[PATCH 0/2] remoteproc: stm32: add support of detaching a remote processor

[PATCH 0/2] remoteproc: stm32: add support of detaching a remote processor

[Arnaud Pouliquen]

This patchset is the stm32mp1 platform implementation of the detach operation
added in series [1].

On detach, the stm32 rproc driver sends a mailbox signal to the remote 
processor to inform it that it will be detached. 

Applied and tested on Bjorn's "for_next" branch (2b81aa17008e)

[1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=447171

Arnaud Pouliquen (2):
  dt-bindings: remoteproc: stm32-rproc: add new mailbox channel for
    detach
  remoteproc: stm32: add capability to detach

 .../bindings/remoteproc/st,stm32-rproc.yaml   | 11 +++++-
 drivers/remoteproc/stm32_rproc.c              | 38 ++++++++++++++++++-
 2 files changed, 45 insertions(+), 4 deletions(-)

-- 
2.17.1

[PATCH 1/2] dt-bindings: remoteproc: stm32-rproc: add new mailbox channel for detach

[Arnaud Pouliquen]

Add the "detach" mailbox item, that allows to define a mailbox to
send a IPCC signal to the remote processor on remoteproc detach action.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---
 .../bindings/remoteproc/st,stm32-rproc.yaml           | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
index a1171dfba024..f5976cb431c0 100644
--- a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
+++ b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
@@ -65,16 +65,23 @@ properties:
           Unidirectional channel:
             - from local to remote, where ACK from the remote means that it is
               ready for shutdown
+       - description: |
+          A channel (d) used by the local proc to notify the remote proc that it
+          has to stop interprocessor communnication.
+          Unidirectional channel:
+            - from local to remote, where ACK from the remote means that communnication
+              as been stopped on the remote side.
     minItems: 1
-    maxItems: 3
+    maxItems: 4
 
   mbox-names:
     items:
       - const: vq0
       - const: vq1
       - const: shutdown
+      - const: detach
     minItems: 1
-    maxItems: 3
+    maxItems: 4
 
   memory-region:
     description:
-- 
2.17.1

[PATCH 2/2] remoteproc: stm32: add capability to detach

[Arnaud Pouliquen]

From: Arnaud Pouliquen <arnaud.pouliquen@foss-st.com>

A mechanism similar to the shutdown mailbox signal is implemented to
detach a remote processor.

Upon detachment, a signal is sent to the remote firmware, allowing it
to perform specific actions such as stopping RPMsg communication.

The Cortex-M hold boot is also disabled to allow the remote processor
to restart in case of crash.

Notice that for this feature to be supported, the remote firmware 
resource table must be stored at the beginning of a 1kB section 
(default size provided to the remoteproc core).

This restriction should be lifted in the future by using a backup register
to store the actual size of the resource table. 

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss-st.com>
---
 drivers/remoteproc/stm32_rproc.c | 38 ++++++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
index 3d45f51de4d0..298ef5b19e27 100644
--- a/drivers/remoteproc/stm32_rproc.c
+++ b/drivers/remoteproc/stm32_rproc.c
@@ -28,7 +28,7 @@
 #define RELEASE_BOOT		1
 
 #define MBOX_NB_VQ		2
-#define MBOX_NB_MBX		3
+#define MBOX_NB_MBX		4
 
 #define STM32_SMC_RCC		0x82001000
 #define STM32_SMC_REG_WRITE	0x1
@@ -38,6 +38,7 @@
 #define STM32_MBX_VQ1		"vq1"
 #define STM32_MBX_VQ1_ID	1
 #define STM32_MBX_SHUTDOWN	"shutdown"
+#define STM32_MBX_DETACH	"detach"
 
 #define RSC_TBL_SIZE		1024
 
@@ -336,6 +337,15 @@ static const struct stm32_mbox stm32_rproc_mbox[MBOX_NB_MBX] = {
 			.tx_done = NULL,
 			.tx_tout = 500, /* 500 ms time out */
 		},
+	},
+	{
+		.name = STM32_MBX_DETACH,
+		.vq_id = -1,
+		.client = {
+			.tx_block = true,
+			.tx_done = NULL,
+			.tx_tout = 200, /* 200 ms time out to detach should be fair enough */
+		},
 	}
 };
 
@@ -461,6 +471,25 @@ static int stm32_rproc_attach(struct rproc *rproc)
 	return stm32_rproc_set_hold_boot(rproc, true);
 }
 
