Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Michael Walle <michael@walle.cc>
To:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Shawn Guo <shawnguo@kernel.org>, Li Yang <leoyang.li@nxp.com>,
        =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>,
        "David S . Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Frank Rowand <frowand.list@gmail.com>
Cc:     linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        netdev@vger.kernel.org, Ahmad Fatoum <a.fatoum@pengutronix.de>,
        Michael Walle <michael@walle.cc>, Rob Herring <robh@kernel.org>
Subject: [PATCH v1 02/14] of: base: add of_parse_phandle_with_optional_args()
Date:   Thu, 25 Aug 2022 23:44:11 +0200
Message-Id: <20220825214423.903672-3-michael@walle.cc>
In-Reply-To: <20220825214423.903672-1-michael@walle.cc>
References: <20220825214423.903672-1-michael@walle.cc>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Add a new variant of the of_parse_phandle_with_args() which treats the
cells name as optional. If it's missing, it is assumed that the phandle
has no arguments.

Up until now, a nvmem node didn't have any arguments, so all the device
trees haven't any '#*-cells' property. But there is a need for an
additional argument for the phandle, for which we need a '#*-cells'
property. Therefore, we need to support nvmem nodes with and without
this property.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Rob Herring <robh@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 766d002bddb9..a0fe1a017452 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1008,6 +1008,31 @@ static inline int of_parse_phandle_with_fixed_args(const struct device_node *np,
 					    index, out_args);
 }
 
+/**
+ * of_parse_phandle_with_optional_args() - Find a node pointed by phandle in a list
+ * @np:		pointer to a device tree node containing a list
+ * @list_name:	property name that contains a list
+ * @cells_name:	property name that specifies phandles' arguments count
+ * @index:	index of a phandle to parse out
+ * @out_args:	optional pointer to output arguments structure (will be filled)
+ *
+ * Same as of_parse_phandle_with_args() except that if the cells_name property
+ * is not found, cell_count of 0 is assumed.
+ *
+ * This is used to useful, if you have a phandle which didn't have arguments
+ * before and thus doesn't have a '#*-cells' property but is now migrated to
+ * having arguments while retaining backwards compatibility.
+ */
+static inline int of_parse_phandle_with_optional_args(const struct device_node *np,
+						      const char *list_name,
+						      const char *cells_name,
+						      int index,
+						      struct of_phandle_args *out_args)
+{
+	return __of_parse_phandle_with_args(np, list_name, cells_name,
+					    0, index, out_args);
+}
+
 /**
  * of_property_count_u8_elems - Count the number of u8 elements in a property
  *
-- 
2.30.2