zephyr: Allow using devicetree node labels to construct machine objects.

Zephyr v3.7.0 added a new feature to allow getting devices by their
devicetree node labels. Use this feature in the MicroPython Zephyr port
to simplify constructing machine module objects, including Pin, SPI,
I2C, and UART. It's still possible to use the more verbose device names
(e.g., gpio@400ff040, i2c@40066000, spi@4002c000), but now we can also
use their devicetree node labels (e.g., gpiob, i2c0, spi0).

Node labels aren't standardized across all SoC families because they
generally try to follow their respective SoC hardware user manual naming
convention, however many boards define common labels for devices routed
to Arduino headers (e.g., arduino_i2c, arduino_serial, and arduino_spi).
That means I2C("arduino_i2c") will work on quite a few boards (>100 in
the main Zephyr tree).

Signed-off-by: Maureen Helm <maureen.helm@analog.com>

4 files changed, 28 insertions, 23 deletions

diff --git a/docs/zephyr/quickref.rst b/docs/zephyr/quickref.rst
index 31a4ac46c..63d4bced0 100644
--- a/docs/zephyr/quickref.rst
+++ b/docs/zephyr/quickref.rst
@@ -36,10 +36,7 @@ Use the :ref:`machine.Pin <machine.Pin>` class::
 
     from machine import Pin
 
-    gpio1 = "gpio@400ff040"             # GPIO1 device name
-    gpio2 = "gpio@400ff080"             # GPIO2 device name
-
-    pin = Pin((gpio1, 21), Pin.IN)      # create input pin on GPIO1
+    pin = Pin(("gpiob", 21), Pin.IN)    # create input pin on GPIO port B
     print(pin)                          # print pin port and number
 
     pin.init(Pin.OUT, Pin.PULL_UP, value=1)     # reinitialize pin
@@ -50,14 +47,14 @@ Use the :ref:`machine.Pin <machine.Pin>` class::
     pin.on()                            # set pin to high
     pin.off()                           # set pin to low
 
-    pin = Pin((gpio1, 21), Pin.IN)              # create input pin on GPIO1
+    pin = Pin(("gpiob", 21), Pin.IN)              # create input pin on GPIO port B
 
-    pin = Pin((gpio1, 21), Pin.OUT, value=1)    # set pin high on creation
+    pin = Pin(("gpiob", 21), Pin.OUT, value=1)    # set pin high on creation
 
-    pin = Pin((gpio1, 21), Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor
+    pin = Pin(("gpiob", 21), Pin.IN, Pin.PULL_UP) # enable internal pull-up resistor
 
-    switch = Pin((gpio2, 6), Pin.IN)            # create input pin for a switch
-    switch.irq(lambda t: print("SW2 changed"))  # enable an interrupt when switch state is changed
+    switch = Pin(("gpioc", 6), Pin.IN)            # create input pin for a switch
+    switch.irq(lambda t: print("SW2 changed"))    # enable an interrupt when switch state is changed
 
 Hardware I2C bus
 ----------------
@@ -66,7 +63,7 @@ Hardware I2C is accessed via the :ref:`machine.I2C <machine.I2C>` class::
 
     from machine import I2C
 
-    i2c = I2C("i2c@40066000")   # construct an i2c bus
+    i2c = I2C("i2c0")           # construct an i2c bus
     print(i2c)                  # print device name
 
     i2c.scan()                  # scan the device for available I2C slaves
@@ -87,11 +84,11 @@ Hardware SPI is accessed via the :ref:`machine.SPI <machine.SPI>` class::
 
     from machine import SPI
 
-    spi = SPI("spi@4002c000")   # construct a spi bus with default configuration
+    spi = SPI("spi0")           # construct a spi bus with default configuration
     spi.init(baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB) # set configuration
 
     # equivalently, construct spi bus and set configuration at the same time
-    spi = SPI("spi@4002c000", baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
+    spi = SPI("spi0", baudrate=100000, polarity=0, phase=0, bits=8, firstbit=SPI.MSB)
     print(spi)                  # print device name and bus configuration
 
     spi.read(4)                 # read 4 bytes on MISO
@@ -149,7 +146,7 @@ Use the :ref:`zsensor.Sensor <zsensor.Sensor>` class to access sensor data::
     import zsensor
     from zsensor import Sensor
 
