Add Pinmux Register Address Lookup Tool

README.md

@@ -82,6 +82,23 @@ rules by running:
 sudo udevadm control --reload-rules && sudo udevadm trigger
 ```
 
+# Pinmux Lookup Tool
+
+The `jetson-gpio-pinmux-lookup` command-line tool helps you find the pinmux register address for GPIO pins. This is useful for debugging or setting up pinmux configurations.
+
+**Usage:**
+```shell
+jetson-gpio-pinmux-lookup <gpio_pin_number>
+```
+
+**Example:**
+```shell
+jetson-gpio-pinmux-lookup 7
+# Output on Orin Device: GPIO Pin 7: Mux Register Address = 0x2430070
+```
+
+The tool accepts BOARD mode GPIO pin numbers (1-40) and returns the corresponding pinmux register address in hexadecimal format.
+
 # Running the sample scripts
 
 With the permissions set as needed, the sample applications provided in the
@@ -184,8 +201,11 @@ None.
 It is possible that the GPIO you are trying to use is already being used
 external to the current application. In such a condition, the Jetson GPIO
 library will warn you if the GPIO being used is configured to anything but the
-default direction (input). It will also warn you if you try cleaning up before
-setting up the mode and channels. To disable warnings, call:
+default direction (input). It will also warn you if:
+* You try cleaning up before setting up the mode and channels.
+* (Orin NX/Nano only) The pinmux for a requested pin is not properly confirgured to GPIO and the correct direction.
+
+To disable warnings, call:
 ```python
 GPIO.setwarnings(False)
 ```

lib/python/Jetson/GPIO/constants.py

@@ -0,0 +1,31 @@
+# Pin Numbering Modes
+BOARD = 10
+BCM = 11
+TEGRA_SOC = 1000
+CVM = 1001
+
+# The constants and their offsets are implemented to prevent HIGH from being
+# used in place of other variables (ie. HIGH and RISING should not be
+# interchangeable)
+
+# Pull up/down options
+_PUD_OFFSET = 20
+PUD_OFF = 0 + _PUD_OFFSET
+PUD_DOWN = 1 + _PUD_OFFSET
+PUD_UP = 2 + _PUD_OFFSET
+
+HIGH = 1
+LOW = 0
+
+# Edge possibilities
+# These values (with _EDGE_OFFSET subtracted) must match gpio_event.py:*_EDGE
+_EDGE_OFFSET = 30
+RISING = 1 + _EDGE_OFFSET
+FALLING = 2 + _EDGE_OFFSET
+BOTH = 3 + _EDGE_OFFSET
+
+# GPIO directions. UNKNOWN constant is for gpios that are not yet setup
+UNKNOWN = -1
+OUT = 0
+IN = 1
+HARD_PWM = 43

lib/python/Jetson/GPIO/gpio.py

@@ -19,6 +19,7 @@
 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 # DEALINGS IN THE SOFTWARE.
 
+from Jetson.GPIO.constants import *
 from Jetson.GPIO import gpio_event as event
 from Jetson.GPIO import gpio_pin_data
 from Jetson.GPIO import gpio_cdev
@@ -32,40 +33,6 @@
 if not os.access(_GPIOCHIP_ROOT, os.W_OK):
     raise RuntimeError("The current user does not have permissions set to access the library functionalites. Please configure permissions or use the root user to run this. It is also possible that {} does not exist. Please check if that file is present.".format(_GPIOCHIP_ROOT))
 
-
-
-# Pin Numbering Modes
-BOARD = 10
-BCM = 11
-TEGRA_SOC = 1000
-CVM = 1001
-
-# The constants and their offsets are implemented to prevent HIGH from being
-# used in place of other variables (ie. HIGH and RISING should not be
-# interchangeable)
-
-# Pull up/down options
-_PUD_OFFSET = 20
-PUD_OFF = 0 + _PUD_OFFSET
-PUD_DOWN = 1 + _PUD_OFFSET
-PUD_UP = 2 + _PUD_OFFSET
-
-HIGH = 1
-LOW = 0
-
-# Edge possibilities
-# These values (with _EDGE_OFFSET subtracted) must match gpio_event.py:*_EDGE
-_EDGE_OFFSET = 30
-RISING = 1 + _EDGE_OFFSET
-FALLING = 2 + _EDGE_OFFSET
-BOTH = 3 + _EDGE_OFFSET
-
-# GPIO directions. UNKNOWN constant is for gpios that are not yet setup
-UNKNOWN = -1
-OUT = 0
-IN = 1
-HARD_PWM = 43
-
 model, JETSON_INFO, _channel_data_by_mode = gpio_pin_data.get_data()
 RPI_INFO = JETSON_INFO
 
@@ -159,6 +126,10 @@ def _do_one_channel(ch_info, direction, initial, consumer):
     request = gpio_cdev.request_handle(ch_info.line_offset, cdev_direction, initial, consumer)
 
     gpio_cdev.open_line(ch_info, request)
+
+    if _gpio_warnings:
+        gpio_cdev.check_pinmux(ch_info, direction)
+
     _channel_configuration[ch_info.channel] = direction
 
 

lib/python/Jetson/GPIO/gpio_cdev.py

@@ -28,6 +28,12 @@
 import os
 import fcntl
 import ctypes
+from dataclasses import dataclass
+import mmap
+import sys
+import warnings
+from Jetson.GPIO.gpio_pin_data import ChannelInfo
+from Jetson.GPIO.constants import OUT, HARD_PWM
 
 GPIO_HIGH = 1
 
@@ -282,4 +288,87 @@ def set_value(line_handle, value):
     except (OSError, IOError) as e:
         raise GPIOError(e.errno, "Setting line value: " + e.strerror)
 
+_GPIO_IN_OUT_MASK = (1 << 6) | (1 << 4)
+"""
+A mask for the in/out bit and the tristate bit. We use this for the corrected register value.
