[PATCH net 0/2] net: ipa: enable register retention

[PATCH net 0/2] net: ipa: enable register retention

[Alex Elder]

With runtime power management in place, we sometimes need to issue
a command to enable retention of IPA register values before power
collapse.  This requires a new Device Tree property, whose presence
will also be used to signal that the command is required.

					-Alex

Alex Elder (2):
  dt-bindings: net: qcom,ipa: add optional qcom,qmp property
  net: ipa: request IPA register values be retained

 .../devicetree/bindings/net/qcom,ipa.yaml     |  6 +++
 drivers/net/ipa/ipa_power.c                   | 52 +++++++++++++++++++
 drivers/net/ipa/ipa_power.h                   |  7 +++
 drivers/net/ipa/ipa_uc.c                      |  5 ++
 4 files changed, 70 insertions(+)

-- 
2.32.0

[PATCH net 1/2] dt-bindings: net: qcom,ipa: add optional qcom,qmp property

[Alex Elder]

For some systems, the IPA driver must make a request to ensure that
its registers are retained across power collapse of the IPA hardware.
On such systems, we'll use the existence of the "qcom,qmp" property
as a signal that this request is required.

Signed-off-by: Alex Elder <elder@linaro.org>
---
 Documentation/devicetree/bindings/net/qcom,ipa.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/qcom,ipa.yaml b/Documentation/devicetree/bindings/net/qcom,ipa.yaml
index b86edf67ce626..58ecc62adfaae 100644
--- a/Documentation/devicetree/bindings/net/qcom,ipa.yaml
+++ b/Documentation/devicetree/bindings/net/qcom,ipa.yaml
@@ -107,6 +107,10 @@ properties:
           - const: imem
           - const: config
 
+  qcom,qmp:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: phandle to the AOSS side-channel message RAM
+
   qcom,smem-states:
     $ref: /schemas/types.yaml#/definitions/phandle-array
     description: State bits used in by the AP to signal the modem.
@@ -222,6 +226,8 @@ examples:
                                      "imem",
                                      "config";
 
+                qcom,qmp = <&aoss_qmp>;
+
                 qcom,smem-states = <&ipa_smp2p_out 0>,
                                    <&ipa_smp2p_out 1>;
                 qcom,smem-state-names = "ipa-clock-enabled-valid",
-- 
2.32.0

[PATCH net 2/2] net: ipa: request IPA register values be retained

[Alex Elder]

In some cases, the IPA hardware needs to request the always-on
subsystem (AOSS) to coordinate with the IPA microcontroller to
retain IPA register values at power collapse.  This is done by
issuing a QMP request to the AOSS microcontroller.  A similar
request ondoes that request.

We must get and hold the "QMP" handle early, because we might get
back EPROBE_DEFER for that.  But the actual request should be sent
while we know the IPA clock is active, and when we know the
microcontroller is operational.

Fixes: 2775cbc5afeb6 ("net: ipa: rename "ipa_clock.c"")
Signed-off-by: Alex Elder <elder@linaro.org>
---
 drivers/net/ipa/ipa_power.c | 52 +++++++++++++++++++++++++++++++++++++
 drivers/net/ipa/ipa_power.h |  7 +++++
 drivers/net/ipa/ipa_uc.c    |  5 ++++
 3 files changed, 64 insertions(+)

diff --git a/drivers/net/ipa/ipa_power.c b/drivers/net/ipa/ipa_power.c
index b1c6c0fcb654f..f2989aac47a62 100644
--- a/drivers/net/ipa/ipa_power.c
+++ b/drivers/net/ipa/ipa_power.c
@@ -11,6 +11,8 @@
 #include <linux/pm_runtime.h>
 #include <linux/bitops.h>
 
+#include "linux/soc/qcom/qcom_aoss.h"
+
 #include "ipa.h"
 #include "ipa_power.h"
 #include "ipa_endpoint.h"
@@ -64,6 +66,7 @@ enum ipa_power_flag {
  * struct ipa_power - IPA power management information
  * @dev:		IPA device pointer
  * @core:		IPA core clock
+ * @qmp:		QMP handle for AOSS communication
  * @spinlock:		Protects modem TX queue enable/disable
  * @flags:		Boolean state flags
  * @interconnect_count:	Number of elements in interconnect[]
@@ -72,6 +75,7 @@ enum ipa_power_flag {
 struct ipa_power {
 	struct device *dev;
 	struct clk *core;
+	struct qmp *qmp;
 	spinlock_t spinlock;	/* used with STOPPED/STARTED power flags */
 	DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
 	u32 interconnect_count;
@@ -382,6 +386,47 @@ void ipa_power_modem_queue_active(struct ipa *ipa)
 	clear_bit(IPA_POWER_FLAG_STARTED, ipa->power->flags);
 }
 
