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Date: Fri, 10 May 2024 09:29:15 -0600
From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Andrew Davis <afd@ti.com>
Cc: Bjorn Andersson <andersson@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>, Nishanth Menon <nm@ti.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Tero Kristo <kristo@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Hari Nagalla <hnagalla@ti.com>, linux-remoteproc@vger.kernel.org,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v9 2/5] remoteproc: k3-m4: Add a remoteproc driver for
 M4F subsystem
Message-ID: <Zj49S4zadm4mDbmF@p14s>
References: <20240426191811.32414-1-afd@ti.com>
 <20240426191811.32414-3-afd@ti.com>
 <ZjlBrf2mxENSZb8E@p14s>
 <b66e8bbe-8228-401a-9bb8-848b2d132ca0@ti.com>
 <CANLsYkzZg+BCsn59aX5Uz7LtzYYbcmep3j64JFGN4A+eo1yxoA@mail.gmail.com>
 <e8315809-090a-4282-9306-24d878a108af@ti.com>
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In-Reply-To: <e8315809-090a-4282-9306-24d878a108af@ti.com>

On Thu, May 09, 2024 at 10:54:51AM -0500, Andrew Davis wrote:
> On 5/9/24 10:22 AM, Mathieu Poirier wrote:
> > On Wed, 8 May 2024 at 09:36, Andrew Davis <afd@ti.com> wrote:
> > > 
> > > On 5/6/24 3:46 PM, Mathieu Poirier wrote:
> > > > Good day,
> > > > 
> > > > I have started reviewing this patchset.  Comments will be scattered over
> > > > multiple days and as such, I will explicitly inform you when  am done with the
> > > > review.
> > > > 
> > > > On Fri, Apr 26, 2024 at 02:18:08PM -0500, Andrew Davis wrote:
> > > > > From: Martyn Welch <martyn.welch@collabora.com>
> > > > > 
> > > > > The AM62x and AM64x SoCs of the TI K3 family has a Cortex M4F core in
> > > > > the MCU domain. This core is typically used for safety applications in a
> > > > > stand alone mode. However, some application (non safety related) may
> > > > > want to use the M4F core as a generic remote processor with IPC to the
> > > > > host processor. The M4F core has internal IRAM and DRAM memories and are
> > > > > exposed to the system bus for code and data loading.
> > > > > 
> > > > > A remote processor driver is added to support this subsystem, including
> > > > > being able to load and boot the M4F core. Loading includes to M4F
> > > > > internal memories and predefined external code/data memories. The
> > > > > carve outs for external contiguous memory is defined in the M4F device
> > > > > node and should match with the external memory declarations in the M4F
> > > > > image binary. The M4F subsystem has two resets. One reset is for the
> > > > > entire subsystem i.e including the internal memories and the other, a
> > > > > local reset is only for the M4F processing core. When loading the image,
> > > > > the driver first releases the subsystem reset, loads the firmware image
> > > > > and then releases the local reset to let the M4F processing core run.
> > > > > 
> > > > > Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
> > > > > Signed-off-by: Hari Nagalla <hnagalla@ti.com>
> > > > > Signed-off-by: Andrew Davis <afd@ti.com>
> > > > > ---
> > > > >    drivers/remoteproc/Kconfig               |  13 +
> > > > >    drivers/remoteproc/Makefile              |   1 +
> > > > >    drivers/remoteproc/ti_k3_m4_remoteproc.c | 785 +++++++++++++++++++++++
> > > > >    3 files changed, 799 insertions(+)
> > > > >    create mode 100644 drivers/remoteproc/ti_k3_m4_remoteproc.c
> > > > > 
> > > > > diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
> > > > > index 48845dc8fa852..1a7c0330c91a9 100644
> > > > > --- a/drivers/remoteproc/Kconfig
> > > > > +++ b/drivers/remoteproc/Kconfig
> > > > > @@ -339,6 +339,19 @@ config TI_K3_DSP_REMOTEPROC
> > > > >         It's safe to say N here if you're not interested in utilizing
> > > > >         the DSP slave processors.
> > > > > 
> > > > > +config TI_K3_M4_REMOTEPROC
> > > > > +    tristate "TI K3 M4 remoteproc support"
> > > > > +    depends on ARCH_K3 || COMPILE_TEST
> > > > > +    select MAILBOX
> > > > > +    select OMAP2PLUS_MBOX
> > > > > +    help
> > > > > +      Say m here to support TI's M4 remote processor subsystems
> > > > > +      on various TI K3 family of SoCs through the remote processor
> > > > > +      framework.
> > > > > +
> > > > > +      It's safe to say N here if you're not interested in utilizing
> > > > > +      a remote processor.
