staging:iio: Add common ADIS library

A lot of the devices from the ADIS family use the same methods for accessing
registers, sampling data and trigger handling. They also have similar register
layout for the control registers.

This patch adds a common library for these devices. The library implements
functions for reading and writing registers as buffer and trigger management. It
also provides a set functions for accessing the control registers and for
running the devices internal self-test. Having this common library code will
allow us to remove a lot of duplicated code.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/imu/Kconfig

@@ -15,3 +15,16 @@ config ADIS16400
 	  (adis16400 series also have magnetometers).
 
 endmenu
+
+config IIO_ADIS_LIB
+	tristate
+	help
+	  A set of IO helper functions for the Analog Devices ADIS* device family.
+
+config IIO_ADIS_LIB_BUFFER
+	bool
+	select IIO_TRIGGER
+	select IIO_SW_RING
+	help
+	  A set of buffer helper functions for the Analog Devices ADIS* device
+	  family.

drivers/staging/iio/imu/Makefile

@@ -5,3 +5,8 @@
 adis16400-y             := adis16400_core.o
 adis16400-$(CONFIG_IIO_BUFFER) += adis16400_ring.o adis16400_trigger.o
 obj-$(CONFIG_ADIS16400) += adis16400.o
+
+adis_lib-y += adis.o
+adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_trigger.o
+adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_buffer.o
+obj-$(CONFIG_IIO_ADIS_LIB) += adis_lib.o

