usb_hid: switch Battery Strength to use feature reports

This means we will no longer send them routinely and instead rely on
the HID driver to send them when the host requests it. This also
moves the reporting out of the power management code where it probably
did not belong in the first place.

Change-Id: I9c8420e81897f1f6caaa55ffacc7525589f1ef75

3 files changed, 63 insertions, 47 deletions

diff --git a/firmware/export/powermgmt.h b/firmware/export/powermgmt.h
index b7ca6772f3..235f5302f9 100644
--- a/firmware/export/powermgmt.h
+++ b/firmware/export/powermgmt.h
@@ -166,9 +166,6 @@ void set_poweroff_timeout(int timeout);
 void set_battery_capacity(int capacity); /* set local battery capacity value */
 int  get_battery_capacity(void); /* get local battery capacity value */
 void set_battery_type(int type); /* set local battery type */
-#ifdef USB_ENABLE_HID
-void set_battery_reporting(bool enable);
-#endif
 
 void set_sleeptimer_duration(int minutes);
 int get_sleep_timer(void);
diff --git a/firmware/powermgmt.c b/firmware/powermgmt.c
index 969d6167da..6cac300cdf 100644
--- a/firmware/powermgmt.c
+++ b/firmware/powermgmt.c
@@ -48,9 +48,6 @@
 #if (CONFIG_PLATFORM & PLATFORM_HOSTED)
 #include <time.h>
 #endif
-#ifdef USB_ENABLE_HID
-#include "usbstack/usb_hid.h"
-#endif
 
 #if (defined(IAUDIO_X5) || defined(IAUDIO_M5) || defined(COWON_D2)) \
     && !defined (SIMULATOR)
@@ -640,17 +637,6 @@ static void collect_power_history(void)
     power_history[0] = power_hist_item();
 }
 
-#ifdef USB_ENABLE_HID
-static bool battery_reporting = false;
-static int battery_report_percent = -1;
-
-void set_battery_reporting(bool enable)
-{
-    battery_reporting = enable;
-    battery_report_percent = -1;
-}
-#endif
-
 /*
  * Monitor the presence of a charger and perform critical frequent steps
  * such as running the battery voltage filter.
@@ -764,13 +750,6 @@ static void power_thread(void)
             next_power_hist += HZ*60;
             collect_power_history();
         }
-
-#ifdef USB_ENABLE_HID
-        if (battery_reporting && battery_report_percent != battery_percent) {
-            battery_report_percent = battery_percent;
-            usb_hid_send(HID_USAGE_PAGE_GENERIC_DEVICE_CONTROLS, battery_report_percent);
-        }
-#endif
     }
 } /* power_thread */
 
diff --git a/firmware/usbstack/usb_hid.c b/firmware/usbstack/usb_hid.c
index 0b672e6452..5885b60e32 100644
--- a/firmware/usbstack/usb_hid.c
+++ b/firmware/usbstack/usb_hid.c
@@ -42,6 +42,7 @@
 /* HID main items (HID1_11.pdf, page 38) */
 #define INPUT                           0x80
 #define OUTPUT                          0x90
+#define FEATURE                         0xB0
 #define COLLECTION                      0xA0
 #define COLLECTION_PHYSICAL             0x00
 #define COLLECTION_APPLICATION          0x01
@@ -90,6 +91,7 @@
 #define HID_BUF_SIZE_REPORT             160
 #define HID_NUM_BUFFERS                 5
 #define SET_REPORT_BUF_LEN 2
+#define GET_REPORT_BUF_LEN 2
 
 #ifdef LOGF_ENABLE
 
@@ -103,6 +105,8 @@
 #define HID_BUF_INC(i) do { (i) = ((i) + 1) % HID_NUM_BUFFERS; } while (0)
 #define PACK_VAL(dest, val) *(dest)++ = (val) & 0xff
 
+#define REPORT_ID_BACKGROUND REPORT_ID_COUNT
+
 typedef enum
 {
     REPORT_ID_KEYBOARD = 1,
@@ -110,7 +114,6 @@ typedef enum
 #ifdef HAVE_USB_HID_MOUSE
     REPORT_ID_MOUSE,
 #endif
-    REPORT_ID_BACKGROUND,
     REPORT_ID_COUNT,
 } report_id_t;
 
@@ -452,15 +455,6 @@ static uint8_t buf_set_mouse(unsigned char *buf, int id)
 }
 #endif /* HAVE_USB_HID_MOUSE */
 
-#define BUF_LEN_BACKGROUND 1
-static uint8_t buf_set_background(unsigned char *buf, int id)
-{
-    memset(buf, 0, BUF_LEN_BACKGROUND);
-    buf[0] = (uint8_t)id;
-
-    return BUF_LEN_BACKGROUND;
-}
-
 static size_t descriptor_report_get(unsigned char *dest)
 {
     unsigned char *report = dest;
@@ -562,22 +556,25 @@ static size_t descriptor_report_get(unsigned char *dest)
     PACK_VAL(report, END_COLLECTION);
 #endif /* HAVE_USB_HID_MOUSE */
 
