linux-kernel - [PATCH 4/6] usb: cdns3: support power-off of controller when in host role

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Message-Id: <20231113-j7200-usb-suspend-v1-4-ad1ee714835c@bootlin.com>
Date:   Mon, 13 Nov 2023 15:26:59 +0100
From:   Théo Lebrun <theo.lebrun@...tlin.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Roger Quadros <rogerq@...nel.org>,
        Peter Chen <peter.chen@...nel.org>,
        Pawel Laszczak <pawell@...ence.com>,
        Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>
Cc:     linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Théo Lebrun <theo.lebrun@...tlin.com>
Subject: [PATCH 4/6] usb: cdns3: support power-off of controller when in
 host role

The controller is not being reconfigured at resume. Change resume to
redo hardware config if quirk CDNS3_RESET_ON_RESUME is active.

Platform data comes from the parent driver (eg cdns3-ti).

The quirk should be passed if the platform driver knows that the
controller might be in reset state at resume. We do NOT reconfigure the
hardware without this quirk to avoid losing state if we did a suspend
without reset.

If the quirk is on, we notify the xHCI subsystem that:

1. We reset on resume. It will therefore redo the xHC init & trigger
   such message as "root hub lost power or was reset" in dmesg.

2. It should disable/enable clocks on suspend/resume. This does not
   matter on our platform as xhci-plat does not get access to any clock
   but it would be the right thing to do if we indeed had such clocks.

Signed-off-by: Théo Lebrun <theo.lebrun@...tlin.com>
---
 drivers/usb/cdns3/core.h |  1 +
 drivers/usb/cdns3/host.c | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/usb/cdns3/core.h b/drivers/usb/cdns3/core.h
index 81a9c9d6be08..7487067ba23f 100644
--- a/drivers/usb/cdns3/core.h
+++ b/drivers/usb/cdns3/core.h
@@ -44,6 +44,7 @@ struct cdns3_platform_data {
 			bool suspend, bool wakeup);
 	unsigned long quirks;
 #define CDNS3_DEFAULT_PM_RUNTIME_ALLOW	BIT(0)
+#define CDNS3_RESET_ON_RESUME		BIT(1)
 };
 
 /**
diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
index 6164fc4c96a4..a81019a7c8cc 100644
--- a/drivers/usb/cdns3/host.c
+++ b/drivers/usb/cdns3/host.c
@@ -88,6 +88,9 @@ static int __cdns_host_init(struct cdns *cdns)
 		goto err1;
 	}
 
+	if (cdns->pdata && cdns->pdata->quirks & CDNS3_RESET_ON_RESUME)
+		cdns->xhci_plat_data->quirks |= XHCI_RESET_ON_RESUME | XHCI_SUSPEND_RESUME_CLKS;
+
 	if (cdns->pdata && (cdns->pdata->quirks & CDNS3_DEFAULT_PM_RUNTIME_ALLOW))
 		cdns->xhci_plat_data->quirks |= XHCI_DEFAULT_PM_RUNTIME_ALLOW;
 
@@ -124,6 +127,18 @@ static void cdns_host_exit(struct cdns *cdns)
 	cdns_drd_host_off(cdns);
 }
 
+static int cdns_host_suspend(struct cdns *cdns, bool do_wakeup)
+{
+	if (!do_wakeup)
+		cdns_drd_host_off(cdns);
+	return 0;
+}
+
+static int cdns_host_resume(struct cdns *cdns, bool hibernated)
+{
+	return cdns_drd_host_on(cdns);
+}
+
 int cdns_host_init(struct cdns *cdns)
 {
 	struct cdns_role_driver *rdrv;
@@ -137,6 +152,11 @@ int cdns_host_init(struct cdns *cdns)
 	rdrv->state	= CDNS_ROLE_STATE_INACTIVE;
 	rdrv->name	= "host";
 
+	if (cdns->pdata && cdns->pdata->quirks & CDNS3_RESET_ON_RESUME) {
+		rdrv->suspend = cdns_host_suspend;
+		rdrv->resume = cdns_host_resume;
+	}
+
 	cdns->roles[USB_ROLE_HOST] = rdrv;
 
 	return 0;

-- 
2.41.0