drivers/staging/iio/imu/adis.c

@@ -0,0 +1,338 @@
+/*
+ * Common library for ADIS16XXX devices
+ *
+ * Copyright 2012 Analog Devices Inc.
+ *   Author: Lars-Peter Clausen <lars@metafoo.de>
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/delay.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/module.h>
+#include <asm/unaligned.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+
+#include "adis.h"
+
+#define ADIS_MSC_CTRL_DATA_RDY_EN	BIT(2)
+#define ADIS_MSC_CTRL_DATA_RDY_POL_HIGH	BIT(1)
+#define ADIS_MSC_CTRL_DATA_RDY_DIO2	BIT(0)
+#define ADIS_GLOB_CMD_SW_RESET		BIT(7)
+
+/**
+ * adis_write_reg_8() - Write single byte to a register
+ * @adis: The adis device
+ * @reg: The address of the register to be written
+ * @val: The value to write
+ */
+int adis_write_reg_8(struct adis *adis, unsigned int reg, uint8_t val)
+{
+	int ret;
+
+	mutex_lock(&adis->txrx_lock);
+	adis->tx[0] = ADIS_WRITE_REG(reg);
+	adis->tx[1] = val;
+
+	ret = spi_write(adis->spi, adis->tx, 2);
+	mutex_unlock(&adis->txrx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adis_write_reg_8);
+
+/**
+ * adis_write_reg_16() - Write 2 bytes to a pair of registers
+ * @adis: The adis device
+ * @reg: The address of the lower of the two registers
+ * @val: Value to be written
+ */
+int adis_write_reg_16(struct adis *adis, unsigned int reg, uint16_t value)
+{
+	int ret;
+	struct spi_message msg;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = adis->tx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+			.delay_usecs = adis->data->write_delay,
+		}, {
+			.tx_buf = adis->tx + 2,
+			.bits_per_word = 8,
+			.len = 2,
+			.delay_usecs = adis->data->write_delay,
+		},
+	};
+
+	mutex_lock(&adis->txrx_lock);
+	adis->tx[0] = ADIS_WRITE_REG(reg);
+	adis->tx[1] = value & 0xff;
+	adis->tx[2] = ADIS_WRITE_REG(reg + 1);
+	adis->tx[3] = (value >> 8) & 0xff;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfers[0], &msg);
+	spi_message_add_tail(&xfers[1], &msg);
+	ret = spi_sync(adis->spi, &msg);
+	mutex_unlock(&adis->txrx_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adis_write_reg_16);
+
+/**
+ * adis_read_reg_16() - read 2 bytes from a 16-bit register
+ * @adis: The adis device
+ * @reg: The address of the lower of the two registers
+ * @val: The value read back from the device
+ */
+int adis_read_reg_16(struct adis *adis, unsigned int reg, uint16_t *val)
+{
+	struct spi_message msg;
+	int ret;
+	struct spi_transfer xfers[] = {
+		{
+			.tx_buf = adis->tx,
+			.bits_per_word = 8,
+			.len = 2,
+			.cs_change = 1,
+			.delay_usecs = adis->data->read_delay,
+		}, {
+			.rx_buf = adis->rx,
+			.bits_per_word = 8,
+			.len = 2,
+			.delay_usecs = adis->data->read_delay,
+		},
+	};
+
+	mutex_lock(&adis->txrx_lock);
+	adis->tx[0] = ADIS_READ_REG(reg);
+	adis->tx[1] = 0;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfers[0], &msg);
+	spi_message_add_tail(&xfers[1], &msg);
+	ret = spi_sync(adis->spi, &msg);
+	if (ret) {
+		dev_err(&adis->spi->dev, "Failed to read 16 bit register 0x%02X: %d\n",
+				reg, ret);
+		goto error_ret;
+	}
+	*val = get_unaligned_be16(adis->rx);
+
+error_ret:
+	mutex_unlock(&adis->txrx_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adis_read_reg_16);
+
+/**
+ * adis_enable_irq() - Enable or disable data ready IRQ
+ * @adis: The adis device
+ * @enable: Whether to enable the IRQ
+ *
+ * Returns 0 on success, negative error code otherwise
+ */
+int adis_enable_irq(struct adis *adis, bool enable)
+{
+	int ret = 0;
+	uint16_t msc;
+
+	ret = adis_read_reg_16(adis, adis->data->msc_ctrl_reg, &msc);
+	if (ret)
+		goto error_ret;
+
+	msc |= ADIS_MSC_CTRL_DATA_RDY_POL_HIGH;
+	msc &= ~ADIS_MSC_CTRL_DATA_RDY_DIO2;
+	if (enable)
+		msc |= ADIS_MSC_CTRL_DATA_RDY_EN;
+	else
+		msc &= ~ADIS_MSC_CTRL_DATA_RDY_EN;
+
+	ret = adis_write_reg_16(adis, adis->data->msc_ctrl_reg, msc);
+
+error_ret:
+	return ret;
+}
+EXPORT_SYMBOL(adis_enable_irq);
+
+/**
+ * adis_check_status() - Check the device for error conditions
+ * @adis: The adis device
+ *
+ * Returns 0 on success, a negative error code otherwise
+ */
+int adis_check_status(struct adis *adis)
+{
+	uint16_t status;
+	int ret;
+	int i;
+
+	ret = adis_read_reg_16(adis, adis->data->diag_stat_reg, &status);
+	if (ret < 0)
+		return ret;
+
+	status &= adis->data->status_error_mask;
+
+	if (status == 0)
+		return 0;
+
+	for (i = 0; i < 16; ++i) {
+		if (status & BIT(i)) {
+			dev_err(&adis->spi->dev, "%s.\n",
+				adis->data->status_error_msgs[i]);
+		}
+	}
+
+	return -EIO;
+}
+EXPORT_SYMBOL_GPL(adis_check_status);
+
+/**
+ * adis_reset() - Reset the device
+ * @adis: The adis device
+ *
+ * Returns 0 on success, a negative error code otherwise
+ */
+int adis_reset(struct adis *adis)
+{
+	int ret;
+
+	ret = adis_write_reg_8(adis, adis->data->glob_cmd_reg,
+			ADIS_GLOB_CMD_SW_RESET);
+	if (ret)
+		dev_err(&adis->spi->dev, "Failed to reset device: %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adis_reset);
+
+static int adis_self_test(struct adis *adis)
+{
+	int ret;
+
+	ret = adis_write_reg_16(adis, adis->data->msc_ctrl_reg,
+			adis->data->self_test_mask);
+	if (ret) {
+		dev_err(&adis->spi->dev, "Failed to initiate self test: %d\n",
+			ret);
+		return ret;
+	}
+
+	msleep(adis->data->startup_delay);
+
+	return adis_check_status(adis);
+}
+
+/**
+ * adis_inital_startup() - Performs device self-test
+ * @adis: The adis device
+ *
+ * Returns 0 if the device is operational, a negative error code otherwise.
+ *
+ * This function should be called early on in the device initialization sequence
+ * to ensure that the device is in a sane and known state and that it is usable.
+ */
+int adis_initial_startup(struct adis *adis)
+{
+	int ret;
+
+	ret = adis_self_test(adis);
+	if (ret) {
+		dev_err(&adis->spi->dev, "Self-test failed, trying reset.\n");
+		adis_reset(adis);
+		msleep(adis->data->startup_delay);
+		ret = adis_self_test(adis);
+		if (ret) {
+			dev_err(&adis->spi->dev, "Second self-test failed, giving up.\n");
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(adis_initial_startup);
+
+/**
+ * adis_single_conversion() - Performs a single sample conversion
+ * @indio_dev: The IIO device
+ * @chan: The IIO channel
+ * @error_mask: Mask for the error bit
+ * @val: Result of the conversion
+ *
+ * Returns IIO_VAL_INT on success, a negative error code otherwise.
+ *
+ * The function performs a single conversion on a given channel and post
+ * processes the value accordingly to the channel spec. If a error_mask is given
+ * the function will check if the mask is set in the returned raw value. If it
+ * is set the function will perform a self-check. If the device does not report
+ * a error bit in the channels raw value set error_mask to 0.
+ */
+int adis_single_conversion(struct iio_dev *indio_dev,
+	const struct iio_chan_spec *chan, unsigned int error_mask, int *val)
+{
+	struct adis *adis = iio_device_get_drvdata(indio_dev);
+	uint16_t val16;
+	int ret;
+
+	mutex_lock(&indio_dev->mlock);
+
+	ret = adis_read_reg_16(adis, chan->address, &val16);
+	if (ret)
+		goto err_unlock;
+
+	if (val16 & error_mask) {
+		ret = adis_check_status(adis);
+		if (ret)
+			goto err_unlock;
+	}
+
+	if (chan->scan_type.sign == 's')
+		*val = sign_extend32(val16, chan->scan_type.realbits - 1);
+	else
+		*val = val16 & ((1 << chan->scan_type.realbits) - 1);
+
+	ret = IIO_VAL_INT;
+err_unlock:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adis_single_conversion);
+
+/**
+ * adis_init() - Initialize adis device structure
+ * @adis:	The adis device
+ * @indio_dev:	The iio device
+ * @spi:	The spi device
+ * @data:	Chip specific data
+ *
+ * Returns 0 on success, a negative error code otherwise.
+ *
+ * This function must be called, before any other adis helper function may be
+ * called.
+ */
+int adis_init(struct adis *adis, struct iio_dev *indio_dev,
+	struct spi_device *spi, const struct adis_data *data)
+{
+	mutex_init(&adis->txrx_lock);
+	adis->spi = spi;
+	adis->data = data;
+	iio_device_set_drvdata(indio_dev, adis);
+
+	return adis_enable_irq(adis, false);
+}
+EXPORT_SYMBOL_GPL(adis_init);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("Common library code for ADIS16XXX devices");