Message-ID: <465b1e4c-0a71-4ad2-978c-a66958aedac3@amd.com>
Date: Thu, 23 May 2024 12:11:22 -0500
From: Tanmay Shah <tanmay.shah@....com>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: andersson@...nel.org, linux-remoteproc@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] drivers: remoteproc: xlnx: add attach detach
 support



On 5/23/24 12:05 PM, Mathieu Poirier wrote:
> On Wed, May 22, 2024 at 09:36:26AM -0500, Tanmay Shah wrote:
>> 
>> 
>> On 5/21/24 12:56 PM, Mathieu Poirier wrote:
>> > Hi Tanmay,
>> > 
>> > On Fri, May 10, 2024 at 05:51:25PM -0700, Tanmay Shah wrote:
>> >> It is possible that remote processor is already running before
>> >> linux boot or remoteproc platform driver probe. Implement required
>> >> remoteproc framework ops to provide resource table address and
>> >> connect or disconnect with remote processor in such case.
>> >> 
>> >> Signed-off-by: Tanmay Shah <tanmay.shah@....com>
>> >> ---
>> >> 
>> >> Changes in v2:
>> >>   - Fix following sparse warnings
>> >> 
>> >> drivers/remoteproc/xlnx_r5_remoteproc.c:827:21: sparse:    expected struct rsc_tbl_data *rsc_data_va
>> >> drivers/remoteproc/xlnx_r5_remoteproc.c:844:18: sparse:    expected struct resource_table *rsc_addr
>> >> drivers/remoteproc/xlnx_r5_remoteproc.c:898:24: sparse:    expected void volatile [noderef] __iomem *addr
>> >> 
>> >>  drivers/remoteproc/xlnx_r5_remoteproc.c | 164 +++++++++++++++++++++++-
>> >>  1 file changed, 160 insertions(+), 4 deletions(-)
>> >> 
>> >> diff --git a/drivers/remoteproc/xlnx_r5_remoteproc.c b/drivers/remoteproc/xlnx_r5_remoteproc.c
>> >> index 84243d1dff9f..039370cffa32 100644
>> >> --- a/drivers/remoteproc/xlnx_r5_remoteproc.c
>> >> +++ b/drivers/remoteproc/xlnx_r5_remoteproc.c
>> >> @@ -25,6 +25,10 @@
>> >>  /* RX mailbox client buffer max length */
>> >>  #define MBOX_CLIENT_BUF_MAX	(IPI_BUF_LEN_MAX + \
>> >>  				 sizeof(struct zynqmp_ipi_message))
>> >> +
>> >> +#define RSC_TBL_XLNX_MAGIC	((uint32_t)'x' << 24 | (uint32_t)'a' << 16 | \
>> >> +				 (uint32_t)'m' << 8 | (uint32_t)'p')
>> >> +
>> >>  /*
>> >>   * settings for RPU cluster mode which
>> >>   * reflects possible values of xlnx,cluster-mode dt-property
>> >> @@ -73,6 +77,15 @@ struct mbox_info {
>> >>  	struct mbox_chan *rx_chan;
>> >>  };
>> >>  
>> >> +/* Xilinx Platform specific data structure */
>> >> +struct rsc_tbl_data {
>> >> +	const int version;
>> >> +	const u32 magic_num;
>> >> +	const u32 comp_magic_num;
>> > 
>> > Why is a complement magic number needed?
>> 
>> Actually magic number is 64-bit. There is good chance that
>> firmware can have 32-bit op-code or data same as magic number, but very less
>> chance of its complement in the next address. So, we can assume magic number
>> is 64-bit. 
>>
> 
> So why not having a magic number that is a u64?
> 
>> > 
>> >> +	const u32 rsc_tbl_size;
>> >> +	const uintptr_t rsc_tbl;
>> >> +} __packed;
>> >> +
>> >>  /*
>> >>   * Hardcoded TCM bank values. This will stay in driver to maintain backward
>> >>   * compatibility with device-tree that does not have TCM information.
