the processing is done to allow for
the reserved_mem array to be dynamically sized.

It is possible to process the statically-placed reserved memory regions
without needing to store them in the reserved_mem array until after the
page tables have been setup because all the information stored in the
array is readily available in the devicetree and can be referenced at
any time.
Dynamically-placed reserved memory regions on the other hand get
assigned a start address only at runtime, and hence need a place to be
stored once they are allocated since there is no other referrence to the
start address for these regions.

Hence this patch changes the processing order of the reserved memory
regions in the following ways:

Step 1:
fdt_scan_reserved_mem() scans through the child nodes of
the reserved_memory node using the flattened devicetree and does the
following:

1) If the node represents a statically-placed reserved memory region,
   i.e. if it is defined using the "reg" property:
   - Call memblock_reserve() or memblock_mark_nomap() as needed.

2) If the node represents a dynamically-placed reserved memory region,
   i.e. if it is defined using "alloc-ranges" and "size" properties:
   - Call __reserved_mem_alloc_size() which will:
     i) Allocate memory for the reserved region and call
     memblock_mark_nomap() as needed.
     ii) Call the region specific initialization function using
     fdt_init_reserved_mem_node().
     iii) Save the region information in the reserved_mem array using
     fdt_reserved_mem_save_node().

Step 2:
1) This stage of the reserved memory processing is now only used to add
   the statically-placed reserved memory regions into the reserved_mem
   array using fdt_scan_reserved_mem_reg_nodes(), as well as call their
   region specific initialization functions.

2) This step has also been moved to be after the page tables are
   setup. Moving this will allow us to replace the reserved_mem
   array with a dynamically sized array before storing the rest of
   these regions.

Signed-off-by: Oreoluwa Babatunde <quic_obabatun@quicinc.com>
Link: https://lore.kernel.org/r/20241008220624.551309-2-quic_obabatun@quicinc.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
2024-10-15 10:34:15 -05:00

