boards: arm: Add Legend 3.5" board

This commit adds support for the Legend 3.5" board revision.
This board revision is found on the Seagate FireCuda Gaming
Hub and Gaming Drive Hub for Xbox devices. It contains the following
hardware components:
- A B1414 LED strip connected to the PA7 pin (SPI MOSI)
- A SPI flash (FM25F005) connected on SPI2 bus
- A PWM LED connected on TIM3 CH3
- An external 24 MHz oscillator

Signed-off-by: Maxime Bittan <maxime.bittan@seagate.com>
Signed-off-by: Simon Guinot <simon.guinot@seagate.com>

boards/arm/legend/doc/index.rst

@@ -5,7 +5,7 @@ Legend
 
 Overview
 ********
-The Legend board family contains two revisions: 25hdd and 25ssd.
+The Legend board family contains three revisions: 25hdd, 25ssd, and 35.
 
 The Legend 2.5" HDD board (revision 25hdd) can be found in the Seagate FireCuda
 Gaming Hard Drive, Gaming Drive for Xbox and Gaming Drive for PlayStation
@@ -18,13 +18,23 @@ The Legend 2.5" SSD board (revision 25ssd) is found in the Seagate SSD Gaming
 Drive for Xbox. A Realtek RTS5411S USB hub is embedded and connected to a Phison
 U17 2.5" SSD, as well as a STM32F070 MCU.
 
-On both boards, the Zephyr port is running on the STM32F070 MCU.
+The Legend 3.5" board (revision 35) can be found in the Seagate FireCuda Gaming
+Hub and Gaming Drive Hub for Xbox devices. A Genesys Logic GL3523-S USB hub is
+connected to an ASMedia ASM1153 USB-to-SATA bridge controller and a STM32F070
+MCU. The two chips are connected together using I2C.
+
+On all boards, the Zephyr port is running on the STM32F070 MCU.
 
 .. image:: img/firecuda_gaming_hard_drive.png
-   :width: 750px
+   :width: 550px
    :align: center
    :alt: Seagate FireCuda Gaming Hard Drive
 
+.. image:: img/firecuda_gaming_hub.png
+   :width: 550px
+   :align: center
+   :alt: Seagate FireCuda Gaming Hub
+
 Hardware
 ********
 
@@ -44,7 +54,7 @@ Hardware
 Supported Features
 ==================
 
-All the hardware features available on the Legend 2.5" boards are supported by
+All the hardware features available on the Legend boards are supported by
 Zephyr.
 
 +-----------+------------+-------------------------------------+
@@ -96,9 +106,9 @@ Connections and IOs
 +---------+-----------------+----------------------------+
 | PA7     | LED strip       | SPI1 MOSI                  |
 +---------+-----------------+----------------------------+
-| PA12    | USB             | USB DM (SSD only)          |
+| PA12    | USB             | USB DM (25ssd and 35 only) |
 +---------+-----------------+----------------------------+
-| PA13    | USB             | USB DP (SSD only)          |
+| PA13    | USB             | USB DP (25ssd and 35 only) |
 +---------+-----------------+----------------------------+
 
 Programming and Debugging

boards/arm/legend/legend_35.overlay

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2021 Seagate Technology LLC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	model = "Seagate Legend 3.5 board";
+	compatible = "legend35", "seagate,legend35";
+
+	aliases {
+		pwm-led0 = &pwm_led0;
+		led-strip = &led_strip_spi;
+	};
+
+	led_pwm: pwmleds {
+		compatible = "pwm-leds";
+		label = "LED PWM";
+
+		pwm_led0: pwm_led_0 {
+			label = "Activity LED";
+			pwms = <&pwm3 3 255 PWM_POLARITY_NORMAL>;
+		};
+	};
+};
+
+&clk_hse {
+	clock-frequency = <DT_FREQ_M(24)>; /* 24MHz external clock */
+	status = "okay";
+};
+
+&pll {
+	clocks = <&clk_hse>;
+	prediv = <1>;
+	mul = <2>;
+	status = "okay";
+};
+
+&rcc {
+	clocks = <&pll>;
+	clock-frequency = <DT_FREQ_M(48)>;
+	ahb-prescaler = <1>;
+	apb1-prescaler = <1>;
+};
+
+&led_strip_spi {
+	chain-length = <12>;
+	status = "okay";
+};
+
+
+&timers3 {
+	status = "okay";
+};
+
+&pwm3 {
+	status = "okay";
+};
+
+&usb {
+	status = "okay";
+};

boards/arm/legend/revision.cmake

@@ -1,4 +1,4 @@
-set(LEGEND_REVISIONS "25hdd" "25ssd")
+set(LEGEND_REVISIONS "25hdd" "25ssd" "35")
 if (NOT DEFINED BOARD_REVISION)
   set(BOARD_REVISION "25hdd")
 else()