[U-Boot] [PATCH v2 25/34] sound: x86: Add beeping support in i8254

[Simon Glass]

Adjust the code to allow beeping at different frequencies, using a
calculated value for timer 2.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

Changes in v2:
- Rename PPC_PORTB to SYSCTL_PORTB
- Use PIT_TICK_RATE instead of creating a new define

 arch/x86/include/asm/i8254.h | 18 ++++++++++++++++++
 arch/x86/lib/i8254.c         | 35 +++++++++++++++++++++++++++++++----
 2 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/i8254.h b/arch/x86/include/asm/i8254.h
index 65c97614d3e..d769daf85dc 100644
--- a/arch/x86/include/asm/i8254.h
+++ b/arch/x86/include/asm/i8254.h
@@ -35,4 +35,22 @@
 /* The clock frequency of the i8253/i8254 PIT */
 #define PIT_TICK_RATE	1193182
 
+/**
+ * i8254_enable_beep() - Start a beep using the PCAT timer
+ *
+ * This starts beeping using the legacy i8254 timer. The beep may be silenced
+ * after a delay with i8254_disable_beep().
+ *
+ * @frequency_hz: Frequency of beep in Hz
+ * @return 0 if OK, -EINVAL if frequency_hz is 0
+ */
+int i8254_enable_beep(uint frequency_hz);
+
+/**
+ * i8254_disable_beep() - Disable the bepper
+ *
+ * This stops any existing beep
+ */
+void i8254_disable_beep(void);
+
 #endif /* _ASMI386_I8954_H_ */
diff --git a/arch/x86/lib/i8254.c b/arch/x86/lib/i8254.c
index 1f1012488cb..d0227954b16 100644
--- a/arch/x86/lib/i8254.c
+++ b/arch/x86/lib/i8254.c
@@ -8,8 +8,20 @@
 #include <asm/io.h>
 #include <asm/i8254.h>
 
-#define TIMER1_VALUE	18	/* 15.6us */
-#define TIMER2_VALUE	0x0a8e	/* 440Hz */
+#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)
 {
@@ -29,8 +41,23 @@ int i8254_init(void)
 	 */
 	outb(PIT_CMD_CTR2 | PIT_CMD_BOTH | PIT_CMD_MODE3,
 	     PIT_BASE + PIT_COMMAND);
-	outb(TIMER2_VALUE & 0xff, PIT_BASE + PIT_T2);
-	outb(TIMER2_VALUE >> 8, PIT_BASE + PIT_T2);
+	i8254_set_beep_freq(BEEP_FREQUENCY_HZ);
+
+	return 0;
+}
+
+int i8254_enable_beep(uint frequency_hz)
+{
+	if (!frequency_hz)
+		return -EINVAL;
+
+	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);
+}
-- 
2.21.0.rc0.258.g878e2cd30e-goog