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removed alarm/dtc-overlay

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Kevin Mihelich 2017-05-16 03:21:34 +00:00
parent 3613e7da8a
commit 70a978ec9f
4 changed files with 0 additions and 1073 deletions
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402
alarm/dtc-overlay/0001-dtc-Symbol-and-local-fixup-generation-support.patch
View file

@ -1,402 +0,0 @@
From 78077bd72707579bffab6b1d3e7f1a8f5b2b127f Mon Sep 17 00:00:00 2001
From: Pantelis Antoniou
<pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
Date: Tue, 21 Oct 2014 22:39:57 +0300
Subject: [PATCH 1/3] dtc: Symbol and local fixup generation support
Enable the generation of symbols & local fixup information
for trees compiled with the -@ (--symbols) option.
Using this patch labels in the tree and their users emit information
in __symbols__ and __local_fixups__ nodes. Using this information
it is possible to implement run time dynamic tree loading.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
Documentation/manual.txt | 5 ++
checks.c | 61 +++++++++++++++++++++
dtc.c | 9 ++-
dtc.h | 28 ++++++++++
flattree.c | 139 +++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 240 insertions(+), 2 deletions(-)
diff --git a/Documentation/manual.txt b/Documentation/manual.txt
index 398de32..4359958 100644
--- a/Documentation/manual.txt
+++ b/Documentation/manual.txt
@@ -119,6 +119,11 @@ Options:
Make space for <number> reserve map entries
Relevant for dtb and asm output only.
+ -@
+ Generates a __symbols__ node at the root node of the resulting blob
+ for any node labels used, and for any local references using phandles
+ it also generates a __local_fixups__ node that tracks them.
+
-S <bytes>
Ensure the blob at least <bytes> long, adding additional
space if needed.
diff --git a/checks.c b/checks.c
index 3bf0fa4..f203986 100644
--- a/checks.c
+++ b/checks.c
@@ -457,6 +457,7 @@ static void fixup_phandle_references(struct check *c, struct node *dt,
struct node *node, struct property *prop)
{
struct marker *m = prop->val.markers;
+ struct fixup_entry *fe, **fep;
struct node *refnode;
cell_t phandle;
@@ -470,9 +471,28 @@ static void fixup_phandle_references(struct check *c, struct node *dt,
continue;
}
+ /* if it's a local reference, we need to record it */
+ if (symbol_fixup_support) {
+
+ /* allocate a new local fixup entry */
+ fe = xmalloc(sizeof(*fe));
+
+ fe->node = node;
+ fe->prop = prop;
+ fe->offset = m->offset;
+ fe->next = NULL;
+
+ /* append it to the local fixups */
+ fep = &dt->local_fixups;
+ while (*fep)
+ fep = &(*fep)->next;
+ *fep = fe;
+ }
+
phandle = get_node_phandle(dt, refnode);
*((cell_t *)(prop->val.val + m->offset)) = cpu_to_fdt32(phandle);
}
+
}
ERROR(phandle_references, NULL, NULL, fixup_phandle_references, NULL,
&duplicate_node_names, &explicit_phandles);
@@ -651,6 +671,45 @@ static void check_obsolete_chosen_interrupt_controller(struct check *c,
}
TREE_WARNING(obsolete_chosen_interrupt_controller, NULL);
+static void check_auto_label_phandles(struct check *c, struct node *dt,
+ struct node *node)
+{
+ struct label *l;
+ struct symbol *s, **sp;
+ int has_label;
+
+ if (!symbol_fixup_support)
+ return;
+
+ has_label = 0;
+ for_each_label(node->labels, l) {
+ has_label = 1;
+ break;
+ }
+
+ if (!has_label)
+ return;
+
+ /* force allocation of a phandle for this node */
+ (void)get_node_phandle(dt, node);
+
+ /* add the symbol */
+ for_each_label(node->labels, l) {
+
+ s = xmalloc(sizeof(*s));
+ s->label = l;
+ s->node = node;
+ s->next = NULL;
+
+ /* add it to the symbols list */
+ sp = &dt->symbols;
+ while (*sp)
+ sp = &((*sp)->next);
+ *sp = s;
+ }
+}
+NODE_WARNING(auto_label_phandles, NULL);
+
static struct check *check_table[] = {
&duplicate_node_names, &duplicate_property_names,
&node_name_chars, &node_name_format, &property_name_chars,
