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From:   nikita.shubin@maquefel.me
To:     nikita.shubin@maquefel.me
Cc:     Ohad Ben-Cohen <ohad@wizery.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        linux-remoteproc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 0/3] remoteproc: imx_rproc: add virtio support
Date:   Mon,  6 Apr 2020 14:33:07 +0300
Message-Id: <20200406113310.3041-1-nikita.shubin@maquefel.me>
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This patch set introduces virtio support for imx7d-m4 communication:

- support booting loaded vim imx-rproc firmware
- implement .kick method support using mailbox in imx-processor
- parse vdev0vring0, vdev0vring1, vdev0buffer memory regions required
for virtio_rpmsg_bus initialization

Regarding imx7d-m4 boot proccess

Citing ARM documentation:

At Reset, Cortex-M3 and Cortex-M4 processors always boot from a vector table at address zero.

"With uninitialized memory at address zero (for example, unprogrammed Flash or uninitialized RAM),
the processor will read a spurious initial Main Stack Pointer value from address zero and a spurious
code entry point (Reset vector) from address 0x4, possibly containing an illegal instruction
set state specifier (ESPR.T bit) in bit[0]."

So to successfully boot m4 coproc we need to write Stack Pointer and Program counter, i see no
obvious to get Stack Pointer value, so two ways exist ethier form a special elf section:

"
.loader :
  {
    LONG(__StackTop);
    LONG(Reset_Handler + 1);
  } > m_start
"

and put it at 0x0 address:

"
m_start               (RX)  : ORIGIN = 0x00000000, LENGTH = 0x00008000
"

Or (the way i've chosen) only put Entry Point at 0x04 and set stack as first instruction:

"
Reset_Handler:
	ldr   sp, =__stack      /* set stack pointer */
"

Regarding mailboxes and memory regions :

This code is heavily derived from stm32-rproc (i.e. copy pasted) and this fact needs to
reflected in commits, please tell me how to emphasize this fact.

Attaching succesful trace booting m4 (with Add rpmsg tty driver applied) :

