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AM3358 device tree

Steve Ziuchkovski
Expert 1255 points
Other Parts Discussed in Thread: AM3358, TPS65218, TPS65910, TPS65217

We're developing a board based on the AM3358 SoC that will run Linux. We're going to have to develop a device tree for our board, which is something pretty new to myself.

We have the AM3358-evmsk evaluation module, and in TI's kernel source code is the device tree for this eval board. I'm guessing this is a good place to start for our board. Here are some questions, though:

  • What files should we include in our device tree to fully cover the peripherals that are inside the AM3358 SoC?
    • It looks like including am33xx.dtsi should bring in most things.
  • Is there a reason that dt-bindings/pwm/pwm.h is included in the EVMSK device tree, and not as part of the am33xx.dtsi file? The schematics of the eval board don't show any PWM devices other than the AM3358 itself.
  • Is there a ready-made device tree for the TPS65218 PMIC?
    • TI's kernel includes .dtsi files for the TPS65910 (on the eval board) and for the TPS65217.
    • Is the TPS65217 compatible, perhaps?
  • 0
    TI__Guru**** 393215 points

    Hi Steve,

    Steve Ziuchkovski said:
    Is there a reason that dt-bindings/pwm/pwm.h is included in the EVMSK device tree, and not as part of the am33xx.dtsi file? The schematics of the eval board don't show any PWM devices other than the AM3358 itself.

    Actually the Starter Kit uses one PWM for LCD backlight brightness control. This is signal LCD_BACKLIGHTEN on the schematics.

    Afraid I cannot answer the SW questions though, I'm not an expert.

  • 0 in reply to Biser Gatchev-XID
    Expert 1255 points

    Biser Gatchev-XID said:

    Afraid I cannot answer the SW questions though, I'm not an expert.

    Thanks Biser. Should I expect some sort of answer in this forum from someone else?

  • 0 in reply to Biser Gatchev-XID
    TI__Expert 4475 points

    Hi,

    To initialize your custom board you have to modify am335x-evmsk.dts - this is your main configuration file also am33xx.dtsi - this is a general configuration of peripherals. Also you can modify the arch/arm/mach-omap2/devices.c file - see the omap2_init_devices() procedure. If missing a ready made device tree for the TPS65218 PMIC in a official SDK this mean that not created yet. For a compatible I think rather not fully. There are some differences in a data sheet.

    BR
    Ivan

  • 0 in reply to Ivan Matrakov
    Expert 1255 points

    Ivan Matrakov said:

    If missing a ready made device tree for the TPS65218 PMIC in a official SDK this mean that not created yet. For a compatible I think rather not fully. There are some differences in a data sheet.

    Exactly what purpose does having the TPS* in the device tree serve? It this to allow easier control/configuration of the PMIC?

    The new PMIC has an I2C interface, and we can obviously connect this to the ARM and talk to it this way.