@@ -669,6 +728,8 @@ static struct check *check_table[] = {
&avoid_default_addr_size,
&obsolete_chosen_interrupt_controller,
+ &auto_label_phandles,
+
&always_fail,
};
diff --git a/dtc.c b/dtc.c
index 8c4add6..91e91e7 100644
--- a/dtc.c
+++ b/dtc.c
@@ -29,6 +29,7 @@ int reservenum; /* Number of memory reservation slots */
int minsize; /* Minimum blob size */
int padsize; /* Additional padding to blob */
int phandle_format = PHANDLE_BOTH; /* Use linux,phandle or phandle properties */
+int symbol_fixup_support = 0;
static void fill_fullpaths(struct node *tree, const char *prefix)
{
@@ -51,7 +52,7 @@ static void fill_fullpaths(struct node *tree, const char *prefix)
#define FDT_VERSION(version) _FDT_VERSION(version)
#define _FDT_VERSION(version) #version
static const char usage_synopsis[] = "dtc [options] <input file>";
-static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv";
+static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:@hv";
static struct option const usage_long_opts[] = {
{"quiet", no_argument, NULL, 'q'},
{"in-format", a_argument, NULL, 'I'},
@@ -69,6 +70,7 @@ static struct option const usage_long_opts[] = {
{"phandle", a_argument, NULL, 'H'},
{"warning", a_argument, NULL, 'W'},
{"error", a_argument, NULL, 'E'},
+ {"symbols", no_argument, NULL, '@'},
{"help", no_argument, NULL, 'h'},
{"version", no_argument, NULL, 'v'},
{NULL, no_argument, NULL, 0x0},
@@ -99,6 +101,7 @@ static const char * const usage_opts_help[] = {
"\t\tboth - Both \"linux,phandle\" and \"phandle\" properties",
"\n\tEnable/disable warnings (prefix with \"no-\")",
"\n\tEnable/disable errors (prefix with \"no-\")",
+ "\n\tEnable symbols/fixup support",
"\n\tPrint this help and exit",
"\n\tPrint version and exit",
NULL,
@@ -186,7 +189,9 @@ int main(int argc, char *argv[])
case 'E':
parse_checks_option(false, true, optarg);
break;
-
+ case '@':
+ symbol_fixup_support = 1;
+ break;
case 'h':
usage(NULL);
default:
diff --git a/dtc.h b/dtc.h
index 56212c8..16354fa 100644
--- a/dtc.h
+++ b/dtc.h
@@ -54,6 +54,7 @@ extern int reservenum; /* Number of memory reservation slots */
extern int minsize; /* Minimum blob size */
extern int padsize; /* Additional padding to blob */
extern int phandle_format; /* Use linux,phandle or phandle properties */
+extern int symbol_fixup_support;/* enable symbols & fixup support */
#define PHANDLE_LEGACY 0x1
#define PHANDLE_EPAPR 0x2
@@ -132,6 +133,20 @@ struct label {
struct label *next;
};
+struct fixup_entry {
+ int offset;
+ struct node *node;
+ struct property *prop;
+ struct fixup_entry *next;
+ bool local_fixup_generated;
+};
+
+struct symbol {
+ struct label *label;
+ struct node *node;
+ struct symbol *next;
+};
+
struct property {
bool deleted;
char *name;
@@ -158,6 +173,10 @@ struct node {
int addr_cells, size_cells;
struct label *labels;
+
+ struct symbol *symbols;
+ struct fixup_entry *local_fixups;
+ bool emit_local_fixup_node;
};
#define for_each_label_withdel(l0, l) \
@@ -181,6 +200,15 @@ struct node {
for_each_child_withdel(n, c) \
if (!(c)->deleted)
+#define for_each_fixup_entry(f, fe) \
+ for ((fe) = (f)->entries; (fe); (fe) = (fe)->next)
+
+#define for_each_symbol(n, s) \
+ for ((s) = (n)->symbols; (s); (s) = (s)->next)
+
+#define for_each_local_fixup_entry(n, fe) \
+ for ((fe) = (n)->local_fixups; (fe); (fe) = (fe)->next)
+
void add_label(struct label **labels, char *label);
void delete_labels(struct label **labels);
diff --git a/flattree.c b/flattree.c
index bd99fa2..3a58949 100644
--- a/flattree.c
+++ b/flattree.c
@@ -255,6 +255,142 @@ static int stringtable_insert(struct data *d, const char *str)
return i;
}
+static void emit_local_fixups(struct node *tree, struct emitter *emit,
+ void *etarget, struct data *strbuf, struct version_info *vi,
+ struct node *node)
+{
+ struct fixup_entry *fe, *fen;
+ struct node *child;
+ int nameoff, count;
+ cell_t *buf;
+ struct data d;
+