>> >> @@ -95,20 +108,24 @@ static const struct mem_bank_data zynqmp_tcm_banks_lockstep[] = {
>> >>  /**
>> >>   * struct zynqmp_r5_core
>> >>   *
>> >> + * @rsc_tbl_va: resource table virtual address
>> >>   * @dev: device of RPU instance
>> >>   * @np: device node of RPU instance
>> >>   * @tcm_bank_count: number TCM banks accessible to this RPU
>> >>   * @tcm_banks: array of each TCM bank data
>> >>   * @rproc: rproc handle
>> >> + * @rsc_tbl_size: resource table size retrieved from remote
>> >>   * @pm_domain_id: RPU CPU power domain id
>> >>   * @ipi: pointer to mailbox information
>> >>   */
>> >>  struct zynqmp_r5_core {
>> >> +	struct resource_table *rsc_tbl_va;
>> > 
>> > Shouldn't this be of type "void __iomem *"?  Did sparse give you trouble on that
>> > one?
>> 
>> I fixed sparse warnings with typecast below [1].
>> 
> 
> My point is, ioremap_wc() returns a "void__iomem *" so why not using that
> instead of a "struct resource_table *"?

Ack.

> 
> 
>> > 
>> >>  	struct device *dev;
>> >>  	struct device_node *np;
>> >>  	int tcm_bank_count;
>> >>  	struct mem_bank_data **tcm_banks;
>> >>  	struct rproc *rproc;
>> >> +	u32 rsc_tbl_size;
>> >>  	u32 pm_domain_id;
>> >>  	struct mbox_info *ipi;
>> >>  };
>> >> @@ -621,10 +638,19 @@ static int zynqmp_r5_rproc_prepare(struct rproc *rproc)
>> >>  {
>> >>  	int ret;
>> >>  
>> >> -	ret = add_tcm_banks(rproc);
>> >> -	if (ret) {
>> >> -		dev_err(&rproc->dev, "failed to get TCM banks, err %d\n", ret);
>> >> -		return ret;
>> >> +	/**
>> > 
>> > Using "/**" is for comments that will endup in the documentation, which I don't
>> > think is needed here.  Please correct throughout the patch.
>> 
>> Thanks. Ack, I will use only /* format.
>> 
>> > 
>> >> +	 * For attach/detach use case, Firmware is already loaded so
>> >> +	 * TCM isn't really needed at all. Also, for security TCM can be
>> >> +	 * locked in such case and linux may not have access at all.
>> >> +	 * So avoid adding TCM banks. TCM power-domains requested during attach
>> >> +	 * callback.
>> >> +	 */
>> >> +	if (rproc->state != RPROC_DETACHED) {
>> >> +		ret = add_tcm_banks(rproc);
>> >> +		if (ret) {
>> >> +			dev_err(&rproc->dev, "failed to get TCM banks, err %d\n", ret);
>> >> +			return ret;
>> >> +		}
>> >>  	}
>> >>  
>> >>  	ret = add_mem_regions_carveout(rproc);
>> >> @@ -662,6 +688,123 @@ static int zynqmp_r5_rproc_unprepare(struct rproc *rproc)
>> >>  	return 0;
>> >>  }
>> >>  
>> >> +static struct resource_table *zynqmp_r5_get_loaded_rsc_table(struct rproc *rproc,
>> >> +							     size_t *size)
>> >> +{
>> >> +	struct zynqmp_r5_core *r5_core;
>> >> +
>> >> +	r5_core = rproc->priv;
>> >> +
>> >> +	*size = r5_core->rsc_tbl_size;
>> >> +
>> >> +	return r5_core->rsc_tbl_va;
>> >> +}
>> >> +
>> >> +static int zynqmp_r5_get_rsc_table_va(struct zynqmp_r5_core *r5_core)
>> >> +{
>> >> +	struct device *dev = r5_core->dev;
>> >> +	struct rsc_tbl_data *rsc_data_va;
>> >> +	struct resource_table *rsc_addr;
>> >> +	struct resource res_mem;
>> >> +	struct device_node *np;
>> >> +	int ret;
>> >> +
>> >> +	/**
>> >> +	 * It is expected from remote processor firmware to provide resource
>> >> +	 * table address via struct rsc_tbl_data data structure.
>> >> +	 * Start address of first entry under "memory-region" property list
>> >> +	 * contains that data structure which holds resource table address, size
>> >> +	 * and some magic number to validate correct resource table entry.
