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This introduces a new "detached" state for remote processors that are deemed to be running at the time Linux boots and the infrastructure for "attaching" to these. It then introduces the support for performing this operation for the STM32 platform. The coredump functionality is moved out from the core file and gains support for an optional mode where the recovery phase awaits the notification from devcoredump that the dump should be released. This allows userspace to grab the coredump in scenarios where vmalloc space is too low for creating a complete copy of the coredump before handing this to devcoredump. A new character device based interface is introduced to allow tying the stoppage of a remote processor to the termination of a user space process. This is useful in situations when such process provides crucial resources/operations for the firmware running on the remote processor. The Texas Instrument K3 driver gains support for the C66x and C71x DSPs. Qualcomm remoteprocs gains support for stashing relocation information in IMEM, to aid post mortem debugging and the crash notification mechanism is generalized to be reusable in cases where loosely coupled drivers needs to know about the status of a remote processor. One such example is the IPA hardware block, which is jointly owned with the modem and migrated to this improved interface. It also introduces a number of bug fixes and debug improvements for the Qualcomm modem remoteproc driver. And it cleans up the inconsistent interface for remoteproc drivers to implement power management. -----BEGIN PGP SIGNATURE----- iQJPBAABCAA5FiEEBd4DzF816k8JZtUlCx85Pw2ZrcUFAl8yKn4bHGJqb3JuLmFu ZGVyc3NvbkBsaW5hcm8ub3JnAAoJEAsfOT8Nma3FwNQQAMH8rbJ1wY+FM5vYfchF IIruKUAuiUYf3Wtx96nRRM81nWQWE0+gh37CGdQ0J+5XMhtVVgHH5cIcTcTqHfAG J8rdkcFP4ntyLPa2qP5tPeMj0rqD/cHvzD10PyrJjvP12i9+0mJGR/nDHRRAhyg1 HMTfq5kQsIRt3SYnHrwzD3nvk+O6aEtyogjDX9VhQ3Qx62pKVLiPCUy4FIZ2XzY2 XvNdITqN1IbqMMEgWNLBrFbU8RDnFZgGUFjuVmy+9SalKifh1s0nmdDxmFihbbhj pltc8mLRabhkkdqctvz6nh85epkqmoA15WL+BTLDVIpQ4zSJxFeRq+yK5m3V5EzZ Ld5ukS3IYaLLFOT1OvwjUVbrSVYnb3SMFI6W2v8J/BouBzFzzfYaq4QmvW4GGPEw MWMoicpmZousVGfUREFkmYj/8XqfgoVZ8gpLVxNDuluFU5swjoAK2FfQet4KCf0d /+A77nWvcRuHFYLv8FAiAxxRY2Dnx8rPnIm8wNd4Nj9Lx7lhkVPRwCgBr4SyXX60 FAGqZmg5S0Q5JUVA1s76n/1jbDywr6+a9ez48izivck1eYqAwSOAtt57Ol4A9tEq OGX8bvnJBXM9mDOV2jRCOr3vfn9Y3kqn8ia20gNsmifUM6RkvvSzz4bdhwd0Aj2H 0PWNiyPI+OKV8L64Q4sASbDR =9cjt -----END PGP SIGNATURE----- Merge tag 'rproc-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc Pull remoteproc updates from Bjorn Andersson: "This introduces a new "detached" state for remote processors that are deemed to be running at the time Linux boots and the infrastructure for "attaching" to these. It then introduces the support for performing this operation for the STM32 platform. The coredump functionality is moved out from the core file and gains support for an optional mode where the recovery phase awaits the notification from devcoredump that the dump should be released. This allows userspace to grab the coredump in scenarios where vmalloc space is too low for creating a complete copy of the coredump before handing this to devcoredump. A new character device based interface is introduced to allow tying the stoppage of a remote processor to the termination of a user space process. This is useful in situations when such process provides crucial resources/operations for the firmware running on the remote processor. The Texas Instrument K3 driver gains support for the C66x and C71x DSPs. Qualcomm remoteprocs gains support for stashing relocation information in IMEM, to aid post mortem debugging and the crash notification mechanism is generalized to be reusable in cases where loosely coupled drivers needs to know about the status of a remote processor. One such example is the IPA hardware block, which is jointly owned with the modem and migrated to this improved interface. It also introduces a number of bug fixes and debug improvements for the Qualcomm modem remoteproc driver. And it cleans up the inconsistent interface for remoteproc drivers to implement power management" * tag 'rproc-v5.9' of git://git.kernel.org/pub/scm/linux/kernel/git/andersson/remoteproc: (56 commits) remoteproc: core: Register the character device interface remoteproc: Add remoteproc character device interface remoteproc: kill IPA notify code net: ipa: new notification infrastructure remoteproc: k3-dsp: Add support for C71x DSPs dt-bindings: remoteproc: k3-dsp: Update bindings for C71x DSPs remoteproc: k3-dsp: Add support for L2RAM loading on C66x DSPs remoteproc: k3-dsp: Add a remoteproc driver of K3 C66x DSPs dt-bindings: remoteproc: Add bindings for C66x DSPs on TI K3 SoCs remoteproc: k3: Add TI-SCI processor control helper functions remoteproc: Introduce rproc_of_parse_firmware() helper dt-bindings: arm: keystone: Add common TI SCI bindings remoteproc: qcom_q6v5_mss: Remove redundant running state remoteproc: qcom: q6v5: Update running state before requesting stop remoteproc: qcom_q6v5_mss: Add modem debug policy support remoteproc: qcom_q6v5_mss: Validate modem blob firmware size before load remoteproc: qcom_q6v5_mss: Validate MBA firmware size before load rpmsg: update documentation remoteproc: qcom_q6v5_mss: Add MBA log extraction support remoteproc: Add coredump debugfs entry ...
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341 lines
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============================================
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Remote Processor Messaging (rpmsg) Framework
