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of/fdt: Convert FDT functions to use libfdt
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The kernel FDT functions predate libfdt and are much more limited in
functionality. Also, the kernel functions and libfdt functions are
not compatible with each other because they have different definitions
of node offsets. To avoid this incompatibility and in preparation to
add more FDT parsing functions which will need libfdt, let's first
convert the existing code to use libfdt.

The FDT unflattening, top-level FDT scanning, and property retrieval
functions are converted to use libfdt. The scanning code should be
re-worked to be more efficient and understandable by using libfdt to
find nodes directly by path or compatible strings.

Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Grant Likely <grant.likely@linaro.org>
Tested-by: Stephen Chivers <schivers@csc.com>
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Rob Herring committed Apr 30, 2014
1 parent 9d0c4df commit e6a6928
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Showing 4 changed files with 60 additions and 153 deletions.
1 change: 1 addition & 0 deletions drivers/of/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ config OF_SELFTEST
config OF_FLATTREE
bool
select DTC
select LIBFDT

config OF_EARLY_FLATTREE
bool
Expand Down
2 changes: 2 additions & 0 deletions drivers/of/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -10,3 +10,5 @@ obj-$(CONFIG_OF_PCI) += of_pci.o
obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
obj-$(CONFIG_OF_MTD) += of_mtd.o
obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o

CFLAGS_fdt.o = -I$(src)/../../scripts/dtc/libfdt
209 changes: 57 additions & 152 deletions drivers/of/fdt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,58 +19,11 @@
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/libfdt.h>

#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
#include <asm/page.h>

char *of_fdt_get_string(struct boot_param_header *blob, u32 offset)
{
return ((char *)blob) +
be32_to_cpu(blob->off_dt_strings) + offset;
}

/**
* of_fdt_get_property - Given a node in the given flat blob, return
* the property ptr
*/
void *of_fdt_get_property(struct boot_param_header *blob,
unsigned long node, const char *name,
int *size)
{
unsigned long p = node;

do {
u32 tag = be32_to_cpup((__be32 *)p);
u32 sz, noff;
const char *nstr;

p += 4;
if (tag == OF_DT_NOP)
continue;
if (tag != OF_DT_PROP)
return NULL;

sz = be32_to_cpup((__be32 *)p);
noff = be32_to_cpup((__be32 *)(p + 4));
p += 8;
if (be32_to_cpu(blob->version) < 0x10)
p = ALIGN(p, sz >= 8 ? 8 : 4);

nstr = of_fdt_get_string(blob, noff);
if (nstr == NULL) {
pr_warning("Can't find property index name !\n");
return NULL;
}
if (strcmp(name, nstr) == 0) {
if (size)
*size = sz;
return (void *)p;
}
p += sz;
p = ALIGN(p, 4);
} while (1);
}

/**
* of_fdt_is_compatible - Return true if given node from the given blob has
* compat in its compatible list
Expand All @@ -88,7 +41,7 @@ int of_fdt_is_compatible(struct boot_param_header *blob,
int cplen;
unsigned long l, score = 0;

cp = of_fdt_get_property(blob, node, "compatible", &cplen);
cp = fdt_getprop(blob, node, "compatible", &cplen);
if (cp == NULL)
return 0;
while (cplen > 0) {
Expand Down Expand Up @@ -147,28 +100,27 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
*/
static void * unflatten_dt_node(struct boot_param_header *blob,
void *mem,
void **p,
int *poffset,
struct device_node *dad,
struct device_node ***allnextpp,
unsigned long fpsize)
{
const __be32 *p;
struct device_node *np;
struct property *pp, **prev_pp = NULL;
char *pathp;
u32 tag;
const char *pathp;
unsigned int l, allocl;
static int depth = 0;
int old_depth;
int offset;
int has_name = 0;
int new_format = 0;

tag = be32_to_cpup(*p);
if (tag != OF_DT_BEGIN_NODE) {
pr_err("Weird tag at start of node: %x\n", tag);
pathp = fdt_get_name(blob, *poffset, &l);
if (!pathp)
return mem;
}
*p += 4;
pathp = *p;
l = allocl = strlen(pathp) + 1;
*p = PTR_ALIGN(*p + l, 4);

allocl = l++;