>> >> +	 */
>> >> +	np = of_parse_phandle(r5_core->np, "memory-region", 0);
>> >> +	if (!np) {
>> >> +		dev_err(dev, "failed to get memory region dev node\n");
>> >> +		return -EINVAL;
>> >> +	}
>> >> +
>> >> +	ret = of_address_to_resource(np, 0, &res_mem);
>> >> +	if (ret) {
>> >> +		dev_err(dev, "failed to get memory-region resource addr\n");
>> >> +		return -EINVAL;
>> >> +	}
>> >> +
>> >> +	rsc_data_va = (struct rsc_tbl_data *)devm_ioremap_wc(dev, res_mem.start,
>> >> +							     sizeof(struct rsc_tbl_data));
>> > 
>> > There is no point in holding memory until the driver is unloaded.  Please use
>> > ioremap_wc() and free at the end of the function.
>> > 
>> 
>> Ack.
>> 
>> >> +	if (!rsc_data_va) {
>> >> +		dev_err(dev, "failed to map resource table data address\n");
>> >> +		return -EIO;
>> >> +	}
>> >> +
>> >> +	/**
>> >> +	 * If RSC_TBL_XLNX_MAGIC number and its complement isn't found then
>> >> +	 * do not consider resource table address valid and don't attach
>> >> +	 */
>> >> +	if (rsc_data_va->magic_num != RSC_TBL_XLNX_MAGIC ||
>> >> +	    rsc_data_va->comp_magic_num != ~RSC_TBL_XLNX_MAGIC) {
>> >> +		dev_dbg(dev, "invalid magic number, won't attach\n");
>> >> +		return -EINVAL;
>> >> +	}
>> >> +
>> >> +	rsc_addr = (struct resource_table *)ioremap_wc(rsc_data_va->rsc_tbl,
>> >> +						       rsc_data_va->rsc_tbl_size);
>> 
>> [1] Here typecast is done.
>> 
>> >> +	if (!rsc_addr) {
>> >> +		dev_err(dev, "failed to get rsc_addr\n");
>> >> +		return -EINVAL;
>> >> +	}
>> >> +
>> >> +	/**
>> >> +	 * As of now resource table version 1 is expected. Don't fail to attach
>> >> +	 * but warn users about it.
>> >> +	 */
>> >> +	if (rsc_addr->ver != 1)
>> >> +		dev_warn(dev, "unexpected resource table version %d\n",
>> >> +			 rsc_addr->ver);
>> >> +
>> >> +	r5_core->rsc_tbl_size = rsc_data_va->rsc_tbl_size;
>> >> +	r5_core->rsc_tbl_va = rsc_addr;
>> >> +
>> >> +	return 0;
>> >> +}
>> >> +
>> >> +static int zynqmp_r5_attach(struct rproc *rproc)
>> >> +{
>> >> +	struct zynqmp_r5_core *r5_core = rproc->priv;
>> >> +	int i, pm_domain_id, ret;
>> >> +
>> >> +	/*
>> >> +	 * Firmware is loaded in TCM. Request TCM power domains to notify
>> >> +	 * platform management controller that TCM is in use. This will be
>> >> +	 * released during unprepare callback.
>> >> +	 */
>> >> +	for (i = 0; i < r5_core->tcm_bank_count; i++) {
>> >> +		pm_domain_id = r5_core->tcm_banks[i]->pm_domain_id;
>> >> +		ret = zynqmp_pm_request_node(pm_domain_id,
>> >> +					     ZYNQMP_PM_CAPABILITY_ACCESS, 0,
>> >> +					     ZYNQMP_PM_REQUEST_ACK_BLOCKING);
>> >> +		if (ret < 0)
>> >> +			pr_warn("TCM %d can't be requested\n", i);
>> >> +	}
>> >> +
>> >> +	return 0;
>> >> +}
>> >> +
>> >> +static int zynqmp_r5_detach(struct rproc *rproc)
>> >> +{
>> >> +	struct zynqmp_r5_core *r5_core = rproc->priv;
>> >> +
>> >> +	/*
>> >> +	 * Generate last notification to remote after clearing virtio flag.
