u-boot devfdt_get_addr_index函数
fdt_addr_t devfdt_get_addr_index(const struct udevice *dev, int index)
{
#if CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)
fdt_addr_t addr;
if (CONFIG_IS_ENABLED(OF_TRANSLATE)) {
const fdt32_t *reg;
int len = 0;
int na, ns;
//在fdt_blob是parent设备的偏移
//获取address_cells数量
na = fdt_address_cells(gd->fdt_blob,
dev_of_offset(dev->parent));
if (na < 1) {
debug("bad #address-cells\n");
return FDT_ADDR_T_NONE;
}
//获取size_cells数量 ns = fdt_size_cells(gd->fdt_blob, dev_of_offset(dev->parent));
if (ns < 0) {
debug("bad #size-cells\n");
return FDT_ADDR_T_NONE;
}
reg = fdt_getprop(gd->fdt_blob, dev_of_offset(dev), "reg",
&len);
if (!reg || (len <= (index * sizeof(fdt32_t) * (na + ns)))) {
debug("Req index out of range\n");
return FDT_ADDR_T_NONE;
}
reg += index * (na + ns);
if (ns) {
/*
* Use the full-fledged translate function for complex
* bus setups.
*/
addr = fdt_translate_address((void *)gd->fdt_blob,
dev_of_offset(dev), reg);
} else {
/* Non translatable if #size-cells == 0 */
addr = fdt_read_number(reg, na);
}
} else {
/*
* Use the "simple" translate function for less complex
* bus setups.
*/
addr = fdtdec_get_addr_size_auto_parent(gd->fdt_blob,
dev_of_offset(dev->parent), dev_of_offset(dev),
"reg", index, NULL, false);
if (CONFIG_IS_ENABLED(SIMPLE_BUS) && addr != FDT_ADDR_T_NONE) {
if (device_get_uclass_id(dev->parent) ==
UCLASS_SIMPLE_BUS)
addr = simple_bus_translate(dev->parent, addr);
}
}
#if defined(CONFIG_TRANSLATION_OFFSET)
/*
* Some platforms need a special address translation. Those
* platforms (e.g. mvebu in SPL) can configure a translation
* offset by setting this value in the GD and enaling this
* feature via CONFIG_TRANSLATION_OFFSET. This value will
* get added to all addresses returned by devfdt_get_addr().
*/
addr += gd->translation_offset;
#endif
return addr;
#else
return FDT_ADDR_T_NONE;
#endif
}
