[PATCH 2/8] of: Add helper to retrieve ECC memory bits

[Maxime Ripard]

The /memory device tree bindings allow to store the ECC detection and
correction bits through the ecc-detection-bits and ecc-correction-bits
properties.

Our next patches rely on whether ECC is enabled, so let's add a helper
to retrieve the ECC correction bits from the /memory node.

Signed-off-by: Maxime Ripard <mrip...@kernel.org>
---
 include/linux/of.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/linux/of.h b/include/linux/of.h
index a0bedd038a05..2fbee65a7aa9 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1510,10 +1510,35 @@ static inline int of_get_available_child_count(const 
struct device_node *np)
                num++;
 
        return num;
 }
 
+/**
+ * of_memory_get_ecc_correction_bits() - Returns the number of ECC correction 
bits
+ *
+ * Search for the number of bits in memory that can be corrected by the
+ * ECC algorithm.
+ *
+ * Returns:
+ * The number of ECC bits, 0 if there's no ECC support, a negative error
+ * code on failure.
+ */
+static inline int of_memory_get_ecc_correction_bits(void)
+{
+       struct device_node *mem;
+       u32 val = 0;
+
+       mem = of_find_node_by_path("/memory");
+       if (!mem)
+               return -ENODEV;
+
+       of_property_read_u32(mem, "ecc-correction-bits", &val);
+       of_node_put(mem);
+
+       return val;
+}
+
 #define _OF_DECLARE_STUB(table, name, compat, fn, fn_type)             \
        static const struct of_device_id __of_table_##name              \
                __attribute__((unused))                                 \
                 = { .compatible = compat,                              \
                     .data = (fn == (fn_type)NULL) ? fn : fn }

-- 
2.44.0