>> >> +	 * Remote can avoid polling on virtio reset flag if kick is generated
>> >> +	 * during detach by host and check virtio reset flag on kick interrupt.
>> >> +	 */
>> >> +	zynqmp_r5_rproc_kick(rproc, 0);
>> >> +
>> >> +	iounmap((void __iomem *)r5_core->rsc_tbl_va);
>> >> +	r5_core->rsc_tbl_va = NULL;
>> > 
>> > This is puzzling...  What happens to ->tsc_tbl_va when the remote processor is
>> > re-attached? 
>> 
>> Actually I don't see re-attach in life cycle. I might be missing something.
>> Following is lifecycle I have tested:
>> 
>> 1) During driver probe, if resource table is found in memory, then state is
>>    moved to detach.
> 
> Right.
> 
>> 2) Then user executes echo start > remoteproc* command, and state moved to attach.
> 
> Right.
> 
>> 3) After work is done with remote, user executes echo stop > remoteproc* command,
>>    and state is moved to offline.
>> 
> 
> Right.  But you have an ops::detach() function, which means you expect users to
> be able to detach() and re-attach() as many times as they want.
> 
>> From here, remote is offline state, and I can't re-attach to it without loading
>> firmware again. which is regular start/stop states. Please let me know if I am missing
>> something.
>> 
>> From here, load firmware, and executing echo start > remoteproc* moves
>> rproc state to running. Load firmware loads resource table from elf.
>> 
>> So, I believe attach is happening only during probe. And then, once r5 stops, user
>> needs to load firmware and start R5. I think this use case is good for now.
>>
> 
> If you don't want people to detach() and re-attach(), remove ops::detach()
> entirely.  But if you go this way it is only a matter of time before
> someone asks for the feature or provide a fix for it.
> 

Does that mean implement whatever is in detach, in ops::stop() ?
I am okay with that. Current use case is expected to attach only during boot time.

>> > 
>> > I will not look at the SRAM part.  Please re-submit when we are done with the
>> > attach/detach feature.
>> > 
>> 
>> Okay sounds good to me.
>> Reviews are still welcomed if anyone in the community decides to review it.
>> 
>> Thanks,
>> Tanmay
>>  > Thanks,
>> > Mathieu
>> > 
>> >> +
>> >> +	return 0;
>> >> +}
>> >> +
>> >>  static const struct rproc_ops zynqmp_r5_rproc_ops = {
>> >>  	.prepare	= zynqmp_r5_rproc_prepare,
>> >>  	.unprepare	= zynqmp_r5_rproc_unprepare,
>> >> @@ -673,6 +816,9 @@ static const struct rproc_ops zynqmp_r5_rproc_ops = {
>> >>  	.sanity_check	= rproc_elf_sanity_check,
>> >>  	.get_boot_addr	= rproc_elf_get_boot_addr,
>> >>  	.kick		= zynqmp_r5_rproc_kick,
>> >> +	.get_loaded_rsc_table = zynqmp_r5_get_loaded_rsc_table,
>> >> +	.attach		= zynqmp_r5_attach,
>> >> +	.detach		= zynqmp_r5_detach,
>> >>  };
>> >>  
>> >>  /**
>> >> @@ -723,6 +869,16 @@ static struct zynqmp_r5_core *zynqmp_r5_add_rproc_core(struct device *cdev)
>> >>  		goto free_rproc;
>> >>  	}
>> >>  
>> >> +	/*
>> >> +	 * Move rproc state to DETACHED to give one time opportunity to attach
>> >> +	 * if firmware is already available in the memory. This can happen if
>> >> +	 * firmware is loaded via debugger or by any other agent in the system.
>> >> +	 * If firmware isn't available in the memory and resource table isn't found,
>> >> +	 * then rproc state stay OFFLINE.
>> >> +	 */
>> >> +	if (!zynqmp_r5_get_rsc_table_va(r5_core))
>> >> +		r5_rproc->state = RPROC_DETACHED;
>> >> +
>> >>  	r5_core->rproc = r5_rproc;
>> >>  	return r5_core;
>> >>  
>> >> -- 
>> >> 2.25.1
>> >> 
>> 

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