pinephone: Add volume_key environment variable

When the user has a volume key pressed volume_key variable will
contain either value 'down' or 'up', otherwise it will be empty.

Signed-off-by: Ondrej Jirman <megous@megous.com>

board/sunxi/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_SUN7I_GMAC)	+= gmac.o
 obj-$(CONFIG_MACH_SUN4I)	+= dram_sun4i_auto.o
 obj-$(CONFIG_MACH_SUN5I)	+= dram_sun5i_auto.o
 obj-$(CONFIG_MACH_SUN7I)	+= dram_sun5i_auto.o
+obj-$(CONFIG_MACH_SUN50I)	+= lradc.o

board/sunxi/board.c

@@ -39,6 +39,7 @@
 #include <spl.h>
 #include <sy8106a.h>
 #include <asm/setup.h>
+#include "lradc.h"
 
 #if defined CONFIG_VIDEO_LCD_PANEL_I2C && !(defined CONFIG_SPL_BUILD)
 /* So that we can use pin names in Kconfig and sunxi_name_to_gpio() */
@@ -622,6 +623,12 @@ void sunxi_board_init(void)
 {
 	int power_failed = 0;
 
+#ifdef CONFIG_MACH_SUN50I
+	// we init the lradc in SPL to get the ADC started early to have
+	// a valid sample when U-Boot main binary gets executed.
+	lradc_enable();
+#endif
+
 #ifdef CONFIG_PINEPHONE_LEDS
 	/* PD18:G PD19:R PD20:B */
 	gpio_request(SUNXI_GPD(18), "led:green");
@@ -905,6 +912,17 @@ int misc_init_r(void)
 		env_set("mmc_bootdev", "1");
 	}
 
+#ifdef CONFIG_MACH_SUN50I
+	int key = lradc_get_pressed_key();
+	if (key == KEY_VOLUMEDOWN)
+		env_set("volume_key", "down");
+	else if (key == KEY_VOLUMEUP)
+		env_set("volume_key", "up");
+	
+	// no longer needed
+	lradc_disable();
+#endif
+
 	setup_environment(gd->fdt_blob);
 
 #ifdef CONFIG_USB_ETHER

board/sunxi/lradc.c

@@ -0,0 +1,81 @@
+#include <common.h>
+#include <asm/io.h>
+#include "lradc.h"
+
+#define LRADC_BASE		0x1c21800
+
+#define LRADC_CTRL		(LRADC_BASE + 0x00)
+#define LRADC_INTC		(LRADC_BASE + 0x04)
+#define LRADC_INTS		(LRADC_BASE + 0x08)
+#define LRADC_DATA0		(LRADC_BASE + 0x0c)
+#define LRADC_DATA1		(LRADC_BASE + 0x10)
+
+/* LRADC_CTRL bits */
+#define FIRST_CONVERT_DLY(x)	((x) << 24) /* 8 bits */
+#define CHAN_SELECT(x)		((x) << 22) /* 2 bits */
+#define CONTINUE_TIME_SEL(x)	((x) << 16) /* 4 bits */
+#define KEY_MODE_SEL(x)		((x) << 12) /* 2 bits */
+#define LEVELA_B_CNT(x)		((x) << 8)  /* 4 bits */
+#define HOLD_KEY_EN(x)		((x) << 7)
+#define HOLD_EN(x)		((x) << 6)
+#define LEVELB_VOL(x)		((x) << 4)  /* 2 bits */
+#define SAMPLE_RATE(x)		((x) << 2)  /* 2 bits */
+#define ENABLE(x)		((x) << 0)
+
+/* LRADC_INTC and LRADC_INTS bits */
+#define CHAN1_KEYUP_IRQ		BIT(12)
+#define CHAN1_ALRDY_HOLD_IRQ	BIT(11)
+#define CHAN1_HOLD_IRQ		BIT(10)
+#define	CHAN1_KEYDOWN_IRQ	BIT(9)
+#define CHAN1_DATA_IRQ		BIT(8)
+#define CHAN0_KEYUP_IRQ		BIT(4)
+#define CHAN0_ALRDY_HOLD_IRQ	BIT(3)
+#define CHAN0_HOLD_IRQ		BIT(2)
+#define	CHAN0_KEYDOWN_IRQ	BIT(1)
+#define CHAN0_DATA_IRQ		BIT(0)
+
+// this is for PinePhone only
+
+int lradc_get_pressed_key(void)
+{
+	uint32_t val;
+	uint32_t vref = 3000000 * 2 / 3;
+
+	val = readl(LRADC_DATA0) & 0x3f;
+	val = val * vref / 63;
+
+//	printf("lradc=%u\n", val);
+
+	if (val < 200000) // 158730
+		return KEY_VOLUMEUP;
+	else if (val < 400000) // 349206
+		return KEY_VOLUMEDOWN;
+
+	return 0;
+}
+
+void lradc_enable(void)
+{
+	// aldo3 is always on and defaults to 3V
+
+	writel(0xffffffff, LRADC_INTS);
+	writel(0, LRADC_INTC);
+
+	/*
+	 * Set sample time to 4 ms / 250 Hz. Wait 2 * 4 ms for key to
+	 * stabilize on press, wait (1 + 1) * 4 ms for key release
+	 */
+	writel(FIRST_CONVERT_DLY(0) | LEVELA_B_CNT(0) | HOLD_EN(0) |
+		SAMPLE_RATE(0) | ENABLE(1), LRADC_CTRL);
+
+}
+
+void lradc_disable(void)
+{
+	writel(0xffffffff, LRADC_INTS);
+	writel(0, LRADC_INTC);
+
+	/* Disable lradc, leave other settings unchanged */
+	writel(FIRST_CONVERT_DLY(2) | LEVELA_B_CNT(1) | HOLD_EN(1) |
+		SAMPLE_RATE(2), LRADC_CTRL);
+}

board/sunxi/lradc.h

@@ -0,0 +1,11 @@
+#pragma once
+
+enum {
+	KEY_NONE = 0,
+	KEY_VOLUMEDOWN = 1,
+	KEY_VOLUMEUP = 2,
+};
+
+int lradc_get_pressed_key(void);
+void lradc_enable(void);
+void lradc_disable(void);