linux-kernel - [PATCH v4 4/6] PCI: brcmstb: Do not turn off regulators if EP can wake up

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Message-Id: <20210401212148.47033-5-jim2101024@gmail.com>
Date:   Thu,  1 Apr 2021 17:21:44 -0400
From:   Jim Quinlan <jim2101024@...il.com>
To:     linux-pci@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Rob Herring <robh@...nel.org>, Mark Brown <broonie@...nel.org>,
        bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com,
        james.quinlan@...adcom.com
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM
        BCM2711/BCM2835 ARM ARCHITECTURE),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v4 4/6] PCI: brcmstb: Do not turn off regulators if EP can wake up

If any downstream device may wake up during S2/S3 suspend, we do not want
to turn off its power when suspending.

Signed-off-by: Jim Quinlan <jim2101024@...il.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 58 +++++++++++++++++++++++----
 1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 1b0de0c7da60..4c79aff66de7 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -193,6 +193,7 @@ static inline void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie,
 static inline void brcm_pcie_perst_set_4908(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_7278(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_generic(struct brcm_pcie *pcie, u32 val);
+static bool brcm_pcie_link_up(struct brcm_pcie *pcie);
 
 static const char * const supplies[] = {
 	"vpcie12v-supply",
@@ -304,22 +305,65 @@ struct brcm_pcie {
 	void			(*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
 	struct regulator_bulk_data supplies[PCIE_BRCM_MAX_EP_REGULATORS];
 	unsigned int		num_supplies;
+	bool			ep_wakeup_capable;
 };
 
-static int brcm_set_regulators(struct brcm_pcie *pcie, bool on)
+static int pci_dev_may_wakeup(struct pci_dev *dev, void *data)
 {
+	bool *ret = data;
+
+	if (device_may_wakeup(&dev->dev)) {
+		*ret = true;
+		dev_dbg(&dev->dev, "disable cancelled for wake-up device\n");
+	}
+	return (int) *ret;
+}
+
+enum {
+	TURN_OFF,		/* Turn regulators off, unless an EP is wakeup-capable */
+	TURN_OFF_ALWAYS,	/* Turn regulators off, no exceptions */
+	TURN_ON,		/* Turn regulators on, unless pcie->ep_wakeup_capable */
+};
+
+static int brcm_set_regulators(struct brcm_pcie *pcie, int how)
+{
+	struct pci_host_bridge *bridge = pci_host_bridge_from_priv(pcie);
 	struct device *dev = pcie->dev;
 	int ret;
 
 	if (!pcie->num_supplies)
 		return 0;
-	if (on)
+	if (how == TURN_ON) {
+		if (pcie->ep_wakeup_capable) {
+			/*
+			 * We are resuming from a suspend.  In the
+			 * previous suspend we did not disable the power
+			 * supplies, so there is no need to enable them
+			 * (and falsely increase their usage count).
+			 */
+			pcie->ep_wakeup_capable = false;
+			return 0;
+		}
+	} else if (how == TURN_OFF) {
+		/*
+		 * If at least one device on this bus is enabled as a
+		 * wake-up source, do not turn off regulators.
+		 */
+		pcie->ep_wakeup_capable = false;
+		if (bridge->bus && brcm_pcie_link_up(pcie)) {
+			pci_walk_bus(bridge->bus, pci_dev_may_wakeup, &pcie->ep_wakeup_capable);
+			if (pcie->ep_wakeup_capable)
+				return 0;
+		}
+	}
+
+	if (how == TURN_ON)
 		ret = regulator_bulk_enable(pcie->num_supplies, pcie->supplies);
 	else
 		ret = regulator_bulk_disable(pcie->num_supplies, pcie->supplies);
 	if (ret)
 		dev_err(dev, "failed to %s EP regulators\n",
-			on ? "enable" : "disable");
+			how == TURN_ON ? "enable" : "disable");
 	return ret;
 }
 
@@ -1206,7 +1250,7 @@ static int brcm_pcie_suspend(struct device *dev)
 	brcm_phy_stop(pcie);
 	clk_disable_unprepare(pcie->clk);
 
-	return brcm_set_regulators(pcie, false);
+	return brcm_set_regulators(pcie, TURN_OFF);
 }
 
 static int brcm_pcie_resume(struct device *dev)
@@ -1221,7 +1265,7 @@ static int brcm_pcie_resume(struct device *dev)
 	if (ret)
 		return ret;
 
-	ret = brcm_set_regulators(pcie, true);
+	ret = brcm_set_regulators(pcie, TURN_ON);
 	if (ret)
 		return ret;
 
@@ -1261,7 +1305,7 @@ static void __brcm_pcie_remove(struct brcm_pcie *pcie)
 	brcm_phy_stop(pcie);
 	reset_control_assert(pcie->rescal);
 	clk_disable_unprepare(pcie->clk);
-	brcm_set_regulators(pcie, false);
+	brcm_set_regulators(pcie, TURN_OFF_ALWAYS);
 }
 
 static int brcm_pcie_remove(struct platform_device *pdev)
@@ -1360,7 +1404,7 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 		goto fail;
 	}
 
-	ret = brcm_set_regulators(pcie, true);
+	ret = brcm_set_regulators(pcie, TURN_ON);
 	if (ret)
 		goto fail;
 
-- 
2.17.1