+"""
+
+_MAP_MASK = mmap.PAGESIZE - 1
+
+@dataclass
+class PadCtlRegister:
+    """
+    Simple dataclass for parsing the value of a PADCTL register.\n
+    bit 1:0 reserved\n
+    bit 3:2 pull up/down 0=none; 1=down; 2=up; 3=reserved\n
+    bit 4 tristate config 0=passthrough; 1=tristate\n
+    bit 6 input/output 0=output; 1=input\n
+    bit 10 gpio/sfio 0=gpio; 1=sfio\n
+    bit 12 schmt 0=disabled; 1=enable
+    """
+    is_gpio: bool
+    is_input: bool
+    is_tristate: bool
+
+    def __init__(self, value: int):
+        self.is_gpio = (value & (1 << 10)) == 0
+        self.is_input = (value & (1 << 6)) != 0
+        self.is_tristate = (value & (1 << 4)) != 0
+
+    @property
+    def is_bidi(self) -> bool:
+        return self.is_input and not self.is_tristate
+
+def check_pinmux(ch_info: ChannelInfo, direction: int) -> None:
+    if ch_info.reg_block_base_addr is None or ch_info.reg_offset is None:
+        warnings.warn("pinmux checks not implemented for current device.")
+        return
+
+    try:
+        mem_fd = os.open('/dev/mem', os.O_RDONLY | os.O_SYNC)
+        reg_address = ch_info.reg_block_base_addr + ch_info.reg_offset
+        reg_page_start = reg_address & ~_MAP_MASK
+        reg_page_offset = reg_address - reg_page_start
+
+        # Map 2 pages of /dev/mem starting from the page where the register starts to handle registers across the page boundary
+        with mmap.mmap(mem_fd, length=mmap.PAGESIZE * 2, flags=mmap.MAP_SHARED, prot=mmap.PROT_READ, offset=reg_page_start) as devmem:
+            reg_value = int.from_bytes(devmem[reg_page_offset:reg_page_offset + 4], byteorder=sys.byteorder)
+            reg = PadCtlRegister(reg_value)
+
+            # If the register is in a bidrectional state (input enabled, no tristate) we can skip the checks
+            if reg.is_bidi:
+                return
+
+            is_out = direction == OUT
+            # If user sets direction to input, but register is output, warn user
+            if not is_out and not reg.is_input:
+                corrected_input = reg_value | _GPIO_IN_OUT_MASK
+                warnings.warn(
+f"""
+[WARNING] User requested input for channel "{ch_info.channel}", but it is set to output in pinmux. For more information on resolving this, please see
+https://docs.nvidia.com/jetson/archives/r36.3/DeveloperGuide/HR/JetsonModuleAdaptationAndBringUp/JetsonOrinNxNanoSeries.html#generating-the-pinmux-dtsi-files
+
+This can be resolved *temporarily* (until next restart) by running:
+    sudo busybox devmem 0x{reg_address:X} w 0x{corrected_input:X}
+"""
+                    )
+                return
+
+            # Same as above, but for when user requests output
+            if is_out and reg.is_input:
+                corrected_output = reg_value & ~_GPIO_IN_OUT_MASK
+                warnings.warn(
+f"""
+[WARNING] User requested output for channel "{ch_info.channel}", but it is set to input in pinmux. For more information on resolving this, please see
+https://docs.nvidia.com/jetson/archives/r36.3/DeveloperGuide/HR/JetsonModuleAdaptationAndBringUp/JetsonOrinNxNanoSeries.html#generating-the-pinmux-dtsi-files
+
+This can be resolved *temporarily* (until next restart) by running:
+    sudo busybox devmem 0x{reg_address:X} w 0x{corrected_output:X}
+"""
+                    )
+                return
 
+    except (OSError, IOError) as e:
+        warnings.warn('Could not open /dev/mem for pinmux check. If you want pinmux checks, make sure your user has permissions to read /dev/mem and that it exists. Error: ' + e)
+    finally:
+        os.close(mem_fd)