iio: adc: Add TI ADS1015 ADC driver support

The driver has sysfs readings with runtime PM support for power saving.
It also offers buffer support that can be used together with IIO software
triggers.

Datasheet can be found here:
	http://www.ti.com.cn/cn/lit/ds/symlink/ads1015.pdf

Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 626 insertions, 0 deletions

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ce152261b438..e8a0811232aa 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -394,6 +394,19 @@ config TI_ADC128S052
 	  This driver can also be built as a module. If so, the module will be
 	  called ti-adc128s052.
 
+config TI_ADS1015
+	tristate "Texas Instruments ADS1015 ADC"
+	depends on I2C && !SENSORS_ADS1015
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  If you say yes here you get support for Texas Instruments ADS1015
+	  ADC chip.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ti-ads1015.
+
 config TI_ADS8688
 	tristate "Texas Instruments ADS8688"
 	depends on SPI && OF
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 76c008158fa9..b1aa456e6af3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
 obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
 obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
+obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
 obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
 obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/ti-ads1015.c b/drivers/iio/adc/ti-ads1015.c
new file mode 100644
index 000000000000..73cbf0b54e54
--- /dev/null
+++ b/drivers/iio/adc/ti-ads1015.c
@@ -0,0 +1,612 @@
+/*
+ * ADS1015 - Texas Instruments Analog-to-Digital Converter
+ *
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * IIO driver for ADS1015 ADC 7-bit I2C slave address:
+ *	* 0x48 - ADDR connected to Ground
+ *	* 0x49 - ADDR connected to Vdd
+ *	* 0x4A - ADDR connected to SDA
+ *	* 0x4B - ADDR connected to SCL
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/pm_runtime.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+
+#include <linux/i2c/ads1015.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
+#define ADS1015_DRV_NAME "ads1015"
+
+#define ADS1015_CONV_REG	0x00
+#define ADS1015_CFG_REG		0x01
+
+#define ADS1015_CFG_DR_SHIFT	5
+#define ADS1015_CFG_MOD_SHIFT	8
+#define ADS1015_CFG_PGA_SHIFT	9
+#define ADS1015_CFG_MUX_SHIFT	12
+
+#define ADS1015_CFG_DR_MASK	GENMASK(7, 5)
+#define ADS1015_CFG_MOD_MASK	BIT(8)
+#define ADS1015_CFG_PGA_MASK	GENMASK(11, 9)
+#define ADS1015_CFG_MUX_MASK	GENMASK(14, 12)
+
+/* device operating modes */
+#define ADS1015_CONTINUOUS	0
+#define ADS1015_SINGLESHOT	1
+
+#define ADS1015_SLEEP_DELAY_MS		2000
+#define ADS1015_DEFAULT_PGA		2
+#define ADS1015_DEFAULT_DATA_RATE	4
+#define ADS1015_DEFAULT_CHAN		0
+
+enum ads1015_channels {
+	ADS1015_AIN0_AIN1 = 0,
+	ADS1015_AIN0_AIN3,
+	ADS1015_AIN1_AIN3,
+	ADS1015_AIN2_AIN3,
+	ADS1015_AIN0,
+	ADS1015_AIN1,
+	ADS1015_AIN2,
+	ADS1015_AIN3,
+	ADS1015_TIMESTAMP,
+};
+
+static const unsigned int ads1015_data_rate[] = {
+	128, 250, 490, 920, 1600, 2400, 3300, 3300
+};
+
+static const struct {
+	int scale;
+	int uscale;
+} ads1015_scale[] = {
+	{3, 0},
+	{2, 0},
+	{1, 0},
+	{0, 500000},
+	{0, 250000},
+	{0, 125000},
+	{0, 125000},
+	{0, 125000},
+};
+
+#define ADS1015_V_CHAN(_chan, _addr) {				\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+				BIT(IIO_CHAN_INFO_SCALE) |	\
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = _addr,					\
+	.scan_type = {						\
+		.sign = 's',					\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.shift = 4,					\
+		.endianness = IIO_CPU,				\
+	},							\
+}
+
+#define ADS1015_V_DIFF_CHAN(_chan, _chan2, _addr) {		\
+	.type = IIO_VOLTAGE,					\
+	.differential = 1,					\
+	.indexed = 1,						\
+	.address = _addr,					\
+	.channel = _chan,					\
+	.channel2 = _chan2,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+				BIT(IIO_CHAN_INFO_SCALE) |	\
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),	\
