iio: adc: ltc2497: split protocol independent part in a separate module

This allows to share most of this driver for the ltc2496 driver added in
the next commit that is an SPI variant of the ltc2497. Initially I named
the generic part ltc249x, but wild card names are frowned upon, so the
generic part is called ltc2497-core even though it's not obvious that
this is then to be reused for the ltc2496 driver.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

4 files changed, 288 insertions, 209 deletions

diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index bf8354cdbc34..5f8d7ac6bbe2 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -51,7 +51,7 @@ obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
 obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
 obj-$(CONFIG_LTC2471) += ltc2471.o
 obj-$(CONFIG_LTC2485) += ltc2485.o
-obj-$(CONFIG_LTC2497) += ltc2497.o
+obj-$(CONFIG_LTC2497) += ltc2497.o ltc2497-core.o
 obj-$(CONFIG_MAX1027) += max1027.o
 obj-$(CONFIG_MAX11100) += max11100.o
 obj-$(CONFIG_MAX1118) += max1118.o
diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c
new file mode 100644
index 000000000000..f5f7039caacc
--- /dev/null
+++ b/drivers/iio/adc/ltc2497-core.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ltc2497-core.c - Common code for Analog Devices/Linear Technology
+ * LTC2496 and LTC2497 ADCs
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+
+#include "ltc2497.h"
+
+#define LTC2497_SGL			BIT(4)
+#define LTC2497_DIFF			0
+#define LTC2497_SIGN			BIT(3)
+
+static int ltc2497core_wait_conv(struct ltc2497core_driverdata *ddata)
+{
+	s64 time_elapsed;
+
+	time_elapsed = ktime_ms_delta(ktime_get(), ddata->time_prev);
+
+	if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
+		/* delay if conversion time not passed
+		 * since last read or write
+		 */
+		if (msleep_interruptible(
+		    LTC2497_CONVERSION_TIME_MS - time_elapsed))
+			return -ERESTARTSYS;
+
+		return 0;
+	}
+
+	if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
+		/* We're in automatic mode -
+		 * so the last reading is still not outdated
+		 */
+		return 0;
+	}
+
+	return 1;
+}
+
+static int ltc2497core_read(struct ltc2497core_driverdata *ddata, u8 address, int *val)
+{
+	int ret;
+
+	ret = ltc2497core_wait_conv(ddata);
+	if (ret < 0)
+		return ret;
+
+	if (ret || ddata->addr_prev != address) {
+		ret = ddata->result_and_measure(ddata, address, NULL);
+		if (ret < 0)
+			return ret;
+		ddata->addr_prev = address;
+
+		if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
+			return -ERESTARTSYS;
+	}
+
+	ret = ddata->result_and_measure(ddata, address, val);
+	if (ret < 0)
+		return ret;
+
+	ddata->time_prev = ktime_get();
+
+	return ret;
+}
+
+static int ltc2497core_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct ltc2497core_driverdata *ddata = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+		ret = ltc2497core_read(ddata, chan->address, val);
+		mutex_unlock(&indio_dev->mlock);
+		if (ret < 0)
+			return ret;
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		ret = regulator_get_voltage(ddata->ref);
+		if (ret < 0)
+			return ret;
+
+		*val = ret / 1000;
+		*val2 = 17;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+#define LTC2497_CHAN(_chan, _addr, _ds_name) { \
+	.type = IIO_VOLTAGE, \
+	.indexed = 1, \
+	.channel = (_chan), \
+	.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+	.datasheet_name = (_ds_name), \
+}