+ if (node->emit_local_fixup_node) {
+
+ /* emit the external fixups (do not emit /) */
+ if (node != tree) {
+ emit->beginnode(etarget, NULL);
+ emit->string(etarget, node->name, 0);
+ emit->align(etarget, sizeof(cell_t));
+ }
+
+ for_each_local_fixup_entry(tree, fe) {
+ if (fe->node != node || fe->local_fixup_generated)
+ continue;
+
+ /* count the number of fixup entries */
+ count = 0;
+ for_each_local_fixup_entry(tree, fen) {
+ if (fen->prop != fe->prop)
+ continue;
+ fen->local_fixup_generated = true;
+ count++;
+ }
+
+ /* allocate buffer */
+ buf = xmalloc(count * sizeof(cell_t));
+
+ /* collect all the offsets in buffer */
+ count = 0;
+ for_each_local_fixup_entry(tree, fen) {
+ if (fen->prop != fe->prop)
+ continue;
+ fen->local_fixup_generated = true;
+ buf[count++] = cpu_to_fdt32(fen->offset);
+ }
+ d = empty_data;
+ d.len = count * sizeof(cell_t);
+ d.val = (char *)buf;
+
+ nameoff = stringtable_insert(strbuf, fe->prop->name);
+ emit->property(etarget, fe->prop->labels);
+ emit->cell(etarget, count * sizeof(cell_t));
+ emit->cell(etarget, nameoff);
+
+ if ((vi->flags & FTF_VARALIGN) &&
+ (count * sizeof(cell_t)) >= 8)
+ emit->align(etarget, 8);
+
+ emit->data(etarget, d);
+ emit->align(etarget, sizeof(cell_t));
+
+ free(buf);
+ }
+ }
+
+ for_each_child(node, child)
+ emit_local_fixups(tree, emit, etarget, strbuf, vi, child);
+
+ if (node->emit_local_fixup_node && node != tree)
+ emit->endnode(etarget, tree->labels);
+}
+
+static void emit_symbols_node(struct node *tree, struct emitter *emit,
+ void *etarget, struct data *strbuf,
+ struct version_info *vi)
+{
+ struct symbol *sym;
+ int nameoff, vallen;
+
+ /* do nothing if no symbols */
+ if (!tree->symbols)
+ return;
+
+ emit->beginnode(etarget, NULL);
+ emit->string(etarget, "__symbols__", 0);
+ emit->align(etarget, sizeof(cell_t));
+
+ for_each_symbol(tree, sym) {
+
+ vallen = strlen(sym->node->fullpath);
+
+ nameoff = stringtable_insert(strbuf, sym->label->label);
+
+ emit->property(etarget, NULL);
+ emit->cell(etarget, vallen + 1);
+ emit->cell(etarget, nameoff);
+
+ if ((vi->flags & FTF_VARALIGN) && vallen >= 8)
+ emit->align(etarget, 8);
+
+ emit->string(etarget, sym->node->fullpath,
+ strlen(sym->node->fullpath));
+ emit->align(etarget, sizeof(cell_t));
+ }
+
+ emit->endnode(etarget, NULL);
+}
+
+static void emit_local_fixups_node(struct node *tree, struct emitter *emit,
+ void *etarget, struct data *strbuf,
+ struct version_info *vi)
+{
+ struct fixup_entry *fe;
+ struct node *node;
+
+ /* do nothing if no local fixups */
+ if (!tree->local_fixups)
+ return;
+
+ /* mark all nodes that need a local fixup generated (and parents) */
+ for_each_local_fixup_entry(tree, fe) {
+ node = fe->node;
+ while (node != NULL && !node->emit_local_fixup_node) {
+ node->emit_local_fixup_node = true;
+ node = node->parent;
+ }
+ }
+
+ /* emit the local fixups node now */
+ emit->beginnode(etarget, NULL);
+ emit->string(etarget, "__local_fixups__", 0);
+ emit->align(etarget, sizeof(cell_t));
+
+ emit_local_fixups(tree, emit, etarget, strbuf, vi, tree);
+
+ emit->endnode(etarget, tree->labels);
+}
+
static void flatten_tree(struct node *tree, struct emitter *emit,
void *etarget, struct data *strbuf,
struct version_info *vi)
@@ -310,6 +446,9 @@ static void flatten_tree(struct node *tree, struct emitter *emit,
flatten_tree(child, emit, etarget, strbuf, vi);
}
+ emit_symbols_node(tree, emit, etarget, strbuf, vi);
+ emit_local_fixups_node(tree, emit, etarget, strbuf, vi);
+
emit->endnode(etarget, tree->labels);
}
--
2.2.2

304
alarm/dtc-overlay/0002-dtc-Plugin-object-device-tree-support.patch
View file

@ -1,304 +0,0 @@
From b29e0699719c15866ce92af0598b2d61418fe89b Mon Sep 17 00:00:00 2001
From: Pantelis Antoniou
<pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
Date: Tue, 21 Oct 2014 22:39:58 +0300
Subject: [PATCH 2/3] dtc: Plugin (object) device tree support.