-    accel = Sensor("fxos8700@1d") # create sensor object for the accelerometer
+    accel = Sensor("fxos8700")    # create sensor object for the accelerometer
 
     accel.measure()               # obtain a measurement reading from the accelerometer
 
diff --git a/ports/zephyr/README.md b/ports/zephyr/README.md
index 39010b2ac..4590eb719 100644
--- a/ports/zephyr/README.md
+++ b/ports/zephyr/README.md
@@ -107,7 +107,7 @@ To blink an LED:
     import time
     from machine import Pin
 
-    LED = Pin(("gpio@400ff040", 21), Pin.OUT)
+    LED = Pin(("gpiob", 21), Pin.OUT)
     while True:
         LED.value(1)
         time.sleep(0.5)
@@ -115,18 +115,18 @@ To blink an LED:
         time.sleep(0.5)
 
 The above code uses an LED location for a FRDM-K64F board (port B, pin 21;
-following Zephyr conventions port are identified by "GPIO_x", where *x*
-starts from 0). You will need to adjust it for another board (using board's
-reference materials). To execute the above sample, copy it to clipboard, in
-MicroPython REPL enter "paste mode" using Ctrl+E, paste clipboard, press
-Ctrl+D to finish paste mode and start execution.
+following Zephyr conventions port are identified by their devicetree node
+label. You will need to adjust it for another board (using board's reference
+materials). To execute the above sample, copy it to clipboard, in MicroPython
+REPL enter "paste mode" using Ctrl+E, paste clipboard, press Ctrl+D to finish
+paste mode and start execution.
 
 To respond to Pin change IRQs, on a FRDM-K64F board run:
 
     from machine import Pin
 
-    SW2 = Pin(("gpio@400ff080", 6), Pin.IN)
-    SW3 = Pin(("gpio@400ff000", 4), Pin.IN)
+    SW2 = Pin(("gpioc", 6), Pin.IN)
+    SW3 = Pin(("gpioa", 4), Pin.IN)
 
     SW2.irq(lambda t: print("SW2 changed"))
     SW3.irq(lambda t: print("SW3 changed"))
@@ -138,14 +138,14 @@ Example of using I2C to scan for I2C slaves:
 
     from machine import I2C
 
-    i2c = I2C("i2c@40066000")
+    i2c = I2C("i2c0")
     i2c.scan()
 
 Example of using SPI to write a buffer to the MOSI pin:
 
     from machine import SPI
 
-    spi = SPI("spi@4002c000")
+    spi = SPI("spi0")
     spi.init(baudrate=500000, polarity=1, phase=1, bits=8, firstbit=SPI.MSB)
     spi.write(b'abcd')
 
diff --git a/ports/zephyr/prj.conf b/ports/zephyr/prj.conf
index d3983fcc2..eac04216c 100644
--- a/ports/zephyr/prj.conf
+++ b/ports/zephyr/prj.conf
@@ -16,6 +16,8 @@ CONFIG_FPU=y
 CONFIG_MAIN_STACK_SIZE=4736
 CONFIG_POLL=y
 
+CONFIG_DEVICE_DT_METADATA=y
+
 # Enable sensor subsystem (doesn't add code if not used).
 # Specific sensors should be enabled per-board.
 CONFIG_SENSOR=y
diff --git a/ports/zephyr/zephyr_device.c b/ports/zephyr/zephyr_device.c
index 2ef331742..51784bc78 100644
--- a/ports/zephyr/zephyr_device.c
+++ b/ports/zephyr/zephyr_device.c
@@ -31,6 +31,12 @@ const struct device *zephyr_device_find(mp_obj_t name) {
     const char *dev_name = mp_obj_str_get_str(name);
     const struct device *dev = device_get_binding(dev_name);
 
+    #ifdef CONFIG_DEVICE_DT_METADATA
+    if (dev == NULL) {
+        dev = device_get_by_dt_nodelabel(dev_name);
+    }
+    #endif
+
     if (dev == NULL) {
         #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
         mp_raise_ValueError(MP_ERROR_TEXT("device not found"));