/* version 0x10 has a more compact unit name here instead of the full
* path. we accumulate the full path size using "fpsize", we'll rebuild
Expand All @@ -186,7 +138,7 @@ static void * unflatten_dt_node(struct boot_param_header *blob,
fpsize = 1;
allocl = 2;
l = 1;
*pathp = '\0';
pathp = "";
} else {
/* account for '/' and path size minus terminal 0
* already in 'l'
Expand Down Expand Up @@ -233,32 +185,23 @@ static void * unflatten_dt_node(struct boot_param_header *blob,
}
}
/* process properties */
while (1) {
u32 sz, noff;
char *pname;

tag = be32_to_cpup(*p);
if (tag == OF_DT_NOP) {
*p += 4;
continue;
}
if (tag != OF_DT_PROP)
for (offset = fdt_first_property_offset(blob, *poffset);
(offset >= 0);
(offset = fdt_next_property_offset(blob, offset))) {
const char *pname;
u32 sz;

if (!(p = fdt_getprop_by_offset(blob, offset, &pname, &sz))) {
offset = -FDT_ERR_INTERNAL;
break;
*p += 4;
sz = be32_to_cpup(*p);
noff = be32_to_cpup(*p + 4);
*p += 8;
if (be32_to_cpu(blob->version) < 0x10)
*p = PTR_ALIGN(*p, sz >= 8 ? 8 : 4);

pname = of_fdt_get_string(blob, noff);
}

if (pname == NULL) {
pr_info("Can't find property name in list !\n");
break;
}
if (strcmp(pname, "name") == 0)
has_name = 1;
l = strlen(pname) + 1;
pp = unflatten_dt_alloc(&mem, sizeof(struct property),
__alignof__(struct property));
if (allnextpp) {
Expand All @@ -270,26 +213,25 @@ static void * unflatten_dt_node(struct boot_param_header *blob,
if ((strcmp(pname, "phandle") == 0) ||
(strcmp(pname, "linux,phandle") == 0)) {
if (np->phandle == 0)
np->phandle = be32_to_cpup((__be32*)*p);
np->phandle = be32_to_cpup(p);
}
/* And we process the "ibm,phandle" property
* used in pSeries dynamic device tree
* stuff */
if (strcmp(pname, "ibm,phandle") == 0)
np->phandle = be32_to_cpup((__be32 *)*p);
pp->name = pname;
np->phandle = be32_to_cpup(p);
pp->name = (char *)pname;
pp->length = sz;
pp->value = *p;
pp->value = (__be32 *)p;
*prev_pp = pp;
prev_pp = &pp->next;
}
*p = PTR_ALIGN((*p) + sz, 4);
}
/* with version 0x10 we may not have the name property, recreate
* it here from the unit name if absent
*/
if (!has_name) {
char *p1 = pathp, *ps = pathp, *pa = NULL;
const char *p1 = pathp, *ps = pathp, *pa = NULL;
int sz;

while (*p1) {
Expand Down Expand Up @@ -326,19 +268,18 @@ static void * unflatten_dt_node(struct boot_param_header *blob,
if (!np->type)
np->type = "<NULL>";
}
while (tag == OF_DT_BEGIN_NODE || tag == OF_DT_NOP) {
if (tag == OF_DT_NOP)
*p += 4;
else
mem = unflatten_dt_node(blob, mem, p, np, allnextpp,
fpsize);
tag = be32_to_cpup(*p);
}
if (tag != OF_DT_END_NODE) {
pr_err("Weird tag at end of node: %x\n", tag);
return mem;
}
*p += 4;

old_depth = depth;
*poffset = fdt_next_node(blob, *poffset, &depth);
if (depth < 0)
depth = 0;
while (*poffset > 0 && depth > old_depth)
mem = unflatten_dt_node(blob, mem, poffset, np, allnextpp,
fpsize);

if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
pr_err("unflatten: error %d processing FDT\n", *poffset);

return mem;
}

Expand All @@ -359,7 +300,8 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
void * (*dt_alloc)(u64 size, u64 align))
{
unsigned long size;
void *start, *mem;
int start;
void *mem;
struct device_node **allnextp = mynodes;

pr_debug(" -> unflatten_device_tree()\n");
Expand All @@ -380,7 +322,7 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
}

