[nrf52][i2c] Add nrfx i2c driver

Use twim(i2c) driver from nrfx library.  See comments and patterns in
target/nrf-pca10056 for info on how to properly utilize driver as it
requires some GLOBAL_DEFINES and gpio defines.

external/platform/nrfx/rules.mk

@@ -3,6 +3,9 @@ LOCAL_DIR := $(GET_LOCAL_DIR)
 MODULE := $(LOCAL_DIR)
 
 MODULE_SRCS := \
+	$(LOCAL_DIR)/drivers/src/nrfx_twi.c \
+	$(LOCAL_DIR)/drivers/src/nrfx_twi_twim.c \
+	$(LOCAL_DIR)/drivers/src/nrfx_twim.c \
 	$(LOCAL_DIR)/drivers/src/nrfx_usbd.c \
 	$(LOCAL_DIR)/mdk/system_nrf52.c \
 	$(LOCAL_DIR)/soc/nrfx_atomic.c \

platform/nrf52xxx/i2c_master.c

@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2020 Eric Holland
+ *
+ * Use of this source code is governed by a MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT
+ */
+
+#include <nrfx.h>
+/*
+  To use the twim driver, NRFX_TWIM_ENABLED must be set to 1 in the GLOBAL_DEFINES
+  additionally, NRFX_TWIM0_ENABLED and/or NRFX_TWIM1_ENABLED must also be 1 to specify
+  which modules are active.  These would ideally be set in either a project rule.mk
+  or in a targets rules.mk.
+
+  The pins to be used for each of the active TWIM modules should be defined as:
+  TWIM0_SCL_PIN, TWIM0_SDA_PIN  (if twim0 is used)
+  TWIM1_SCL_PIN, TWIM1_SDA_PIN  (if twim1 is used)
+  and ideally be defined in the targets include/gpioconfig.h since it is included here.
+*/
+
+#if (NRFX_TWIM_ENABLED)
+#include <nrfx_log.h>
+#include <nrfx_twim.h>
+#include <dev/i2c.h>
+#include <kernel/event.h>
+#include <kernel/mutex.h>
+#include <lk/debug.h>
+#include <lk/err.h>
+#include <target/gpioconfig.h>
+
+
+#define TWIM_MASTER_TIMEOUT_MS 1000
+
+typedef struct twim_dev {
+    nrfx_twim_t twim;
+    event_t evt;
+    mutex_t lock;
+    nrfx_twim_evt_type_t result;
+} twim_dev_t;
+
+#if (NRFX_TWIM0_ENABLED)
+static twim_dev_t twim0 = { NRFX_TWIM_INSTANCE(0),
+                            EVENT_INITIAL_VALUE(twim0.evt, false, 0),
+                            MUTEX_INITIAL_VALUE(twim0.lock),
+                            0
+                          };
+
+void nrf52_SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0_IRQ(void) {
+    arm_cm_irq_entry();
+    nrfx_twim_0_irq_handler();
+    arm_cm_irq_exit(true);
+}
+#endif
+
+#if (NRFX_TWIM1_ENABLED)
+static twim_dev_t twim1 = { NRFX_TWIM_INSTANCE(0),
+                            EVENT_INITIAL_VALUE(twim1.evt, false, 0),
+                            MUTEX_INITIAL_VALUE(twim1.lock),
+                            0
+                          };
+
+void nrf52_SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1_IRQ(void) {
+    arm_cm_irq_entry();
+    nrfx_twim_1_irq_handler();
+    arm_cm_irq_exit(true);
+}
+#endif
+
+static inline twim_dev_t *get_nrfx_twim(int bus) {
+    switch (bus) {
+#if (NRFX_TWIM0_ENABLED)
+        case 0:
+            return &twim0;
+#endif
+#if (NRFX_TWIM1_ENABLED)
+        case 1:
+            return &twim1;
+#endif
+        default:
+            return NULL;
+    }
+}
+
+void i2c_twim_evt_handler(nrfx_twim_evt_t const *p_event,void *p_context) {
+    twim_dev_t *twim = (twim_dev_t *)p_context;
+    twim->result = p_event->type;
+    event_signal(&twim->evt, false);
+}
+
+void i2c_init_early(void) {}
+
+void i2c_init() {
+    nrfx_err_t status;
+
+#if (NRFX_TWIM0_ENABLED)
+    //Pins should be defined in target/gpioconfig.h
+    const nrfx_twim_config_t twim0_config = NRFX_TWIM_DEFAULT_CONFIG(TWIM0_SCL_PIN, TWIM0_SDA_PIN);
+
+    status = nrfx_twim_init(&twim0.twim, &twim0_config, i2c_twim_evt_handler, &twim0);
+    dprintf(ALWAYS,"%p\n", &twim0);
+    if (status == NRFX_SUCCESS) {
+        nrfx_twim_enable(&twim0.twim);
+    } else {
+        NRFX_LOG_ERROR("ERROR in twim0 init:%s \n",NRFX_LOG_ERROR_STRING_GET(status));
+    }
+#endif
+
+#if (NRFX_TWIM1_ENABLED)
+    //Pins should be defined in target/gpioconfig.h
+    const nrfx_twim_config_t twim1_config = NRFX_TWIM_DEFAULT_CONFIG(TWIM1_SCL_PIN, TWIM1_SDA_PIN);
+
+    status = nrfx_twim_init(&twim1, &twim1_config, i2c_twim_evt_handler, &twim1);
+    if (status == NRFX_SUCCESS) {
+        nrfx_twim_enable(&twim1);
+    } else {
+        NRFX_LOG_ERROR("ERROR in twim1 init:%s \n",NRFX_LOG_ERROR_STRING_GET(status));
+    }
+#endif
+}
+
+static status_t i2c_xfer(int bus, nrfx_twim_xfer_desc_t *desc) {
+    twim_dev_t *twim = get_nrfx_twim(bus);
+    if (twim == NULL) return ERR_INVALID_ARGS;
+
+    mutex_acquire(&twim->lock);
+
+    nrfx_err_t nrfx_status = nrfx_twim_xfer(&twim->twim, desc, 0);
+
+    event_wait_timeout(&twim->evt, TWIM_MASTER_TIMEOUT_MS);
+    event_unsignal(&twim->evt);
+    mutex_release(&twim->lock);
+
+    if (nrfx_status != NRFX_SUCCESS) {
+        NRFX_LOG_ERROR("%s:%s \n", __func__, NRFX_LOG_ERROR_STRING_GET(nrfx_status));
+        return (status_t)nrfx_status;
+    }
+    return NO_ERROR;
+}
+
+status_t i2c_transmit(int bus, uint8_t address, const void *buf, size_t count) {
+
+    nrfx_twim_xfer_desc_t xfer = NRFX_TWIM_XFER_DESC_TX(address, (uint8_t *)buf, count);
+
+    return i2c_xfer(bus, &xfer);
+}
+
+status_t i2c_receive(int bus, uint8_t address, void *buf, size_t count) {
+
+    nrfx_twim_xfer_desc_t xfer = NRFX_TWIM_XFER_DESC_RX(address, (uint8_t *)buf, count);
+
+    return i2c_xfer(bus, &xfer);
+}
+
+status_t i2c_write_reg_bytes(int bus, uint8_t address, uint8_t reg, const uint8_t *val,
+                             size_t cnt) {
+
+    nrfx_twim_xfer_desc_t xfer = NRFX_TWIM_XFER_DESC_TXTX(address, &reg, 1, (uint8_t *)val, cnt);
+
+    return i2c_xfer(bus, &xfer);
+}
+
+status_t i2c_read_reg_bytes(int bus, uint8_t address, uint8_t reg, uint8_t *val, size_t cnt) {
+    nrfx_twim_xfer_desc_t xfer = NRFX_TWIM_XFER_DESC_TXRX(address, &reg, 1, (uint8_t *)val, cnt);
+
+    return i2c_xfer(bus, &xfer);
+}
+
+#endif // NRFX_TWIM_ENABLED