> > > > > +
> > > > >    config TI_K3_R5_REMOTEPROC
> > > > >       tristate "TI K3 R5 remoteproc support"
> > > > >       depends on ARCH_K3
> > > > > diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
> > > > > index 91314a9b43cef..5ff4e2fee4abd 100644
> > > > > --- a/drivers/remoteproc/Makefile
> > > > > +++ b/drivers/remoteproc/Makefile
> > > > > @@ -37,5 +37,6 @@ obj-$(CONFIG_ST_REMOTEPROC)                += st_remoteproc.o
> > > > >    obj-$(CONFIG_ST_SLIM_REMOTEPROC)   += st_slim_rproc.o
> > > > >    obj-$(CONFIG_STM32_RPROC)          += stm32_rproc.o
> > > > >    obj-$(CONFIG_TI_K3_DSP_REMOTEPROC) += ti_k3_dsp_remoteproc.o
> > > > > +obj-$(CONFIG_TI_K3_M4_REMOTEPROC)   += ti_k3_m4_remoteproc.o
> > > > >    obj-$(CONFIG_TI_K3_R5_REMOTEPROC)  += ti_k3_r5_remoteproc.o
> > > > >    obj-$(CONFIG_XLNX_R5_REMOTEPROC)   += xlnx_r5_remoteproc.o
> > > > > diff --git a/drivers/remoteproc/ti_k3_m4_remoteproc.c b/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > > > > new file mode 100644
> > > > > index 0000000000000..0030e509f6b5d
> > > > > --- /dev/null
> > > > > +++ b/drivers/remoteproc/ti_k3_m4_remoteproc.c
> > > > > @@ -0,0 +1,785 @@
> > > > > +// SPDX-License-Identifier: GPL-2.0-only
> > > > > +/*
> > > > > + * TI K3 Cortex-M4 Remote Processor(s) driver
> > > > > + *
> > > > > + * Copyright (C) 2021-2024 Texas Instruments Incorporated - https://www.ti.com/
> > > > > + *  Hari Nagalla <hnagalla@ti.com>
> > > > > + */
> > > > > +
> > > > > +#include <linux/io.h>
> > > > > +#include <linux/mailbox_client.h>
> > > > > +#include <linux/module.h>
> > > > > +#include <linux/of_address.h>
> > > > > +#include <linux/of_reserved_mem.h>
> > > > > +#include <linux/platform_device.h>
> > > > > +#include <linux/remoteproc.h>
> > > > > +#include <linux/reset.h>
> > > > > +#include <linux/slab.h>
> > > > > +
> > > > > +#include "omap_remoteproc.h"
> > > > > +#include "remoteproc_internal.h"
> > > > > +#include "ti_sci_proc.h"
> > > > > +
> > > > > +/**
> > > > > + * struct k3_m4_rproc_mem - internal memory structure
> > > > > + * @cpu_addr: MPU virtual address of the memory region
> > > > > + * @bus_addr: Bus address used to access the memory region
> > > > > + * @dev_addr: Device address of the memory region from remote processor view
> > > > > + * @size: Size of the memory region
> > > > > + */
> > > > > +struct k3_m4_rproc_mem {
> > > > > +    void __iomem *cpu_addr;
> > > > > +    phys_addr_t bus_addr;
> > > > > +    u32 dev_addr;
> > > > > +    size_t size;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > + * struct k3_m4_rproc_mem_data - memory definitions for a remote processor
> > > > > + * @name: name for this memory entry
> > > > > + * @dev_addr: device address for the memory entry
> > > > > + */
> > > > > +struct k3_m4_rproc_mem_data {
> > > > > +    const char *name;
> > > > > +    const u32 dev_addr;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > + * struct k3_m4_rproc_dev_data - device data structure for a remote processor
> > > > > + * @mems: pointer to memory definitions for a remote processor
> > > > > + * @num_mems: number of memory regions in @mems
> > > > > + * @uses_lreset: flag to denote the need for local reset management
> > > > > + */
> > > > > +struct k3_m4_rproc_dev_data {
> > > > > +    const struct k3_m4_rproc_mem_data *mems;
> > > > > +    u32 num_mems;
> > > > > +    bool uses_lreset;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > + * struct k3_m4_rproc - k3 remote processor driver structure
> > > > > + * @dev: cached device pointer
> > > > > + * @rproc: remoteproc device handle
> > > > > + * @mem: internal memory regions data
> > > > > + * @num_mems: number of internal memory regions
> > > > > + * @rmem: reserved memory regions data
> > > > > + * @num_rmems: number of reserved memory regions
> > > > > + * @reset: reset control handle
> > > > > + * @data: pointer to device data
> > > > > + * @tsp: TI-SCI processor control handle
> > > > > + * @ti_sci: TI-SCI handle
> > > > > + * @ti_sci_id: TI-SCI device identifier
> > > > > + * @mbox: mailbox channel handle
> > > > > + * @client: mailbox client to request the mailbox channel
> > > > > + */
> > > > > +struct k3_m4_rproc {
> > > > > +    struct device *dev;
> > > > > +    struct rproc *rproc;
> > > > > +    struct k3_m4_rproc_mem *mem;
> > > > > +    int num_mems;
> > > > > +    struct k3_m4_rproc_mem *rmem;
> > > > > +    int num_rmems;
> > > > > +    struct reset_control *reset;
> > > > > +    const struct k3_m4_rproc_dev_data *data;
> > > > > +    struct ti_sci_proc *tsp;
> > > > > +    const struct ti_sci_handle *ti_sci;
> > > > > +    u32 ti_sci_id;
> > > > > +    struct mbox_chan *mbox;
> > > > > +    struct mbox_client client;
> > > > > +};
> > > > > +
> > > > > +/**
> > > > > + * k3_m4_rproc_mbox_callback() - inbound mailbox message handler
> > > > > + * @client: mailbox client pointer used for requesting the mailbox channel
> > > > > + * @data: mailbox payload
> > > > > + *
> > > > > + * This handler is invoked by the K3 mailbox driver whenever a mailbox
> > > > > + * message is received. Usually, the mailbox payload simply contains
> > > > > + * the index of the virtqueue that is kicked by the remote processor,
> > > > > + * and we let remoteproc core handle it.
> > > > > + *
> > > > > + * In addition to virtqueue indices, we also have some out-of-band values
> > > > > + * that indicate different events. Those values are deliberately very
> > > > > + * large so they don't coincide with virtqueue indices.
