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Date: Mon, 6 May 2024 14:46:37 -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: <ZjlBrf2mxENSZb8E@p14s>
References: <20240426191811.32414-1-afd@ti.com>
 <20240426191811.32414-3-afd@ti.com>
Precedence: bulk
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In-Reply-To: <20240426191811.32414-3-afd@ti.com>

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?

> +
> +	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?

> +	} 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.

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
>