nfp: nfpcore: add rtsym writing function

Add an rtsym API function that combines the lookup of a symbol and the
writing of a value to it. Values can be written as unsigned 32 or 64 bits.

Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nffw.h

@@ -100,6 +100,8 @@ nfp_rtsym_lookup(struct nfp_rtsym_table *rtbl, const char *name);
 
 u64 nfp_rtsym_read_le(struct nfp_rtsym_table *rtbl, const char *name,
 		      int *error);
+int nfp_rtsym_write_le(struct nfp_rtsym_table *rtbl, const char *name,
+		       u64 value);
 u8 __iomem *
 nfp_rtsym_map(struct nfp_rtsym_table *rtbl, const char *name, const char *id,
 	      unsigned int min_size, struct nfp_cpp_area **area);

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_rtsym.c

@@ -286,6 +286,49 @@ u64 nfp_rtsym_read_le(struct nfp_rtsym_table *rtbl, const char *name,
 	return val;
 }
 
+/**
+ * nfp_rtsym_write_le() - Write an unsigned scalar value to a symbol
+ * @rtbl:	NFP RTsym table
+ * @name:	Symbol name
+ * @value:	Value to write
+ *
+ * Lookup a symbol and write a value to it. Symbol can be 4 or 8 bytes in size.
+ * If 4 bytes then the lower 32-bits of 'value' are used. Value will be
+ * written as simple little-endian unsigned value.
+ *
+ * Return: 0 on success or error code.
+ */
+int nfp_rtsym_write_le(struct nfp_rtsym_table *rtbl, const char *name,
+		       u64 value)
+{
+	const struct nfp_rtsym *sym;
+	int err;
+	u32 id;
+
+	sym = nfp_rtsym_lookup(rtbl, name);
+	if (!sym)
+		return -ENOENT;
+
+	id = NFP_CPP_ISLAND_ID(sym->target, NFP_CPP_ACTION_RW, 0, sym->domain);
+
+	switch (sym->size) {
+	case 4:
+		err = nfp_cpp_writel(rtbl->cpp, id, sym->addr, value);
+		break;
+	case 8:
+		err = nfp_cpp_writeq(rtbl->cpp, id, sym->addr, value);
+		break;
+	default:
+		nfp_err(rtbl->cpp,
+			"rtsym '%s' unsupported or non-scalar size: %lld\n",
+			name, sym->size);
+		err = -EINVAL;
+		break;
+	}
+
+	return err;
+}
+
 u8 __iomem *
 nfp_rtsym_map(struct nfp_rtsym_table *rtbl, const char *name, const char *id,
 	      unsigned int min_size, struct nfp_cpp_area **area)