Enables the generation of a __fixups__ node for trees compiled
using the -@ option that are using the /plugin/ tag.
The __fixups__ node make possible the dynamic resolution of phandle
references which are present in the plugin tree but lie in the
tree that are applying the overlay against.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
Documentation/manual.txt | 5 ++++
checks.c | 45 ++++++++++++++++++++++++++++++++--
dtc-lexer.l | 5 ++++
dtc-parser.y | 22 ++++++++++++++---
dtc.h | 12 +++++++++
flattree.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 147 insertions(+), 5 deletions(-)
diff --git a/Documentation/manual.txt b/Documentation/manual.txt
index 4359958..18d1333 100644
--- a/Documentation/manual.txt
+++ b/Documentation/manual.txt
@@ -124,6 +124,9 @@ Options:
for any node labels used, and for any local references using phandles
it also generates a __local_fixups__ node that tracks them.
+ When using the /plugin/ tag all unresolved label references to
+ be tracked in the __fixups__ node, making dynamic resolution possible.
+
-S <bytes>
Ensure the blob at least <bytes> long, adding additional
space if needed.
@@ -158,6 +161,8 @@ Here is a very rough overview of the layout of a DTS source file:
devicetree: '/' nodedef
+ plugindecl: '/' 'plugin' '/' ';'
+
nodedef: '{' list_of_property list_of_subnode '}' ';'
property: label PROPNAME '=' propdata ';'
diff --git a/checks.c b/checks.c
index f203986..2778e89 100644
--- a/checks.c
+++ b/checks.c
@@ -457,6 +457,7 @@ static void fixup_phandle_references(struct check *c, struct node *dt,
struct node *node, struct property *prop)
{
struct marker *m = prop->val.markers;
+ struct fixup *f, **fp;
struct fixup_entry *fe, **fep;
struct node *refnode;
cell_t phandle;
@@ -466,8 +467,48 @@ static void fixup_phandle_references(struct check *c, struct node *dt,
refnode = get_node_by_ref(dt, m->ref);
if (! refnode) {
- FAIL(c, "Reference to non-existent node or label \"%s\"\n",
- m->ref);
+ if (!dt->is_plugin) {
+ FAIL(c, "Reference to non-existent node or label \"%s\"\n",
+ m->ref);
+ continue;
+ }
+
+ /* allocate fixup entry */
+ fe = xmalloc(sizeof(*fe));
+
+ fe->node = node;
+ fe->prop = prop;
+ fe->offset = m->offset;
+ fe->next = NULL;
+
+ /* search for an already existing fixup */
+ for_each_fixup(dt, f)
+ if (strcmp(f->ref, m->ref) == 0)
+ break;
+
+ /* no fixup found, add new */
+ if (f == NULL) {
+ f = xmalloc(sizeof(*f));
+ f->ref = m->ref;
+ f->entries = NULL;
+ f->next = NULL;
+
+ /* add it to the tree */
+ fp = &dt->fixups;
+ while (*fp)
+ fp = &(*fp)->next;
+ *fp = f;
+ }
+
+ /* and now append fixup entry */
+ fep = &f->entries;
+ while (*fep)
+ fep = &(*fep)->next;
+ *fep = fe;
+
+ /* mark the entry as unresolved */
+ *((cell_t *)(prop->val.val + m->offset)) =
+ cpu_to_fdt32(0xdeadbeef);
continue;
}
diff --git a/dtc-lexer.l b/dtc-lexer.l
index 0ee1caf..dd44ba2 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -113,6 +113,11 @@ static void lexical_error(const char *fmt, ...);
return DT_V1;
}
+<*>"/plugin/" {
+ DPRINT("Keyword: /plugin/\n");
+ return DT_PLUGIN;
+ }
+
<*>"/memreserve/" {
DPRINT("Keyword: /memreserve/\n");
BEGIN_DEFAULT();
diff --git a/dtc-parser.y b/dtc-parser.y
index ea57e0a..776fdd5 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -19,6 +19,7 @@
*/
%{
#include <stdio.h>
+#include <inttypes.h>
#include "dtc.h"
#include "srcpos.h"
@@ -52,9 +53,11 @@ extern bool treesource_error;
struct node *nodelist;
struct reserve_info *re;
uint64_t integer;
+ bool is_plugin;
}
%token DT_V1
+%token DT_PLUGIN
%token DT_MEMRESERVE
