sound: Add an ACPI driver for Maxim MAX98357ac

This chip is used on coral and we need to generate ACPI tables for sound
to make it work. Add a driver that does just this (i.e. at present does
not actually support playing sound).

Signed-off-by: Simon Glass <sjg@chromium.org>
[bmeng: Use the correct acpi_irq_polarity enum number]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/sound/max98357a.txt b/doc/device-tree-bindings/sound/max98357a.txt
new file mode 100644
index 0000000000..4bce14ce80
--- /dev/null
+++ b/doc/device-tree-bindings/sound/max98357a.txt
@@ -0,0 +1,22 @@
+Maxim MAX98357A audio DAC
+
+This node models the Maxim MAX98357A DAC.
+
+Required properties:
+- compatible   : "maxim,max98357a"
+
+Optional properties:
+- sdmode-gpios : GPIO specifier for the chip's SD_MODE pin.
+        If this option is not specified then driver does not manage
+        the pin state (e.g. chip is always on).
+- sdmode-delay : specify delay time for SD_MODE pin.
+        If this option is specified, which means it's required i2s clocks
+        ready before SD_MODE is unmuted in order to avoid the speaker pop noise.
+        It's observed that 5ms is sufficient.
+
+Example:
+
+max98357a {
+	compatible = "maxim,max98357a";
+	sdmode-gpios = <&qcom_pinmux 25 0>;
+};