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cmd/fdt: support single value replacement within an array

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With this commit we can modify single values within an array of a dts
property.

This is useful if we have for example a pwm-backlight where we want to
modifiy the pwm frequency per u-boot script.

The pwm is described in dts like this:

backlight {
	pwms = <0x0000002b 0x00000000 0x004c4b40>;
};

For changing the frequency, here the 3rd parameter, we simply type:

fdt set /backlight pwms <? ? 0x1E8480>;

For doing all this we:
- backup the property content into our 'SCRATCHPAD'
- only modify the array-cell if the new content doesn't start with '?'

Signed-off-by: Hannes Schmelzer <hannes.schmelzer@br-automation.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Hannes Schmelzer 2017-05-30 15:05:44 +02:00 committed by Simon Glass
parent aafbe82fb6
commit 9620d87259
1 changed files with 21 additions and 8 deletions
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29
cmd/fdt.c
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@ -257,6 +257,7 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
char *prop; /* property */
int nodeoffset; /* node offset from libfdt */
static char data[SCRATCHPAD]; /* storage for the property */
const void *ptmp;
int len; /* new length of the property */
int ret; /* return value */
@ -268,13 +269,6 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
pathp = argv[2];
prop = argv[3];
if (argc == 4) {
len = 0;
} else {
ret = fdt_parse_prop(&argv[4], argc - 4, data, &len);
if (ret != 0)
return ret;
}
nodeoffset = fdt_path_offset (working_fdt, pathp);
if (nodeoffset < 0) {
@ -286,6 +280,21 @@ static int do_fdt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
return 1;
}
if (argc == 4) {
len = 0;
} else {
ptmp = fdt_getprop(working_fdt, nodeoffset, prop, &len);
if (len > SCRATCHPAD) {
printf("prop (%d) doesn't fit in scratchpad!\n",
len);
return 1;
}
memcpy(data, ptmp, len);
ret = fdt_parse_prop(&argv[4], argc - 4, data, &len);
if (ret != 0)
return ret;
}
ret = fdt_setprop(working_fdt, nodeoffset, prop, data, len);
if (ret < 0) {
printf ("libfdt fdt_setprop(): %s\n", fdt_strerror(ret));
@ -766,7 +775,11 @@ static int fdt_parse_prop(char * const *newval, int count, char *data, int *len)
cp = newp;
tmp = simple_strtoul(cp, &newp, 0);
*(fdt32_t *)data = cpu_to_fdt32(tmp);
if (*cp != '?')
*(fdt32_t *)data = cpu_to_fdt32(tmp);
else
newp++;
data += 4;
*len += 4;