> > > > > + */
> > > > > +static void k3_m4_rproc_mbox_callback(struct mbox_client *client, void *data)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = container_of(client, struct k3_m4_rproc,
> > > > > +                                              client);
> > > > > +    struct device *dev = kproc->rproc->dev.parent;
> > > > > +    const char *name = kproc->rproc->name;
> > > > > +    u32 msg = (u32)(uintptr_t)(data);
> > > > > +
> > > > > +    dev_dbg(dev, "mbox msg: 0x%x\n", msg);
> > > > > +
> > > > > +    switch (msg) {
> > > > > +    case RP_MBOX_CRASH:
> > > > > +            /*
> > > > > +             * remoteproc detected an exception, but error recovery is not
> > > > > +             * supported. So, just log this for now
> > > > > +             */
> > > > > +            dev_err(dev, "K3 rproc %s crashed\n", name);
> > > > > +            break;
> > > > > +    case RP_MBOX_ECHO_REPLY:
> > > > > +            dev_info(dev, "received echo reply from %s\n", name);
> > > > > +            break;
> > > > > +    default:
> > > > > +            /* silently handle all other valid messages */
> > > > > +            if (msg >= RP_MBOX_READY && msg < RP_MBOX_END_MSG)
> > > > > +                    return;
> > > > > +            if (msg > kproc->rproc->max_notifyid) {
> > > > > +                    dev_dbg(dev, "dropping unknown message 0x%x", msg);
> > > > > +                    return;
> > > > > +            }
> > > > > +            /* msg contains the index of the triggered vring */
> > > > > +            if (rproc_vq_interrupt(kproc->rproc, msg) == IRQ_NONE)
> > > > > +                    dev_dbg(dev, "no message was found in vqid %d\n", msg);
> > > > > +    }
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Kick the remote processor to notify about pending unprocessed messages.
> > > > > + * The vqid usage is not used and is inconsequential, as the kick is performed
> > > > > + * through a simulated GPIO (a bit in an IPC interrupt-triggering register),
> > > > > + * the remote processor is expected to process both its Tx and Rx virtqueues.
> > > > > + */
> > > > > +static void k3_m4_rproc_kick(struct rproc *rproc, int vqid)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = rproc->dev.parent;
> > > > > +    u32 msg = (u32)vqid;
> > > > > +    int ret;
> > > > > +
> > > > > +    /* send the index of the triggered virtqueue in the mailbox payload */
> > > > > +    ret = mbox_send_message(kproc->mbox, (void *)(uintptr_t)msg);
> > > > > +    if (ret < 0)
> > > > > +            dev_err(dev, "failed to send mailbox message, status = %d\n",
> > > > > +                    ret);
> > > > > +}
> > > > > +
> > > > > +/* Put the remote processor into reset */
> > > > > +static int k3_m4_rproc_reset(struct k3_m4_rproc *kproc)
> > > > > +{
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = reset_control_assert(kproc->reset);
> > > > > +    if (ret) {
> > > > > +            dev_err(dev, "local-reset assert failed, ret = %d\n", ret);
> > > > > +            return ret;
> > > > > +    }
> > > > > +
> > > > > +    if (kproc->data->uses_lreset)
> > > > > +            return ret;
> > > > > +
> > > > > +    ret = kproc->ti_sci->ops.dev_ops.put_device(kproc->ti_sci,
> > > > > +                                                kproc->ti_sci_id);
> > > > > +    if (ret) {
> > > > > +            dev_err(dev, "module-reset assert failed, ret = %d\n", ret);
> > > > > +            if (reset_control_deassert(kproc->reset))
> > > > > +                    dev_warn(dev, "local-reset deassert back failed\n");
> > > > > +    }
> > > > > +
> > > > > +    return ret;
> > > > > +}
> > > > > +
> > > > > +/* Release the remote processor from reset */
> > > > > +static int k3_m4_rproc_release(struct k3_m4_rproc *kproc)
> > > > > +{
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    if (kproc->data->uses_lreset)
> > > > > +            goto lreset;
> > > > > +
> > > > > +    ret = kproc->ti_sci->ops.dev_ops.get_device(kproc->ti_sci,
> > > > > +                                                kproc->ti_sci_id);
> > > > > +    if (ret) {
> > > > > +            dev_err(dev, "module-reset deassert failed, ret = %d\n", ret);
> > > > > +            return ret;
> > > > > +    }
> > > > > +
> > > > > +lreset:
> > > > > +    ret = reset_control_deassert(kproc->reset);
> > > > > +    if (ret) {
> > > > > +            dev_err(dev, "local-reset deassert failed, ret = %d\n", ret);
> > > > > +            if (kproc->ti_sci->ops.dev_ops.put_device(kproc->ti_sci,
> > > > > +                                                      kproc->ti_sci_id))
> > > > > +                    dev_warn(dev, "module-reset assert back failed\n");
> > > > > +    }
> > > > > +
> > > > > +    return ret;
> > > > > +}
> > > > > +
> > > > > +static int k3_m4_rproc_request_mbox(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct mbox_client *client = &kproc->client;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    client->dev = dev;
> > > > > +    client->tx_done = NULL;
> > > > > +    client->rx_callback = k3_m4_rproc_mbox_callback;
> > > > > +    client->tx_block = false;
> > > > > +    client->knows_txdone = false;
> > > > > +
> > > > > +    kproc->mbox = mbox_request_channel(client, 0);
> > > > > +    if (IS_ERR(kproc->mbox)) {
> > > > > +            ret = -EBUSY;
> > > > > +            dev_err(dev, "mbox_request_channel failed: %ld\n",
> > > > > +                    PTR_ERR(kproc->mbox));
> > > > > +            return ret;
> > > > > +    }
> > > > > +
> > > > > +    /*
> > > > > +     * Ping the remote processor, this is only for sanity-sake for now;
> > > > > +     * there is no functional effect whatsoever.