+	.scan_index = _addr,					\
+	.scan_type = {						\
+		.sign = 's',					\
+		.realbits = 12,					\
+		.storagebits = 16,				\
+		.shift = 4,					\
+		.endianness = IIO_CPU,				\
+	},							\
+}
+
+struct ads1015_data {
+	struct regmap *regmap;
+	/*
+	 * Protects ADC ops, e.g: concurrent sysfs/buffered
+	 * data reads, configuration updates
+	 */
+	struct mutex lock;
+	struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
+};
+
+static bool ads1015_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == ADS1015_CFG_REG);
+}
+
+static const struct regmap_config ads1015_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = ADS1015_CFG_REG,
+	.writeable_reg = ads1015_is_writeable_reg,
+};
+
+static const struct iio_chan_spec ads1015_channels[] = {
+	ADS1015_V_DIFF_CHAN(0, 1, ADS1015_AIN0_AIN1),
+	ADS1015_V_DIFF_CHAN(0, 3, ADS1015_AIN0_AIN3),
+	ADS1015_V_DIFF_CHAN(1, 3, ADS1015_AIN1_AIN3),
+	ADS1015_V_DIFF_CHAN(2, 3, ADS1015_AIN2_AIN3),
+	ADS1015_V_CHAN(0, ADS1015_AIN0),
+	ADS1015_V_CHAN(1, ADS1015_AIN1),
+	ADS1015_V_CHAN(2, ADS1015_AIN2),
+	ADS1015_V_CHAN(3, ADS1015_AIN3),
+	IIO_CHAN_SOFT_TIMESTAMP(ADS1015_TIMESTAMP),
+};
+
+static int ads1015_set_power_state(struct ads1015_data *data, bool on)
+{
+	int ret;
+	struct device *dev = regmap_get_device(data->regmap);
+
+	if (on) {
+		ret = pm_runtime_get_sync(dev);
+		if (ret < 0)
+			pm_runtime_put_noidle(dev);
+	} else {
+		pm_runtime_mark_last_busy(dev);
+		ret = pm_runtime_put_autosuspend(dev);
+	}
+
+	return ret;
+}
+
+static
+int ads1015_get_adc_result(struct ads1015_data *data, int chan, int *val)
+{
+	int ret, pga, dr, conv_time;
+	bool change;
+
+	if (chan < 0 || chan >= ADS1015_CHANNELS)
+		return -EINVAL;
+
+	pga = data->channel_data[chan].pga;
+	dr = data->channel_data[chan].data_rate;
+
+	ret = regmap_update_bits_check(data->regmap, ADS1015_CFG_REG,
+				       ADS1015_CFG_MUX_MASK |
+				       ADS1015_CFG_PGA_MASK,
+				       chan << ADS1015_CFG_MUX_SHIFT |
+				       pga << ADS1015_CFG_PGA_SHIFT,
+				       &change);
+	if (ret < 0)
+		return ret;
+
+	if (change) {
+		conv_time = DIV_ROUND_UP(USEC_PER_SEC, ads1015_data_rate[dr]);
+		usleep_range(conv_time, conv_time + 1);
+	}
+
+	return regmap_read(data->regmap, ADS1015_CONV_REG, val);
+}
+
+static irqreturn_t ads1015_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct ads1015_data *data = iio_priv(indio_dev);
+	s16 buf[8]; /* 1x s16 ADC val + 3x s16 padding +  4x s16 timestamp */
+	int chan, ret, res;
+
+	memset(buf, 0, sizeof(buf));
+
+	mutex_lock(&data->lock);
+	chan = find_first_bit(indio_dev->active_scan_mask,
+			      indio_dev->masklength);
+	ret = ads1015_get_adc_result(data, chan, &res);
+	if (ret < 0) {
+		mutex_unlock(&data->lock);
+		goto err;
+	}
+
+	buf[0] = res;
+	mutex_unlock(&data->lock);
+
+	iio_push_to_buffers_with_timestamp(indio_dev, buf, iio_get_time_ns());
+
+err:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int ads1015_set_scale(struct ads1015_data *data, int chan,
+			     int scale, int uscale)
+{
+	int i, ret, rindex = -1;
+
+	for (i = 0; i < ARRAY_SIZE(ads1015_scale); i++)
+		if (ads1015_scale[i].scale == scale &&
+		    ads1015_scale[i].uscale == uscale) {
+			rindex = i;
+			break;
+		}
+	if (rindex < 0)
+		return -EINVAL;
+
+	ret = regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+				 ADS1015_CFG_PGA_MASK,
+				 rindex << ADS1015_CFG_PGA_SHIFT);
+	if (ret < 0)
+		return ret;
+
+	data->channel_data[chan].pga = rindex;
+
+	return 0;
+}
+
+static int ads1015_set_data_rate(struct ads1015_data *data, int chan, int rate)
+{
+	int i, ret, rindex = -1;
+
+	for (i = 0; i < ARRAY_SIZE(ads1015_data_rate); i++)
+		if (ads1015_data_rate[i] == rate) {
+			rindex = i;
+			break;
+		}
+	if (rindex < 0)
+		return -EINVAL;
+
+	ret = regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+				 ADS1015_CFG_DR_MASK,
+				 rindex << ADS1015_CFG_DR_SHIFT);
+	if (ret < 0)
+		return ret;
+
+	data->channel_data[chan].data_rate = rindex;
+
+	return 0;
