[PATCH net-next 3/3] net: phy: realtek: add hwmon support for temp sensor on RTL822x

[Heiner Kallweit <hkallweit1@gmail.com>]

This adds hwmon support for the temperature sensor on RTL822x. It's
available on the standalone versions of the PHY's, and on the integrated
PHY's in RTL8125B/RTL8125D/RTL8126.

Notes:
- over-temp threshold is set by PHY power-on default or BIOS / boot loader
  and it's read-only
- over-temp alarm remains set, even if temperature drops below threshold

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/net/phy/Kconfig         |  6 +++
 drivers/net/phy/Makefile        |  1 +
 drivers/net/phy/realtek.h       | 10 ++++
 drivers/net/phy/realtek_hwmon.c | 83 +++++++++++++++++++++++++++++++++
 drivers/net/phy/realtek_main.c  | 12 +++++
 5 files changed, 112 insertions(+)
 create mode 100644 drivers/net/phy/realtek.h
 create mode 100644 drivers/net/phy/realtek_hwmon.c

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index dc625f2b3..eae53ef88 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -355,6 +355,12 @@ config REALTEK_PHY
 	help
 	  Supports the Realtek 821x PHY.
 
+config REALTEK_PHY_HWMON
+	def_bool REALTEK_PHY && HWMON
+	depends on !(REALTEK_PHY=y && HWMON=m)
+	help
+	  Optional hwmon support for the temperature sensor
+
 config RENESAS_PHY
 	tristate "Renesas PHYs"
 	help
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index ec480e733..ca369a5c9 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -96,6 +96,7 @@ obj-$(CONFIG_NXP_TJA11XX_PHY)	+= nxp-tja11xx.o
 obj-y				+= qcom/
 obj-$(CONFIG_QSEMI_PHY)		+= qsemi.o
 realtek-y += realtek_main.o
+realtek-$(CONFIG_REALTEK_PHY_HWMON) += realtek_hwmon.o
 obj-$(CONFIG_REALTEK_PHY)	+= realtek.o
 obj-$(CONFIG_RENESAS_PHY)	+= uPD60620.o
 obj-$(CONFIG_ROCKCHIP_PHY)	+= rockchip.o
diff --git a/drivers/net/phy/realtek.h b/drivers/net/phy/realtek.h
new file mode 100644
index 000000000..a39b44fa1
--- /dev/null
+++ b/drivers/net/phy/realtek.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef REALTEK_H
+#define REALTEK_H
+
+#include <linux/phy.h>
+
+int rtl822x_hwmon_init(struct phy_device *phydev);
+
+#endif /* REALTEK_H */
diff --git a/drivers/net/phy/realtek_hwmon.c b/drivers/net/phy/realtek_hwmon.c
new file mode 100644
index 000000000..d3284c83f
--- /dev/null
+++ b/drivers/net/phy/realtek_hwmon.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0+
+ *
+ * HWMON support for Realtek PHY's
+ *
+ * Author: Heiner Kallweit <hkallweit1@gmail.com>
+ */
+
+#include <linux/hwmon.h>
+#include <linux/phy.h>
+
+#include "realtek.h"
+
+#define RTL822X_VND2_TSALRM				0xa662
+#define RTL822X_VND2_TSRR				0xbd84
+#define RTL822X_VND2_TSSR				0xb54c
+
+static int rtl822x_hwmon_get_temp(int raw)
+{
+	if (raw >= 512)
+		raw -= 1024;
+
+	return 1000 * raw / 2;
+}
+
+static int rtl822x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, long *val)
+{
+	struct phy_device *phydev = dev_get_drvdata(dev);
+	int raw;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		raw = phy_read_mmd(phydev, MDIO_MMD_VEND2, RTL822X_VND2_TSRR) & 0x3ff;
+		*val = rtl822x_hwmon_get_temp(raw);
+		break;
+	case hwmon_temp_max:
+		/* Chip reduces speed to 1G if threshold is exceeded */
+		raw = phy_read_mmd(phydev, MDIO_MMD_VEND2, RTL822X_VND2_TSSR) >> 6;
+		*val = rtl822x_hwmon_get_temp(raw);
+		break;
+	case hwmon_temp_alarm:
+		raw = phy_read_mmd(phydev, MDIO_MMD_VEND2, RTL822X_VND2_TSALRM);
+		*val = !!(raw & 3);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_ops rtl822x_hwmon_ops = {
+	.visible = 0444,
+	.read = rtl822x_hwmon_read,
+};
+
+static const struct hwmon_channel_info * const rtl822x_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_ALARM),
+	NULL
+};
+
+static const struct hwmon_chip_info rtl822x_hwmon_chip_info = {
+	.ops = &rtl822x_hwmon_ops,
+	.info = rtl822x_hwmon_info,
+};
+
+int rtl822x_hwmon_init(struct phy_device *phydev)
+{
+	struct device *hwdev, *dev = &phydev->mdio.dev;
+	const char *name;
+
+	/* Ensure over-temp alarm is reset. */
+	phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2, RTL822X_VND2_TSALRM, 3);
+
+	name = devm_hwmon_sanitize_name(dev, dev_name(dev));
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	hwdev = devm_hwmon_device_register_with_info(dev, name, phydev,
+						     &rtl822x_hwmon_chip_info,
+						     NULL);
+	return PTR_ERR_OR_ZERO(hwdev);
+}
diff --git a/drivers/net/phy/realtek_main.c b/drivers/net/phy/realtek_main.c
index af9874143..38149958d 100644
--- a/drivers/net/phy/realtek_main.c
+++ b/drivers/net/phy/realtek_main.c
@@ -14,6 +14,8 @@
 #include <linux/delay.h>
 #include <linux/clk.h>
 
+#include "realtek.h"
+
 #define RTL821x_PHYSR				0x11
 #define RTL821x_PHYSR_DUPLEX			BIT(13)
 #define RTL821x_PHYSR_SPEED			GENMASK(15, 14)
@@ -820,6 +822,15 @@ static int rtl822x_write_mmd(struct phy_device *phydev, int devnum, u16 regnum,
 	return ret;
 }
 
+static int rtl822x_probe(struct phy_device *phydev)
+{
+	if (IS_ENABLED(CONFIG_REALTEK_PHY_HWMON) &&
+	    phydev->phy_id != RTL_GENERIC_PHYID)
+		return rtl822x_hwmon_init(phydev);
+
+	return 0;
+}
+
 static int rtl822xb_config_init(struct phy_device *phydev)
 {
 	bool has_2500, has_sgmii;
@@ -1519,6 +1530,7 @@ static struct phy_driver realtek_drvs[] = {
 		.match_phy_device = rtl_internal_nbaset_match_phy_device,
 		.name           = "Realtek Internal NBASE-T PHY",
 		.flags		= PHY_IS_INTERNAL,
+		.probe		= rtl822x_probe,
 		.get_features   = rtl822x_get_features,
 		.config_aneg    = rtl822x_config_aneg,
 		.read_status    = rtl822x_read_status,
-- 
2.47.1