broadcom: restore reset_i2c() and special handling of two I2C ports

Author: dhalbert

ports/broadcom/common-hal/busio/I2C.c

@@ -23,8 +23,28 @@ static BSC0_Type *i2c[NUM_I2C] = {BSC0, BSC1, NULL, BSC3, BSC4, BSC5, BSC6, NULL
 static BSC0_Type *i2c[NUM_I2C] = {BSC0, BSC1, NULL};
 #endif
 
+static bool never_reset_i2c[NUM_I2C];
 static bool i2c_in_use[NUM_I2C];
 
+void reset_i2c(void) {
+    // BSC2 is dedicated to the first HDMI output.
+    never_reset_i2c[2] = true;
+    i2c_in_use[2] = true;
+    #if BCM_VERSION == 2711
+    // BSC7 is dedicated to the second HDMI output.
+    never_reset_i2c[7] = true;
+    i2c_in_use[7] = true;
+    #endif
+    for (size_t i = 0; i < NUM_I2C; i++) {
+        if (never_reset_i2c[i]) {
+            continue;
+        }
+        i2c_in_use[i] = false;
+        i2c[i]->C_b.I2CEN = false;
+        COMPLETE_MEMORY_READS;
+    }
+}
+
 void common_hal_busio_i2c_construct(busio_i2c_obj_t *self,
     const mcu_pin_obj_t *scl, const mcu_pin_obj_t *sda, uint32_t frequency, uint32_t timeout) {
 
@@ -233,6 +253,8 @@ uint8_t common_hal_busio_i2c_write_read(busio_i2c_obj_t *self, uint16_t addr,
 }
 
 void common_hal_busio_i2c_never_reset(busio_i2c_obj_t *self) {
+    never_reset_i2c[self->index] = true;
+
     common_hal_never_reset_pin(self->scl_pin);
     common_hal_never_reset_pin(self->sda_pin);
 }

ports/broadcom/common-hal/busio/I2C.h

@@ -23,3 +23,5 @@ typedef struct {
     bool finish_write;
     uint8_t last_write_data;
 } busio_i2c_obj_t;
+
+void reset_i2c(void);

ports/broadcom/supervisor/port.c

@@ -13,6 +13,7 @@
 #include "genhdr/mpversion.h"
 
 #include "common-hal/rtc/RTC.h"
+#include "common-hal/busio/I2C.h"
 #include "common-hal/busio/SPI.h"
 #include "common-hal/busio/UART.h"
 
@@ -65,6 +66,7 @@ safe_mode_t port_init(void) {
 
 void reset_port(void) {
     #if CIRCUITPY_BUSIO
+    reset_i2c();
     reset_spi();
     reset_uart();
     #endif