drivers: esp32: I2C driver implementation

Supports both master and slave mode, standard and fast modes,
configurable timeouts, and a few other tunable settings.

Signed-off-by: Leandro Pereira <leandro.pereira@intel.com>

boards/xtensa/esp32/esp32_defconfig

@@ -28,3 +28,18 @@ CONFIG_RANDOM_ESP32_RNG=y
 CONFIG_SW_ISR_TABLE=y
 CONFIG_GEN_ISR_TABLES=y
 CONFIG_GEN_IRQ_VECTOR_TABLE=n
+
+CONFIG_I2C=y
+CONFIG_I2C_ESP32=y
+CONFIG_I2C_0=y
+CONFIG_I2C_1=y
+CONFIG_I2C_2=n
+CONFIG_I2C_3=n
+
+# FIXME: ESP32 port should support DTS.
+CONFIG_HAS_DTS_I2C=n
+
+# IRQ priorities are fixed on Xtensa, but Kconfig will ask for these
+# if not set.
+CONFIG_I2C_0_IRQ_PRI=1
+CONFIG_I2C_1_IRQ_PRI=1

drivers/i2c/Kconfig

@@ -369,4 +369,6 @@ config I2C_SDA_RX_HOLD
 	  The hold time on the data signal after a negative edge of i2c clock
 	  while i2c acts as receiver. The unit is i2c module base clock.
 
+source "drivers/i2c/Kconfig.esp32"
+
 endif # I2C

drivers/i2c/Kconfig.esp32

@@ -0,0 +1,79 @@
+# Kconfig.esp32 - ESP32 I2C configuration options
+#
+#
+# Copyright (c) 2017 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+menuconfig I2C_ESP32
+	bool "ESP32 I2C"
+	depends on I2C && SOC_ESP32
+	select GPIO_ESP32
+	default n
+	help
+	  Enables the ESP32 I2C driver
+
+if I2C_ESP32
+
+config I2C_ESP32_TIMEOUT
+	int "I2C timeout to receive a data bit in APB clock cycles"
+	default 200000
+
+if I2C_0
+
+config I2C_0_DEFAULT_CFG
+	# Standard speed, master
+	default 0x12
+
+config I2C_ESP32_0_TX_LSB_FIRST
+	bool "Port 0 Transmit LSB first"
+	default n
+
+config I2C_ESP32_0_RX_LSB_FIRST
+	bool "Port 0 Receive LSB first"
+	default n
+
+config I2C_ESP32_0_IRQ
+	int "Port 0 IRQ line"
+	default 8
+
+config I2C_ESP32_0_SCL_PIN
+	int "Port 0 SCL pin"
+	default 2
+
+config I2C_ESP32_0_SDA_PIN
+	int "Port 0 SDA pin"
+	default 4
+
+endif # I2C_0
+
+if I2C_1
+
+config I2C_1_DEFAULT_CFG
+	# Standard speed, master
+	default 0x12
+
+config I2C_ESP32_1_TX_LSB_FIRST
+	bool "Port 1 Transmit LSB first"
+	default n
+
+config I2C_ESP32_1_RX_LSB_FIRST
+	bool "Port 1 Receive LSB first"
+	default n
+
+config I2C_ESP32_1_IRQ
+	int "Port 1 IRQ line"
+	default 9
+
+config I2C_ESP32_1_SCL_PIN
+	int "Port 1 SCL pin"
+	default 5
+
+config I2C_ESP32_1_SDA_PIN
+	int "Port 1 SDA pin"
+	default 18
+
+endif # I2C_1
+
+endif # I2C_ESP32

drivers/i2c/Makefile

@@ -10,3 +10,4 @@ obj-$(CONFIG_I2C_SBCON) += i2c_sbcon.o
 obj-$(CONFIG_I2C_STM32_V1) += i2c_ll_stm32_v1.o i2c_ll_stm32.o
 obj-$(CONFIG_I2C_STM32_V2) += i2c_ll_stm32_v2.o i2c_ll_stm32.o
 obj-$(CONFIG_TWIHS_SAM) += twihs_sam.o
+obj-$(CONFIG_I2C_ESP32) += i2c_esp32.o