> > > > > +     *
> > > > > +     * Note that the reply will _not_ arrive immediately: this message
> > > > > +     * will wait in the mailbox fifo until the remote processor is booted.
> > > > > +     */
> > > > > +    ret = mbox_send_message(kproc->mbox, (void *)RP_MBOX_ECHO_REQUEST);
> > > > > +    if (ret < 0) {
> > > > > +            dev_err(dev, "mbox_send_message failed: %d\n", ret);
> > > > > +            mbox_free_channel(kproc->mbox);
> > > > > +            return ret;
> > > > > +    }
> > > > > +
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * The M4 cores have a local reset that affects only the CPU, and a
> > > > > + * generic module reset that powers on the device and allows the internal
> > > > > + * memories to be accessed while the local reset is asserted. This function is
> > > > > + * used to release the global reset on remote cores to allow loading into the
> > > > > + * internal RAMs. The .prepare() ops is invoked by remoteproc core before any
> > > > > + * firmware loading, and is followed by the .start() ops after loading to
> > > > > + * actually let the remote cores to run. This callback is invoked only in
> > > > > + * remoteproc mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_prepare(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = kproc->ti_sci->ops.dev_ops.get_device(kproc->ti_sci,
> > > > > +                                                kproc->ti_sci_id);
> > > > > +    if (ret)
> > > > > +            dev_err(dev, "module-reset deassert failed, cannot enable internal RAM loading, ret = %d\n",
> > > > > +                    ret);
> > > > > +
> > > > > +    return ret;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * This function implements the .unprepare() ops and performs the complimentary
> > > > > + * operations to that of the .prepare() ops. The function is used to assert the
> > > > > + * global reset on applicable cores. This completes the second portion of
> > > > > + * powering down the remote core. The cores themselves are only halted in the
> > > > > + * .stop() callback through the local reset, and the .unprepare() ops is invoked
> > > > > + * by the remoteproc core after the remoteproc is stopped to balance the global
> > > > > + * reset. This callback is invoked only in remoteproc mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_unprepare(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = kproc->ti_sci->ops.dev_ops.put_device(kproc->ti_sci,
> > > > > +                                                kproc->ti_sci_id);
> > > > > +    if (ret)
> > > > > +            dev_err(dev, "module-reset assert failed, ret = %d\n", ret);
> > > > > +
> > > > > +    return ret;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * This function implements the .get_loaded_rsc_table() callback and is used
> > > > > + * to provide the resource table for a booted remote processor in IPC-only
> > > > > + * mode. The remote processor firmwares follow a design-by-contract approach
> > > > > + * and are expected to have the resource table at the base of the DDR region
> > > > > + * reserved for firmware usage. This provides flexibility for the remote
> > > > > + * processor to be booted by different bootloaders that may or may not have the
> > > > > + * ability to publish the resource table address and size through a DT
> > > > > + * property.
> > > > > + */
> > > > > +static struct resource_table *k3_m4_get_loaded_rsc_table(struct rproc *rproc,
> > > > > +                                                     size_t *rsc_table_sz)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +
> > > > > +    if (!kproc->rmem[0].cpu_addr) {
> > > > > +            dev_err(dev, "memory-region #1 does not exist, loaded rsc table can't be found");
> > > > > +            return ERR_PTR(-ENOMEM);
> > > > > +    }
> > > > > +
> > > > > +    /*
> > > > > +     * NOTE: The resource table size is currently hard-coded to a maximum
> > > > > +     * of 256 bytes. The most common resource table usage for K3 firmwares
> > > > > +     * is to only have the vdev resource entry and an optional trace entry.
> > > > > +     * The exact size could be computed based on resource table address, but
> > > > > +     * the hard-coded value suffices to support the IPC-only mode.
> > > > > +     */
> > > > > +    *rsc_table_sz = 256;
> > > > > +    return (__force struct resource_table *)kproc->rmem[0].cpu_addr;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Custom function to translate a remote processor device address (internal
> > > > > + * RAMs only) to a kernel virtual address.  The remote processors can access
> > > > > + * their RAMs at either an internal address visible only from a remote
> > > > > + * processor, or at the SoC-level bus address. Both these addresses need to be
> > > > > + * looked through for translation. The translated addresses can be used either
> > > > > + * by the remoteproc core for loading (when using kernel remoteproc loader), or
> > > > > + * by any rpmsg bus drivers.