+static int ipa_power_retention_init(struct ipa_power *power)
+{
+	struct qmp *qmp = qmp_get(power->dev);
+
+	if (IS_ERR(qmp)) {
+		if (PTR_ERR(qmp) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		/* We assume any other error means it's not defined/needed */
+		qmp = NULL;
+	}
+	power->qmp = qmp;
+
+	return 0;
+}
+
+static void ipa_power_retention_exit(struct ipa_power *power)
+{
+	qmp_put(power->qmp);
+	power->qmp = NULL;
+}
+
+/* Control register retention on power collapse */
+void ipa_power_retention(struct ipa *ipa, bool enable)
+{
+	static const char fmt[] = "{ class: bcm, res: ipa_pc, val: %c }";
+	struct ipa_power *power = ipa->power;
+	char buf[36];	/* Exactly enough for fmt[]; size a multiple of 4 */
+	int ret;
+
+	if (!power->qmp)
+		return;		/* Not needed on this platform */
+
+	(void)snprintf(buf, sizeof(buf), fmt, enable ? '1' : '0');
+
+	ret = qmp_send(power->qmp, buf, sizeof(buf));
+	if (ret)
+		dev_err(power->dev, "error %d sending QMP %sable request\n",
+			ret, enable ? "en" : "dis");
+}
+
 int ipa_power_setup(struct ipa *ipa)
 {
 	int ret;
@@ -438,12 +483,18 @@ ipa_power_init(struct device *dev, const struct ipa_power_data *data)
 	if (ret)
 		goto err_kfree;
 
+	ret = ipa_power_retention_init(power);
+	if (ret)
+		goto err_interconnect_exit;
+
 	pm_runtime_set_autosuspend_delay(dev, IPA_AUTOSUSPEND_DELAY);
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_enable(dev);
 
 	return power;
 
+err_interconnect_exit:
+	ipa_interconnect_exit(power);
 err_kfree:
 	kfree(power);
 err_clk_put:
@@ -460,6 +511,7 @@ void ipa_power_exit(struct ipa_power *power)
 
 	pm_runtime_disable(dev);
 	pm_runtime_dont_use_autosuspend(dev);
+	ipa_power_retention_exit(power);
 	ipa_interconnect_exit(power);
 	kfree(power);
 	clk_put(clk);
diff --git a/drivers/net/ipa/ipa_power.h b/drivers/net/ipa/ipa_power.h
index 2151805d7fbb0..6f84f057a2095 100644
--- a/drivers/net/ipa/ipa_power.h
+++ b/drivers/net/ipa/ipa_power.h
@@ -40,6 +40,13 @@ void ipa_power_modem_queue_wake(struct ipa *ipa);
  */
 void ipa_power_modem_queue_active(struct ipa *ipa);
 
+/**
+ * ipa_power_retention() - Control register retention on power collapse
+ * @ipa:	IPA pointer
+ * @enable:	Whether retention should be enabled or disabled
+ */
+void ipa_power_retention(struct ipa *ipa, bool enable);
+
 /**
  * ipa_power_setup() - Set up IPA power management
  * @ipa:	IPA pointer
diff --git a/drivers/net/ipa/ipa_uc.c b/drivers/net/ipa/ipa_uc.c
index 856e55a080a7f..fe11910518d95 100644
--- a/drivers/net/ipa/ipa_uc.c
+++ b/drivers/net/ipa/ipa_uc.c
@@ -11,6 +11,7 @@
 
 #include "ipa.h"
 #include "ipa_uc.h"
+#include "ipa_power.h"
 
