pru_rproc on Linux 4.4

Alexander_Hiam · June 4, 2016, 2:52pm

I just put together some notes from my testing of pru_rproc on the BeagleBone running Linux 4.4 here:

https://gist.github.com/alexanderhiam/2c4187c710b2c409d8dde8c4015fe007

I’ll probably expand on that as I play with it more, but that should be enough to get you up and running.

Alexander_Hiam · June 4, 2016, 3:15pm

Unfortunately, it looks to me like TI has removed the ability to trigger firmware loading from Device Tree(?):

beagleboard/linux/blob/4.4/Documentation/devicetree/bindings/remoteproc/ti,pruss-remoteproc.txt

PRU-ICSS on TI SoCs
===================

Binding status: Unstable - Subject to changes to account for all sub-modules

The Programmable Real-Time Unit and Industrial Communication Subsystem
(PRU-ICSS) is present on various TI SoCs such as AM335x or AM437x. A
PRUSS consists of dual 32-bit RISC cores (Programmable Real-Time Units,
or PRUs), shared RAM, data and instruction RAMs, some internal peripheral
modules to facilitate industrial communication, and an interrupt controller.
The programmable nature of the PRUs provide flexibility to implement custom
peripheral interfaces, fast real-time responses, or specialized data handling.
The common peripheral modules include the following,
  - an Ethernet MII_RT module with two MII ports
  - an MDIO port to control external Ethernet PHYs
  - an Industrial Ethernet Peripheral (IEP) to manage/generate Industrial
    Ethernet functions
  - an Enhanced Capture Module (eCAP)
  - an Industrial Ethernet Timer with 7/9 capture and 16 compare events
  - a 16550-compatible UART to support PROFIBUS

This file has been truncated. show original

Note that the base DT does trigger the loading the the pru_rproc module:

github.com

beagleboard/linux/blob/4.4/arch/arm/boot/dts/am33xx.dtsi#L973


      
          
          			eqep1: eqep@0x48302180 {
          				compatible = "ti,am33xx-eqep";
          				reg = <0x48302180 0x80>;
          				clocks = <&l4ls_gclk>;
          				clock-names = "fck";
          				interrupt-parent = <&intc>;
          				interrupts = <88>;
          				status = "disabled";
          			};
          
          			ehrpwm1: pwm@48302200 {
          				compatible = "ti,am3352-ehrpwm",
          					     "ti,am33xx-ehrpwm";
          				#pwm-cells = <3>;
          				reg = <0x48302200 0x80>;
          				clocks = <&ehrpwm1_tbclk>, <&l4ls_gclk>;
          				clock-names = "tbclk", "fck";
          				status = "disabled";
          			};
          		};

github.com

beagleboard/linux/blob/4.4/drivers/remoteproc/pru_rproc.c#L897


      
          	dev_info(dev, "%s: removing rproc %s\n", __func__, rproc->name);
          
          	if (!pru->use_eth) {
          		if (list_empty(&pru->rproc->rvdevs)) {
          			dev_info(dev, "stopping the manually booted PRU core\n");
          			rproc_shutdown(pru->rproc);
          		}
          	}
          
          	mbox_free_channel(pru->mbox);
          
          	if ((of_machine_is_compatible("ti,am5718-idk") ||
          	     of_machine_is_compatible("ti,k2g-ice")) && pru->use_eth)
          		pruss_cfg_set_gpmux(pru->pruss, pru->id, PRUSS_GP_MUX_SEL_GP);
          
          	rproc_del(rproc);
          	rproc_put(rproc);
          
          	return 0;
          }

However, this seems to happen before the filesystem is populated, so no firmware gets loaded:

[ 3.622936] ti-pruss 4a300000.pruss: creating PRU cores and other child platform devices
[ 3.651714] remoteproc1: 4a334000.pru0 is available
[ 3.651740] remoteproc1: Note: remoteproc is still under development and considered experimental.
[ 3.651750] remoteproc1: THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn’t yet guaranteed.
[ 3.652029] remoteproc1: Direct firmware load for am335x-pru0-fw failed with error -2
[ 3.652050] remoteproc1: failed to load am335x-pru0-fw
[ 3.660836] pru-rproc 4a334000.pru0: booting the PRU core manually
[ 3.660863] remoteproc1: powering up 4a334000.pru0
[ 3.660998] remoteproc1: Direct firmware load for am335x-pru0-fw failed with error -2
[ 3.661016] remoteproc1: request_firmware failed: -2
[ 3.676161] pru-rproc 4a334000.pru0: rproc_boot failed
[ 3.699719] remoteproc1: releasing 4a334000.pru0
[ 3.699953] pru-rproc: probe of 4a334000.pru0 failed with error -2
[ 3.704799] remoteproc1: 4a338000.pru1 is available
[ 3.704824] remoteproc1: Note: remoteproc is still under development and considered experimental.
[ 3.704835] remoteproc1: THE BINARY FORMAT IS NOT YET FINALIZED, and backward compatibility isn’t yet guaranteed.
[ 3.705080] remoteproc1: Direct firmware load for am335x-pru1-fw failed with error -2
[ 3.705102] remoteproc1: failed to load am335x-pru1-fw
[ 3.711287] pru-rproc 4a338000.pru1: booting the PRU core manually
[ 3.711310] remoteproc1: powering up 4a338000.pru1
[ 3.711426] remoteproc1: Direct firmware load for am335x-pru1-fw failed with error -2
[ 3.711443] remoteproc1: request_firmware failed: -2
[ 3.722784] pru-rproc 4a338000.pru1: rproc_boot failed
[ 3.752492] remoteproc1: releasing 4a338000.pru1
[ 3.755009] pru-rproc: probe of 4a338000.pru1 failed with error -2

(/lib/firmware/am335x-pru0-fw does exist, and probing pru_rproc after booting does load it just fine).

So I guess there’s more to figure out…