-    /* Background controls */
-    usb_hid_report = &usb_hid_reports[REPORT_ID_BACKGROUND];
-    usb_hid_report->usage_page = HID_USAGE_PAGE_GENERIC_DEVICE_CONTROLS;
-    usb_hid_report->buf_set = buf_set_background;
-    usb_hid_report->is_key_released = 0;
-
+    /* Background reports */
     pack_parameter(&report, 0, 1, USAGE_PAGE, HID_USAGE_PAGE_GENERIC_DEVICE_CONTROLS);
     pack_parameter(&report, 0, 0, CONSUMER_USAGE, HID_GENERIC_DEVICE_BACKGROUND_CONTROLS);
     pack_parameter(&report, 0, 1, COLLECTION, COLLECTION_APPLICATION);
     pack_parameter(&report, 0, 1, REPORT_ID, REPORT_ID_BACKGROUND);
+    /* Padding */
+    pack_parameter(&report, 0, 0, CONSUMER_USAGE, HID_GENERIC_DEVICE_UNDEFINED);
+    pack_parameter(&report, 0, 1, LOGICAL_MINIMUM, 0);
+    pack_parameter(&report, 0, 1, LOGICAL_MAXIMUM, 255);
+    pack_parameter(&report, 0, 1, REPORT_SIZE, 8);
+    pack_parameter(&report, 0, 1, REPORT_COUNT, 1);
+    pack_parameter(&report, 0, 1, FEATURE, MAIN_ITEM_CONSTANT);
+    /* Battery percentage */
     pack_parameter(&report, 0, 0, CONSUMER_USAGE, HID_GENERIC_DEVICE_BATTERY_STRENGTH);
     pack_parameter(&report, 0, 1, LOGICAL_MINIMUM, 0);
     pack_parameter(&report, 0, 1, LOGICAL_MAXIMUM, 100);
     pack_parameter(&report, 0, 1, REPORT_SIZE, 8);
     pack_parameter(&report, 0, 1, REPORT_COUNT, 1);
-    pack_parameter(&report, 0, 1, INPUT, MAIN_ITEM_VARIABLE);
+    pack_parameter(&report, 0, 1, FEATURE, MAIN_ITEM_VARIABLE);
     PACK_VAL(report, END_COLLECTION);
 
     return (size_t)(report - dest);
@@ -622,7 +619,6 @@ void usb_hid_init_connection(void)
     logf("hid: init connection");
     active = true;
     currently_sending = false;
-    set_battery_reporting(true);
 }
 
 /* called by usb_core_init() */
@@ -643,7 +639,6 @@ void usb_hid_init(void)
 void usb_hid_disconnect(void)
 {
     logf("hid: disconnect");
-    set_battery_reporting(false);
     active = false;
     currently_sending = false;
 }
@@ -677,7 +672,7 @@ static int usb_hid_set_report(struct usb_ctrlrequest *req)
 
     if ((req->wValue >> 8) != REPORT_TYPE_OUTPUT)
     {
-        logf("Unsopported report type");
+        logf("Unsupported report type");
         return 1;
     }
     if ((req->wValue & 0xff) != REPORT_ID_KEYBOARD)
@@ -718,14 +713,47 @@ static int usb_hid_set_report(struct usb_ctrlrequest *req)
     return 0;
 }
 
+static int usb_hid_get_report(struct usb_ctrlrequest *req, unsigned char** dest)
+{
+    if ((req->wValue >> 8) != REPORT_TYPE_FEATURE)
+    {
+        logf("Unsupported report type");
+        return 1;
+    }
+
+    if ((req->wValue & 0xff) != REPORT_ID_BACKGROUND)
+    {
+        logf("Wrong report id");
+        return 2;
+    }
+
+    if (req->wIndex != (uint16_t)usb_interface)
+    {
+        logf("Wrong interface");
+        return 3;
+    }
+
+    if (req->wLength < GET_REPORT_BUF_LEN)
+    {
+        logf("Wrong length");
+        return 4;
+    }
+
+    (*dest)[0] = 0;
+    (*dest)[1] = battery_level();
+    *dest += GET_REPORT_BUF_LEN;
+
+    return 0;
+}
+
 /* called by usb_core_control_request() */
 bool usb_hid_control_request(struct usb_ctrlrequest *req, unsigned char *dest)
 {
+    unsigned char *orig_dest = dest;
     switch (req->bRequestType & USB_TYPE_MASK)
     {
     case USB_TYPE_STANDARD:
     {
-        unsigned char *orig_dest = dest;
         uint8_t type = req->wValue >> 8;
         size_t len;
         logf("hid: type %d %s", type, (type == USB_DT_HID) ? "hid" :
@@ -755,14 +783,26 @@ bool usb_hid_control_request(struct usb_ctrlrequest *req, unsigned char *dest)
     {
         logf("req %d %s", req->bRequest, 
             (req->bRequest == USB_HID_SET_IDLE) ? "set idle" :
-            ((req->bRequest == USB_HID_SET_REPORT) ? "set report" : ""));
+            ((req->bRequest == USB_HID_SET_REPORT) ? "set report" :
+            ((req->bRequest == USB_HID_GET_REPORT) ? "get report" : "")));
         switch (req->bRequest)
         {
         case USB_HID_SET_REPORT:
             if (usb_hid_set_report(req))
                 break;
+        case USB_HID_GET_REPORT:
+            if (usb_hid_get_report(req, &dest))
+                break;
         case USB_HID_SET_IDLE:
-            usb_drv_send(EP_CONTROL, NULL, 0); /* ack */
+            if (dest != orig_dest)
+            {
+                usb_drv_recv(EP_CONTROL, NULL, 0); /* ack */
+                usb_drv_send(EP_CONTROL, orig_dest, dest - orig_dest);
+            }
+            else
+            {
+                usb_drv_send(EP_CONTROL, NULL, 0); /* ack */
+            }
             return true;
         }
         break;