[PATCH v4 1/2] platform: arm64: lenovo-thinkpad-t14s-ec: Add hwmon support for temperatures

[Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>]

Expose the Lenovo ThinkPad T14s EC environmental sensors through
the hwmon subsystem.

The driver now registers a hwmon device providing access to six EC
temperature sensors corresponding to the SoC, keyboard area, base
cover, PMIC/charging circuitry, QTM module and SSD. Sensor labels
are exported to allow user space to identify each measurement.

This allows standard monitoring tools such as lm-sensors to report
platform temperatures.

Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on T14s OLED
Signed-off-by: Daniel Lezcano daniel.lezcano@oss.qualcomm.com
---
 drivers/platform/arm64/Kconfig                |   1 +
 drivers/platform/arm64/lenovo-thinkpad-t14s.c | 131 ++++++++++++++++++
 2 files changed, 132 insertions(+)

diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
index 10f905d7d6bf..121043348740 100644
--- a/drivers/platform/arm64/Kconfig
+++ b/drivers/platform/arm64/Kconfig
@@ -75,6 +75,7 @@ config EC_LENOVO_THINKPAD_T14S
 	depends on ARCH_QCOM || COMPILE_TEST
 	depends on I2C
 	depends on INPUT
+	depends on HWMON
 	select INPUT_SPARSEKMAP
 	select LEDS_CLASS
 	select NEW_LEDS
diff --git a/drivers/platform/arm64/lenovo-thinkpad-t14s.c b/drivers/platform/arm64/lenovo-thinkpad-t14s.c
index 5590302a5694..fc480f093238 100644
--- a/drivers/platform/arm64/lenovo-thinkpad-t14s.c
+++ b/drivers/platform/arm64/lenovo-thinkpad-t14s.c
@@ -11,6 +11,7 @@
 #include <linux/delay.h>
 #include <linux/dev_printk.h>
 #include <linux/err.h>
+#include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/input/sparse-keymap.h>
@@ -21,6 +22,7 @@
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/pm.h>
+#include <linux/units.h>
 
 #define T14S_EC_CMD_ECRD	0x02
 #define T14S_EC_CMD_ECWR	0x03
@@ -67,6 +69,13 @@
 #define T14S_EC_EVT_KEY_FN_F11			0x7a
 #define T14S_EC_EVT_KEY_FN_G			0x7e
 
+#define T14S_EC_SYS_THERM0 0x78 /* SoC (CPU+GPU)  */
+#define T14S_EC_SYS_THERM1 0x79 /* Keyboard       */
+#define T14S_EC_SYS_THERM2 0x7a /* Back cover     */
+#define T14S_EC_SYS_THERM3 0x7b /* Charger / PMIC */
+#define T14S_EC_SYS_THERM6 0x7c /* QTM West       */
+#define T14S_EC_SYS_THERM7 0x7d /* SSD            */
+
 /* Hardware LED blink rate is 1 Hz (500ms off, 500ms on) */
 #define T14S_EC_BLINK_RATE_ON_OFF_MS		500
 
@@ -93,9 +102,19 @@ struct t14s_ec_led_classdev {
 	struct t14s_ec *ec;
 };
 
+struct t14s_ec_hwmon_sys_thermx {
+	const char *label;
+	int reg;
+};
+
+struct t14s_ec_hwmon {
+	struct t14s_ec_hwmon_sys_thermx *sys_thermx;
+};
+
 struct t14s_ec {
 	struct regmap *regmap;
 	struct device *dev;
+	struct t14s_ec_hwmon ec_hwmon;
 	struct t14s_ec_led_classdev led_pwr_btn;
 	struct t14s_ec_led_classdev led_chrg_orange;
 	struct t14s_ec_led_classdev led_chrg_white;
@@ -555,6 +574,114 @@ static irqreturn_t t14s_ec_irq_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static umode_t t14s_ec_hwmon_is_visible(const void *drvdata,
+					enum hwmon_sensor_types type,
+					u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		if (attr == hwmon_temp_input ||
+		    attr == hwmon_temp_label)
+			return 0444;
+		break;
+	default:
+		return 0;
+	}
+
+	return 0;
+}
+
+static int t14s_ec_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
+				     u32 attr, int channel, const char **str)
+{
+	struct t14s_ec *ec = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		if (attr == hwmon_temp_label) {
+			*str = ec->ec_hwmon.sys_thermx[channel].label;
+			return 0;
+		}
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int t14s_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, long *val)
+{
+	struct t14s_ec *ec = dev_get_drvdata(dev);
+	unsigned int value;
+	int ret;
+
+	switch (type) {
+	case hwmon_temp:
+		if (attr == hwmon_temp_input) {
+			ret = t14s_ec_read(ec, ec->ec_hwmon.sys_thermx[channel].reg, &value);
+			if (ret)
+				return ret;
+			*val = value * MILLIDEGREE_PER_DEGREE;
+
+			return 0;
+		}
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops t14s_ec_hwmon_ops = {
+	.is_visible = t14s_ec_hwmon_is_visible,
+	.read = t14s_ec_hwmon_read,
+	.read_string = t14s_ec_hwmon_read_string,
+};
+
+static const struct hwmon_channel_info *t14s_ec_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL,
+			   HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static const struct hwmon_chip_info t14s_ec_chip_info = {
+	.ops = &t14s_ec_hwmon_ops,
+	.info = t14s_ec_hwmon_info,
+};
+
+static int t14s_ec_hwmon_probe(struct t14s_ec *ec)
+{
+	struct device *dev;
+	struct t14s_ec_hwmon_sys_thermx sys_thermx[] = {
+		{ .label = "soc",	.reg = T14S_EC_SYS_THERM0 },
+		{ .label = "keyboard",	.reg = T14S_EC_SYS_THERM1 },
+		{ .label = "base",	.reg = T14S_EC_SYS_THERM2 },
+		{ .label = "charging",	.reg = T14S_EC_SYS_THERM3 },
+		{ .label = "qtm",	.reg = T14S_EC_SYS_THERM6 },
+		{ .label = "ssd",	.reg = T14S_EC_SYS_THERM7 },
+	};
+
+	ec->ec_hwmon.sys_thermx = devm_kmemdup_array(ec->dev, sys_thermx,
+						     ARRAY_SIZE(sys_thermx),
+						     sizeof(sys_thermx[0]), GFP_KERNEL);
+	if (!ec->ec_hwmon.sys_thermx)
+		return -ENOMEM;
+
+	dev = devm_hwmon_device_register_with_info(ec->dev, "t14s_ec", ec,
+						   &t14s_ec_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(dev);
+}
+
 static int t14s_ec_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
@@ -590,6 +717,10 @@ static int t14s_ec_probe(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
+	ret = t14s_ec_hwmon_probe(ec);
+	if (ret < 0)
+		return ret;
+
 	ret = devm_request_threaded_irq(dev, client->irq, NULL,
 					t14s_ec_irq_handler,
 					IRQF_ONESHOT, dev_name(dev), ec);
-- 
2.53.0