platform/nrf52xxx/init.c

@@ -8,6 +8,7 @@
 #include <lk/err.h>
 #include <lk/debug.h>
 #include <arch/arm/cm.h>
+#include <dev/i2c.h>
 #include <dev/uart.h>
 #include <platform.h>
 #include <nrfx.h>
@@ -31,4 +32,7 @@ void platform_init(void) {
             (NRF_FICR->DEVICEADDR[0] >> 16) & 0xFF, \
             (NRF_FICR->DEVICEADDR[0] >>  8) & 0xFF, \
             (NRF_FICR->DEVICEADDR[0] >>  0) & 0xFF);
+    // Note: i2c_init will only instantiate an i2c device if proper defines
+    //   are set.  See comments at top of i2c_master.c for more info.
+    i2c_init();
 }

platform/nrf52xxx/rules.mk

@@ -36,13 +36,18 @@ GLOBAL_INCLUDES += $(LOCAL_DIR)
 GLOBAL_DEFINES += \
 	MEMSIZE=$(MEMSIZE)
 
+# Other important defines
+#GLOBAL_DEFINES += \
+#	NRFX_ENABLE_LOGGING=1 \
+
 MODULE_SRCS += \
+	$(LOCAL_DIR)/i2c_master.c \
 	$(LOCAL_DIR)/init.c \
 	$(LOCAL_DIR)/debug.c \
 	$(LOCAL_DIR)/uart.c \
 	$(LOCAL_DIR)/vectab.c \
 	$(LOCAL_DIR)/gpio.c \
-    $(LOCAL_DIR)/timer.c \
+	$(LOCAL_DIR)/timer.c \
 
 LINKER_SCRIPT += \
 	$(BUILDDIR)/system-twosegment.ld

target/nrf-pca10056/include/target/gpioconfig.h

@@ -18,6 +18,12 @@
 #define UART0_TX_PIN    6
 #define UART0_RX_PIN    8
 
+// Used in platform file  i2c_master.c for configuring twim0 (i2c)
+#define TWIM0_SCL_PIN 27
+#define TWIM0_SDA_PIN 26
 
+// define these if twim1 module is used
+//#define TWIM1_SCL_PIN
+//#define TWIM1_SDA_PIN
 
 #endif

target/nrf-pca10056/rules.mk

@@ -9,6 +9,8 @@ PLATFORM := nrf52xxx
 GLOBAL_DEFINES += \
 	ENABLE_UART0=1 \
 	NRFX_USBD_ENABLED=1 \
+	NRFX_TWIM_ENABLED=1 \
+	NRFX_TWIM0_ENABLED=1 \
 	NRF52840_XXAA \