+
+#define LTC2497_CHAN_DIFF(_chan, _addr) { \
+	.type = IIO_VOLTAGE, \
+	.indexed = 1, \
+	.channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
+	.channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
+	.address = (_addr | _chan), \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+	.differential = 1, \
+}
+
+static const struct iio_chan_spec ltc2497core_channel[] = {
+	LTC2497_CHAN(0, LTC2497_SGL, "CH0"),
+	LTC2497_CHAN(1, LTC2497_SGL, "CH1"),
+	LTC2497_CHAN(2, LTC2497_SGL, "CH2"),
+	LTC2497_CHAN(3, LTC2497_SGL, "CH3"),
+	LTC2497_CHAN(4, LTC2497_SGL, "CH4"),
+	LTC2497_CHAN(5, LTC2497_SGL, "CH5"),
+	LTC2497_CHAN(6, LTC2497_SGL, "CH6"),
+	LTC2497_CHAN(7, LTC2497_SGL, "CH7"),
+	LTC2497_CHAN(8, LTC2497_SGL, "CH8"),
+	LTC2497_CHAN(9, LTC2497_SGL, "CH9"),
+	LTC2497_CHAN(10, LTC2497_SGL, "CH10"),
+	LTC2497_CHAN(11, LTC2497_SGL, "CH11"),
+	LTC2497_CHAN(12, LTC2497_SGL, "CH12"),
+	LTC2497_CHAN(13, LTC2497_SGL, "CH13"),
+	LTC2497_CHAN(14, LTC2497_SGL, "CH14"),
+	LTC2497_CHAN(15, LTC2497_SGL, "CH15"),
+	LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
+	LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
+	LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
+};
+
+static const struct iio_info ltc2497core_info = {
+	.read_raw = ltc2497core_read_raw,
+};
+
+int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev)
+{
+	struct ltc2497core_driverdata *ddata = iio_priv(indio_dev);
+	int ret;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->name = dev_name(dev);
+	indio_dev->info = &ltc2497core_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ltc2497core_channel;
+	indio_dev->num_channels = ARRAY_SIZE(ltc2497core_channel);
+
+	ret = ddata->result_and_measure(ddata, LTC2497_CONFIG_DEFAULT, NULL);
+	if (ret < 0)
+		return ret;
+
+	ddata->ref = devm_regulator_get(dev, "vref");
+	if (IS_ERR(ddata->ref)) {
+		if (PTR_ERR(ddata->ref) != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get vref regulator: %pe\n",
+				ddata->ref);
+
+		return PTR_ERR(ddata->ref);
+	}
+
+	ret = regulator_enable(ddata->ref);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable vref regulator: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	if (dev->platform_data) {
+		struct iio_map *plat_data;
+
+		plat_data = (struct iio_map *)dev->platform_data;
+
+		ret = iio_map_array_register(indio_dev, plat_data);
+		if (ret) {
+			dev_err(&indio_dev->dev, "iio map err: %d\n", ret);
+			goto err_regulator_disable;
+		}
+	}
+
+	ddata->addr_prev = LTC2497_CONFIG_DEFAULT;
+	ddata->time_prev = ktime_get();
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto err_array_unregister;
+
+	return 0;
+
+err_array_unregister:
+	iio_map_array_unregister(indio_dev);
+
+err_regulator_disable:
+	regulator_disable(ddata->ref);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS(ltc2497core_probe, LTC2497);
+
+void ltc2497core_remove(struct iio_dev *indio_dev)
+{
+	struct ltc2497core_driverdata *ddata = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	iio_map_array_unregister(indio_dev);
+
+	regulator_disable(ddata->ref);
+}
+EXPORT_SYMBOL_NS(ltc2497core_remove, LTC2497);
+
+MODULE_DESCRIPTION("common code for LTC2496/LTC2497 drivers");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
index 470406032720..5db63d7c6bc5 100644
--- a/drivers/iio/adc/ltc2497.c
+++ b/drivers/iio/adc/ltc2497.c
@@ -7,27 +7,18 @@
  * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
  */
 