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============================================
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.. note::
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This document describes the rpmsg bus and how to write rpmsg drivers.
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To learn how to add rpmsg support for new platforms, check out remoteproc.txt
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(also a resident of Documentation/).
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Introduction
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============
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Modern SoCs typically employ heterogeneous remote processor devices in
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asymmetric multiprocessing (AMP) configurations, which may be running
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different instances of operating system, whether it's Linux or any other
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flavor of real-time OS.
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OMAP4, for example, has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP.
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Typically, the dual cortex-A9 is running Linux in a SMP configuration,
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and each of the other three cores (two M3 cores and a DSP) is running
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its own instance of RTOS in an AMP configuration.
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Typically AMP remote processors employ dedicated DSP codecs and multimedia
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hardware accelerators, and therefore are often used to offload CPU-intensive
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multimedia tasks from the main application processor.
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These remote processors could also be used to control latency-sensitive
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sensors, drive random hardware blocks, or just perform background tasks
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while the main CPU is idling.
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Users of those remote processors can either be userland apps (e.g. multimedia
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frameworks talking with remote OMX components) or kernel drivers (controlling
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hardware accessible only by the remote processor, reserving kernel-controlled
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resources on behalf of the remote processor, etc..).
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Rpmsg is a virtio-based messaging bus that allows kernel drivers to communicate
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with remote processors available on the system. In turn, drivers could then
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expose appropriate user space interfaces, if needed.
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When writing a driver that exposes rpmsg communication to userland, please
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keep in mind that remote processors might have direct access to the
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system's physical memory and other sensitive hardware resources (e.g. on
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OMAP4, remote cores and hardware accelerators may have direct access to the
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physical memory, gpio banks, dma controllers, i2c bus, gptimers, mailbox
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devices, hwspinlocks, etc..). Moreover, those remote processors might be
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running RTOS where every task can access the entire memory/devices exposed
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to the processor. To minimize the risks of rogue (or buggy) userland code
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exploiting remote bugs, and by that taking over the system, it is often
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desired to limit userland to specific rpmsg channels (see definition below)
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it can send messages on, and if possible, minimize how much control
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it has over the content of the messages.
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Every rpmsg device is a communication channel with a remote processor (thus
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rpmsg devices are called channels). Channels are identified by a textual name
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and have a local ("source") rpmsg address, and remote ("destination") rpmsg
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address.
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When a driver starts listening on a channel, its rx callback is bound with
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a unique rpmsg local address (a 32-bit integer). This way when inbound messages
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arrive, the rpmsg core dispatches them to the appropriate driver according
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to their destination address (this is done by invoking the driver's rx handler
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with the payload of the inbound message).
