hm801: Implement additional button driver.

Several HM-801 DAPs have another buttons circuit.
This patch adds support for such devices so they could work properly.

Change-Id: Ic49e8e46b3e785b91c7c4706003fac3dbc20ae59

firmware/target/arm/rk27xx/adc-target.h

@@ -25,7 +25,12 @@
 
 #define ADC_BATTERY     0
 #define ADC_BUTTONS     1
-#define ADC_UNKNOWN     2
+
+/* HiFiMAN HM-801 usually use this channel for second battery,
+   but some of them use it for buttons.
+ */
+#define ADC_EXTRA       2
+
 #define ADC_VREF        3 /* that is what datasheet says */
 
 #define ADC_UNREG_POWER ADC_BATTERY /* For compatibility */

firmware/target/arm/rk27xx/hm801/button-hm801.c

@@ -24,41 +24,57 @@
 #include "button.h"
 #include "adc.h"
 
+enum keyboard_type_t {
+    KEYBOARD_V1,
+    KEYBOARD_V2,
+};
+
+static enum keyboard_type_t kbd_type;
+
 void button_init_device(void) {
     /* setup button gpio as input */
     GPIO_PCCON &= ~(POWEROFF_BUTTON);
+
+    /* identify keyboard type */
+    SCU_IOMUXB_CON &= ~(1<<2);
+    GPIO_PCCON |= (1<<4);
+    if (GPIO_PCDR & (1<<4)) {
+        kbd_type = KEYBOARD_V1;
+    } else {
+        kbd_type = KEYBOARD_V2;
+    }
 }
 
-int button_read_device(void) {
+static int button_read_device_v1(void) {
     int adc_val = adc_read(ADC_BUTTONS);
     int button =  0;
 
     if (adc_val < 480) { /* middle */
-        if (adc_val < 200) { /* 200 - 0 */
+        if (adc_val < 200) { /* 0 - 200 */
             if (adc_val < 30) {
                 button = BUTTON_UP;
-	    } else {
+            } else {  /* 30 - 200 */
-	        button =  BUTTON_RIGHT; /* 30 - 200 */
+                button =  BUTTON_RIGHT;
             }
         } else { /* 200 - 480 */
-	    if (adc_val < 370) {
+            if (adc_val < 370) { /* 200 - 370 */
                 button =  BUTTON_SELECT;
-	    } else {
+            } else { /* 370 - 480 */
                 button =  BUTTON_DOWN;
             }
         }
     } else { /*  > 480 */
         if (adc_val < 690) { /* 480 - 690 */
-	    if (adc_val < 580) {
+            if (adc_val < 580) { /* 480 - 580 */
                 button =  BUTTON_LEFT;
-	    } else {
+            } else { /* 580 - 690 */
                 button =  BUTTON_NEXT;
             }
         } else { /* > 680 */
-	    if (adc_val < 840) {
+            if (adc_val < 840) { /* 680 - 840 */
                 button =  BUTTON_PREV;
             } else {
-	        if (adc_val < 920) {
+                if (adc_val < 920) { /* 840 - 920 */
                     button =  BUTTON_PLAY;
                 }
             }
@@ -66,3 +82,53 @@ int button_read_device(void) {
     }
     return button | (GPIO_PCDR & POWEROFF_BUTTON);
 }
+
+static int button_read_device_v2(void) {
+    int adc_val = adc_read(ADC_BUTTONS);
+    int adc_val2 = adc_read(ADC_EXTRA);
+    int button =  0;
+
+    /* Buttons on front panel */
+    if (adc_val < 520) { /* middle */
+        if (adc_val < 360) { /* 0 - 360 */
+            if (adc_val < 40) { /* 0 - 40 */
+                button |= BUTTON_UP;
+            } else { /* 40 - 360 */
+                button |= BUTTON_RIGHT;
+            }
+        } else { /* 360 - 520 */
+            button |= BUTTON_SELECT;
+        }
+    } else { /* >= 520 */
+        if (adc_val < 770) { /* 520 - 770 */
+            if (adc_val < 640) { /* 520 - 640 */
+                button |= BUTTON_DOWN;
+            } else { /* 640 - 770 */
+                button |= BUTTON_LEFT;
+            }
+        }
+    }
+
+    /* Buttons on top */
+    if (adc_val2 < 400) { /* 0 - 400 */
+        if (adc_val2 < 120) { /* 0 - 120 */
+            button |= BUTTON_NEXT;
+        } else { /* 120 - 400 */
+            button |= BUTTON_PREV;
+        }
+    } else { /* >= 400 */
+        if (adc_val2 < 560) { /* 400 - 560 */
+            button |= BUTTON_PLAY;
+        }
+    }
+    return button | (GPIO_PCDR & POWEROFF_BUTTON);
+}
+
+int button_read_device(void) {
+    if (kbd_type == KEYBOARD_V1) {
+        return button_read_device_v1();
+    } else {
+        return button_read_device_v2();
+    }
+}
+