ARM: dts: am335x-boneblack: add gpio-line-names
The BeagleBone Black has P8 and P9 headers [0] which expose many of the AM3358 ZCZ SoC balls to stacking expansion boards called "capes", or to other external connections like jumper wires connected to a breadboard. BeagleBone users will often refer to the "Cape Exanpsion Headers" pin diagram [1] as it is in the "Bone101" getting started tutorial. [2] Most of the P8 and P9 header pins can muxed to a GPIO line. The gpio-line-names describe which P8 or P9 pin that line goes to and the default mux for that P8 or P9 pin if it is not GPIO. For example, gpiochip 1 line 0 is connected to P8 header pin 25 (P8_25) however the default device tree has the corresponding BGA ball (ZCZ U7) muxed to mmc1_dat0 as it is used for the on-board eMMC chip. For that GPIO line to be used, one would need to modify the device tree to disable the eMMC and change the pin mux for that ball to GPIO mode. Some of the AM3358 ZCZ balls corresponding to GPIO lines are not routed to a P8 or P9 header, but are instead wired to some peripheral device like on-board eMMC, HDMI framer IC, or status LEDs. Those names are in brackets to denote those GPIO lines can not be used. Some GPIO lines are named "[NC]" as the corresponding balls are not routed to anything on the PCB. The goal for these names is to make it easier for a user viewing the output of gpioinfo to determine which P8 or P9 pin is connected to a GPIO line. The output of gpioinfo on a BeagleBone Black would be: gpiochip0 - 32 lines: line 0: "[ethernet]" unused input active-high line 1: "[ethernet]" unused input active-high line 2: "P9_22 [spi0_sclk]" unused input active-high line 3: "P9_21 [spi0_d0]" unused input active-high line 4: "P9_18 [spi0_d1]" unused input active-high line 5: "P9_17 [spi0_cs0]" unused input active-high line 6: "[sd card]" "cd" input active-low [used] line 7: "P9_42A [ecappwm0]" unused input active-high line 8: "P8_35 [hdmi]" unused input active-high line 9: "P8_33 [hdmi]" unused input active-high line 10: "P8_31 [hdmi]" unused input active-high line 11: "P8_32 [hdmi]" unused input active-high line 12: "P9_20 [i2c2_sda]" unused input active-high line 13: "P9_19 [i2c2_scl]" unused input active-high line 14: "P9_26 [uart1_rxd]" unused input active-high line 15: "P9_24 [uart1_txd]" unused input active-high line 16: "[ethernet]" unused input active-high line 17: "[ethernet]" unused input active-high line 18: "[usb]" unused input active-high line 19: "[hdmi]" unused input active-high line 20: "P9_41B" unused input active-high line 21: "[ethernet]" unused input active-high line 22: "P8_19 [ehrpwm2a]" unused input active-high line 23: "P8_13 [ehrpwm2b]" unused input active-high line 24: "[NC]" unused input active-high line 25: "[NC]" unused input active-high line 26: "P8_14" unused input active-high line 27: "P8_17" unused input active-high line 28: "[ethernet]" unused input active-high line 29: "[ethernet]" unused input active-high line 30: "P9_11 [uart4_rxd]" unused input active-high line 31: "P9_13 [uart4_txd]" unused input active-high gpiochip1 - 32 lines: line 0: "P8_25 [emmc]" unused input active-high line 1: "[emmc]" unused input active-high line 2: "P8_5 [emmc]" unused input active-high line 3: "P8_6 [emmc]" unused input active-high line 4: "P8_23 [emmc]" unused input active-high line 5: "P8_22 [emmc]" unused input active-high line 6: "P8_3 [emmc]" unused input active-high line 7: "P8_4 [emmc]" unused input active-high line 8: "[NC]" unused input active-high line 9: "[NC]" unused input active-high line 10: "[NC]" unused input active-high line 11: "[NC]" unused input active-high line 12: "P8_12" unused input active-high line 13: "P8_11" unused input active-high line 14: "P8_16" unused input active-high line 15: "P8_15" unused input active-high line 16: "P9_15A" unused input active-high line 17: "P9_23" unused input active-high line 18: "P9_14 [ehrpwm1a]" unused input active-high line 19: "P9_16 [ehrpwm1b]" unused input active-high line 20: "[emmc]" unused input active-high line 21: "[usr0 led]" "beaglebone:green:heartbeat" output active-high [used] line 22: "[usr1 led]" "beaglebone:green:mmc0" output active-high [used] line 23: "[usr2 led]" "beaglebone:green:usr2" output active-high [used] line 24: "[usr3 led]" "beaglebone:green:usr3" output active-high [used] line 25: "[hdmi]" "interrupt" input active-high [used] line 26: "[usb]" unused input active-high line 27: "[hdmi audio]" "enable" output active-high [used] line 28: "P9_12" unused input active-high line 29: "P8_26" unused input active-high line 30: "P8_21 [emmc]" unused input active-high line 31: "P8_20 [emmc]" unused input active-high gpiochip2 - 32 lines: line 0: "P9_15B" unused input active-high line 1: "P8_18" unused input active-high line 2: "P8_7" unused input active-high line 3: "P8_8" unused input active-high line 4: "P8_10" unused input active-high line 5: "P8_9" unused input active-high line 6: "P8_45 [hdmi]" unused input active-high line 7: "P8_46 [hdmi]" unused input active-high line 8: "P8_43 [hdmi]" unused input active-high line 9: "P8_44 [hdmi]" unused input active-high line 10: "P8_41 [hdmi]" unused input active-high line 11: "P8_42 [hdmi]" unused input active-high line 12: "P8_39 [hdmi]" unused input active-high line 13: "P8_40 [hdmi]" unused input active-high line 14: "P8_37 [hdmi]" unused input active-high line 15: "P8_38 [hdmi]" unused input active-high line 16: "P8_36 [hdmi]" unused input active-high line 17: "P8_34 [hdmi]" unused input active-high line 18: "[ethernet]" unused input active-high line 19: "[ethernet]" unused input active-high line 20: "[ethernet]" unused input active-high line 21: "[ethernet]" unused input active-high line 22: "P8_27 [hdmi]" unused input active-high line 23: "P8_29 [hdmi]" unused input active-high line 24: "P8_28 [hdmi]" unused input active-high line 25: "P8_30 [hdmi]" unused input active-high line 26: "[emmc]" unused input active-high line 27: "[emmc]" unused input active-high line 28: "[emmc]" unused input active-high line 29: "[emmc]" unused input active-high line 30: "[emmc]" unused input active-high line 31: "[emmc]" unused input active-high gpiochip3 - 32 lines: line 0: "[ethernet]" unused input active-high line 1: "[ethernet]" unused input active-high line 2: "[ethernet]" unused input active-high line 3: "[ethernet]" unused input active-high line 4: "[ethernet]" unused input active-high line 5: "[i2c0]" unused input active-high line 6: "[i2c0]" unused input active-high line 7: "[emu]" unused input active-high line 8: "[emu]" unused input active-high line 9: "[ethernet]" unused input active-high line 10: "[ethernet]" unused input active-high line 11: "[NC]" unused input active-high line 12: "[NC]" unused input active-high line 13: "[usb]" unused input active-high line 14: "P9_31 [spi1_sclk]" unused input active-high line 15: "P9_29 [spi1_d0]" unused input active-high line 16: "P9_30 [spi1_d1]" unused input active-high line 17: "P9_28 [spi1_cs0]" unused input active-high line 18: "P9_42B [ecappwm0]" unused input active-high line 19: "P9_27" unused input active-high line 20: "P9_41A" unused input active-high line 21: "P9_25" unused input active-high line 22: "[NC]" unused input active-high line 23: "[NC]" unused input active-high line 24: "[NC]" unused input active-high line 25: "[NC]" unused input active-high line 26: "[NC]" unused input active-high line 27: "[NC]" unused input active-high line 28: "[NC]" unused input active-high line 29: "[NC]" unused input active-high line 30: "[NC]" unused input active-high line 31: "[NC]" unused input active-high [0] https://git.io/JfgOd [1] https://beagleboard.org/capes [1] https://beagleboard.org/Support/bone101 [2] https://beagleboard.org/static/images/cape-headers.pngReviewed-by:Jason Kridner <jason@beagleboard.org> Reviewed-by:
Robert Nelson <robertcnelson@gmail.com> Signed-off-by:
Drew Fustini <drew@beagleboard.org> Signed-off-by:
Tony Lindgren <tony@atomide.com>
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