> > > > > + */
> > > > > +static void *k3_m4_rproc_da_to_va(struct rproc *rproc, u64 da, size_t len, bool *is_iomem)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    void __iomem *va = NULL;
> > > > > +    phys_addr_t bus_addr;
> > > > > +    u32 dev_addr, offset;
> > > > > +    size_t size;
> > > > > +    int i;
> > > > > +
> > > > > +    if (len == 0)
> > > > > +            return NULL;
> > > > > +
> > > > > +    for (i = 0; i < kproc->num_mems; i++) {
> > > > > +            bus_addr = kproc->mem[i].bus_addr;
> > > > > +            dev_addr = kproc->mem[i].dev_addr;
> > > > > +            size = kproc->mem[i].size;
> > > > > +
> > > > > +            /* handle M4-view addresses */
> > > > > +            if (da >= dev_addr && ((da + len) <= (dev_addr + size))) {
> > > > > +                    offset = da - dev_addr;
> > > > > +                    va = kproc->mem[i].cpu_addr + offset;
> > > > > +                    return (__force void *)va;
> > > > > +            }
> > > > > +
> > > > > +            /* handle SoC-view addresses */
> > > > > +            if (da >= bus_addr && ((da + len) <= (bus_addr + size))) {
> > > > > +                    offset = da - bus_addr;
> > > > > +                    va = kproc->mem[i].cpu_addr + offset;
> > > > > +                    return (__force void *)va;
> > > > > +            }
> > > > > +    }
> > > > > +
> > > > > +    /* handle static DDR reserved memory regions */
> > > > > +    for (i = 0; i < kproc->num_rmems; i++) {
> > > > > +            dev_addr = kproc->rmem[i].dev_addr;
> > > > > +            size = kproc->rmem[i].size;
> > > > > +
> > > > > +            if (da >= dev_addr && ((da + len) <= (dev_addr + size))) {
> > > > > +                    offset = da - dev_addr;
> > > > > +                    va = kproc->rmem[i].cpu_addr + offset;
> > > > > +                    return (__force void *)va;
> > > > > +            }
> > > > > +    }
> > > > > +
> > > > > +    return NULL;
> > > > > +}
> > > > > +
> > > > > +static int k3_m4_rproc_of_get_memories(struct platform_device *pdev,
> > > > > +                                   struct k3_m4_rproc *kproc)
> > > > > +{
> > > > > +    const struct k3_m4_rproc_dev_data *data = kproc->data;
> > > > > +    struct device *dev = &pdev->dev;
> > > > > +    struct resource *res;
> > > > > +    int num_mems = 0;
> > > > > +    int i;
> > > > > +
> > > > > +    num_mems = kproc->data->num_mems;
> > > > > +    kproc->mem = devm_kcalloc(kproc->dev, num_mems,
> > > > > +                              sizeof(*kproc->mem), GFP_KERNEL);
> > > > > +    if (!kproc->mem)
> > > > > +            return -ENOMEM;
> > > > > +
> > > > > +    for (i = 0; i < num_mems; i++) {
> > > > > +            res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> > > > > +                                               data->mems[i].name);
> > > > > +            if (!res) {
> > > > > +                    dev_err(dev, "found no memory resource for %s\n",
> > > > > +                            data->mems[i].name);
> > > > > +                    return -EINVAL;
> > > > > +            }
> > > > > +            if (!devm_request_mem_region(dev, res->start,
> > > > > +                                         resource_size(res),
> > > > > +                                         dev_name(dev))) {
> > > > > +                    dev_err(dev, "could not request %s region for resource\n",
> > > > > +                            data->mems[i].name);
> > > > > +                    return -EBUSY;
> > > > > +            }
> > > > > +
> > > > > +            kproc->mem[i].cpu_addr = devm_ioremap_wc(dev, res->start,
> > > > > +                                                     resource_size(res));
> > > > > +            if (!kproc->mem[i].cpu_addr) {
> > > > > +                    dev_err(dev, "failed to map %s memory\n",
> > > > > +                            data->mems[i].name);
> > > > > +                    return -ENOMEM;
> > > > > +            }
> > > > > +            kproc->mem[i].bus_addr = res->start;
> > > > > +            kproc->mem[i].dev_addr = data->mems[i].dev_addr;
> > > > > +            kproc->mem[i].size = resource_size(res);
> > > > > +
> > > > > +            dev_dbg(dev, "memory %8s: bus addr %pa size 0x%zx va %pK da 0x%x\n",
> > > > > +                    data->mems[i].name, &kproc->mem[i].bus_addr,
> > > > > +                    kproc->mem[i].size, kproc->mem[i].cpu_addr,
> > > > > +                    kproc->mem[i].dev_addr);
> > > > > +    }
> > > > > +    kproc->num_mems = num_mems;
> > > > > +
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +static void k3_m4_rproc_dev_mem_release(void *data)
> > > > > +{
> > > > > +    struct device *dev = data;
> > > > > +
> > > > > +    of_reserved_mem_device_release(dev);
> > > > > +}
> > > > > +
> > > > > +static int k3_m4_reserved_mem_init(struct k3_m4_rproc *kproc)
> > > > > +{
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    struct device_node *np = dev->of_node;
> > > > > +    struct device_node *rmem_np;
> > > > > +    struct reserved_mem *rmem;
> > > > > +    int num_rmems;
> > > > > +    int ret, i;
> > > > > +
> > > > > +    num_rmems = of_property_count_elems_of_size(np, "memory-region",
> > > > > +                                                sizeof(phandle));
> > > > > +    if (num_rmems < 0) {
> > > > > +            dev_err(dev, "device does not reserved memory regions (%pe)\n",
> > > > > +                    ERR_PTR(num_rmems));
> > > > > +            return -EINVAL;
> > > > > +    }
> > > > > +    if (num_rmems < 2) {
> > > > > +            dev_err(dev, "device needs at least two memory regions to be defined, num = %d\n",
> > > > > +                    num_rmems);
> > > > > +            return -EINVAL;
> > > > > +    }
> > > > > +
> > > > > +    /* use reserved memory region 0 for vring DMA allocations */