+static int stm32_rproc_detach(struct rproc *rproc)
+{
+	struct stm32_rproc *ddata = rproc->priv;
+	int err, dummy_data, idx;
+
+	/* Inform the remote processor of the detach */
+	idx = stm32_rproc_mbox_idx(rproc, STM32_MBX_DETACH);
+	if (idx >= 0 && ddata->mb[idx].chan) {
+		/* A dummy data is sent to allow to block on transmit */
+		err = mbox_send_message(ddata->mb[idx].chan,
+					&dummy_data);
+		if (err < 0)
+			dev_warn(&rproc->dev, "warning: remote FW detach without ack\n");
+	}
+
+	/* Allow remote processor to auto-reboot */
+	return stm32_rproc_set_hold_boot(rproc, false);
+}
+
 static int stm32_rproc_stop(struct rproc *rproc)
 {
 	struct stm32_rproc *ddata = rproc->priv;
@@ -597,7 +626,11 @@ stm32_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
 	}
 
 done:
-	/* Assuming the resource table fits in 1kB is fair */
+	/*
+	 * Assuming the resource table fits in 1kB is fair.
+	 * Notice for the detach, that this 1 kB memory area has to be reserved in the coprocessor
+	 * firmware for the resource table. A clean of this whole area is done on detach.
+	 */
 	*table_sz = RSC_TBL_SIZE;
 	return (struct resource_table *)ddata->rsc_va;
 }
@@ -607,6 +640,7 @@ static const struct rproc_ops st_rproc_ops = {
 	.start		= stm32_rproc_start,
 	.stop		= stm32_rproc_stop,
 	.attach		= stm32_rproc_attach,
+	.detach		= stm32_rproc_detach,
 	.kick		= stm32_rproc_kick,
 	.load		= rproc_elf_load_segments,
 	.parse_fw	= stm32_rproc_parse_fw,
-- 
2.17.1

Re: [PATCH 1/2] dt-bindings: remoteproc: stm32-rproc: add new mailbox channel for detach

[Rob Herring]

On Thu, 18 Mar 2021 15:59:22 +0100, Arnaud Pouliquen wrote:
> Add the "detach" mailbox item, that allows to define a mailbox to
> send a IPCC signal to the remote processor on remoteproc detach action.
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
> ---
>  .../bindings/remoteproc/st,stm32-rproc.yaml           | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:
./Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml:68:8: [error] syntax error: expected <block end>, but found '<block sequence start>' (syntax)

dtschema/dtc warnings/errors:
make[1]: *** Deleting file 'Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.example.dts'
Traceback (most recent call last):
  File "/usr/local/bin/dt-extract-example", line 45, in <module>
    binding = yaml.load(open(args.yamlfile, encoding='utf-8').read())
  File "/usr/local/lib/python3.8/dist-packages/ruamel/yaml/main.py", line 343, in load
    return constructor.get_single_data()
  File "/usr/local/lib/python3.8/dist-packages/ruamel/yaml/constructor.py", line 111, in get_single_data
    node = self.composer.get_single_node()
  File "_ruamel_yaml.pyx", line 706, in _ruamel_yaml.CParser.get_single_node
  File "_ruamel_yaml.pyx", line 724, in _ruamel_yaml.CParser._compose_document
  File "_ruamel_yaml.pyx", line 775, in _ruamel_yaml.CParser._compose_node
  File "_ruamel_yaml.pyx", line 889, in _ruamel_yaml.CParser._compose_mapping_node
  File "_ruamel_yaml.pyx", line 775, in _ruamel_yaml.CParser._compose_node
  File "_ruamel_yaml.pyx", line 889, in _ruamel_yaml.CParser._compose_mapping_node
  File "_ruamel_yaml.pyx", line 775, in _ruamel_yaml.CParser._compose_node
  File "_ruamel_yaml.pyx", line 889, in _ruamel_yaml.CParser._compose_mapping_node
  File "_ruamel_yaml.pyx", line 773, in _ruamel_yaml.CParser._compose_node
  File "_ruamel_yaml.pyx", line 852, in _ruamel_yaml.CParser._compose_sequence_node
  File "_ruamel_yaml.pyx", line 904, in _ruamel_yaml.CParser._parse_next_event
ruamel.yaml.parser.ParserError: while parsing a block collection
  in "<unicode string>", line 54, column 7
did not find expected '-' indicator
  in "<unicode string>", line 68, column 8
make[1]: *** [Documentation/devicetree/bindings/Makefile:20: Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.example.dts] Error 1
make[1]: *** Waiting for unfinished jobs....
./Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml:  while parsing a block collection
  in "<unicode string>", line 54, column 7
did not find expected '-' indicator
  in "<unicode string>", line 68, column 8
/builds/robherring/linux-dt-review/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml: ignoring, error parsing file
warning: no schema found in file: ./Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml
make: *** [Makefile:1380: dt_binding_check] Error 2

See https://patchwork.ozlabs.org/patch/1455311

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH 2/2] remoteproc: stm32: add capability to detach

[Bjorn Andersson]

On Thu 18 Mar 09:59 CDT 2021, Arnaud Pouliquen wrote:

> From: Arnaud Pouliquen <arnaud.pouliquen@foss-st.com>
> 
> A mechanism similar to the shutdown mailbox signal is implemented to
> detach a remote processor.
> 
> Upon detachment, a signal is sent to the remote firmware, allowing it
> to perform specific actions such as stopping RPMsg communication.
> 
> The Cortex-M hold boot is also disabled to allow the remote processor
> to restart in case of crash.
> 
> Notice that for this feature to be supported, the remote firmware 
> resource table must be stored at the beginning of a 1kB section 
> (default size provided to the remoteproc core).
> 
> This restriction should be lifted in the future by using a backup register
> to store the actual size of the resource table. 
> 
> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss-st.com>
> ---
>  drivers/remoteproc/stm32_rproc.c | 38 ++++++++++++++++++++++++++++++--
>  1 file changed, 36 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
> index 3d45f51de4d0..298ef5b19e27 100644
> --- a/drivers/remoteproc/stm32_rproc.c
> +++ b/drivers/remoteproc/stm32_rproc.c
> @@ -28,7 +28,7 @@
>  #define RELEASE_BOOT		1
>  
>  #define MBOX_NB_VQ		2
> -#define MBOX_NB_MBX		3
> +#define MBOX_NB_MBX		4
>  
>  #define STM32_SMC_RCC		0x82001000
>  #define STM32_SMC_REG_WRITE	0x1
> @@ -38,6 +38,7 @@
>  #define STM32_MBX_VQ1		"vq1"
>  #define STM32_MBX_VQ1_ID	1
>  #define STM32_MBX_SHUTDOWN	"shutdown"
> +#define STM32_MBX_DETACH	"detach"
>  
>  #define RSC_TBL_SIZE		1024
>  
> @@ -336,6 +337,15 @@ static const struct stm32_mbox stm32_rproc_mbox[MBOX_NB_MBX] = {
>  			.tx_done = NULL,
>  			.tx_tout = 500, /* 500 ms time out */
>  		},
> +	},
> +	{
> +		.name = STM32_MBX_DETACH,
> +		.vq_id = -1,
> +		.client = {
> +			.tx_block = true,
> +			.tx_done = NULL,
> +			.tx_tout = 200, /* 200 ms time out to detach should be fair enough */
> +		},
>  	}
>  };
>  
> @@ -461,6 +471,25 @@ static int stm32_rproc_attach(struct rproc *rproc)
>  	return stm32_rproc_set_hold_boot(rproc, true);
>  }
>  
> +static int stm32_rproc_detach(struct rproc *rproc)
> +{
> +	struct stm32_rproc *ddata = rproc->priv;
> +	int err, dummy_data, idx;
> +
> +	/* Inform the remote processor of the detach */
> +	idx = stm32_rproc_mbox_idx(rproc, STM32_MBX_DETACH);
> +	if (idx >= 0 && ddata->mb[idx].chan) {
> +		/* A dummy data is sent to allow to block on transmit */
> +		err = mbox_send_message(ddata->mb[idx].chan,
> +					&dummy_data);

Isn't it the stm32_ipcc driver on the other side of this call? In which
case I believe "data" is ignored, and you would be able to just pass
NULL here.

As long as "data" isn't dereferenced it's probably better to send some
bugus value, than an address to this variable on the stack. If on the
other hand you pair this with one of the mailbox drivers that
dereferences "data", you should initialize it...

Apart from this, I think the patch looks good!

Regards,
Bjorn

> +		if (err < 0)
> +			dev_warn(&rproc->dev, "warning: remote FW detach without ack\n");
> +	}
> +
> +	/* Allow remote processor to auto-reboot */
> +	return stm32_rproc_set_hold_boot(rproc, false);
> +}
> +
>  static int stm32_rproc_stop(struct rproc *rproc)
>  {
>  	struct stm32_rproc *ddata = rproc->priv;
> @@ -597,7 +626,11 @@ stm32_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
>  	}
>  
>  done:
> -	/* Assuming the resource table fits in 1kB is fair */
> +	/*
> +	 * Assuming the resource table fits in 1kB is fair.
> +	 * Notice for the detach, that this 1 kB memory area has to be reserved in the coprocessor
> +	 * firmware for the resource table. A clean of this whole area is done on detach.
> +	 */
>  	*table_sz = RSC_TBL_SIZE;
>  	return (struct resource_table *)ddata->rsc_va;
>  }
> @@ -607,6 +640,7 @@ static const struct rproc_ops st_rproc_ops = {
>  	.start		= stm32_rproc_start,
>  	.stop		= stm32_rproc_stop,
>  	.attach		= stm32_rproc_attach,
> +	.detach		= stm32_rproc_detach,
>  	.kick		= stm32_rproc_kick,
>  	.load		= rproc_elf_load_segments,
>  	.parse_fw	= stm32_rproc_parse_fw,
> -- 
> 2.17.1
>