Beagleboard:BeagleBone cape interface spec

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This is a list of symlink interfaces based on BeagleBone Cape header pins.[1][2][3]

I2C

Bone bus I2C
Bone bus BBBWL/BBB BBAI SCL SDA Overlay
/dev/bone/i2c/1 I2C0 I2C1 On-board On-board
/dev/bone/i2c/1 I2C1 I2C5 P9.17 P9.18
/dev/bone/i2c/2 I2C2 I2C4 P9.19 P9.20
/dev/bone/i2c/2a I2C2 N/A P9.21 P9.22
/dev/bone/i2c/3 I2C1 I2C3 P9.24 P9.26



SPI

Bone bus SPI
Bone bus BBBWL/BBB BBAI MOSI MISO CLK CS Overlay
/dev/bone/spi/0.x SPI0 SPI2 P9.18 P9.21 P9.22
  • P9.17 (CS0)
/dev/bone/spi/1.x SPI1 SPI3 P9.30 P9.29 P9.31
  • P9.28 (CS0)
  • P9.42 (CS1)



UART

Bone bus UART
Bone bus BBBWL/BBB BBAI TX RX RTSn CTSn Overlays
/dev/bone/uart/1 UART1 UART10 P9.24 P9.26
  • P9.19
  • P8.4 (N/A on AM3358)
  • P9.20
  • P8.3 (N/A on AM3358)
/dev/bone/uart/2 UART2 UART3 P9.21 P9.22
  • P8.38 (N/A on AM5729)
  • P8.37 (N/A on AM5729)
/dev/bone/uart/3 UART3 P9.42
/dev/bone/uart/4 UART4 UART5 P9.13 P9.11
  • P8.33 (N/A on AM5729)
  • P8.6 (N/A on AM3358)
  • P8.35 (N/A on AM5729)
  • P8.5 (N/A on AM3358)
/dev/bone/uart/5 UART5 UART8 P8.37 P8.38 P8.32 P8.31


CAN

Bone bus UART
Bone bus BBBWL/BBB BBAI TX RX Overlays
/dev/bone/can/0 CAN0 P9.20 P9.29
/dev/bone/can/1 CAN1 CAN2 P9.26 P9.24
/dev/bone/can/2 CAN1 (rev A2 and later) P8.8 P8.7


ADC

Work needs to be done to create these symlinks as well as handle major differences in the driver used for the ADC. Maybe just have the "okay" in here and more in the base tree?

/dev/bone/adc/n

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts

  • 0 - AM3358 in_voltage0_raw, AM5729 in_voltage0_raw
  • 1 - AM3358 in_voltage1_raw, AM5729 in_voltage1_raw
  • 2 - AM3358 in_voltage2_raw, AM5729 in_voltage3_raw
  • 3 - AM3358 in_voltage3_raw, AM5729 in_voltage2_raw
  • 4 - AM3358 in_voltage4_raw, AM5729 in_voltage7_raw
  • 5 - AM3358 in_voltage5_raw, AM5729 in_voltage6_raw
  • 6 - AM3358 in_voltage6_raw, AM5729 in_voltage4_raw

PWM/TIMER/ECAP

/dev/bone/pwm/0

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM0-00A0.dts
AM3358 PWM0
AM5729 TIMER13/TIMER15

  • P9.22 - A
  • P9.21 - B

/dev/bone/pwm/1

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM1-00A0.dts
AM3358 PWM1
AM5279 PWM3

  • P9.14 - A
  • P9.16 - B

/dev/bone/pwm/2

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM2-00A0.dts
AM3358 PWM2
AM5729 PWM2

  • P8.19 - A
  • P8.13 - B

/dev/bone/timer/4

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM-TIMER-P8.07.dts
AM3358 TIMER4
AM5729 TIMER11

  • P8.7

/dev/bone/timer/5

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM-TIMER-P8.09.dts
AM3358 TIMER5
AM5729 TIMER14

  • P8.9

/dev/bone/timer/6

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM-TIMER-P8.10.dts
AM3358 TIMER6
AM5729 TIMER10

  • P8.10

/dev/bone/timer/7

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-PWM-TIMER-P8.08.dts
AM3358 TIMER7
AM5729 TIMER12

  • P8.8

/dev/bone/ecap/1

TODO
AM3358 N/A
AM5729 eCAP1_in_PWM1_out

  • P8.15

/dev/bone/ecap/2

TODO
AM3358 N/A
AM5729 eCAP2_in_PWM2_out

  • P8.14

/dev/bone/ecap/3

TODO
AM3358 N/A
AM5729 eCAP3_in_PWM3_out

  • P8.04

MMC

/dev/bone/mmc/2

TODO: need overlay. Note: On Black, this is used by the on-board eMMC. On AI, these pins are available.
AM3358 MMC2
AM5729 MMC3

  • P8.21 - CLK
  • P8.20 - CMD
  • P8.25 - DAT0
  • P8.24 - DAT1
  • P8.5 - DAT2
  • P8.6 - DAT3
  • P8.23 - DAT4
  • P8.22 - DAT5
  • P8.4 - DAT7
  • P8.3 - DAT6

