git.openwrt.org Git - openwrt/staging/linusw.git/blob

   1 From b6b126861062020fb50859c5af71d8846ce43d7c Mon Sep 17 00:00:00 2001
   2 From: Tim Gover <tim.gover@raspberrypi.com>
   3 Date: Mon, 4 Nov 2024 13:44:10 +0000
   4 Subject: [PATCH] dtoverlay: Add an overlay for the Raspberry Pi firmware UART
   5
   6 Add a device-tree overlay to configure the GPIOs for the
   7 Raspberry Pi firmware UART.
   8
   9 Example config.txt
  10 dtoverlay=rpi-fw-uart,txd0_pin=20,rxd0_pin=21
  11
  12 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  13 Signed-off-by: Tim Gover <tim.gover@raspberrypi.com>
  14 ---
  15  arch/arm/boot/dts/overlays/Makefile           |  1 +
  16  arch/arm/boot/dts/overlays/README             | 12 ++++++
  17  .../boot/dts/overlays/rpi-fw-uart-overlay.dts | 41 +++++++++++++++++++
  18  3 files changed, 54 insertions(+)
  19  create mode 100644 arch/arm/boot/dts/overlays/rpi-fw-uart-overlay.dts
  20
  21 --- a/arch/arm/boot/dts/overlays/Makefile
  22 +++ b/arch/arm/boot/dts/overlays/Makefile
  23 @@ -233,6 +233,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
  24         rpi-dacpro.dtbo \
  25         rpi-digiampplus.dtbo \
  26         rpi-ft5406.dtbo \
  27 +       rpi-fw-uart.dtbo \
  28         rpi-poe.dtbo \
  29         rpi-poe-plus.dtbo \
  30         rpi-sense.dtbo \
  31 --- a/arch/arm/boot/dts/overlays/README
  32 +++ b/arch/arm/boot/dts/overlays/README
  33 @@ -4141,6 +4141,18 @@ Params: touchscreen-size-x      Touchscr
  34          touchscreen-swapped-x-y Swap X and Y cordinates (default 0);
  35
  36
  37 +Name:   rpi-fw-uart
  38 +Info:   Configures the firmware software UART driver.
  39 +        This driver requires exclusive usage of the second VPU core. The
  40 +        following config.txt entries should be set when this driver is used.
  41 +        dtparam=audio=off
  42 +        isp_use_vpu0=1
  43 +Load:   dtoverlay=rpi-fw-uart,<param>[=<val>]
  44 +Params: txd0_pin                GPIO pin for TXD0 (any free - default 20)
  45 +
  46 +        rxd0_pin                GPIO pin for RXD0 (any free - default 21)
  47 +
  48 +
  49  Name:   rpi-poe
  50  Info:   Raspberry Pi PoE HAT fan
  51  Load:   dtoverlay=rpi-poe,<param>[=<val>]
  52 --- /dev/null
  53 +++ b/arch/arm/boot/dts/overlays/rpi-fw-uart-overlay.dts
  54 @@ -0,0 +1,41 @@
  55 +// SPDX-License-Identifier: GPL-2.0
  56 +// Overlay for the Raspberry Pi Firmware UART driver
  57 +/dts-v1/;
  58 +/plugin/;
  59 +
  60 +/{
  61 +       compatible = "brcm,bcm2835";
  62 +
  63 +       fragment@0 {
  64 +               target = <&gpio>;
  65 +               __overlay__ {
  66 +                       rpi_fw_uart_pins: rpi_fw_uart_pins@4 {
  67 +                               brcm,pins = <20 21>;
  68 +                               brcm,function = <1 0>; /* output input */
  69 +                               brcm,pull = <0 2>; /* none pull-up */
  70 +                       };
  71 +               };
  72 +       };
  73 +
  74 +       fragment@1 {
  75 +               target = <&soc>;
  76 +               __overlay__ {
  77 +                       rpi_fw_uart: rpi_fw_uart@7e000000 {
  78 +                       compatible = "raspberrypi,firmware-uart";
  79 +                       reg = <0x7e000000 0x100>; /* VideoCore MS sync regs */
  80 +                       firmware = <&firmware>;
  81 +                       pinctrl-names = "default";
  82 +                       pinctrl-0 = <&rpi_fw_uart_pins>;
  83 +                       tx-gpios = <&gpio 20 0>;
  84 +                       rx-gpios = <&gpio 21 0>;
  85 +                       };
  86 +               };
  87 +       };
  88 +
  89 +       __overrides__ {
  90 +               txd0_pin = <&rpi_fw_uart>,"tx-gpios:4",
  91 +                        <&rpi_fw_uart_pins>, "brcm,pins:0";
  92 +               rxd0_pin = <&rpi_fw_uart>,"rx-gpios:4",
  93 +                        <&rpi_fw_uart_pins>, "brcm,pins:4";
  94 +       };
  95 +};