%token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR
%token DT_BITS
@@ -71,6 +74,7 @@ extern bool treesource_error;
%type <data> propdata
%type <data> propdataprefix
+%type <is_plugin> plugindecl
%type <re> memreserve
%type <re> memreserves
%type <array> arrayprefix
@@ -101,10 +105,22 @@ extern bool treesource_error;
%%
sourcefile:
- DT_V1 ';' memreserves devicetree
+ DT_V1 ';' plugindecl memreserves devicetree
{
- the_boot_info = build_boot_info($3, $4,
- guess_boot_cpuid($4));
+ $5->is_plugin = $3;
+ the_boot_info = build_boot_info($4, $5,
+ guess_boot_cpuid($5));
+ }
+ ;
+
+plugindecl:
+ /* empty */
+ {
+ $$ = false;
+ }
+ | DT_PLUGIN ';'
+ {
+ $$ = true;
}
;
diff --git a/dtc.h b/dtc.h
index 16354fa..f163b22 100644
--- a/dtc.h
+++ b/dtc.h
@@ -141,6 +141,12 @@ struct fixup_entry {
bool local_fixup_generated;
};
+struct fixup {
+ char *ref;
+ struct fixup_entry *entries;
+ struct fixup *next;
+};
+
struct symbol {
struct label *label;
struct node *node;
@@ -177,6 +183,9 @@ struct node {
struct symbol *symbols;
struct fixup_entry *local_fixups;
bool emit_local_fixup_node;
+
+ bool is_plugin;
+ struct fixup *fixups;
};
#define for_each_label_withdel(l0, l) \
@@ -200,6 +209,9 @@ struct node {
for_each_child_withdel(n, c) \
if (!(c)->deleted)
+#define for_each_fixup(n, f) \
+ for ((f) = (n)->fixups; (f); (f) = (f)->next)
+
#define for_each_fixup_entry(f, fe) \
for ((fe) = (f)->entries; (fe); (fe) = (fe)->next)
diff --git a/flattree.c b/flattree.c
index 3a58949..2385137 100644
--- a/flattree.c
+++ b/flattree.c
@@ -391,6 +391,68 @@ static void emit_local_fixups_node(struct node *tree, struct emitter *emit,
emit->endnode(etarget, tree->labels);
}
+static void emit_fixups_node(struct node *tree, struct emitter *emit,
+ void *etarget, struct data *strbuf,
+ struct version_info *vi)
+{
+ struct fixup *f;
+ struct fixup_entry *fe;
+ char *name, *s;
+ const char *fullpath;
+ int namesz, nameoff, vallen;
+
+ /* do nothing if no fixups */
+ if (!tree->fixups)
+ return;
+
+ /* emit the external fixups */
+ emit->beginnode(etarget, NULL);
+ emit->string(etarget, "__fixups__", 0);
+ emit->align(etarget, sizeof(cell_t));
+
+ for_each_fixup(tree, f) {
+
+ namesz = 0;
+ for_each_fixup_entry(f, fe) {
+ fullpath = fe->node->fullpath;
+ if (fullpath[0] == '\0')
+ fullpath = "/";
+ namesz += strlen(fullpath) + 1;
+ namesz += strlen(fe->prop->name) + 1;
+ namesz += 32; /* space for :<number> + '\0' */
+ }
+
+ name = xmalloc(namesz);
+
+ s = name;
+ for_each_fixup_entry(f, fe) {
+ fullpath = fe->node->fullpath;
+ if (fullpath[0] == '\0')
+ fullpath = "/";
+ snprintf(s, name + namesz - s, "%s:%s:%d", fullpath,
+ fe->prop->name, fe->offset);
+ s += strlen(s) + 1;
+ }
+
+ nameoff = stringtable_insert(strbuf, f->ref);
+ vallen = s - name - 1;
+
+ emit->property(etarget, NULL);
+ emit->cell(etarget, vallen + 1);
+ emit->cell(etarget, nameoff);
+
+ if ((vi->flags & FTF_VARALIGN) && vallen >= 8)
+ emit->align(etarget, 8);
+
+ emit->string(etarget, name, vallen);
+ emit->align(etarget, sizeof(cell_t));
+
+ free(name);
+ }
+
+ emit->endnode(etarget, tree->labels);
+}
+
static void flatten_tree(struct node *tree, struct emitter *emit,
void *etarget, struct data *strbuf,
struct version_info *vi)
@@ -448,6 +510,7 @@ static void flatten_tree(struct node *tree, struct emitter *emit,
emit_symbols_node(tree, emit, etarget, strbuf, vi);
emit_local_fixups_node(tree, emit, etarget, strbuf, vi);
+ emit_fixups_node(tree, emit, etarget, strbuf, vi);
emit->endnode(etarget, tree->labels);
}
--
2.2.2

325