LCD

TODO

eQEP

/dev/bone/eqep/0

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/bone_eqep0-00A0.dts
AM3358 eQEP0
AM5729 eQEP3

  • P9.42 - A
  • P9.27 - B
  • P9.25 - STROBE (N/A on AI)
  • P9.41 - INDEX (N/A on AI)
  • P8.6 - STROBE (N/A on AM3358)
  • P8.5 - INDEX (N/A on AM3358)

/dev/bone/eqep/1

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/bone_eqep1-00A0.dts
AM3358 eQEP1
AM5729 eQEP1

  • P8.34 - A
  • P8.36 - B
  • P9.21 - STROBE (N/A on AM3358)

/dev/bone/eqep/2

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/bone_eqep2b-00A0.dts
AM3358 eQEP2
AM5729 eQEP2

  • P8.12 - A
  • P8.11 - B
  • P8.15 - STROBE on AM3358 only
  • P8.18 - STROBE on AM5729 only
  • P8.16 - INDEX on AM3358 only
  • P9.15 - INDEX on AM5729 only

/dev/bone/eqep/2a

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/bone_eqep2-00A0.dts
AM3358 eQEP2
AM5729 N/A'

  • P8.41 - A
  • P8.42 - B
  • P8.40 - STROBE
  • P8.39 - INDEX

McASP

TODO

PRU

The overlay situation for PRUs is a bit more complex than with other peripherals. The mechanism for loading, starting and stopping the PRUs can go through either UIO or RemoteProc.[4]

/dev/bone/pru/0.0 (eCAP)

Not sure where to put this as it doesn't really have it's own Linux control interface, just an overlay.
TODO: provide overlay, since it is a different pinctrl mode.
AM3358 PRUSS
AM5729 PRUSS1

  • P8.15

/dev/bone/pru/0.0

TODO
AM3358 PRU0
AM5729 PRUSS1, PRU0

PIN AM3358 AM5729
P8.11 out 15 I/O 4
P8.12 out 14 I/O 3
P8.15 in 15 see pru/0.1
P8.16 in 16 see pru/0.1
P8.17 - I/O 15
P9.15 - I/O 5
P9.24 in 16 -
P9.25 I/O 7 see pru/1.1
P9.26 see pru0.1 I/O 17
P9.27 I/O 5 see pru/0.1
P9.28 I/O 3 see pru/1.1
P9.29 I/O 1 see pru/1.1
P9.30 I/O 2 see pru/1.1
P9.31 I/O 0 see pru/1.1
P9.41 I/O 6 see pru/0.1
P9.42 I/O 4 see pru/1.1 or pru/2.0
USR0 - I/O 10
USR2 - I/O 8
USR3 - I/O 7
USR4 - I/O 0

/dev/bone/pru/0.1

TODO
AM3358 PRU1
AM5279 PRUSS1, PRU1

PIN AM3358 AM5729
P8.13 - I/O 7
P8.14 - I/O 9
P8.15 - I/O 16
P8.16 - I/O 18

/dev/bone/pru/1.0

TODO
AM3358 N/A
AM5729 PRUSS2, PRU0

  • P8.3 - I/O 10 (N/A on AM3358)
  • P8.4 - I/O 11 (N/A on AM3358)
  • P8.5 - I/O 5 (N/A on AM3358)
  • P8.6 - I/O 7 (N/A on AM3358)
  • P8.8 - I/O 20 (N/A on AM3358)

/dev/bone/pru/1.1

TODO
AM3358 N/A
AM5729 PRUSS2, PRU1

  • P8.7 - I/O 16 (N/A on AM3358)
  • P8.9 - I/O 6 (N/A on AM3358)
  • P8.10 - I/O 15 (N/A on AM3358)

GPIO

TODO
For each of the pins with a GPIO, there should be a symlink that comes from the names

Methodology

The methodology for applied in the kernel and software images to expose the software interfaces is to be documented here. The most fundamental elements are the device tree entries, including overlays, and udev rules.

Device Trees

udev rules [5]

10-of-symlink.rules[6]

#From: https://github.com/mvduin/py-uio/blob/master/etc/udev/rules.d/10-of-symlink.rules
# allow declaring a symlink for a device in DT
ATTR{device/of_node/symlink}!="", \
	ENV{OF_SYMLINK}="%s{device/of_node/symlink}"

ENV{OF_SYMLINK}!="", ENV{DEVNAME}!="", \
	SYMLINK+="%E{OF_SYMLINK}", \
	TAG+="systemd", ENV{SYSTEMD_ALIAS}+="/dev/%E{OF_SYMLINK}"

TBD

#Also courtesy of mvduin
# create symlinks for gpios exported to sysfs by DT
SUBSYSTEM=="gpio", ACTION=="add", TEST=="value", ATTR{label}!="sysfs", \
        RUN+="/bin/mkdir -p /dev/bone/gpio", \
        RUN+="/bin/ln -sT '/sys/class/gpio/%k' /dev/bone/gpio/%s{label}"

Verification

TODO: The steps used to verify all of these configurations is to be documented here. It will serve to document what has been tested, how to reproduce the configurations, and how to verify each major triannual release. All faults will be documented in the issue tracker.

References