[PATCH v4 0/2] remoteproc: stm32: add support of detaching a remote processor

Update from V3:
add Reviewed by Rob Herring in patch 1/2 for bindings

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              | 39 ++++++++++++++++++-
 2 files changed, 46 insertions(+), 4 deletions(-)

-- 
2.17.1


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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>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../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..64afdcfb613d 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


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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.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/remoteproc/stm32_rproc.c | 39 ++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
index 3d45f51de4d0..7353f9e7e7af 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 +626,12 @@ 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. On detach, the remoteproc core re-initializes this
+	 * entire area by overwriting it with the initial values stored in rproc->clean_table.
+	 */
 	*table_sz = RSC_TBL_SIZE;
 	return (struct resource_table *)ddata->rsc_va;
 }

@@ -607,6 +641,7 @@ 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


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On Wed 31 Mar 02:33 CDT 2021, Arnaud Pouliquen wrote:

Seems I posted my comment on v1, rather than this latest version. Please
let me know if we should do anything about this dummy_data.

Regards,
Bjorn

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Hello Bjorn

On 4/13/21 11:34 PM, Bjorn Andersson wrote:

On Wed 31 Mar 02:33 CDT 2021, Arnaud Pouliquen wrote:

quoted

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.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/remoteproc/stm32_rproc.c | 39 ++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/stm32_rproc.c b/drivers/remoteproc/stm32_rproc.c
index 3d45f51de4d0..7353f9e7e7af 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);

Seems I posted my comment on v1, rather than this latest version. Please
let me know if we should do anything about this dummy_data.

Thanks for pointing this out, you are right, the mailbox driver is stm32_ipcc
and it only sends a signal to the remote processor.

As message can be queued by the mailbox framework using a local variable seems
not a good option. As this code is a copy/past of the kick and stop?
I propose to get this one and I will send a new patch to fix the usage in the
whole driver.

Thanks,
Arnaud

Regards,
Bjorn

quoted

+		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 +626,12 @@ 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. On detach, the remoteproc core re-initializes this
+	 * entire area by overwriting it with the initial values stored in rproc->clean_table.
+	 */
 	*table_sz = RSC_TBL_SIZE;
 	return (struct resource_table *)ddata->rsc_va;
 }

@@ -607,6 +641,7 @@ 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

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On Wed 14 Apr 02:23 CDT 2021, Arnaud POULIQUEN wrote:

On 4/13/21 11:34 PM, Bjorn Andersson wrote:

quoted

On Wed 31 Mar 02:33 CDT 2021, Arnaud Pouliquen wrote:

[..]

quoted

quoted

+		err = mbox_send_message(ddata->mb[idx].chan,
+					&dummy_data);

Seems I posted my comment on v1, rather than this latest version. Please
let me know if we should do anything about this dummy_data.

Thanks for pointing this out, you are right, the mailbox driver is stm32_ipcc
and it only sends a signal to the remote processor.

As message can be queued by the mailbox framework using a local variable seems
not a good option. As this code is a copy/past of the kick and stop?
I propose to get this one and I will send a new patch to fix the usage in the
whole driver.

That works for me, I've merged the two patches.

Thanks,
Bjorn

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