drivers: sensor: add Innovative Sensor Technology TSic xx6 driver

Add driver for TSic 206/306/316/506F/516/716 temperature sensor.
The driver uses PWM capture driver to read a single wire with
Manchester-like encoding.

Signed-off-by: Jeppe Odgaard <jeppe.odgaard@prevas.dk>

drivers/sensor/CMakeLists.txt

@@ -61,6 +61,7 @@ add_subdirectory_ifdef(CONFIG_S11059 s11059)
 add_subdirectory_ifdef(CONFIG_SBS_GAUGE sbs_gauge)
 add_subdirectory_ifdef(CONFIG_SX9500 sx9500)
 add_subdirectory_ifdef(CONFIG_TH02 th02)
+add_subdirectory_ifdef(CONFIG_TSIC_XX6 tsic_xx6)
 add_subdirectory_ifdef(CONFIG_VOLTAGE_DIVIDER voltage_divider)
 add_subdirectory_ifdef(CONFIG_TACH_ENE_KB1200 ene_tach_kb1200)
 

drivers/sensor/Kconfig

@@ -142,6 +142,7 @@ source "drivers/sensor/s11059/Kconfig"
 source "drivers/sensor/sbs_gauge/Kconfig"
 source "drivers/sensor/sx9500/Kconfig"
 source "drivers/sensor/th02/Kconfig"
+source "drivers/sensor/tsic_xx6/Kconfig"
 source "drivers/sensor/voltage_divider/Kconfig"
 source "drivers/sensor/ene_tach_kb1200/Kconfig"
 

drivers/sensor/tsic_xx6/CMakeLists.txt

@@ -0,0 +1,5 @@
+# Copyright (c) 2024 Vitrolife A/S
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources_ifdef(CONFIG_TSIC_XX6 tsic_xx6.c)

drivers/sensor/tsic_xx6/Kconfig

@@ -0,0 +1,11 @@
+# Copyright (c) 2024 Vitrolife A/S
+# SPDX-License-Identifier: Apache-2.0
+
+config TSIC_XX6
+	bool "TSic xx6 driver"
+	default y
+	depends on DT_HAS_IST_TSIC_XX6_ENABLED
+	select PWM
+	select PWM_CAPTURE
+	help
+	  Enable driver for TSic 206/306/316/506F/516/716.

