sound: Add a driver for the i8254 beep

Add a sound driver which can output simple beeps using this legacy timer.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/sound/Kconfig

@@ -40,6 +40,18 @@ config I2S_SAMSUNG
 	  option provides an implementation for sound_init() and
 	  sound_play().
 
+config SOUND_I8254
+	bool "Intel i8254 timer / beeper"
+	depends on SOUND
+	help
+	  This enables support for a beeper that uses the i8254 timer chip.
+	  This can emit beeps at a fixed frequency. It is possible to control
+	  the length of the beeps, by turning a beep on, waiting for a period
+	  of time, then turning it off.
+
+	  This is quite an old feature, called PIT (Programmable Interval
+	  Timer), but is nonetheless still available on modern x86 machines.
+
 config SOUND_INTEL_HDA
 	bool "Intel HDA audio codec"
 	depends on SOUND

drivers/sound/Makefile

@@ -16,4 +16,5 @@ obj-$(CONFIG_SOUND_MAX98088)	+= max98088.o maxim_codec.o
 obj-$(CONFIG_SOUND_MAX98090)	+= max98090.o maxim_codec.o
 obj-$(CONFIG_SOUND_MAX98095)	+= max98095.o maxim_codec.o
 obj-$(CONFIG_SOUND_INTEL_HDA)	+= hda_codec.o
+obj-$(CONFIG_SOUND_I8254)	+= i8254_beep.o
 obj-$(CONFIG_SOUND_IVYBRIDGE)	+= ivybridge_sound.o

drivers/sound/i8254_beep.c

@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Google LLC
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <sound.h>
+#include <asm/i8254.h>
+
+int i8254_start_beep(struct udevice *dev, int frequency_hz)
+{
+	return i8254_enable_beep(frequency_hz);
+}
+
+int i8254_stop_beep(struct udevice *dev)
+{
+	i8254_disable_beep();
+
+	return 0;
+}
+
+static const struct sound_ops i8254_ops = {
+	.start_beep	= i8254_start_beep,
+	.stop_beep	= i8254_stop_beep,
+};
+
+static const struct udevice_id i8254_ids[] = {
+	{ .compatible = "i8254,beeper" },
+	{ }
+};
+
+U_BOOT_DRIVER(i8254_drv) = {
+	.name		= "i8254_drv",
+	.id		= UCLASS_SOUND,
+	.of_match	= i8254_ids,
+	.ops		= &i8254_ops,
+};