/* First pass, scan for size */
start = ((void *)blob) + be32_to_cpu(blob->off_dt_struct);
start = 0;
size = (unsigned long)unflatten_dt_node(blob, 0, &start, NULL, NULL, 0);
size = ALIGN(size, 4);

Expand All @@ -395,10 +337,8 @@ static void __unflatten_device_tree(struct boot_param_header *blob,
pr_debug(" unflattening %p...\n", mem);

/* Second pass, do actual unflattening */
start = ((void *)blob) + be32_to_cpu(blob->off_dt_struct);
start = 0;
unflatten_dt_node(blob, mem, &start, NULL, &allnextp, 0);
if (be32_to_cpup(start) != OF_DT_END)
pr_warning("Weird tag at end of tree: %08x\n", be32_to_cpup(start));
if (be32_to_cpup(mem + size) != 0xdeadbeef)
pr_warning("End of tree marker overwritten: %08x\n",
be32_to_cpup(mem + size));
Expand Down Expand Up @@ -574,47 +514,19 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
void *data),
void *data)
{
unsigned long p = ((unsigned long)initial_boot_params) +
be32_to_cpu(initial_boot_params->off_dt_struct);
int rc = 0;
int depth = -1;

do {
u32 tag = be32_to_cpup((__be32 *)p);
const char *pathp;

p += 4;
if (tag == OF_DT_END_NODE) {
depth--;
continue;
}
if (tag == OF_DT_NOP)
continue;
if (tag == OF_DT_END)
break;
if (tag == OF_DT_PROP) {
u32 sz = be32_to_cpup((__be32 *)p);
p += 8;
if (be32_to_cpu(initial_boot_params->version) < 0x10)
p = ALIGN(p, sz >= 8 ? 8 : 4);
p += sz;
p = ALIGN(p, 4);
continue;
}
if (tag != OF_DT_BEGIN_NODE) {
pr_err("Invalid tag %x in flat device tree!\n", tag);
return -EINVAL;
}
depth++;
pathp = (char *)p;
p = ALIGN(p + strlen(pathp) + 1, 4);
const void *blob = initial_boot_params;
const char *pathp;
int offset, rc = 0, depth = -1;

for (offset = fdt_next_node(blob, -1, &depth);
offset >= 0 && depth >= 0 && !rc;
offset = fdt_next_node(blob, offset, &depth)) {

pathp = fdt_get_name(blob, offset, NULL);
if (*pathp == '/')
pathp = kbasename(pathp);
rc = it(p, pathp, depth, data);
if (rc != 0)
break;
} while (1);

rc = it(offset, pathp, depth, data);
}
return rc;
}

Expand All @@ -623,14 +535,7 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
*/
unsigned long __init of_get_flat_dt_root(void)
{
unsigned long p = ((unsigned long)initial_boot_params) +
be32_to_cpu(initial_boot_params->off_dt_struct);

while (be32_to_cpup((__be32 *)p) == OF_DT_NOP)
p += 4;
BUG_ON(be32_to_cpup((__be32 *)p) != OF_DT_BEGIN_NODE);
p += 4;
return ALIGN(p + strlen((char *)p) + 1, 4);
return 0;
}

/**
Expand All @@ -642,7 +547,7 @@ unsigned long __init of_get_flat_dt_root(void)
const void *__init of_get_flat_dt_prop(unsigned long node, const char *name,
int *size)
{
return of_fdt_get_property(initial_boot_params, node, name, size);
return fdt_getprop(initial_boot_params, node, name, size);
}

/**
Expand Down
1 change: 0 additions & 1 deletion include/linux/of_fdt.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,6 @@ extern char __dtb_start[];
extern char __dtb_end[];

/* For scanning the flat device-tree at boot time */
extern char *find_flat_dt_string(u32 offset);
extern int of_scan_flat_dt(int (*it)(unsigned long node, const char *uname,
int depth, void *data),
void *data);
Expand Down

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