Add tsys01 meas-spec driver support

Support for TSYS01 temperature sensor
Signed-off-by: Ludovic Tancerel <ludovic.tancerel@maplehightech.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/temperature/Kconfig

@@ -23,4 +23,15 @@ config TMP006
 	  This driver can also be built as a module. If so, the module will
 	  be called tmp006.
 
+config TSYS01
+	tristate "Measurement Specialties TSYS01 temperature sensor using I2C bus connection"
+	depends on I2C
+	select IIO_MS_SENSORS_I2C
+	help
+	  If you say yes here you get support for the Measurement Specialties
+	  TSYS01 I2C temperature sensor.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called tsys01.
+
 endmenu

drivers/iio/temperature/Makefile

@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_MLX90614) += mlx90614.o
 obj-$(CONFIG_TMP006) += tmp006.o
+obj-$(CONFIG_TSYS01) += tsys01.o

drivers/iio/temperature/tsys01.c

+/*
+ * tsys01.c - Support for Measurement-Specialties tsys01 temperature sensor
+ *
+ * Copyright (c) 2015 Measurement-Specialties
+ *
+ * Licensed under the GPL-2.
+ *
+ * Datasheet:
+ *  http://www.meas-spec.com/downloads/TSYS01_Digital_Temperature_Sensor.pdf
+ */
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/stat.h>
+#include "../common/ms_sensors/ms_sensors_i2c.h"
+
+/* TSYS01 Commands */
+#define TSYS01_RESET				0x1E
+#define TSYS01_CONVERSION_START			0x48
+#define TSYS01_ADC_READ				0x00
+#define TSYS01_PROM_READ			0xA0
+
+#define TSYS01_PROM_WORDS_NB			8
+
+struct tsys01_dev {
+	void *client;
+	struct mutex lock; /* lock during conversion */
+
+	int (*reset)(void *cli, u8 cmd, unsigned int delay);
+	int (*convert_and_read)(void *cli, u8 conv, u8 rd,
+				unsigned int delay, u32 *adc);
+	int (*read_prom_word)(void *cli, int cmd, u16 *word);
+
+	u16 prom[TSYS01_PROM_WORDS_NB];
+};
+
+/* Multiplication coefficients for temperature computation */
+static const int coeff_mul[] = { -1500000, 1000000, -2000000,
+				 4000000, -2000000 };
+
+static int tsys01_read_temperature(struct iio_dev *indio_dev,
+				   s32 *temperature)
+{
+	int ret, i;
+	u32 adc;
+	s64 temp = 0;
+	struct tsys01_dev *dev_data = iio_priv(indio_dev);
+
+	mutex_lock(&dev_data->lock);
+	ret = dev_data->convert_and_read(dev_data->client,
+					 TSYS01_CONVERSION_START,
+					 TSYS01_ADC_READ, 9000, &adc);
+	mutex_unlock(&dev_data->lock);
+	if (ret)
+		return ret;
+
+	adc >>= 8;
+
+	/* Temperature algorithm */
+	for (i = 4; i > 0; i--) {
+		temp += coeff_mul[i] *
+			(s64)dev_data->prom[5 - i];
+		temp *= (s64)adc;
+		temp = div64_s64(temp, 100000);
+	}
+	temp *= 10;
+	temp += coeff_mul[0] * (s64)dev_data->prom[5];
+	temp = div64_s64(temp, 100000);
+
+	*temperature = temp;
+
+	return 0;
+}
+
+static int tsys01_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *channel, int *val,
+			   int *val2, long mask)
+{
+	int ret;
+	s32 temperature;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (channel->type) {
+		case IIO_TEMP:	/* in milli °C */
+			ret = tsys01_read_temperature(indio_dev, &temperature);
+			if (ret)
+				return ret;
+			*val = temperature;
+
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_chan_spec tsys01_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_PROCESSED),
+	}
+};
+
+static const struct iio_info tsys01_info = {
+	.read_raw = tsys01_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static bool tsys01_crc_valid(u16 *n_prom)
+{
+	u8 cnt;
+	u8 sum = 0;
+
+	for (cnt = 0; cnt < TSYS01_PROM_WORDS_NB; cnt++)
+		sum += ((n_prom[0] >> 8) + (n_prom[0] & 0xFF));
+
+	return (sum == 0);
+}
+
+static int tsys01_read_prom(struct iio_dev *indio_dev)
+{
+	int i, ret;
+	struct tsys01_dev *dev_data = iio_priv(indio_dev);
+	char buf[7 * TSYS01_PROM_WORDS_NB + 1];
+	char *ptr = buf;
+
+	for (i = 0; i < TSYS01_PROM_WORDS_NB; i++) {
+		ret = dev_data->read_prom_word(dev_data->client,
+					       TSYS01_PROM_READ + (i << 1),
+					       &dev_data->prom[i]);
+		if (ret)
+			return ret;
+
+		ret = sprintf(ptr, "0x%04x ", dev_data->prom[i]);
+		ptr += ret;
+	}
+
+	if (!tsys01_crc_valid(dev_data->prom)) {
+		dev_err(&indio_dev->dev, "prom crc check error\n");
+		return -ENODEV;
+	}
+	*ptr = 0;
+	dev_info(&indio_dev->dev, "PROM coefficients : %s\n", buf);
+
+	return 0;
+}
+
+static int tsys01_probe(struct iio_dev *indio_dev, struct device *dev)
+{
+	int ret;
+	struct tsys01_dev *dev_data = iio_priv(indio_dev);
+
+	mutex_init(&dev_data->lock);
+
+	indio_dev->info = &tsys01_info;
+	indio_dev->name = dev->driver->name;
+	indio_dev->dev.parent = dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = tsys01_channels;
+	indio_dev->num_channels = ARRAY_SIZE(tsys01_channels);
+
+	ret = dev_data->reset(dev_data->client, TSYS01_RESET, 3000);
+	if (ret)
+		return ret;
+
+	ret = tsys01_read_prom(indio_dev);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static int tsys01_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct tsys01_dev *dev_data;
+	struct iio_dev *indio_dev;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_WORD_DATA |
+				     I2C_FUNC_SMBUS_WRITE_BYTE |
+				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+		dev_err(&client->dev,
+			"Adapter does not support some i2c transaction\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev_data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	dev_data = iio_priv(indio_dev);
+	dev_data->client = client;
+	dev_data->reset = ms_sensors_reset;
+	dev_data->read_prom_word = ms_sensors_read_prom_word;
+	dev_data->convert_and_read = ms_sensors_convert_and_read;
+
+	i2c_set_clientdata(client, indio_dev);
+
+	return tsys01_probe(indio_dev, &client->dev);
+}
+
+static const struct i2c_device_id tsys01_id[] = {
+	{"tsys01", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, tsys01_id);
+
+static struct i2c_driver tsys01_driver = {
+	.probe = tsys01_i2c_probe,
+	.id_table = tsys01_id,
+	.driver = {
+		   .name = "tsys01",
+		   },
+};
+
+module_i2c_driver(tsys01_driver);
+
+MODULE_DESCRIPTION("Measurement-Specialties tsys01 temperature driver");
+MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
+MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
+MODULE_LICENSE("GPL v2");