+}
+
+static int ads1015_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan, int *val,
+			    int *val2, long mask)
+{
+	int ret, idx;
+	struct ads1015_data *data = iio_priv(indio_dev);
+
+	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&data->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev)) {
+			ret = -EBUSY;
+			break;
+		}
+
+		ret = ads1015_set_power_state(data, true);
+		if (ret < 0)
+			break;
+
+		ret = ads1015_get_adc_result(data, chan->address, val);
+		if (ret < 0) {
+			ads1015_set_power_state(data, false);
+			break;
+		}
+
+		/* 12 bit res, D0 is bit 4 in conversion register */
+		*val = sign_extend32(*val >> 4, 11);
+
+		ret = ads1015_set_power_state(data, false);
+		if (ret < 0)
+			break;
+
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		idx = data->channel_data[chan->address].pga;
+		*val = ads1015_scale[idx].scale;
+		*val2 = ads1015_scale[idx].uscale;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		idx = data->channel_data[chan->address].data_rate;
+		*val = ads1015_data_rate[idx];
+		ret = IIO_VAL_INT;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&data->lock);
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
+static int ads1015_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan, int val,
+			     int val2, long mask)
+{
+	struct ads1015_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		ret = ads1015_set_scale(data, chan->address, val, val2);
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		ret = ads1015_set_data_rate(data, chan->address, val);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int ads1015_buffer_preenable(struct iio_dev *indio_dev)
+{
+	return ads1015_set_power_state(iio_priv(indio_dev), true);
+}
+
+static int ads1015_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	return ads1015_set_power_state(iio_priv(indio_dev), false);
+}
+
+static const struct iio_buffer_setup_ops ads1015_buffer_setup_ops = {
+	.preenable	= ads1015_buffer_preenable,
+	.postenable	= iio_triggered_buffer_postenable,
+	.predisable	= iio_triggered_buffer_predisable,
+	.postdisable	= ads1015_buffer_postdisable,
+	.validate_scan_mask = &iio_validate_scan_mask_onehot,
+};
+
+static IIO_CONST_ATTR(scale_available, "3 2 1 0.5 0.25 0.125");
+static IIO_CONST_ATTR(sampling_frequency_available,
+		      "128 250 490 920 1600 2400 3300");
+
+static struct attribute *ads1015_attributes[] = {
+	&iio_const_attr_scale_available.dev_attr.attr,
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ads1015_attribute_group = {
+	.attrs = ads1015_attributes,
+};
+
+static const struct iio_info ads1015_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= ads1015_read_raw,
+	.write_raw	= ads1015_write_raw,
+	.attrs		= &ads1015_attribute_group,
+};
+
+#ifdef CONFIG_OF
+static int ads1015_get_channels_config_of(struct i2c_client *client)
+{
+	struct ads1015_data *data = i2c_get_clientdata(client);
+	struct device_node *node;
+
+	if (!client->dev.of_node ||
+	    !of_get_next_child(client->dev.of_node, NULL))
+		return -EINVAL;
+
+	for_each_child_of_node(client->dev.of_node, node) {
+		u32 pval;
+		unsigned int channel;
+		unsigned int pga = ADS1015_DEFAULT_PGA;
+		unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
+
+		if (of_property_read_u32(node, "reg", &pval)) {
+			dev_err(&client->dev, "invalid reg on %s\n",
+				node->full_name);
+			continue;
+		}
+
+		channel = pval;
+		if (channel >= ADS1015_CHANNELS) {
+			dev_err(&client->dev,
+				"invalid channel index %d on %s\n",
+				channel, node->full_name);
+			continue;
+		}
+
+		if (!of_property_read_u32(node, "ti,gain", &pval)) {
+			pga = pval;
+			if (pga > 6) {
+				dev_err(&client->dev, "invalid gain on %s\n",
+					node->full_name);
+				return -EINVAL;
+			}
+		}
+
+		if (!of_property_read_u32(node, "ti,datarate", &pval)) {
+			data_rate = pval;
+			if (data_rate > 7) {
+				dev_err(&client->dev,
+					"invalid data_rate on %s\n",
+					node->full_name);
+				return -EINVAL;