> > > > > +    ret = of_reserved_mem_device_init_by_idx(dev, np, 0);
> > > > > +    if (ret) {
> > > > > +            dev_err(dev, "device cannot initialize DMA pool (%pe)\n",
> > > > > +                    ERR_PTR(ret));
> > > > > +            return ret;
> > > > > +    }
> > > > > +    ret = devm_add_action_or_reset(dev, k3_m4_rproc_dev_mem_release, dev);
> > > > > +    if (ret)
> > > > > +            return ret;
> > > > > +
> > > > > +    num_rmems--;
> > > > > +    kproc->rmem = devm_kcalloc(dev, num_rmems, sizeof(*kproc->rmem), GFP_KERNEL);
> > > > > +    if (!kproc->rmem)
> > > > > +            return -ENOMEM;
> > > > > +
> > > > > +    /* use remaining reserved memory regions for static carveouts */
> > > > > +    for (i = 0; i < num_rmems; i++) {
> > > > > +            rmem_np = of_parse_phandle(np, "memory-region", i + 1);
> > > > > +            if (!rmem_np)
> > > > > +                    return -EINVAL;
> > > > > +
> > > > > +            rmem = of_reserved_mem_lookup(rmem_np);
> > > > > +            if (!rmem) {
> > > > > +                    of_node_put(rmem_np);
> > > > > +                    return -EINVAL;
> > > > > +            }
> > > > > +            of_node_put(rmem_np);
> > > > > +
> > > > > +            kproc->rmem[i].bus_addr = rmem->base;
> > > > > +            /* 64-bit address regions currently not supported */
> > > > > +            kproc->rmem[i].dev_addr = (u32)rmem->base;
> > > > > +            kproc->rmem[i].size = rmem->size;
> > > > > +            kproc->rmem[i].cpu_addr = devm_ioremap_wc(dev, rmem->base, rmem->size);
> > > > > +            if (!kproc->rmem[i].cpu_addr) {
> > > > > +                    dev_err(dev, "failed to map reserved memory#%d at %pa of size %pa\n",
> > > > > +                            i + 1, &rmem->base, &rmem->size);
> > > > > +                    return -ENOMEM;
> > > > > +            }
> > > > > +
> > > > > +            dev_dbg(dev, "reserved memory%d: bus addr %pa size 0x%zx va %pK da 0x%x\n",
> > > > > +                    i + 1, &kproc->rmem[i].bus_addr,
> > > > > +                    kproc->rmem[i].size, kproc->rmem[i].cpu_addr,
> > > > > +                    kproc->rmem[i].dev_addr);
> > > > > +    }
> > > > > +    kproc->num_rmems = num_rmems;
> > > > > +
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +static struct ti_sci_proc *k3_m4_rproc_of_get_tsp(struct device *dev,
> > > > > +                                              const struct ti_sci_handle *sci)
> > > > > +{
> > > > > +    struct ti_sci_proc *tsp;
> > > > > +    u32 temp[2];
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = of_property_read_u32_array(dev->of_node, "ti,sci-proc-ids",
> > > > > +                                     temp, 2);
> > > > > +    if (ret < 0)
> > > > > +            return ERR_PTR(ret);
> > > > > +
> > > > > +    tsp = devm_kzalloc(dev, sizeof(*tsp), GFP_KERNEL);
> > > > > +    if (!tsp)
> > > > > +            return ERR_PTR(-ENOMEM);
> > > > > +
> > > > > +    tsp->dev = dev;
> > > > > +    tsp->sci = sci;
> > > > > +    tsp->ops = &sci->ops.proc_ops;
> > > > > +    tsp->proc_id = temp[0];
> > > > > +    tsp->host_id = temp[1];
> > > > > +
> > > > > +    return tsp;
> > > > > +}
> > > > > +
> > > > > +static void k3_m4_release_tsp(void *data)
> > > > > +{
> > > > > +    struct ti_sci_proc *tsp = data;
> > > > > +
> > > > > +    ti_sci_proc_release(tsp);
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Power up the M4F remote processor.
> > > > > + *
> > > > > + * This function will be invoked only after the firmware for this rproc
> > > > > + * was loaded, parsed successfully, and all of its resource requirements
> > > > > + * were met. This callback is invoked only in remoteproc mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_start(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = k3_m4_rproc_request_mbox(rproc);
> > > > > +    if (ret)
> > > > > +            return ret;
> > > > > +
> > > > > +    ret = k3_m4_rproc_release(kproc);
> > > > > +    if (ret)
> > > > > +            goto put_mbox;
> > > > > +
> > > > > +    return 0;
> > > > > +
> > > > > +put_mbox:
> > > > > +    mbox_free_channel(kproc->mbox);
> > > > > +    return ret;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Stop the M4 remote processor.
> > > > > + *
> > > > > + * This function puts the M4 processor into reset, and finishes processing
> > > > > + * of any pending messages. This callback is invoked only in remoteproc mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_stop(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +
> > > > > +    mbox_free_channel(kproc->mbox);
> > > > > +
> > > > > +    k3_m4_rproc_reset(kproc);
> > > > > +
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Attach to a running M4 remote processor (IPC-only mode)
> > > > > + *
> > > > > + * This rproc attach callback only needs to request the mailbox, the remote
> > > > > + * processor is already booted, so there is no need to issue any TI-SCI
> > > > > + * commands to boot the M4 core. This callback is used only in IPC-only mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_attach(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +    int ret;
> > > > > +
> > > > > +    ret = k3_m4_rproc_request_mbox(rproc);
> > > > > +    if (ret)
> > > > > +            return ret;
> > > > > +
> > > > > +    dev_info(dev, "M4 initialized in IPC-only mode\n");
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +/*
> > > > > + * Detach from a running M4 remote processor (IPC-only mode)
> > > > > + *
> > > > > + * This rproc detach callback performs the opposite operation to attach callback
> > > > > + * and only needs to release the mailbox, the M4 core is not stopped and will
> > > > > + * be left to continue to run its booted firmware. This callback is invoked only in
> > > > > + * IPC-only mode.