alarm/dtc-overlay/0003-dtc-Document-the-dynamic-plugin-internals.patch
View file

@ -1,325 +0,0 @@
From 4225e23356d58e574f97803387562cf53c72476a Mon Sep 17 00:00:00 2001
From: Pantelis Antoniou
<pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
Date: Tue, 21 Oct 2014 22:39:59 +0300
Subject: [PATCH 3/3] dtc: Document the dynamic plugin internals
Provides the document explaining the internal mechanics of
plugins and options.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
---
Documentation/dt-object-internal.txt | 301 +++++++++++++++++++++++++++++++++++
1 file changed, 301 insertions(+)
create mode 100644 Documentation/dt-object-internal.txt
diff --git a/Documentation/dt-object-internal.txt b/Documentation/dt-object-internal.txt
new file mode 100644
index 0000000..b5ce9b4
--- /dev/null
+++ b/Documentation/dt-object-internal.txt
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+Device Tree Dynamic Object format internals
+-------------------------------------------
+
+The Device Tree for most platforms is a static representation of
+the hardware capabilities. This is insufficient for many platforms
+that need to dynamically insert device tree fragments to the
+running kernel's live tree.
+
+This document explains the the device tree object format and the
+modifications made to the device tree compiler, which make it possible.
+
+1. Simplified Problem Definition
+--------------------------------
+
+Assume we have a platform which boots using following simplified device tree.
+
+---- foo.dts -----------------------------------------------------------------
+ /* FOO platform */
+ / {
+ compatible = "corp,foo";
+
+ /* shared resources */
+ res: res {
+ };
+
+ /* On chip peripherals */
+ ocp: ocp {
+ /* peripherals that are always instantiated */
+ peripheral1 { ... };
+ }
+ };
+---- foo.dts -----------------------------------------------------------------
+
+We have a number of peripherals that after probing (using some undefined method)
+should result in different device tree configuration.
+
+We cannot boot with this static tree because due to the configuration of the
+foo platform there exist multiple conficting peripherals DT fragments.
+
+So for the bar peripheral we would have this:
+
+---- foo+bar.dts -------------------------------------------------------------
+ /* FOO platform + bar peripheral */
+ / {
+ compatible = "corp,foo";
+
+ /* shared resources */
+ res: res {
+ };
+
+ /* On chip peripherals */
+ ocp: ocp {
+ /* peripherals that are always instantiated */
+ peripheral1 { ... };
+
+ /* bar peripheral */
+ bar {
+ compatible = "corp,bar";
+ ... /* various properties and child nodes */
+ }
+ }
+ };
+---- foo+bar.dts -------------------------------------------------------------
+
+While for the baz peripheral we would have this:
+
+---- foo+baz.dts -------------------------------------------------------------
+ /* FOO platform + baz peripheral */
+ / {
+ compatible = "corp,foo";
+
+ /* shared resources */
+ res: res {
+ /* baz resources */
+ baz_res: res_baz { ... };
+ };
+
+ /* On chip peripherals */
+ ocp: ocp {
+ /* peripherals that are always instantiated */
+ peripheral1 { ... };
+
+ /* baz peripheral */
+ baz {
+ compatible = "corp,baz";
+ /* reference to another point in the tree */
+ ref-to-res = <&baz_res>;
+ ... /* various properties and child nodes */
+ }
+ }
+ };
+---- foo+baz.dts -------------------------------------------------------------
+
+We note that the baz case is more complicated, since the baz peripheral needs to
+reference another node in the DT tree.