 /**
  * DOC:  The IPA embedded microcontroller
@@ -154,6 +155,7 @@ static void ipa_uc_response_hdlr(struct ipa *ipa, enum ipa_irq_id irq_id)
 	case IPA_UC_RESPONSE_INIT_COMPLETED:
 		if (ipa->uc_powered) {
 			ipa->uc_loaded = true;
+			ipa_power_retention(ipa, true);
 			pm_runtime_mark_last_busy(dev);
 			(void)pm_runtime_put_autosuspend(dev);
 			ipa->uc_powered = false;
@@ -184,6 +186,9 @@ void ipa_uc_deconfig(struct ipa *ipa)
 
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_UC_1);
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_UC_0);
+	if (ipa->uc_loaded)
+		ipa_power_retention(ipa, false);
+
 	if (!ipa->uc_powered)
 		return;
 
-- 
2.32.0

Re: [PATCH net 2/2] net: ipa: request IPA register values be retained

[Jakub Kicinski]

On Tue,  1 Feb 2022 08:04:12 -0600 Alex Elder wrote:
> Fixes: 2775cbc5afeb6 ("net: ipa: rename "ipa_clock.c"")

The Fixes tag should point at the place the code was introduced, 
even if it moved or otherwise the patch won't apply as far back.

Re: [PATCH net 2/2] net: ipa: request IPA register values be retained

[Alex Elder]

On 2/2/22 11:02 PM, Jakub Kicinski wrote:
> On Tue,  1 Feb 2022 08:04:12 -0600 Alex Elder wrote:
>> Fixes: 2775cbc5afeb6 ("net: ipa: rename "ipa_clock.c"")
> 
> The Fixes tag should point at the place the code was introduced,
> even if it moved or otherwise the patch won't apply as far back.

The problem was not "activated" until this commit:
   1aac309d32075 net: ipa: use autosuspend


And that commit was merged together in a series that
included the one I mentioned above:
   2775cbc5afeb6 net: ipa: rename "ipa_clock.c"

The rename commit is two commits after "use autosuspend".

The merge commit was:
   863434886497d Merge branch 'ipa-autosuspend'


Until autosuspend is enabled, this new code is
completely unnecessary, so back-porting it beyond
that is pointless.  I supplied the commit in the
"Fixes" tag because I thought it would be close
to equivalent and would avoid some trouble back-porting.

Perhaps the "use autosuspend" commit is the one that
should be in the "Fixes" tag, but I don't believe it
should be back-ported any further than that.

Re-spinning the series to fix the tag is trivial, but
before I do that, can you tell me which commit you
recommend I use in the "Fixes" tag?

The original commit that introduced the microcontroller
code (and also included the clock/power code) is:
   a646d6ec90983 soc: qcom: ipa: modem and microcontroller

Thanks.

					-Alex

Re: [PATCH net 2/2] net: ipa: request IPA register values be retained

[Jakub Kicinski]

On Thu, 3 Feb 2022 05:22:23 -0600 Alex Elder wrote:
> On 2/2/22 11:02 PM, Jakub Kicinski wrote:
> > On Tue,  1 Feb 2022 08:04:12 -0600 Alex Elder wrote:  
> >> Fixes: 2775cbc5afeb6 ("net: ipa: rename "ipa_clock.c"")  
> > 
> > The Fixes tag should point at the place the code was introduced,
> > even if it moved or otherwise the patch won't apply as far back.  
> 
> The problem was not "activated" until this commit:
>    1aac309d32075 net: ipa: use autosuspend
> 
> 
> And that commit was merged together in a series that
> included the one I mentioned above:
>    2775cbc5afeb6 net: ipa: rename "ipa_clock.c"
> 
> The rename commit is two commits after "use autosuspend".
> 
> The merge commit was:
>    863434886497d Merge branch 'ipa-autosuspend'
> 
> 
> Until autosuspend is enabled, this new code is
> completely unnecessary, so back-porting it beyond
> that is pointless.  I supplied the commit in the
> "Fixes" tag because I thought it would be close
> to equivalent and would avoid some trouble back-porting.
> 
> Perhaps the "use autosuspend" commit is the one that
> should be in the "Fixes" tag, but I don't believe it
> should be back-ported any further than that.
> 
> Re-spinning the series to fix the tag is trivial, but
> before I do that, can you tell me which commit you
> recommend I use in the "Fixes" tag?
> 
> The original commit that introduced the microcontroller
> code (and also included the clock/power code) is:
>    a646d6ec90983 soc: qcom: ipa: modem and microcontroller

Thanks for the explanation 1aac309d32075 sounds like the right choice.
Let me just swap it for you and apply the v2.