iio:proximity:sx9310: Extract common Semtech sensor logic

Before adding new Semtech sensors, move common logic to all Semtech SAR
sensor in its own file:
- interface with IIO subsystem,
- interrupt management,
- channel access conrol,
- event processing.

The change adds a bidirectional interface between sx93xx and sx_common.

The change is quite mechanical, as the impacted functions are moved
and renamed.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20220101203817.290512-3-gwendal@chromium.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/proximity/Kconfig

@@ -112,11 +112,17 @@ config SRF04
 	  To compile this driver as a module, choose M here: the
 	  module will be called srf04.
 
+config SX_COMMON
+	tristate
+	help
+	  Common Semtech proximity sensor code.
+
 config SX9310
 	tristate "SX9310/SX9311 Semtech proximity sensor"
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
 	select REGMAP_I2C
+	select SX_COMMON
 	depends on I2C
 	help
 	  Say Y here to build a driver for Semtech's SX9310/SX9311 capacitive

drivers/iio/proximity/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_RFD77402)		+= rfd77402.o
 obj-$(CONFIG_SRF04)		+= srf04.o
 obj-$(CONFIG_SRF08)		+= srf08.o
 obj-$(CONFIG_SX9310)		+= sx9310.o
+obj-$(CONFIG_SX_COMMON) 	+= sx_common.o
 obj-$(CONFIG_SX9500)		+= sx9500.o
 obj-$(CONFIG_VCNL3020)		+= vcnl3020.o
 obj-$(CONFIG_VL53L0X_I2C)	+= vl53l0x-i2c.o

drivers/iio/proximity/sx_common.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2021 Google LLC.
+ *
+ * Code shared between most Semtech SAR sensor driver.
+ */
+
+#ifndef IIO_SX_COMMON_H
+#define IIO_SX_COMMON_H
+
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+#include <linux/regulator/consumer.h>
+#include <linux/types.h>
+
+struct device;
+struct i2c_client;
+struct regmap_config;
+struct sx_common_data;
+
+#define SX_COMMON_REG_IRQ_SRC				0x00
+
+#define SX_COMMON_MAX_NUM_CHANNELS	4
+static_assert(SX_COMMON_MAX_NUM_CHANNELS < BITS_PER_LONG);
+
+struct sx_common_reg_default {
+	u8 reg;
+	u8 def;
+};
+
+/**
+ * struct sx_common_ops: function pointers needed by common code
+ *
+ * List functions needed by common code to gather information or configure
+ * the sensor.
+ *
+ * @read_prox_data:	Function to read raw proximity data.
+ * @check_whoami:	Set device name based on whoami register.
+ * @init_compensation:	Function to set initial compensation.
+ * @wait_for_sample:	When there are no physical IRQ, function to wait for a
+ *			sample to be ready.
+ * @get_default_reg:	Populate the initial value for a given register.
+ */
+struct sx_common_ops {
+	int (*read_prox_data)(struct sx_common_data *data,
+			      const struct iio_chan_spec *chan, __be16 *val);
+	int (*check_whoami)(struct device *dev, struct iio_dev *indio_dev);
+	int (*init_compensation)(struct iio_dev *indio_dev);
+	int (*wait_for_sample)(struct sx_common_data *data);
+	const struct sx_common_reg_default  *
+		(*get_default_reg)(struct device *dev, int idx,
+				   struct sx_common_reg_default *reg_def);
+};
+
+/**
+ * struct sx_common_chip_info: Semtech Sensor private chip information
+ *
+ * @reg_stat:		Main status register address.
+ * @reg_irq_msk:	IRQ mask register address.
+ * @reg_enable_chan:	Address to enable/disable channels.
+ *			Each phase presented by the sensor is an IIO channel..
+ * @reg_reset:		Reset register address.
+ * @mask_enable_chan:	Mask over the channels bits in the enable channel
+ *			register.
+ * @stat_offset:	Offset to check phase status.
+ * @irq_msk_offset:	Offset to enable interrupt in the IRQ mask
+ *			register.
+ * @num_channels:	Number of channels.
+ * @num_default_regs:	Number of internal registers that can be configured.
+ *
+ * @ops:		Private functions pointers.
+ * @iio_channels:	Description of exposed iio channels.
+ * @num_iio_channels:	Number of iio_channels.
+ * @iio_info:		iio_info structure for this driver.
+ */
+struct sx_common_chip_info {
+	unsigned int reg_stat;
+	unsigned int reg_irq_msk;
+	unsigned int reg_enable_chan;
+	unsigned int reg_reset;
+
+	unsigned int mask_enable_chan;
+	unsigned int stat_offset;
+	unsigned int irq_msk_offset;
+	unsigned int num_channels;
+	int num_default_regs;
+
+	struct sx_common_ops ops;
+
+	const struct iio_chan_spec *iio_channels;
+	int num_iio_channels;
+	struct iio_info iio_info;
+};
+
+/**
+ * struct sx_common_data: Semtech Sensor private data structure.
+ *
+ * @chip_info:		Structure defining sensor internals.
+ * @mutex:		Serialize access to registers and channel configuration.
+ * @completion:		completion object to wait for data acquisition.
+ * @client:		I2C client structure.
+ * @trig:		IIO trigger object.
+ * @regmap:		Register map.
+ * @num_default_regs:	Number of default registers to set at init.
+ * @supplies:		Power supplies object.
+ * @chan_prox_stat:	Last reading of the proximity status for each channel.
+ *			We only send an event to user space when this changes.
+ * @trigger_enabled:	True when the device trigger is enabled.
+ * @buffer:		Buffer to store raw samples.
+ * @suspend_ctrl:	Remember enabled channels and sample rate during suspend.
+ * @chan_read:		Bit field for each raw channel enabled.
+ * @chan_event:		Bit field for each event enabled.
+ */
+struct sx_common_data {
+	const struct sx_common_chip_info *chip_info;
+
+	struct mutex mutex;
+	struct completion completion;
+	struct i2c_client *client;
+	struct iio_trigger *trig;
+	struct regmap *regmap;
+
+	struct regulator_bulk_data supplies[2];
+	unsigned long chan_prox_stat;
+	bool trigger_enabled;
+
+	/* Ensure correct alignment of timestamp when present. */
+	struct {
+		__be16 channels[SX_COMMON_MAX_NUM_CHANNELS];
+		s64 ts __aligned(8);
+	} buffer;
+
+	unsigned int suspend_ctrl;
+	unsigned long chan_read;
+	unsigned long chan_event;
+};
+
+int sx_common_read_proximity(struct sx_common_data *data,
+			     const struct iio_chan_spec *chan, int *val);
+
+int sx_common_read_event_config(struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan,
+				enum iio_event_type type,
+				enum iio_event_direction dir);
+int sx_common_write_event_config(struct iio_dev *indio_dev,
+				 const struct iio_chan_spec *chan,
+				 enum iio_event_type type,
+				 enum iio_event_direction dir, int state);
+
+int sx_common_probe(struct i2c_client *client,
+		    const struct sx_common_chip_info *chip_info,
+		    const struct regmap_config *regmap_config);
+
+/* 3 is the number of events defined by a single phase. */
+extern const struct iio_event_spec sx_common_events[3];
+
+#endif  /* IIO_SX_COMMON_H */