+			}
+		}
+
+		data->channel_data[channel].pga = pga;
+		data->channel_data[channel].data_rate = data_rate;
+	}
+
+	return 0;
+}
+#endif
+
+static void ads1015_get_channels_config(struct i2c_client *client)
+{
+	unsigned int k;
+
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ads1015_data *data = iio_priv(indio_dev);
+	struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
+
+	/* prefer platform data */
+	if (pdata) {
+		memcpy(data->channel_data, pdata->channel_data,
+		       sizeof(data->channel_data));
+		return;
+	}
+
+#ifdef CONFIG_OF
+	if (!ads1015_get_channels_config_of(client))
+		return;
+#endif
+	/* fallback on default configuration */
+	for (k = 0; k < ADS1015_CHANNELS; ++k) {
+		data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
+		data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
+	}
+}
+
+static int ads1015_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct iio_dev *indio_dev;
+	struct ads1015_data *data;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+
+	mutex_init(&data->lock);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &ads1015_info;
+	indio_dev->name = ADS1015_DRV_NAME;
+	indio_dev->channels = ads1015_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ads1015_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	/* we need to keep this ABI the same as used by hwmon ADS1015 driver */
+	ads1015_get_channels_config(client);
+
+	data->regmap = devm_regmap_init_i2c(client, &ads1015_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "Failed to allocate register map\n");
+		return PTR_ERR(data->regmap);
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 ads1015_trigger_handler,
+					 &ads1015_buffer_setup_ops);
+	if (ret < 0) {
+		dev_err(&client->dev, "iio triggered buffer setup failed\n");
+		return ret;
+	}
+	ret = pm_runtime_set_active(&client->dev);
+	if (ret)
+		goto err_buffer_cleanup;
+	pm_runtime_set_autosuspend_delay(&client->dev, ADS1015_SLEEP_DELAY_MS);
+	pm_runtime_use_autosuspend(&client->dev);
+	pm_runtime_enable(&client->dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failed to register IIO device\n");
+		goto err_buffer_cleanup;
+	}
+
+	return 0;
+
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	return ret;
+}
+
+static int ads1015_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct ads1015_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	pm_runtime_disable(&client->dev);
+	pm_runtime_set_suspended(&client->dev);
+	pm_runtime_put_noidle(&client->dev);
+
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	/* power down single shot mode */
+	return regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+				  ADS1015_CFG_MOD_MASK,
+				  ADS1015_SINGLESHOT << ADS1015_CFG_MOD_SHIFT);
+}
+
+#ifdef CONFIG_PM
+static int ads1015_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct ads1015_data *data = iio_priv(indio_dev);
+
+	return regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+				  ADS1015_CFG_MOD_MASK,
+				  ADS1015_SINGLESHOT << ADS1015_CFG_MOD_SHIFT);
+}
+
+static int ads1015_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+	struct ads1015_data *data = iio_priv(indio_dev);
+
+	return regmap_update_bits(data->regmap, ADS1015_CFG_REG,
+				  ADS1015_CFG_MOD_MASK,
+				  ADS1015_CONTINUOUS << ADS1015_CFG_MOD_SHIFT);
+}
+#endif
+
+static const struct dev_pm_ops ads1015_pm_ops = {
+	SET_RUNTIME_PM_OPS(ads1015_runtime_suspend,
+			   ads1015_runtime_resume, NULL)
+};
+
+static const struct i2c_device_id ads1015_id[] = {
+	{"ads1015", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ads1015_id);
+
+static struct i2c_driver ads1015_driver = {
+	.driver = {
+		.name = ADS1015_DRV_NAME,
+		.pm = &ads1015_pm_ops,
+	},
+	.probe		= ads1015_probe,
+	.remove		= ads1015_remove,
+	.id_table	= ads1015_id,
+};
+
+module_i2c_driver(ads1015_driver);
+
+MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
+MODULE_DESCRIPTION("Texas Instruments ADS1015 ADC driver");
+MODULE_LICENSE("GPL v2");