drivers/sensor/tsic_xx6/tsic_xx6.c

@@ -0,0 +1,284 @@
+/*
+ * Copyright (c) 2024, Vitrolife A/S
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#define DT_DRV_COMPAT ist_tsic_xx6
+
+#include <zephyr/device.h>
+#include <zephyr/drivers/pwm.h>
+#include <zephyr/drivers/sensor.h>
+#include <zephyr/kernel.h>
+#include <zephyr/logging/log.h>
+#include <zephyr/sys/atomic.h>
+#include <zephyr/sys/util.h>
+#include <zephyr/sys/util_macro.h>
+
+LOG_MODULE_REGISTER(TSIC_XX6, CONFIG_SENSOR_LOG_LEVEL);
+
+#define FRAME_BIT_PERIOD_US 125
+
+enum {
+	FRAME_PARITIY_BIT_LSB,
+	FRAME_DATA_BIT_0,
+	FRAME_DATA_BIT_1,
+	FRAME_DATA_BIT_2,
+	FRAME_DATA_BIT_3,
+	FRAME_DATA_BIT_4,
+	FRAME_DATA_BIT_5,
+	FRAME_DATA_BIT_6,
+	FRAME_DATA_BIT_7,
+	FRAME_START_BIT_LSB,
+	/* Theres a single bit period between the two packets that is constant high. This bit will
+	 * be part of the 2nd packet's start bit thus frame length is not affected.
+	 */
+	FRAME_PARITIY_BIT_MSB,
+	FRAME_DATA_BIT_8,
+	FRAME_DATA_BIT_9,
+	FRAME_DATA_BIT_10,
+	FRAME_DATA_BIT_11,
+	FRAME_DATA_BIT_12,
+	FRAME_DATA_BIT_13,
+	FRAME_ZERO_BIT_0,
+	FRAME_ZERO_BIT_1,
+	FRAME_START_BIT_MSB,
+	FRAME_READY_BIT,
+	FRAME_FLAGS,
+};
+
+struct tsic_xx6_config {
+	const struct pwm_dt_spec pwm;
+	const int8_t lower_temperature_limit;
+	const uint8_t higher_temperature_limit;
+	const uint8_t data_bits;
+};
+
+struct tsic_xx6_data {
+	uint64_t frame_cycles;
+	struct sensor_value val;
+
+	ATOMIC_DEFINE(frame, FRAME_FLAGS);
+	uint32_t buf;
+	uint8_t buf_index;
+};
+
+static inline void tsic_xx6_buf_reset(struct tsic_xx6_data *data)
+{
+	data->buf_index = FRAME_START_BIT_MSB;
+}
+
+static inline bool tsic_xx6_is_buf_reset(struct tsic_xx6_data *data)
+{
+	return data->buf_index == FRAME_START_BIT_MSB;
+}
+
+static inline bool tsic_xx6_is_data_line_idle(struct tsic_xx6_data *data, uint64_t period_cycles)
+{
+	/* If the period is larger than two frames assume the data line has been idle */
+	return period_cycles > data->frame_cycles * 2;
+}
+
+static void tsic_xx6_pwm_callback(const struct device *dev, uint32_t channel,
+				  uint32_t period_cycles, uint32_t pulse_cycles, int status,
+				  void *user_data)
+{
+	const struct device *tsic_xx6_dev = user_data;
+	const struct tsic_xx6_config *config = tsic_xx6_dev->config;
+	struct tsic_xx6_data *data = tsic_xx6_dev->data;
+	uint32_t low_cycles;
+	bool val;
+
+	if (dev != config->pwm.dev || channel != config->pwm.channel) {
+		return;
+	}
+
+	if (status != 0) {
+		LOG_ERR("callback failed: %d", status);
+		return;
+	}
+
+	if (!tsic_xx6_is_buf_reset(data) && tsic_xx6_is_data_line_idle(data, period_cycles)) {
+		LOG_ERR("unexpected data idle");
+		tsic_xx6_buf_reset(data);
+	}
+
+	/*
+	 * Calculate low cycles: The sensor sends the pulse in the last part of the period. The PWM
+	 * capture driver triggers on rising edge with normal polarity. Therefore only the low part
+	 * of the frame bit is present.
+	 */
+	low_cycles = period_cycles - pulse_cycles;
+
+	/* 25 % duty cycle is 0, 75 % duty cycle is 1 */
+	val = low_cycles * 2 < data->frame_cycles;
+	WRITE_BIT(data->buf, data->buf_index, val);
+
+	if (data->buf_index > 0) {
+		--data->buf_index;
+	} else {
+		WRITE_BIT(data->buf, FRAME_READY_BIT, 1);
+		(void)atomic_set(data->frame, data->buf);
+		tsic_xx6_buf_reset(data);
+	}
+}
+
+static inline bool tsic_xx6_parity_check(uint8_t data, bool parity)
+{
+	bool data_parity = false;
+	size_t i;
+
+	for (i = 0; i < 8; ++i) {
+		data_parity ^= FIELD_GET(BIT(i), data);
+	}
+
+	return (parity ^ data_parity) == 0;
+}
+
+static int tsic_xx6_get_data_bits(const struct tsic_xx6_config *config, uint16_t *data_bits,
+				  uint32_t frame)
+{
+	uint8_t frame_data_bit_high =
+		config->data_bits == 14 ? FRAME_DATA_BIT_13 : FRAME_DATA_BIT_10;
+	uint8_t data_msb = FIELD_GET(GENMASK(frame_data_bit_high, FRAME_DATA_BIT_8), frame);
+	uint8_t data_lsb = FIELD_GET(GENMASK(FRAME_DATA_BIT_7, FRAME_DATA_BIT_0), frame);
+	bool parity_msb = FIELD_GET(BIT(FRAME_PARITIY_BIT_MSB), frame);
+	bool parity_lsb = BIT(FRAME_PARITIY_BIT_LSB) & frame;
+
+	if (!tsic_xx6_parity_check(data_msb, parity_msb) ||
+	    !tsic_xx6_parity_check(data_lsb, parity_lsb)) {
+		return -EIO;
+	}
+
+	*data_bits = data_msb << 8 | data_lsb;
+
+	return 0;
+}
+
+static void tsic_xx6_get_value(const struct tsic_xx6_config *config, struct tsic_xx6_data *data,
+			       uint16_t data_bits)
+{
+	int64_t tmp;
+
+	/* Apply the datasheet formula scaled to micro celcius */
+	tmp = data_bits * (config->higher_temperature_limit - config->lower_temperature_limit);
+	tmp = tmp * 1000000 / (BIT(config->data_bits) - 1);
+	tmp += (int64_t)config->lower_temperature_limit * 1000000;
+
+	data->val.val1 = tmp / 1000000;
+	data->val.val2 = tmp % 1000000;
+}
+
+static int tsic_xx6_sample_fetch(const struct device *dev, enum sensor_channel chan)
+{
+	const struct tsic_xx6_config *config = dev->config;
+	struct tsic_xx6_data *data = dev->data;
+	uint32_t frame;
+	uint16_t data_bits;
+	int rc;
+
+	if (chan != SENSOR_CHAN_ALL && chan != SENSOR_CHAN_AMBIENT_TEMP) {
+		return -ENOTSUP;
+	}
+
+	frame = atomic_and(data->frame, ~BIT(FRAME_READY_BIT));
+
+	if (FIELD_GET(BIT(FRAME_READY_BIT), frame) == 0) {
+		return -EBUSY;
+	}
+
+	rc = tsic_xx6_get_data_bits(config, &data_bits, frame);
+	if (rc != 0) {
+		return rc;
+	}
+
+	tsic_xx6_get_value(config, data, data_bits);
+
+	return 0;
+}
+
+static int tsic_xx6_channel_get(const struct device *dev, enum sensor_channel chan,
+				struct sensor_value *val)
+{
+	struct tsic_xx6_data *data = dev->data;
+
+	if (chan != SENSOR_CHAN_AMBIENT_TEMP) {
+		return -ENOTSUP;
+	}
+
+	*val = data->val;
+
+	return 0;
+}
+
+static const struct sensor_driver_api tsic_xx6_driver_api = {.sample_fetch = tsic_xx6_sample_fetch,
+							     .channel_get = tsic_xx6_channel_get};
+
+static int tsic_xx6_get_frame_cycles(const struct tsic_xx6_config *config, uint64_t *frame_cycles)
+{
+	uint64_t tmp;
+	int rc;
+
+	rc = pwm_get_cycles_per_sec(config->pwm.dev, config->pwm.channel, &tmp);
+	if (rc != 0) {
+		return rc;
+	}
+
+	if (u64_mul_overflow(tmp, FRAME_BIT_PERIOD_US, &tmp)) {
+		return -ERANGE;
+	}
+
+	*frame_cycles = tmp / USEC_PER_SEC;
+
+	return 0;
+}
+
+static int tsic_xx6_init(const struct device *dev)
+{
+	const struct tsic_xx6_config *config = dev->config;
+	struct tsic_xx6_data *data = dev->data;
+	int rc;
+
+	if (!pwm_is_ready_dt(&config->pwm)) {
+		return -ENODEV;
+	}
+
+	rc = tsic_xx6_get_frame_cycles(config, &data->frame_cycles);
+	if (rc != 0) {
+		return rc;
+	}
+
+	rc = pwm_configure_capture(config->pwm.dev, config->pwm.channel,
+				   config->pwm.flags | PWM_CAPTURE_TYPE_BOTH |
+					   PWM_CAPTURE_MODE_CONTINUOUS,
+				   tsic_xx6_pwm_callback, (void *)dev);
+	if (rc != 0) {
+		return rc;
+	}
+
+	tsic_xx6_buf_reset(data);
+
+	rc = pwm_enable_capture(config->pwm.dev, config->pwm.channel);
+	if (rc != 0) {
+		return rc;
+	}
+
+	return 0;
+}
+
+#define TSIC_XX6_DEVICE(n)                                                                         \
+                                                                                                   \
+	static struct tsic_xx6_data tsic_xx6_data_##n;                                             \
+                                                                                                   \
+	static const struct tsic_xx6_config tsic_xx6_config_##n = {                                \
+		.pwm = PWM_DT_SPEC_INST_GET(n),                                                    \
+		.lower_temperature_limit = (int8_t)DT_INST_PROP(n, lower_temperature_limit),       \
+		.higher_temperature_limit = DT_INST_PROP(n, higher_temperature_limit),             \
+		.data_bits = DT_INST_PROP(n, data_bits),                                           \
+	};                                                                                         \
+                                                                                                   \
+	SENSOR_DEVICE_DT_INST_DEFINE(n, &tsic_xx6_init, NULL, &tsic_xx6_data_##n,                  \
+				     &tsic_xx6_config_##n, POST_KERNEL,                            \
+				     CONFIG_SENSOR_INIT_PRIORITY, &tsic_xx6_driver_api);
+
+DT_INST_FOREACH_STATUS_OKAY(TSIC_XX6_DEVICE)