[  143.240616] remoteproc remoteproc0: powering up imx-rproc
[  143.251768] remoteproc remoteproc0: Booting fw image huginn.elf, size 466876
[  143.251786] imx-rproc imx7d-cm4: iommu not present
[  143.251825] remoteproc remoteproc0: rsc: type 3
[  143.251837] remoteproc remoteproc0: vdev rsc: id 7, dfeatures 0x1, cfg len 0, 2 vrings
[  143.251924] remoteproc remoteproc0: vdev rsc: vring0: da 0xffffffff, qsz 16, align 16
[  143.251935] remoteproc remoteproc0: vdev rsc: vring1: da 0xffffffff, qsz 16, align 16
[  143.251955] imx-rproc imx7d-cm4: map memory: 0x00900000+20000
[  143.251987] imx-rproc imx7d-cm4: map memory: 0x00920000+2000
[  143.252003] imx-rproc imx7d-cm4: map memory: 0x00922000+2000
[  143.252020] remoteproc remoteproc0: phdr: type 1 da 0x20200000 memsz 0x240 filesz 0x240
[  143.252032] remoteproc remoteproc0: da = 0x20200000 len = 0x240 va = 0x(ptrval)
[  143.252043] remoteproc remoteproc0: phdr: type 1 da 0x20200240 memsz 0x5b38 filesz 0x5b38
[  143.252053] remoteproc remoteproc0: da = 0x20200240 len = 0x5b38 va = 0x(ptrval)
[  143.252105] remoteproc remoteproc0: phdr: type 1 da 0x20205d78 memsz 0x4b58 filesz 0x758
[  143.252115] remoteproc remoteproc0: da = 0x20205d78 len = 0x4b58 va = 0x(ptrval)
[  143.252159] remoteproc remoteproc0: da = 0x200006cc len = 0x8c va = 0x(ptrval)
[  143.252176] remoteproc remoteproc0: Started from 0x202002f5
[  143.252211]  imx7d-cm4#vdev0buffer: assigned reserved memory node vdev0buffer@00924000
[  143.252232] virtio virtio0: reset !
[  143.252241] virtio virtio0: status: 1
[  143.260567] virtio_rpmsg_bus virtio0: status: 3
[  143.260598] remoteproc remoteproc0: vring0: va c083c000 qsz 16 notifyid 0
[  143.260614] remoteproc remoteproc0: vring1: va c0872000 qsz 16 notifyid 1
[  143.260651] virtio_rpmsg_bus virtio0: buffers: va c0894000, dma 0x00924000
[  143.260666] Added buffer head 0 to (ptrval)
[  143.260674] Added buffer head 1 to (ptrval)
[  143.260680] Added buffer head 2 to (ptrval)
[  143.260686] Added buffer head 3 to (ptrval)
[  143.260692] Added buffer head 4 to (ptrval)
[  143.260697] Added buffer head 5 to (ptrval)
[  143.260703] Added buffer head 6 to (ptrval)
[  143.260709] Added buffer head 7 to (ptrval)
[  143.260715] Added buffer head 8 to (ptrval)
[  143.260721] Added buffer head 9 to (ptrval)
[  143.260727] Added buffer head 10 to (ptrval)
[  143.260733] Added buffer head 11 to (ptrval)
[  143.260738] Added buffer head 12 to (ptrval)
[  143.260744] Added buffer head 13 to (ptrval)
[  143.260750] Added buffer head 14 to (ptrval)
[  143.260756] Added buffer head 15 to (ptrval)
[  143.260771] virtio_rpmsg_bus virtio0: status: 7
[  143.260779] remoteproc remoteproc0: kicking vq index: 0
[  143.260788] remoteproc remoteproc0: sending message : vqid = 0
[  143.260802] imx_mu 30aa0000.mailbox: Send data on wrong channel type: 1
[  143.260810] virtio_rpmsg_bus virtio0: rpmsg host is online
[  143.261680]  imx7d-cm4#vdev0buffer: registered virtio0 (type 7)
[  143.261694] remoteproc remoteproc0: remote processor imx-rproc is now up
[  143.354880] remoteproc remoteproc0: vq index 0 is interrupted
[  143.354895] virtqueue callback for (ptrval) ((ptrval))
[  143.354912] virtio_rpmsg_bus virtio0: From: 0x0, To: 0x35, Len: 40, Flags: 0, Reserved: 0
[  143.354924] rpmsg_virtio RX: 00 00 00 00 35 00 00 00 00 00 00 00 28 00 00 00  ....5.......(...
[  143.354932] rpmsg_virtio RX: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00 00 00  rpmsg-tty-raw...
[  143.354939] rpmsg_virtio RX: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[  143.354945] rpmsg_virtio RX: 00 00 00 00 00 00 00 00                          ........
[  143.354956] NS announcement: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00 00 00  rpmsg-tty-raw...
[  143.354963] NS announcement: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[  143.354969] NS announcement: 00 00 00 00 00 00 00 00                          ........
[  143.354980] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-raw addr 0x0
[  143.356584] rpmsg_tty virtio0.rpmsg-tty-raw.-1.0: new channel: 0x400 -> 0x0 : ttyRPMSG0
[  143.356651] Added buffer head 0 to (ptrval)
[  143.356658] No more buffers in queue
[  143.356667] virtio_rpmsg_bus virtio0: Received 1 messages
[  143.404302] remoteproc remoteproc0: vq index 0 is interrupted
[  143.404319] virtqueue callback for (ptrval) ((ptrval))
[  143.404337] virtio_rpmsg_bus virtio0: From: 0x1, To: 0x35, Len: 40, Flags: 0, Reserved: 0
[  143.404350] rpmsg_virtio RX: 01 00 00 00 35 00 00 00 00 00 00 00 28 00 00 00  ....5.......(...
[  143.404391] rpmsg_virtio RX: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00 00 00  rpmsg-tty-raw...
[  143.404399] rpmsg_virtio RX: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[  143.404405] rpmsg_virtio RX: 01 00 00 00 00 00 00 00                          ........
[  143.404417] NS announcement: 72 70 6d 73 67 2d 74 74 79 2d 72 61 77 00 00 00  rpmsg-tty-raw...
[  143.404424] NS announcement: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[  143.404430] NS announcement: 01 00 00 00 00 00 00 00                          ........
[  143.404441] virtio_rpmsg_bus virtio0: creating channel rpmsg-tty-raw addr 0x1
[  143.411114] rpmsg_tty virtio0.rpmsg-tty-raw.-1.1: new channel: 0x401 -> 0x1 : ttyRPMSG1