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User API
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========
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::
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int rpmsg_send(struct rpmsg_channel *rpdev, void *data, int len);
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sends a message across to the remote processor on a given channel.
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The caller should specify the channel, the data it wants to send,
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and its length (in bytes). The message will be sent on the specified
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channel, i.e. its source and destination address fields will be
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set to the channel's src and dst addresses.
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In case there are no TX buffers available, the function will block until
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one becomes available (i.e. until the remote processor consumes
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a tx buffer and puts it back on virtio's used descriptor ring),
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or a timeout of 15 seconds elapses. When the latter happens,
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-ERESTARTSYS is returned.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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int rpmsg_sendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst);
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sends a message across to the remote processor on a given channel,
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to a destination address provided by the caller.
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The caller should specify the channel, the data it wants to send,
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its length (in bytes), and an explicit destination address.
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The message will then be sent to the remote processor to which the
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channel belongs, using the channel's src address, and the user-provided
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dst address (thus the channel's dst address will be ignored).
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In case there are no TX buffers available, the function will block until
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one becomes available (i.e. until the remote processor consumes
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a tx buffer and puts it back on virtio's used descriptor ring),
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or a timeout of 15 seconds elapses. When the latter happens,
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-ERESTARTSYS is returned.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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int rpmsg_send_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
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void *data, int len);
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sends a message across to the remote processor, using the src and dst
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addresses provided by the user.
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The caller should specify the channel, the data it wants to send,
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its length (in bytes), and explicit source and destination addresses.
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The message will then be sent to the remote processor to which the
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channel belongs, but the channel's src and dst addresses will be
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ignored (and the user-provided addresses will be used instead).
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In case there are no TX buffers available, the function will block until
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one becomes available (i.e. until the remote processor consumes
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a tx buffer and puts it back on virtio's used descriptor ring),
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or a timeout of 15 seconds elapses. When the latter happens,
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-ERESTARTSYS is returned.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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int rpmsg_trysend(struct rpmsg_channel *rpdev, void *data, int len);
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sends a message across to the remote processor on a given channel.
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The caller should specify the channel, the data it wants to send,
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and its length (in bytes). The message will be sent on the specified
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channel, i.e. its source and destination address fields will be
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set to the channel's src and dst addresses.
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In case there are no TX buffers available, the function will immediately
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return -ENOMEM without waiting until one becomes available.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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int rpmsg_trysendto(struct rpmsg_channel *rpdev, void *data, int len, u32 dst)
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sends a message across to the remote processor on a given channel,
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to a destination address provided by the user.
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The user should specify the channel, the data it wants to send,
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its length (in bytes), and an explicit destination address.
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The message will then be sent to the remote processor to which the
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channel belongs, using the channel's src address, and the user-provided
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dst address (thus the channel's dst address will be ignored).
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In case there are no TX buffers available, the function will immediately
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return -ENOMEM without waiting until one becomes available.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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int rpmsg_trysend_offchannel(struct rpmsg_channel *rpdev, u32 src, u32 dst,
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void *data, int len);
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sends a message across to the remote processor, using source and
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destination addresses provided by the user.
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The user should specify the channel, the data it wants to send,
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its length (in bytes), and explicit source and destination addresses.
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The message will then be sent to the remote processor to which the
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channel belongs, but the channel's src and dst addresses will be
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ignored (and the user-provided addresses will be used instead).
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In case there are no TX buffers available, the function will immediately
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return -ENOMEM without waiting until one becomes available.
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The function can only be called from a process context (for now).
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Returns 0 on success and an appropriate error value on failure.
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::
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struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
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rpmsg_rx_cb_t cb, void *priv,
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struct rpmsg_channel_info chinfo);
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every rpmsg address in the system is bound to an rx callback (so when
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inbound messages arrive, they are dispatched by the rpmsg bus using the
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appropriate callback handler) by means of an rpmsg_endpoint struct.
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This function allows drivers to create such an endpoint, and by that,
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bind a callback, and possibly some private data too, to an rpmsg address
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(either one that is known in advance, or one that will be dynamically
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assigned for them).
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Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
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is already created for them when they are probed by the rpmsg bus
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(using the rx callback they provide when they registered to the rpmsg bus).
