linux-kernel - [PATCH net-next v2] net: phy: broadcom: Implement suspend/resume for AC131 and BCM5241

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Message-Id: <20220815190725.2749403-1-f.fainelli@gmail.com>
Date:   Mon, 15 Aug 2022 12:07:25 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernelorg
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        netdev@...r.kernel.org (open list:BROADCOM ETHERNET PHY DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net-next v2] net: phy: broadcom: Implement suspend/resume for AC131 and BCM5241

Implement the suspend/resume procedure for the Broadcom AC131 and BCM5241 type
of PHYs (10/100 only) by entering the standard power down followed by the
proprietary standby mode in the auxiliary mode 4 shadow register. On resume,
the PHY software reset is enough to make it come out of standby mode so we can
utilize brcm_fet_config_init() as the resume hook.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
Changes in v2:

- utilize phy_modify() to write to MII_BRCM_FET_SHDW_AUXMODE4 (Russell)

 drivers/net/phy/broadcom.c | 39 ++++++++++++++++++++++++++++++++++++++
 include/linux/brcmphy.h    |  1 +
 2 files changed, 40 insertions(+)

diff --git a/drivers/net/phy/broadcom.c b/drivers/net/phy/broadcom.c
index 31fbcdddc9ad..ad71c88c87e7 100644
--- a/drivers/net/phy/broadcom.c
+++ b/drivers/net/phy/broadcom.c
@@ -766,6 +766,41 @@ static irqreturn_t brcm_fet_handle_interrupt(struct phy_device *phydev)
 	return IRQ_HANDLED;
 }
 
+static int brcm_fet_suspend(struct phy_device *phydev)
+{
+	int reg, err, err2, brcmtest;
+
+	/* We cannot use a read/modify/write here otherwise the PHY continues
+	 * to drive LEDs which defeats the purpose of low power mode.
+	 */
+	err = phy_write(phydev, MII_BMCR, BMCR_PDOWN);
+	if (err < 0)
+		return err;
+
+	/* Enable shadow register access */
+	brcmtest = phy_read(phydev, MII_BRCM_FET_BRCMTEST);
+	if (brcmtest < 0)
+		return brcmtest;
+
+	reg = brcmtest | MII_BRCM_FET_BT_SRE;
+
+	err = phy_write(phydev, MII_BRCM_FET_BRCMTEST, reg);
+	if (err < 0)
+		return err;
+
+	/* Set standby mode */
+	err = phy_modify(phydev, MII_BRCM_FET_SHDW_AUXMODE4,
+			 MII_BRCM_FET_SHDW_AM4_STANDBY,
+			 MII_BRCM_FET_SHDW_AM4_STANDBY);
+
+	/* Disable shadow register access */
+	err2 = phy_write(phydev, MII_BRCM_FET_BRCMTEST, brcmtest);
+	if (!err)
+		err = err2;
+
+	return err;
+}
+
 static int bcm54xx_phy_probe(struct phy_device *phydev)
 {
 	struct bcm54xx_phy_priv *priv;
@@ -1033,6 +1068,8 @@ static struct phy_driver broadcom_drivers[] = {
 	.config_init	= brcm_fet_config_init,
 	.config_intr	= brcm_fet_config_intr,
 	.handle_interrupt = brcm_fet_handle_interrupt,
+	.suspend	= brcm_fet_suspend,
+	.resume		= brcm_fet_config_init,
 }, {
 	.phy_id		= PHY_ID_BCM5241,
 	.phy_id_mask	= 0xfffffff0,
@@ -1041,6 +1078,8 @@ static struct phy_driver broadcom_drivers[] = {
 	.config_init	= brcm_fet_config_init,
 	.config_intr	= brcm_fet_config_intr,
 	.handle_interrupt = brcm_fet_handle_interrupt,
+	.suspend	= brcm_fet_suspend,
+	.resume		= brcm_fet_config_init,
 }, {
 	.phy_id		= PHY_ID_BCM5395,
 	.phy_id_mask	= 0xfffffff0,
diff --git a/include/linux/brcmphy.h b/include/linux/brcmphy.h
index 6ff567ece34a..9e77165f3ef6 100644
--- a/include/linux/brcmphy.h
+++ b/include/linux/brcmphy.h
@@ -293,6 +293,7 @@
 #define MII_BRCM_FET_SHDW_MC_FAME	0x4000	/* Force Auto MDIX enable */
 
 #define MII_BRCM_FET_SHDW_AUXMODE4	0x1a	/* Auxiliary mode 4 */
+#define MII_BRCM_FET_SHDW_AM4_STANDBY	0x0008	/* Standby enable */
 #define MII_BRCM_FET_SHDW_AM4_LED_MASK	0x0003
 #define MII_BRCM_FET_SHDW_AM4_LED_MODE1 0x0001
 
-- 
2.25.1