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/* SPDX-License-Identifier: GPL-2.0+ */
#ifndef _LINUX_OF_PRIVATE_H
#define _LINUX_OF_PRIVATE_H
/*
* Private symbols used by OF support code
*
* Paul Mackerras August 1996.
* Copyright (C) 1996-2005 Paul Mackerras.
*/
#define FDT_ALIGN_SIZE 8
#define MAX_RESERVED_REGIONS 64
/**
* struct alias_prop - Alias property in 'aliases' node
* @link: List node to link the structure in aliases_lookup list
* @alias: Alias property name
* @np: Pointer to device_node that the alias stands for
* @id: Index value from end of alias name
* @stem: Alias string without the index
*
* The structure represents one alias property of 'aliases' node as
* an entry in aliases_lookup list.
*/
struct alias_prop {
struct list_head link;
const char *alias;
struct device_node *np;
int id;
char stem[];
};
#if defined(CONFIG_SPARC)
#define OF_ROOT_NODE_ADDR_CELLS_DEFAULT 2
#else
#define OF_ROOT_NODE_ADDR_CELLS_DEFAULT 1
#endif
#define OF_ROOT_NODE_SIZE_CELLS_DEFAULT 1
extern struct mutex of_mutex;
extern raw_spinlock_t devtree_lock;
extern struct list_head aliases_lookup;
extern struct kset *of_kset;
#if defined(CONFIG_OF_DYNAMIC)
extern int of_property_notify(int action, struct device_node *np,
struct property *prop, struct property *old_prop);
extern void of_node_release(struct kobject *kobj);
extern int __of_changeset_apply_entries(struct of_changeset *ocs,
int *ret_revert);
extern int __of_changeset_apply_notify(struct of_changeset *ocs);
extern int __of_changeset_revert_entries(struct of_changeset *ocs,
int *ret_apply);
extern int __of_changeset_revert_notify(struct of_changeset *ocs);
#else /* CONFIG_OF_DYNAMIC */
static inline int of_property_notify(int action, struct device_node *np,
struct property *prop, struct property *old_prop)
{
return 0;
}
#endif /* CONFIG_OF_DYNAMIC */
#if defined(CONFIG_OF_DYNAMIC) && defined(CONFIG_OF_ADDRESS)
void of_platform_register_reconfig_notifier(void);
#else
static inline void of_platform_register_reconfig_notifier(void) { }
#endif
#if defined(CONFIG_OF_KOBJ)
int of_node_is_attached(const struct device_node *node);
int __of_add_property_sysfs(struct device_node *np, struct property *pp);
void __of_remove_property_sysfs(struct device_node *np, const struct property *prop);
void __of_update_property_sysfs(struct device_node *np, struct property *newprop,
const struct property *oldprop);
int __of_attach_node_sysfs(struct device_node *np);
void __of_detach_node_sysfs(struct device_node *np);
#else
static inline int __of_add_property_sysfs(struct device_node *np, struct property *pp)
{
return 0;
}
static inline void __of_remove_property_sysfs(struct device_node *np, const struct property *prop) {}
static inline void __of_update_property_sysfs(struct device_node *np,
struct property *newprop, const struct property *oldprop) {}
static inline int __of_attach_node_sysfs(struct device_node *np)
{
return 0;
}
static inline void __of_detach_node_sysfs(struct device_node *np) {}
#endif
#if defined(CONFIG_OF_RESOLVE)
int of_resolve_phandles(struct device_node *tree);
#endif
void __of_phandle_cache_inv_entry(phandle handle);
#if defined(CONFIG_OF_OVERLAY)
void of_overlay_mutex_lock(void);
void of_overlay_mutex_unlock(void);
#else
static inline void of_overlay_mutex_lock(void) {};
static inline void of_overlay_mutex_unlock(void) {};
#endif
#if defined(CONFIG_OF_UNITTEST) && defined(CONFIG_OF_OVERLAY)
extern void __init unittest_unflatten_overlay_base(void);
#else
static inline void unittest_unflatten_overlay_base(void) {};
#endif
extern void *__unflatten_device_tree(const void *blob,
struct device_node *dad,
struct device_node **mynodes,
void *(*dt_alloc)(u64 size, u64 align),
bool detached);
/**
* General utilities for working with live trees.
*
* All functions with two leading underscores operate
* without taking node references, so you either have to
* own the devtree lock or work on detached trees only.
*/
struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags);
void __of_prop_free(struct property *prop);
struct device_node *__of_node_dup(const struct device_node *np,
const char *full_name);
struct device_node *__of_find_node_by_path(const struct device_node *parent,
const char *path);
struct device_node *__of_find_node_by_full_path(struct device_node *node,
const char *path);
extern const void *__of_get_property(const struct device_node *np,
const char *name, int *lenp);
extern int __of_add_property(struct device_node *np, struct property *prop);
extern int __of_remove_property(struct device_node *np, struct property *prop);
extern int __of_update_property(struct device_node *np,
struct property *newprop, struct property **oldprop);
extern void __of_detach_node(struct device_node *np);
extern void __of_sysfs_remove_bin_file(struct device_node *np,
const struct property *prop);
/* illegal phandle value (set when unresolved) */
#define OF_PHANDLE_ILLEGAL 0xdeadbeef
/* iterators for transactions, used for overlays */
/* forward iterator */
#define for_each_transaction_entry(_oft, _te) \
list_for_each_entry(_te, &(_oft)->te_list, node)
/* reverse iterator */
#define for_each_transaction_entry_reverse(_oft, _te) \
list_for_each_entry_reverse(_te, &(_oft)->te_list, node)
extern int of_bus_n_addr_cells(struct device_node *np);
extern int of_bus_n_size_cells(struct device_node *np);
const __be32 *of_irq_parse_imap_parent(const __be32 *imap, int len,
struct of_phandle_args *out_irq);
struct bus_dma_region;
#if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
int of_dma_get_range(struct device_node *np,
const struct bus_dma_region **map);
struct device_node *__of_get_dma_parent(const struct device_node *np);
#else
static inline int of_dma_get_range(struct device_node *np,
const struct bus_dma_region **map)
{
return -ENODEV;
}
static inline struct device_node *__of_get_dma_parent(const struct device_node *np)
{
return of_get_parent(np);
}
#endif
int fdt_scan_reserved_mem(void);
void __init fdt_scan_reserved_mem_reg_nodes(void);
bool of_fdt_device_is_available(const void *blob, unsigned long node);
#endif /* _LINUX_OF_PRIVATE_H */
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