+
+2. Device Tree Object Format Requirements
+-----------------------------------------
+
+Since the device tree is used for booting a number of very different hardware
+platforms it is imperative that we tread very carefully.
+
+2.a) No changes to the Device Tree binary format. We cannot modify the tree
+format at all and all the information we require should be encoded using device
+tree itself. We can add nodes that can be safely ignored by both bootloaders and
+the kernel.
+
+2.b) Changes to the DTS source format should be absolutely minimal, and should
+only be needed for the DT fragment definitions, and not the base boot DT.
+
+2.c) An explicit option should be used to instruct DTC to generate the required
+information needed for object resolution. Platforms that don't use the
+dynamic object format can safely ignore it.
+
+2.d) Finally, DT syntax changes should be kept to a minimum. It should be
+possible to express everything using the existing DT syntax.
+
+3. Implementation
+-----------------
+
+The basic unit of addressing in Device Tree is the phandle. Turns out it's
+relatively simple to extend the way phandles are generated and referenced
+so that it's possible to dynamically convert symbolic references (labels)
+to phandle values.
+
+We can roughly divide the operation into two steps.
+
+3.a) Compilation of the base board DTS file using the '-@' option
+generates a valid DT blob with an added __symbols__ node at the root node,
+containing a list of all nodes that are marked with a label.
+
+Using the foo.dts file above the following node will be generated;
+
+$ dtc -@ -O dtb -o foo.dtb -b 0 foo.dts
+$ fdtdump foo.dtb
+...
+/ {
+ ...
+ res {
+ ...
+ linux,phandle = <0x00000001>;
+ phandle = <0x00000001>;
+ ...
+ };
+ ocp {
+ ...
+ linux,phandle = <0x00000002>;
+ phandle = <0x00000002>;
+ ...
+ };
+ __symbols__ {
+ res="/res";
+ ocp="/ocp";
+ };
+};
+
+Notice that all the nodes that had a label have been recorded, and that
+phandles have been generated for them.
+
+This blob can be used to boot the board normally, the __symbols__ node will
+be safely ignored both by the bootloader and the kernel (the only loss will
+be a few bytes of memory and disk space).
+
+3.b) The Device Tree fragments must be compiled with the same option but they
+must also have a tag (/plugin/) that allows undefined references to labels
+that are not present at compilation time to be recorded so that the runtime
+loader can fix them.
+
+So the bar peripheral's DTS format would be of the form:
+
+/plugin/; /* allow undefined label references and record them */
+/ {
+ .... /* various properties for loader use; i.e. part id etc. */
+ fragment@0 {
+ target = <&ocp>;
+ __overlay__ {
+ /* bar peripheral */
+ bar {
+ compatible = "corp,bar";
+ ... /* various properties and child nodes */
+ }
+ };
+ };
+};
+
+Note that there's a target property that specifies the location where the
+contents of the overlay node will be placed, and it references the label
+in the foo.dts file.
+
+$ dtc -@ -O dtb -o bar.dtbo -b 0 bar.dts
+$ fdtdump bar.dtbo
+...
+/ {
+ ... /* properties */
+ fragment@0 {
+ target = <0xdeadbeef>;
+ __overlay__ {
+ bar {
+ compatible = "corp,bar";
+ ... /* various properties and child nodes */
+ }
+ };
+ };
+ __fixups__ {
+ ocp = "/fragment@0:target:0";
+ };
+};
+
+No __symbols__ has been generated (no label in bar.dts).
+Note that the target's ocp label is undefined, so the phandle handle
+value is filled with the illegal value '0xdeadbeef', while a __fixups__
+node has been generated, which marks the location in the tree where
+the label lookup should store the runtime phandle value of the ocp node.