-#include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/driver.h>
-#include <linux/iio/sysfs.h>
 #include <linux/module.h>
 #include <linux/of.h>
-#include <linux/regulator/consumer.h>
 
-#define LTC2497_ENABLE			0xA0
-#define LTC2497_SGL			BIT(4)
-#define LTC2497_DIFF			0
-#define LTC2497_SIGN			BIT(3)
-#define LTC2497_CONFIG_DEFAULT		LTC2497_ENABLE
-#define LTC2497_CONVERSION_TIME_MS	150ULL
+#include "ltc2497.h"
 
-struct ltc2497_st {
+struct ltc2497_driverdata {
+	/* this must be the first member */
+	struct ltc2497core_driverdata common_ddata;
 	struct i2c_client *client;
-	struct regulator *ref;
-	ktime_t	time_prev;
-	u8 addr_prev;
 	/*
 	 * DMA (thus cache coherency maintenance) requires the
 	 * transfer buffers to live in their own cache lines.
@@ -35,232 +26,59 @@ struct ltc2497_st {
 	__be32 buf ____cacheline_aligned;
 };
 
-static int ltc2497_wait_conv(struct ltc2497_st *st)
+static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
+				      u8 address, int *val)
 {
-	s64 time_elapsed;
-
-	time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev);
-
-	if (time_elapsed < LTC2497_CONVERSION_TIME_MS) {
-		/* delay if conversion time not passed
-		 * since last read or write
-		 */
-		if (msleep_interruptible(
-		    LTC2497_CONVERSION_TIME_MS - time_elapsed))
-			return -ERESTARTSYS;
-
-		return 0;
-	}
-
-	if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) {
-		/* We're in automatic mode -
-		 * so the last reading is stil not outdated
-		 */
-		return 0;
-	}
-
-	return 1;
-}
-
-static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val)
-{
-	struct i2c_client *client = st->client;
-	int ret;
-
-	ret = ltc2497_wait_conv(st);
-	if (ret < 0)
-		return ret;
-
-	if (ret || st->addr_prev != address) {
-		ret = i2c_smbus_write_byte(st->client,
-					   LTC2497_ENABLE | address);
-		if (ret < 0)
-			return ret;
-		st->addr_prev = address;
-		if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS))
-			return -ERESTARTSYS;
-	}
-	ret = i2c_master_recv(client, (char *)&st->buf, 3);
-	if (ret < 0)  {
-		dev_err(&client->dev, "i2c_master_recv failed\n");
-		return ret;
-	}
-	st->time_prev = ktime_get();
-
-	/* convert and shift the result,
-	 * and finally convert from offset binary to signed integer
-	 */
-	*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
-
-	return ret;
-}
-
-static int ltc2497_read_raw(struct iio_dev *indio_dev,
-			    struct iio_chan_spec const *chan,
-			    int *val, int *val2, long mask)
-{
-	struct ltc2497_st *st = iio_priv(indio_dev);
+	struct ltc2497_driverdata *st =
+		container_of(ddata, struct ltc2497_driverdata, common_ddata);
 	int ret;
 
-	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		mutex_lock(&indio_dev->mlock);
-		ret = ltc2497_read(st, chan->address, val);
-		mutex_unlock(&indio_dev->mlock);
-		if (ret < 0)
-			return ret;
-
-		return IIO_VAL_INT;
-
-	case IIO_CHAN_INFO_SCALE:
-		ret = regulator_get_voltage(st->ref);
-		if (ret < 0)
+	if (val) {
+		ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
+		if (ret < 0) {
+			dev_err(&st->client->dev, "i2c_master_recv failed\n");
 			return ret;
+		}
 
-		*val = ret / 1000;
-		*val2 = 17;
-
-		return IIO_VAL_FRACTIONAL_LOG2;
-
-	default:
-		return -EINVAL;
+		*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
 	}
-}
 
-#define LTC2497_CHAN(_chan, _addr, _ds_name) { \
-	.type = IIO_VOLTAGE, \
-	.indexed = 1, \
-	.channel = (_chan), \
-	.address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
-	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
-	.datasheet_name = (_ds_name), \
-}
-
-#define LTC2497_CHAN_DIFF(_chan, _addr) { \
-	.type = IIO_VOLTAGE, \
-	.indexed = 1, \
-	.channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \
-	.channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\
-	.address = (_addr | _chan), \
-	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
-	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
-	.differential = 1, \
+	ret = i2c_smbus_write_byte(st->client,
+				   LTC2497_ENABLE | address);
+	if (ret)
+		dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
+			ERR_PTR(ret));
+	return ret;
 }
 
