On 11/23/2011 08:54 PM, Simon Glass wrote:
Add a function to lookup a property which is a phandle in a node, and another to read a fixed-length integer array from an fdt property. Also add a function to read boolean properties.
Signed-off-by: Simon Glass sjg@chromium.org
Looking at the U-Boot custodians web page, you need to send the core DT changes (well, probably anything DT related) to Jerry Van Baren.
+/**
- Look up a property in a node and return its contents in an integer
- array of given length. The property must have at least enough data for
- the array (4*count bytes). It may have more, but this will be ignored.
- @param blob FDT blob
- @param node node to examine
- @param prop_name name of property to find
- @param array array to fill with data
- @param count number of array elements
- @return 0 if ok, or -FDT_ERR_NOTFOUND if the property is not found,
or -FDT_ERR_BADLAYOUT if not enough data- */
+int fdtdec_get_int_array(const void *blob, int node, const char *prop_name,
int *array, int count);
The kernel's equivalent of this function retrieves an array of U32s. Is one version more correct than the other?
+/**
- Look up a boolean property in a node and return it.
- A boolean properly is true if present in the device tree and false if not
- present, or present with a 0 value.
- @param blob FDT blob
- @param node node to examine
- @param prop_name name of property to find
- @return 1 if the properly is present; 0 if it isn't present or is 0
- */
+int fdtdec_get_bool(const void *blob, int node, const char *prop_name);
Does U-Boot allow use of the "bool" type here?
+/**
- Look up a property in a node and check that it has a minimum length.
- @param blob FDT blob
- @param node node to examine
- @param prop_name name of property to find
- @param min_len minimum property length in bytes
- @param err 0 if ok, or -FDT_ERR_NOTFOUND if the property is not
found, or -FDT_ERR_BADLAYOUT if not enough data
- @return pointer to cell, which is only valid if err == 0
- */
+static const void *get_prop_len(const void *blob, int node,
const char *prop_name, int min_len, int *err)
Based on the function name, I'd expect it to return the length of the property; perhaps get_prop_check_min_len?
+/**
- Look up a boolean property in a node and return it.
- A boolean properly is true if present in the device tree and false if not
- present, or present with a 0 value.
- @param blob FDT blob
- @param node node to examine
- @param prop_name name of property to find
- @return 1 if the properly is present; 0 if it isn't present or is 0
- */
+int fdtdec_get_bool(const void *blob, int node, const char *prop_name) +{
- const s32 *cell;
- int len;
- debug("%s: %s\n", __func__, prop_name);
- cell = fdt_getprop(blob, node, prop_name, &len);
- if (!cell)
return 0;- if (len >= sizeof(u32) && *cell == 0)
return 0;- return 1;
+}
In the kernel, I believe that property existence is all that's usually checked. Is that wrong? Did the definition of a boolean property's value in the function description above come from the specification? If a property had a length of 0/1/2/3 with a zero value, it seems very odd to treat that as true.