[PATCH v3 8/8] dt-binding: mtd: Document gpio-addr-flash

From: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
To: robh@kernel.org, David Woodhouse <dwmw2@infradead.org>,
	Brian Norris <computersforpeace@gmail.com>,
	Boris Brezillon <boris.brezillon@bootlin.com>,
	Marek Vasut <marek.vasut@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	Zhouyang Jia <jiazhouyang09@gmail.com>,
	linux-mtd@lists.infradead.org,
	open list <linux-kernel@vger.kernel.org>,
	devicetree@vger.kernel.org
Cc: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Subject: [PATCH v3 8/8] dt-binding: mtd: Document gpio-addr-flash
Date: Wed, 26 Sep 2018 08:39:34 +0200	[thread overview]
Message-ID: <20180926063934.9229-1-ricardo.ribalda@gmail.com> (raw)
In-Reply-To: <20180925204813.GA6450@bogus>

Add documentation for gpio-addr-flash. This binding allow creating
flash devices that are paged using GPIOs.

Cc: devicetree@vger.kernel.org
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
---

Changelog v3: 

- Changes suggested by Rob Herring (Thanks!)
  - Add gpio description
  - Improve partition

 .../bindings/mtd/gpio-addr-flash.txt          | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt

diff --git a/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
new file mode 100644
index 000000000000..5006a26e1753
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/gpio-addr-flash.txt
@@ -0,0 +1,54 @@
+Memory Mapped flash with some address lines addressed using GPIOs
+
+Handle the case where a flash device is mostly addressed using physical
+line and supplemented by GPIOs.  This way you can hook up say a 8MiB flash
+to a 2MiB memory range and use the GPIOs to select a particular range.
+
+ - compatible : "cfi-gpio-addr-flash"
+ - reg : Address range of the mtd chip that is memory mapped, this is,
+   on the previous example 2MiB.
+ - bank-width : Width (in bytes) of the bank.  Equal to the
+   device width times the number of interleaved chips.
+ - gpios: List of GPIO specifiers that will be used to address the MSBs address
+   lines. The order goes from LSB to MSB.
+ - probe-type : (optional) "cfi_probe", "jedec_probe". How the mtd chip
+   is going to be probed. If omitted, assumed to be equal to "cfi_probe".
+ - #address-cells, #size-cells : Must be present if the device has
+   sub-nodes representing partitions (see below).  In this case
+   both #address-cells and #size-cells must be equal to 1.
+
+The device tree may optionally contain sub-nodes describing partitions of the
+address space. Check partition.txt for more details.
+
+Example:
+
+	flash@300000 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "cfi-gpio-addr-flash";
+		bank-width = <2>;
+		reg = < 0x00300000 0x00200000 >;
+		gpios = <&gpio_0 3 0>, <&gpio_0 4 0>;
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				reg = < 0x0 0x200000 >;
+				label = "Golden Bitstream";
+			};
+			partition@200000 {
+				reg = < 0x200000 0x200000 >;
+				label = "User Bitstream";
+			};
+			partition@400000 {
+				reg = < 0x400000 0x200000 >;
+				label = "V4L Controls";
+			};
+			partition@600000 {
+				reg = < 0x600000 0x200000 >;
+				label = "Production Data";
+			};
+		}
+	} ;
-- 
2.19.0

