From b44edf476bc4fc65855288aee61ce7e1deb4e495 Mon Sep 17 00:00:00 2001
From: Jesse Vincent <jesse@keyboard.io>
Date: Wed, 13 Oct 2021 21:39:36 -0700
Subject: [PATCH] Start to implement "suspend a missing device"

---
 .../driver/keyboardio/Model100Side.cpp        | 63 +++++++++++++++++--
 .../driver/keyboardio/Model100Side.h          |  9 ++-
 2 files changed, 65 insertions(+), 7 deletions(-)

diff --git a/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.cpp b/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.cpp
index a5c7ff02..152fcdc1 100644
--- a/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.cpp
+++ b/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.cpp
@@ -103,23 +103,67 @@ byte Model100Side::setLEDSPIFrequency(byte frequency) {
 }
 
 
+// GD32 I2C implements timeouts which will cause a stall when a device does not answer.
+// This method will verify that the device is around and ready to talk.
+bool Model100Side::isDeviceAvailable() {
+// if we don’t know the device is around,
+	return true;
+    // if the counter is zero, that's the special value that means "we know it's there"
+    if (unavailable_device_check_countdown_ == 0) {
+        return true;
+    }
+
+    // if the time to check counter is 1, check for the device
+
+    else if ( --unavailable_device_check_countdown_ == 0 ) {
+        uint8_t wire_result;
+        Wire.beginTransmission(addr);
+        wire_result = Wire.endTransmission();
+        //if the check succeeds
+        if (wire_result == 0) {
+	    unavailable_device_check_countdown_ = 0; // TODO this is already true
+            return true;
+        } else {
+		Wire.beginTransmission (wire_result);
+        	wire_result = Wire.endTransmission();
+
+            // set the time to check counter to max
+            unavailable_device_check_countdown_ = UNAVAILABLE_DEVICE_COUNTDOWN_MAX;
+            return false;
+        }
+    } else {
+        // we've decremented the counter, but it's not time to probe for the device yet.
+        return false;
+    }
+
+}
+
+void Model100Side::markDeviceUnavailable() {
+     unavailable_device_check_countdown_ = 1; // We think there was a comms problem. Check on the next cycle
+}
+
 uint8_t Model100Side::writeData(uint8_t *data, uint8_t length) {
+  if (isDeviceAvailable() == false ) {
+	  return 1;
+  }
   Wire.beginTransmission(addr);
   Wire.write(data, length);
   uint8_t result = Wire.endTransmission();
+  if (result) { markDeviceUnavailable(); }
   return result;
 }
 
 int Model100Side::readRegister(uint8_t cmd) {
-
   byte return_value = 0;
-
   uint8_t data[] = {cmd};
   uint8_t result  = writeData(data, ELEMENTS(data));
 
+  // If the setup failed, return. This means there was a problem asking for the register
+  if (result) {
+	return -1;
+  }
 
-
-  delayMicroseconds(15); // We may be able to drop this in the future
+  delayMicroseconds(15); // TODO We may be able to drop this in the future
   // but will need to verify with correctly
   // sized pull-ups on both the left and right
   // hands' i2c SDA and SCL lines
@@ -132,6 +176,7 @@ int Model100Side::readRegister(uint8_t cmd) {
   if (Wire.available()) {
     return Wire.read();
   } else {
+    //markDeviceUnavailable();
     return -1;
   }
 
@@ -140,15 +185,21 @@ int Model100Side::readRegister(uint8_t cmd) {
 
 // gives information on the key that was just pressed or released.
 bool Model100Side::readKeys() {
+  if (isDeviceAvailable() == false ) {
+	  return false;
+  }
 
   uint8_t row_counter = 0;
   // perform blocking read into buffer
   uint8_t read = 0;
-  Wire.requestFrom(addr, 5);    // request 1 byte from the keyscanner
+  uint8_t bytes_returned =0;
+  bytes_returned = Wire.requestFrom(addr, 5);    // request 5 bytes from the keyscanner
+ if (bytes_returned < 5) {
+	return false;
+ }
   if (Wire.available()) {
     read = Wire.read();
     if (TWI_REPLY_KEYDATA == read) {
-
       while (Wire.available()) {
         keyData.rows[row_counter++] = Wire.read();
       }
diff --git a/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.h b/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.h
index bc10680e..35df1b1f 100644
--- a/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.h
+++ b/plugins/Kaleidoscope-Hardware-Keyboardio-Model100/src/kaleidoscope/driver/keyboardio/Model100Side.h
@@ -78,9 +78,12 @@ class Model100Side {
   void setAllLEDsTo(cRGB color);
   keydata_t getKeyData();
   bool readKeys();
+
   LEDData_t ledData;
-  uint8_t controllerAddress();
 
+  uint8_t controllerAddress();
+  bool isDeviceAvailable();
+  void markDeviceUnavailable();
   void setBrightness(uint8_t brightness) {
     brightness_adjustment_ = 255 - brightness;
   }
@@ -93,6 +96,10 @@ class Model100Side {
   int addr;
   int ad01;
   keydata_t keyData;
+  // a value of 0 is "device seen" - anything else is how many cycles before we should 
+  // check for the device
+  uint16_t unavailable_device_check_countdown_ = 1;
+  static const uint16_t UNAVAILABLE_DEVICE_COUNTDOWN_MAX = 0xFFFFU;
   byte nextLEDBank = 0;
   void sendLEDBank(byte bank);
   int readRegister(uint8_t cmd);