I2C clock bugfixes

Explictly set the I2C clock source, else was not clocked correctly
when started from BTT bootloader.

Allow for selection between Standard, Fast, and Fast Plus modes,
default to Fast mode (400kHz).

Src/i2c.c

@@ -26,6 +26,10 @@
 
 #ifdef I2C_PORT
 
+#ifndef I2C_KHZ
+#define I2C_KHZ 400
+#endif
+
 #ifdef I2C1_ALT_PINMAP
   #define I2C1_SCL_PIN 6
   #define I2C1_SDA_PIN 7
@@ -41,9 +45,18 @@
 
 static uint8_t keycode = 0;
 static keycode_callback_ptr keypad_callback = NULL;
+
 static I2C_HandleTypeDef i2c_port = {
     .Instance = I2CPORT,
-    .Init.Timing = 0x20303E5D,
+#if I2C_KHZ == 100
+    .Init.Timing = 0x307075B1,
+#elif I2C_KHZ == 400
+    .Init.Timing = 0x00B03FDB,
+#elif I2C_KHZ == 1000
+    .Init.Timing = 0x0050174F,
+#else
+    #error "I2C speed not defined"
+#endif
     .Init.OwnAddress1 = 0,
     .Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT,
     .Init.DualAddressMode = I2C_DUALADDRESS_DISABLE,

Src/main.c

@@ -316,9 +316,10 @@ void SystemClock_Config(void)
       Error_Handler();
     }
 
-    PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_SPI123 | RCC_PERIPHCLK_SPI45;
-    PeriphClkInitStruct.Spi123ClockSelection = RCC_SPI123CLKSOURCE_PLL;
-    PeriphClkInitStruct.Spi45ClockSelection  = RCC_SPI45CLKSOURCE_PLL2;
+    PeriphClkInitStruct.PeriphClockSelection  = RCC_PERIPHCLK_SPI123 | RCC_PERIPHCLK_SPI45 | RCC_PERIPHCLK_I2C123;
+    PeriphClkInitStruct.Spi123ClockSelection  = RCC_SPI123CLKSOURCE_PLL;
+    PeriphClkInitStruct.Spi45ClockSelection   = RCC_SPI45CLKSOURCE_PLL2;
+    PeriphClkInitStruct.I2c1235ClockSelection = RCC_I2C123CLKSOURCE_D2PCLK1;
 
 #if RTC_ENABLE
     PeriphClkInitStruct.PeriphClockSelection = PeriphClkInitStruct.PeriphClockSelection | RCC_PERIPHCLK_RTC;