GK SDK 源码库: XMIPCLinuxV100R005C00SPC030 (kernel/tools/open_source excluded)

source/bootloader/u-boot-2020.01/arch/x86/lib/i8254.c

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2002
+ * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/i8254.h>
+
+#define TIMER1_VALUE		18	/* 15.6us */
+#define BEEP_FREQUENCY_HZ	440
+#define SYSCTL_PORTB		0x61
+#define PORTB_BEEP_ENABLE	0x3
+
+static void i8254_set_beep_freq(uint frequency_hz)
+{
+	uint countdown;
+
+	countdown = PIT_TICK_RATE / frequency_hz;
+
+	outb(countdown & 0xff, PIT_BASE + PIT_T2);
+	outb((countdown >> 8) & 0xff, PIT_BASE + PIT_T2);
+}
+
+int i8254_init(void)
+{
+	/*
+	 * Initialize counter 1, used to refresh request signal.
+	 * This is required for legacy purpose as some codes like
+	 * vgabios utilizes counter 1 to provide delay functionality.
+	 */
+	outb(PIT_CMD_CTR1 | PIT_CMD_LOW | PIT_CMD_MODE2,
+	     PIT_BASE + PIT_COMMAND);
+	outb(TIMER1_VALUE, PIT_BASE + PIT_T1);
+
+	/*
+	 * Initialize counter 2, used to drive the speaker.
+	 * To start a beep, set both bit0 and bit1 of port 0x61.
+	 * To stop it, clear both bit0 and bit1 of port 0x61.
+	 */
+	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
+	     PIT_BASE + PIT_COMMAND);
+	i8254_set_beep_freq(BEEP_FREQUENCY_HZ);
+
+	return 0;
+}
+
+int i8254_enable_beep(uint frequency_hz)
+{
+	if (!frequency_hz)
+		return -EINVAL;
+
+	/* make sure i8254 is setup correctly before generating beeps */
+	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
+	     PIT_BASE + PIT_COMMAND);
+
+	i8254_set_beep_freq(frequency_hz);
+	setio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
+
+	return 0;
+}
+
+void i8254_disable_beep(void)
+{
+	clrio_8(SYSCTL_PORTB, PORTB_BEEP_ENABLE);
+}