dts/bindings/sensor/ist,tsic-xx6.yaml

@@ -0,0 +1,40 @@
+# Copyright (c) 2024, Vitrolife A/S
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  TSic xx6 temperature sensor.
+  https://www.ist-ag.com/sites/default/files/downloads/ATTSic_E.pdf
+
+  Example:
+    tsic_716: tsic_716 {
+      status = "okay";
+      compatible = "ist,tsic-xx6";
+      pwms = <&pwm2 1 PWM_USEC(5) PWM_POLARITY_NORMAL>;
+      data-bits = <14>;
+      lower-temperature-limit = <(-10)>;
+      higher-temperature-limit = <60>;
+    };
+
+compatible: "ist,tsic-xx6"
+
+properties:
+  pwms:
+    required: true
+    type: phandle-array
+    description: Reference to a PWM instance with PWM capture support.
+
+  lower-temperature-limit:
+    required: true
+    type: int
+    description: Lowest temperature supported by the device in celcius degrees.
+
+  higher-temperature-limit:
+    required: true
+    type: int
+    description: Highest temperature supported by the device in celcius degrees.
+
+  data-bits:
+    required: true
+    type: int
+    description: Data bits per reading.
+    enum: [11, 14]

dts/bindings/vendor-prefixes.txt

@@ -321,6 +321,7 @@ isee	ISEE 2007 S.L.
 isentek	Isentek Inc.
 isil	Intersil
 issi	Integrated Silicon Solutions Inc.
+ist	Innovative Sensor Technology IST AG
 ite	ITE Tech. Inc.
 itead	ITEAD Intelligent Systems Co.Ltd
 ivo	InfoVision Optoelectronics Kunshan Co. Ltd.