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So things should just work for simple drivers: they already have an
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endpoint, their rx callback is bound to their rpmsg address, and when
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relevant inbound messages arrive (i.e. messages which their dst address
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equals to the src address of their rpmsg channel), the driver's handler
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is invoked to process it.
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That said, more complicated drivers might do need to allocate
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additional rpmsg addresses, and bind them to different rx callbacks.
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To accomplish that, those drivers need to call this function.
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Drivers should provide their channel (so the new endpoint would bind
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to the same remote processor their channel belongs to), an rx callback
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function, an optional private data (which is provided back when the
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rx callback is invoked), and an address they want to bind with the
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callback. If addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
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dynamically assign them an available rpmsg address (drivers should have
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a very good reason why not to always use RPMSG_ADDR_ANY here).
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Returns a pointer to the endpoint on success, or NULL on error.
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::
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void rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
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destroys an existing rpmsg endpoint. user should provide a pointer
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to an rpmsg endpoint that was previously created with rpmsg_create_ept().
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::
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int register_rpmsg_driver(struct rpmsg_driver *rpdrv);
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registers an rpmsg driver with the rpmsg bus. user should provide
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a pointer to an rpmsg_driver struct, which contains the driver's
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->probe() and ->remove() functions, an rx callback, and an id_table
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specifying the names of the channels this driver is interested to
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be probed with.
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::
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void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv);
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unregisters an rpmsg driver from the rpmsg bus. user should provide
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a pointer to a previously-registered rpmsg_driver struct.
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Returns 0 on success, and an appropriate error value on failure.
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Typical usage
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=============
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The following is a simple rpmsg driver, that sends an "hello!" message
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on probe(), and whenever it receives an incoming message, it dumps its
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content to the console.
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::
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/rpmsg.h>
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static void rpmsg_sample_cb(struct rpmsg_channel *rpdev, void *data, int len,
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void *priv, u32 src)
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{
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print_hex_dump(KERN_INFO, "incoming message:", DUMP_PREFIX_NONE,
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16, 1, data, len, true);
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}
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static int rpmsg_sample_probe(struct rpmsg_channel *rpdev)
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{
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int err;
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dev_info(&rpdev->dev, "chnl: 0x%x -> 0x%x\n", rpdev->src, rpdev->dst);
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/* send a message on our channel */
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err = rpmsg_send(rpdev, "hello!", 6);
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if (err) {
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pr_err("rpmsg_send failed: %d\n", err);
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return err;
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}
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return 0;
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}
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static void rpmsg_sample_remove(struct rpmsg_channel *rpdev)
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{
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dev_info(&rpdev->dev, "rpmsg sample client driver is removed\n");
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}
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static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
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{ .name = "rpmsg-client-sample" },
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{ },
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};
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MODULE_DEVICE_TABLE(rpmsg, rpmsg_driver_sample_id_table);
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static struct rpmsg_driver rpmsg_sample_client = {
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.drv.name = KBUILD_MODNAME,
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.id_table = rpmsg_driver_sample_id_table,
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.probe = rpmsg_sample_probe,
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.callback = rpmsg_sample_cb,
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.remove = rpmsg_sample_remove,
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};
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module_rpmsg_driver(rpmsg_sample_client);
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.. note::
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a similar sample which can be built and loaded can be found
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in samples/rpmsg/.
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Allocations of rpmsg channels
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=============================
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At this point we only support dynamic allocations of rpmsg channels.
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This is possible only with remote processors that have the VIRTIO_RPMSG_F_NS
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virtio device feature set. This feature bit means that the remote
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processor supports dynamic name service announcement messages.
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When this feature is enabled, creation of rpmsg devices (i.e. channels)
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is completely dynamic: the remote processor announces the existence of a
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remote rpmsg service by sending a name service message (which contains
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the name and rpmsg addr of the remote service, see struct rpmsg_ns_msg).
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This message is then handled by the rpmsg bus, which in turn dynamically
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creates and registers an rpmsg channel (which represents the remote service).
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If/when a relevant rpmsg driver is registered, it will be immediately probed
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by the bus, and can then start sending messages to the remote service.
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The plan is also to add static creation of rpmsg channels via the virtio
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config space, but it's not implemented yet.
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