-static const struct iio_chan_spec ltc2497_channel[] = {
-	LTC2497_CHAN(0, LTC2497_SGL, "CH0"),
-	LTC2497_CHAN(1, LTC2497_SGL, "CH1"),
-	LTC2497_CHAN(2, LTC2497_SGL, "CH2"),
-	LTC2497_CHAN(3, LTC2497_SGL, "CH3"),
-	LTC2497_CHAN(4, LTC2497_SGL, "CH4"),
-	LTC2497_CHAN(5, LTC2497_SGL, "CH5"),
-	LTC2497_CHAN(6, LTC2497_SGL, "CH6"),
-	LTC2497_CHAN(7, LTC2497_SGL, "CH7"),
-	LTC2497_CHAN(8, LTC2497_SGL, "CH8"),
-	LTC2497_CHAN(9, LTC2497_SGL, "CH9"),
-	LTC2497_CHAN(10, LTC2497_SGL, "CH10"),
-	LTC2497_CHAN(11, LTC2497_SGL, "CH11"),
-	LTC2497_CHAN(12, LTC2497_SGL, "CH12"),
-	LTC2497_CHAN(13, LTC2497_SGL, "CH13"),
-	LTC2497_CHAN(14, LTC2497_SGL, "CH14"),
-	LTC2497_CHAN(15, LTC2497_SGL, "CH15"),
-	LTC2497_CHAN_DIFF(0, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(1, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(2, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(3, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(4, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(5, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(6, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(7, LTC2497_DIFF),
-	LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN),
-	LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN),
-};
-
-static const struct iio_info ltc2497_info = {
-	.read_raw = ltc2497_read_raw,
-};
-
 static int ltc2497_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
-	struct ltc2497_st *st;
-	struct iio_map *plat_data;
-	int ret;
+	struct ltc2497_driverdata *st;
+	struct device *dev = &client->dev;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 				     I2C_FUNC_SMBUS_WRITE_BYTE))
 		return -EOPNOTSUPP;
 
-	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 	if (!indio_dev)
 		return -ENOMEM;
 
 	st = iio_priv(indio_dev);
 	i2c_set_clientdata(client, indio_dev);
 	st->client = client;
+	st->common_ddata.result_and_measure = ltc2497_result_and_measure;
 
-	indio_dev->dev.parent = &client->dev;
-	indio_dev->name = id->name;
-	indio_dev->info = &ltc2497_info;
-	indio_dev->modes = INDIO_DIRECT_MODE;
-	indio_dev->channels = ltc2497_channel;
-	indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel);
-
-	st->ref = devm_regulator_get(&client->dev, "vref");
-	if (IS_ERR(st->ref))
-		return PTR_ERR(st->ref);
-
-	ret = regulator_enable(st->ref);
-	if (ret < 0)
-		return ret;
-
-	if (client->dev.platform_data) {
-		plat_data = ((struct iio_map *)client->dev.platform_data);
-		ret = iio_map_array_register(indio_dev, plat_data);
-		if (ret) {
-			dev_err(&indio_dev->dev, "iio map err: %d\n", ret);
-			goto err_regulator_disable;
-		}
-	}
-
-	ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT);
-	if (ret < 0)
-		goto err_array_unregister;
-
-	st->addr_prev = LTC2497_CONFIG_DEFAULT;
-	st->time_prev = ktime_get();
-
-	ret = iio_device_register(indio_dev);
-	if (ret < 0)
-		goto err_array_unregister;
-
-	return 0;
-
-err_array_unregister:
-	iio_map_array_unregister(indio_dev);
-
-err_regulator_disable:
-	regulator_disable(st->ref);
-
-	return ret;
+	return ltc2497core_probe(dev, indio_dev);
 }
 
 static int ltc2497_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
-	struct ltc2497_st *st = iio_priv(indio_dev);
 
-	iio_map_array_unregister(indio_dev);
-	iio_device_unregister(indio_dev);
-	regulator_disable(st->ref);
+	ltc2497core_remove(indio_dev);
 
 	return 0;
 }
diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h
new file mode 100644
index 000000000000..d0b42dd6b8ad
--- /dev/null
+++ b/drivers/iio/adc/ltc2497.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#define LTC2497_ENABLE			0xA0
+#define LTC2497_CONFIG_DEFAULT		LTC2497_ENABLE
+#define LTC2497_CONVERSION_TIME_MS	150ULL
+
+struct ltc2497core_driverdata {
+	struct regulator *ref;
+	ktime_t	time_prev;
+	u8 addr_prev;
+	int (*result_and_measure)(struct ltc2497core_driverdata *ddata,
+				  u8 address, int *val);
+};
+
+int ltc2497core_probe(struct device *dev, struct iio_dev *indio_dev);
+void ltc2497core_remove(struct iio_dev *indio_dev);
+
+MODULE_IMPORT_NS(LTC2497);