> > > > > + */
> > > > > +static int k3_m4_rproc_detach(struct rproc *rproc)
> > > > > +{
> > > > > +    struct k3_m4_rproc *kproc = rproc->priv;
> > > > > +    struct device *dev = kproc->dev;
> > > > > +
> > > > > +    mbox_free_channel(kproc->mbox);
> > > > > +    dev_info(dev, "M4 deinitialized in IPC-only mode\n");
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +static const struct rproc_ops k3_m4_rproc_ops = {
> > > > > +    .start          = k3_m4_rproc_start,
> > > > > +    .stop           = k3_m4_rproc_stop,
> > > > > +    .attach         = k3_m4_rproc_attach,
> > > > > +    .detach         = k3_m4_rproc_detach,
> > > > > +    .kick           = k3_m4_rproc_kick,
> > > > > +    .da_to_va       = k3_m4_rproc_da_to_va,
> > > > > +    .get_loaded_rsc_table = k3_m4_get_loaded_rsc_table,
> > > > > +};
> > > > > +
> > > > > +static int k3_m4_rproc_probe(struct platform_device *pdev)
> > > > > +{
> > > > > +    struct device *dev = &pdev->dev;
> > > > > +    struct device_node *np = dev->of_node;
> > > > > +    const struct k3_m4_rproc_dev_data *data;
> > > > > +    struct k3_m4_rproc *kproc;
> > > > > +    struct rproc *rproc;
> > > > > +    const char *fw_name;
> > > > > +    bool r_state = false;
> > > > > +    bool p_state = false;
> > > > > +    int ret = 0;
> > > > > +
> > > > > +    data = device_get_match_data(dev);
> > > > > +    if (!data)
> > > > > +            return -ENODEV;
> > > > > +
> > > > > +    ret = rproc_of_parse_firmware(dev, 0, &fw_name);
> > > > > +    if (ret)
> > > > > +            return dev_err_probe(dev, ret, "failed to parse firmware-name property\n");
> > > > > +
> > > > > +    rproc = devm_rproc_alloc(dev, dev_name(dev), &k3_m4_rproc_ops, fw_name,
> > > > > +                             sizeof(*kproc));
> > > > > +    if (!rproc)
> > > > > +            return -ENOMEM;
> > > > > +
> > > > > +    rproc->has_iommu = false;
> > > > > +    rproc->recovery_disabled = true;
> > > > > +    if (data->uses_lreset) {
> > > > > +            rproc->ops->prepare = k3_m4_rproc_prepare;
> > > > > +            rproc->ops->unprepare = k3_m4_rproc_unprepare;
> > > > > +    }
> > > > > +    kproc = rproc->priv;
> > > > > +    kproc->rproc = rproc;
> > > > > +    kproc->dev = dev;
> > > > > +    kproc->data = data;
> > > > > +
> > > > > +    kproc->ti_sci = devm_ti_sci_get_by_phandle(dev, "ti,sci");
> > > > > +    if (IS_ERR(kproc->ti_sci))
> > > > > +            return dev_err_probe(dev, PTR_ERR(kproc->ti_sci),
> > > > > +                                 "failed to get ti-sci handle\n");
> > > > > +
> > > > > +    ret = of_property_read_u32(np, "ti,sci-dev-id", &kproc->ti_sci_id);
> > > > > +    if (ret)
> > > > > +            return dev_err_probe(dev, ret, "missing 'ti,sci-dev-id' property\n");
> > > > > +
> > > > > +    kproc->reset = devm_reset_control_get_exclusive(dev, NULL);
> > > > > +    if (IS_ERR(kproc->reset))
> > > > > +            return dev_err_probe(dev, PTR_ERR(kproc->reset), "failed to get reset\n");
> > > > 
> > > > What happens when devm_reset_control_get_exclusive() returns NULL?
> > > > 
> > > 
> > > Only the _optional_ version of this fuction can return NULL, this fuction
> > > will always return an error if the reset cannot be taken.
> > > 
> > 
> > What does optional mean?  Regardless, it's only a matter of time
> > before some automated tool starts complaining.
> > 
> 
> The "optional" versions of these reset_get functions (like reset_control_get_optional)
> will return NULL if the reset cannot be found. All the other reset_control_*() functions
> are built to take NULL as an argument without issue. That way if `kproc->reset`
> was set to NULL there is no failure (other than the reset wouldn't work, but as said,
> since this is not the optional version of this function, not finding the reset
> would return an error, never NULL).
>

After following the "optional" parameter in the reset subsystem, I agree with
your assessment.

> And, as NULL is a valid value for kproc->reset to have, no automated tool should ever
> complain (and if it did, the tool would need fixed as NULL is valid here).
>

All the functions using ->reset can handle a NULL value, so we are also good on
that front.