+
+The format of the __fixups__ node entry is
+
+ <label> = "<local-full-path>:<property-name>:<offset>";
+
+<label> Is the label we're referring
+<local-full-path> Is the full path of the node the reference is
+<property-name> Is the name of the property containing the
+ reference
+<offset> The offset (in bytes) of where the property's
+ phandle value is located.
+
+Doing the same with the baz peripheral's DTS format is a little bit more
+involved, since baz contains references to local labels which require
+local fixups.
+
+/plugin/; /* allow undefined label references and record them */
+/ {
+ .... /* various properties for loader use; i.e. part id etc. */
+ fragment@0 {
+ target = <&res>;
+ __overlay__ {
+ /* baz resources */
+ baz_res: res_baz { ... };
+ };
+ };
+ fragment@1 {
+ target = <&ocp>;
+ __overlay__ {
+ /* baz peripheral */
+ baz {
+ compatible = "corp,baz";
+ /* reference to another point in the tree */
+ ref-to-res = <&baz_res>;
+ ... /* various properties and child nodes */
+ }
+ };
+ };
+};
+
+Note that &bar_res reference.
+
+$ dtc -@ -O dtb -o baz.dtbo -b 0 baz.dts
+$ fdtdump baz.dtbo
+...
+/ {
+ ... /* properties */
+ fragment@0 {
+ target = <0xdeadbeef>;
+ __overlay__ {
+ res_baz {
+ ....
+ linux,phandle = <0x00000001>;
+ phandle = <0x00000001>;
+ };
+ };
+ };
+ fragment@1 {
+ target = <0xdeadbeef>;
+ __overlay__ {
+ baz {
+ compatible = "corp,baz";
+ ... /* various properties and child nodes */
+ ref-to-res = <0x00000001>;
+ }
+ };
+ };
+ __fixups__ {
+ res = "/fragment@0:target:0";
+ ocp = "/fragment@1:target:0";
+ };
+ __local_fixups__ {
+ fragment@1 {
+ __overlay__ {
+ baz {
+ ref-to-res = <0>;
+ };
+ };
+ };
+ };
+};
+
+This is similar to the bar case, but the reference of a local label by the
+baz node generates a __local_fixups__ entry that records the place that the
+local reference is being made. Since phandles are allocated starting at 1
+the run time loader must apply an offset to each phandle in every dynamic
+DT object loaded. The __local_fixups__ node records the place of every
+local reference so that the loader can apply the offset.
--
2.2.2

42
alarm/dtc-overlay/PKGBUILD
View file

@ -1,42 +0,0 @@
# Maintainer: Kevin Mihelich <kevin@archlinuxarm.org>
# Contributor: Anatol Pomozov
# Contributor: Frederic Bezies <fredbezies at gmail dot com>
pkgname=dtc-overlay
pkgver=1.4.1
pkgrel=1
pkgdesc='Device Tree Compiler with device tree overlay support'
url='http://www.devicetree.org/Device_Tree_Compiler'
conflicts=('dtc')
arch=(i686 x86_64)
license=(GPL2)
source=(https://www.kernel.org/pub/software/utils/dtc/dtc-$pkgver.tar.xz
0001-dtc-Symbol-and-local-fixup-generation-support.patch
0002-dtc-Plugin-object-device-tree-support.patch
0003-dtc-Document-the-dynamic-plugin-internals.patch)
sha256sums=('77992ad8eac7b68f553d0ba58e5b51604ac803d126196c99e3ae38aaae28bb94'
'6efdc127acdc2f5ff4942c1f8e10e3fef30e6d6774a4d2dd6796d78e083bd74b'
'9e67c8d5b7a7a7da7783167897aab38c0641732f9e0aa3dc6672fd7b13858c13'
'bee82cf8ae70a9d3036e8b95a529f0d73c5209e1d2e209001bf888cd24df5f8b')
prepare() {
cd dtc-$pkgver
patch -p1 -i ../0001-dtc-Symbol-and-local-fixup-generation-support.patch
patch -p1 -i ../0002-dtc-Plugin-object-device-tree-support.patch
patch -p1 -i ../0003-dtc-Document-the-dynamic-plugin-internals.patch
}
build() {
cd dtc-$pkgver
make
}
check() {
cd dtc-$pkgver
make check
}
package() {
cd dtc-$pkgver
make DESTDIR="$pkgdir" PREFIX=/usr install
}