[PATCH 2/5] net: phy: Add phy_modify_mmd() and phy_modify_mmd_changed() from Linux

[Marek Vasut]

Add phy_modify_mmd()/phy_modify_mmd_changed() from Linux 5.1.y as of commit
b8554d4f7288f ("net: phy: add register modifying helpers returning 1 on change")
This is used by the upcoming Marvell 10G PHY driver.

Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
---
Cc: "Ariel D'Alessandro" <ariel.dalessandro at collabora.com>
Cc: "Marek Behún" <kabel at kernel.org>
Cc: Joe Hershberger <joe.hershberger at ni.com>
Cc: Marek Vasut <marek.vasut+renesas at mailbox.org>
Cc: Michael Trimarchi <michael at amarulasolutions.com>
Cc: Nate Drude <nate.d at variscite.com>
Cc: Ramon Fried <rfried.dev at gmail.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Stefan Roese <sr at denx.de>
Cc: Tim Harvey <tharvey at gateworks.com>
Cc: Vladimir Oltean <vladimir.oltean at nxp.com>
---
 drivers/net/phy/phy.c | 54 +++++++++++++++++++++++++++++++++++++++++++
 include/phy.h         |  4 ++++
 2 files changed, 58 insertions(+)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index f720d0a7920..0eeb0cb3a85 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -1158,6 +1158,60 @@ int phy_clear_bits_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val
 	return 0;
 }
 
+/**
+ * phy_modify_mmd_changed - Function for modifying a register on MMD
+ * @phydev: the phy_device struct
+ * @devad: the MMD containing register to modify
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ *
+ * Returns negative errno, 0 if there was no change, and 1 in case of change
+ */
+int phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
+			   u16 mask, u16 set)
+{
+	int new, ret;
+
+	ret = phy_read_mmd(phydev, devad, regnum);
+	if (ret < 0)
+		return ret;
+
+	new = (ret & ~mask) | set;
+	if (new == ret)
+		return 0;
+
+	ret = phy_write_mmd(phydev, devad, regnum, new);
+
+	return ret < 0 ? ret : 1;
+}
+
+/**
+ * phy_modify_mmd - Convenience function for modifying a register on MMD
+ * @phydev: the phy_device struct
+ * @devad: the MMD containing register to modify
+ * @regnum: register number to modify
+ * @mask: bit mask of bits to clear
+ * @set: new value of bits set in mask to write to @regnum
+ *
+ * NOTE: MUST NOT be called from interrupt context,
+ * because the bus read/write functions may wait for an interrupt
+ * to conclude the operation.
+ */
+int phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
+		   u16 mask, u16 set)
+{
+	int ret;
+
+	ret = phy_modify_mmd_changed(phydev, devad, regnum, mask, set);
+
+	return ret < 0 ? ret : 0;
+}
+
 bool phy_interface_is_ncsi(void)
 {
 #ifdef CONFIG_PHY_NCSI
diff --git a/include/phy.h b/include/phy.h
index 4a9de461152..34675b2c9c0 100644
--- a/include/phy.h
+++ b/include/phy.h
@@ -289,6 +289,10 @@ int phy_read_mmd(struct phy_device *phydev, int devad, int regnum);
 int phy_write_mmd(struct phy_device *phydev, int devad, int regnum, u16 val);
 int phy_set_bits_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val);
 int phy_clear_bits_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val);
+int phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
+			   u16 mask, u16 set);
+int phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
+		   u16 mask, u16 set);
 
 int phy_startup(struct phy_device *phydev);
 int phy_config(struct phy_device *phydev);
-- 
2.39.2