> > > > > +
> > > > > +    kproc->tsp = k3_m4_rproc_of_get_tsp(dev, kproc->ti_sci);
> > > > > +    if (IS_ERR(kproc->tsp))
> > > > > +            return dev_err_probe(dev, PTR_ERR(kproc->tsp),
> > > > > +                                 "failed to construct ti-sci proc control\n");
> > > > > +
> > > > > +    ret = ti_sci_proc_request(kproc->tsp);
> > > > > +    if (ret < 0)
> > > > > +            return dev_err_probe(dev, ret, "ti_sci_proc_request failed\n");
> > > > > +    ret = devm_add_action_or_reset(dev, k3_m4_release_tsp, kproc->tsp);
> > > > > +    if (ret)
> > > > > +            return ret;
> > > > > +
> > > > > +    ret = k3_m4_rproc_of_get_memories(pdev, kproc);
> > > > > +    if (ret)
> > > > > +            return ret;
> > > > > +
> > > > > +    ret = k3_m4_reserved_mem_init(kproc);
> > > > > +    if (ret)
> > > > > +            return dev_err_probe(dev, ret, "reserved memory init failed\n");
> > > > > +
> > > > > +    ret = kproc->ti_sci->ops.dev_ops.is_on(kproc->ti_sci, kproc->ti_sci_id,
> > > > > +                                           &r_state, &p_state);
> > > > > +    if (ret)
> > > > > +            return dev_err_probe(dev, ret,
> > > > > +                                 "failed to get initial state, mode cannot be determined\n");
> > > > > +
> > > > > +    /* configure devices for either remoteproc or IPC-only mode */
> > > > > +    if (p_state) {
> > > > > +            dev_info(dev, "configured M4 for IPC-only mode\n");
> > > > > +            rproc->state = RPROC_DETACHED;
> > > > > +            /* override rproc ops with only required IPC-only mode ops */
> > > > > +            rproc->ops->prepare = NULL;
> > > > > +            rproc->ops->unprepare = NULL;
> > > > > +            rproc->ops->start = NULL;
> > > > > +            rproc->ops->stop = NULL;
> > > > > +            rproc->ops->attach = k3_m4_rproc_attach;
> > > > > +            rproc->ops->detach = k3_m4_rproc_detach;
> > > > > +            rproc->ops->get_loaded_rsc_table = k3_m4_get_loaded_rsc_table;
> > > > 
> > > > Why are the last 3 assignment needed when they are already set in the
> > > > declaration of k3_m4_rproc_ops?
> > > > 
> > > 
> > > Good point, seems none of these overrides should be needed, start()/stop()
> > > are not called for ATTCHED/DETACHED cores anyway, opposite is true for attach()/detach().
> > > 
> > > I'll drop these overrides.
> > > 
> > > > > +    } else {
> > > > > +            dev_info(dev, "configured M4 for remoteproc mode\n");
> > > > > +            /*
> > > > > +             * ensure the M4 local reset is asserted to ensure the core
> > > > > +             * doesn't execute bogus code in .prepare() when the module
> > > > > +             * reset is released.
> > > > > +             */
> > > > > +            if (data->uses_lreset) {
> > > > > +                    ret = reset_control_status(kproc->reset);
> > > > > +                    if (ret < 0) {
> > > > > +                            return dev_err_probe(dev, ret, "failed to get reset status\n");
> > > > > +                    } else if (ret == 0) {
> > > > > +                            dev_warn(dev, "local reset is deasserted for device\n");
> > > > > +                            k3_m4_rproc_reset(kproc);
> > > > > +                    }
> > > > > +            }
> > > > > +    }
> > > > > +
> > > > > +    ret = devm_rproc_add(dev, rproc);
> > > > > +    if (ret)
> > > > > +            return dev_err_probe(dev, ret,
> > > > > +                                 "failed to add register device with remoteproc core\n");
> > > > > +
> > > > > +    return 0;
> > > > > +}
> > > > > +
> > > > > +static const struct k3_m4_rproc_mem_data am64_m4_mems[] = {
> > > > > +    { .name = "iram", .dev_addr = 0x0 },
> > > > > +    { .name = "dram", .dev_addr = 0x30000 },
> > > > > +};
> > > > 
> > > > Is this hardcoded in the hardware and never expected to change?  If not please
> > > > add to the DT bindings.
> > > > 
> > > 
> > > This is a hardware hardcoded address and will be the same for this class
> > > of K3 M4 cores.
> > > 
> > > Thanks,
> > > Andrew
> > > 
> > > > More comments later or tomorrow.
> > > > 
> > > > Thanks,
> > > > Mathieu
> > > > 
> > > > > +
> > > > > +static const struct k3_m4_rproc_dev_data am64_m4_data = {
> > > > > +    .mems = am64_m4_mems,
> > > > > +    .num_mems = ARRAY_SIZE(am64_m4_mems),
> > > > > +    .uses_lreset = true,
> > > > > +};
> > > > > +
> > > > > +static const struct of_device_id k3_m4_of_match[] = {
> > > > > +    { .compatible = "ti,am64-m4fss", .data = &am64_m4_data, },
> > > > > +    { /* sentinel */ },
> > > > > +};
> > > > > +MODULE_DEVICE_TABLE(of, k3_m4_of_match);
> > > > > +
> > > > > +static struct platform_driver k3_m4_rproc_driver = {
> > > > > +    .probe  = k3_m4_rproc_probe,
> > > > > +    .driver = {
> > > > > +            .name = "k3-m4-rproc",
> > > > > +            .of_match_table = k3_m4_of_match,
> > > > > +    },
> > > > > +};
> > > > > +module_platform_driver(k3_m4_rproc_driver);
> > > > > +
> > > > > +MODULE_AUTHOR("Hari Nagalla <hnagalla@ti.com>");
> > > > > +MODULE_DESCRIPTION("TI K3 M4 Remoteproc driver");
> > > > > +MODULE_LICENSE("GPL");
> > > > > --
> > > > > 2.39.2
> > > > >