common: fdt_support: Support special case of PCI address in fdt_read_prop()

At present fdt_read_prop() can only handle 1 or 2 cells. It is
called by fdt_read_range() which may be used to read PCI address
from <ranges> for a PCI bus node where the number of PCI address
cell is 3. The <ranges> property is an array of:

  { <child address> <parent address> <size in child address space> }

When trying to read <child address> from a PCI bus node using
fdt_read_prop(), as the codes below:

    /* Read <child address> */
    if (child_addr) {
        r = fdt_read_prop(ranges, ranges_len, cell, child_addr,
                          acells);
        if (r)
            return r;
    }

it will fail, because the PCI child address is made up of 3 cells
but fdt_read_prop() cannot handle it. We advance the cell offset
by 1 so that the <child address> can be correctly read.

This adds the special handling of such case.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

diff --git a/common/fdt_support.c b/common/fdt_support.c
index 08d540bfc85b507af8a5c8f5c079f8e5e96e5195..e624bbdf404233b95e2ef0373f80dbbf45f5f0de 100644 (file)
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -1668,22 +1668,36 @@ u64 fdt_get_base_address(const void *fdt, int node)
 }
 
 /*
- * Read a property of size <prop_len>. Currently only supports 1 or 2 cells.
+ * Read a property of size <prop_len>. Currently only supports 1 or 2 cells,
+ * or 3 cells specially for a PCI address.
  */
 static int fdt_read_prop(const fdt32_t *prop, int prop_len, int cell_off,
                         uint64_t *val, int cells)
 {
-       const fdt32_t *prop32 = &prop[cell_off];
-       const unaligned_fdt64_t *prop64 = (const fdt64_t *)&prop[cell_off];
+       const fdt32_t *prop32;
+       const unaligned_fdt64_t *prop64;
 
        if ((cell_off + cells) > prop_len)
                return -FDT_ERR_NOSPACE;
 
+       prop32 = &prop[cell_off];
+
+       /*
+        * Special handling for PCI address in PCI bus <ranges>
+        *
+        * PCI child address is made up of 3 cells. Advance the cell offset
+        * by 1 so that the PCI child address can be correctly read.
+        */
+       if (cells == 3)
+               cell_off += 1;
+       prop64 = (const fdt64_t *)&prop[cell_off];
+
        switch (cells) {
        case 1:
                *val = fdt32_to_cpu(*prop32);
                break;
        case 2:
+       case 3:
                *val = fdt64_to_cpu(*prop64);
                break;
        default: