--- /dev/null
+/**
+ * Copyright (c) 2011 Jonathan Cameron
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * A reference industrial I/O driver to illustrate the functionality available.
+ *
+ * There are numerous real drivers to illustrate the finer points.
+ * The purpose of this driver is to provide a driver with far more comments
+ * and explanatory notes than any 'real' driver would have.
+ * Anyone starting out writing an IIO driver should first make sure they
+ * understand all of this driver except those bits specifically marked
+ * as being present to allow us to 'fake' the presence of hardware.
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include "iio.h"
+
+/*
+ * A few elements needed to fake a bus for this driver
+ * Note instances parmeter controls how many of these
+ * dummy devices are registered.
+ */
+static unsigned instances = 1;
+module_param(instances, int, 0);
+
+/* Pointer array used to fake bus elements */
+static struct iio_dev **iio_dummy_devs;
+
+/* Fake a name for the part number, usually obtained from the id table */
+static const char *iio_dummy_part_number = "iio_dummy_part_no";
+
+/**
+ * struct iio_dummy_accel_calibscale - realworld to register mapping
+ * @val: first value in read_raw - here integer part.
+ * @val2: second value in read_raw etc - here micro part.
+ * @regval: register value - magic device specific numbers.
+ */
+struct iio_dummy_accel_calibscale {
+ int val;
+ int val2;
+ int regval; /* what would be written to hardware */
+};
+
+static const struct iio_dummy_accel_calibscale dummy_scales[] = {
+ { 0, 100, 0x8 }, /* 0.000100 */
+ { 0, 133, 0x7 }, /* 0.000133 */
+ { 733, 13, 0x9 }, /* 733.00013 */
+};
+
+/**
+ * struct iio_dummy_state - device instance specific state.
+ * @dac_val: cache for dac value
+ * @single_ended_adc_val: cache for single ended adc value
+ * @differential_adc_val: cache for differential adc value
+ * @accel_val: cache for acceleration value
+ * @accel_calibbias: cache for acceleration calibbias
+ * @accel_calibscale: cache for acceleration calibscale
+ * @lock: lock to ensure state is consistent
+ */
+struct iio_dummy_state {
+ int dac_val;
+ int single_ended_adc_val;
+ int differential_adc_val[2];
+ int accel_val;
+ int accel_calibbias;
+ const struct iio_dummy_accel_calibscale *accel_calibscale;
+ struct mutex lock;
+};
+
+/*
+ * iio_dummy_channels - Description of available channels
+ *
+ * This array of structures tells the IIO core about what the device
+ * actually provides for a given channel.
+ */
+static struct iio_chan_spec iio_dummy_channels[] = {
+ /* indexed ADC channel in_voltage0_raw etc */
+ {
+ .type = IIO_VOLTAGE,
+ /* Channel has a numeric index of 0 */
+ .indexed = 1,
+ .channel = 0,
+ /* What other information is available? */
+ .info_mask =
+ /*
+ * in_voltage0_offset
+ * Offset for userspace to apply prior to scale
+ * when converting to standard units (microvolts)
+ */
+ (1 << IIO_CHAN_INFO_OFFSET_SEPARATE) |
+ /*
+ * in_voltage0_scale
+ * Multipler for userspace to apply post offset
+ * when converting to standard units (microvolts)
+ */
+ (1 << IIO_CHAN_INFO_SCALE_SEPARATE),
+
+ },
+ /* Differential ADC channel in_voltage1-voltage2_raw etc*/
+ {
+ .type = IIO_VOLTAGE,
+ .differential = 1,
+ /*
+ * Indexing for differential channels uses channel
+ * for the positive part, channel2 for the negative.
+ */
+ .indexed = 1,
+ .channel = 1,
+ .channel2 = 2,
+ .info_mask =
+ /*
+ * in_voltage-voltage_scale
+ * Shared version of scale - shared by differential
+ * input channels of type IIO_VOLTAGE.
+ */
+ (1 << IIO_CHAN_INFO_SCALE_SHARED),
+ },
+ /* Differential ADC channel in_voltage3-voltage4_raw etc*/
+ {
+ .type = IIO_VOLTAGE,
+ .differential = 1,
+ .indexed = 1,
+ .channel = 3,
+ .channel2 = 4,
+ .info_mask =
+ (1 << IIO_CHAN_INFO_SCALE_SHARED),
+ },
+ /* DAC channel out_voltage0_raw */
+ {
+ .type = IIO_VOLTAGE,
+ .output = 1,
+ .indexed = 1,
+ .channel = 0,
+ },
+ /*
+ * 'modified' (i.e. axis specified) acceleration channel
+ * in_accel_z_raw
+ */
+ {
+ .type = IIO_ACCEL,
+ .modified = 1,
+ /* Channel 2 is use for modifiers */
+ .channel2 = IIO_MOD_X,
+ .info_mask =
+ /*
+ * Internal bias correction value. Applied
+ * by the hardware or driver prior to userspace
+ * seeing the readings. Typically part of hardware
+ * calibration.
+ */
+ (1 << IIO_CHAN_INFO_CALIBBIAS_SEPARATE),
+ },
+};
+
+/**
+ * iio_dummy_read_raw() - data read function.
+ * @indio_dev: the struct iio_dev associated with this device instance
+ * @chan: the channel whose data is to be read
+ * @val: first element of returned value (typically INT)
+ * @val2: second element of returned value (typically MICRO)
+ * @mask: what we actually want to read. 0 is the channel, everything else
+ * is as per the info_mask in iio_chan_spec.
+ */
+static int iio_dummy_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct iio_dummy_state *st = iio_priv(indio_dev);
+ int ret = -EINVAL;
+
+ mutex_lock(&st->lock);
+ switch (mask) {
+ case 0: /* magic value - channel value read */
+ switch (chan->type) {
+ case IIO_VOLTAGE:
+ if (chan->output) {
+ /* Set integer part to cached value */
+ *val = st->dac_val;
+ ret = IIO_VAL_INT;
+ } else if (chan->differential) {
+ if (chan->channel == 1)
+ *val = st->differential_adc_val[0];
+ else
+ *val = st->differential_adc_val[1];
+ ret = IIO_VAL_INT;
+ } else {
+ *val = st->single_ended_adc_val;
+ ret = IIO_VAL_INT;
+ }
+ break;
+ case IIO_ACCEL:
+ *val = st->accel_val;
+ ret = IIO_VAL_INT;
+ break;
+ default:
+ break;
+ }
+ break;
+ case (1 << IIO_CHAN_INFO_OFFSET_SEPARATE):
+ /* only single ended adc -> 7 */
+ *val = 7;
+ ret = IIO_VAL_INT;
+ break;
+ case (1 << IIO_CHAN_INFO_SCALE_SEPARATE):
+ /* only single ended adc -> 0.001333 */
+ *val = 0;
+ *val2 = 1333;
+ ret = IIO_VAL_INT_PLUS_MICRO;
+ break;
+ case (1 << IIO_CHAN_INFO_SCALE_SHARED):
+ /* all differential adc channels -> 0.000001344 */
+ *val = 0;
+ *val2 = 1344;
+ ret = IIO_VAL_INT_PLUS_NANO;
+ break;
+ case (1 << IIO_CHAN_INFO_CALIBBIAS_SEPARATE):
+ /* only the acceleration axis - read from cache */
+ *val = st->accel_calibbias;
+ ret = IIO_VAL_INT;
+ break;
+ case (1 << IIO_CHAN_INFO_CALIBSCALE_SEPARATE):
+ *val = st->accel_calibscale->val;
+ *val2 = st->accel_calibscale->val2;
+ ret = IIO_VAL_INT_PLUS_MICRO;
+ break;
+ default:
+ break;
+ }
+ mutex_unlock(&st->lock);
+ return ret;
+}
+
+/**
+ * iio_dummy_write_raw() - data write function.
+ * @indio_dev: the struct iio_dev associated with this device instance
+ * @chan: the channel whose data is to be read
+ * @val: first element of returned value (typically INT)
+ * @val2: second element of returned value (typically MICRO)
+ * @mask: what we actually want to read. 0 is the channel, everything else
+ * is as per the info_mask in iio_chan_spec.
+ *
+ * Note that all raw writes are assumed IIO_VAL_INT and info mask elements
+ * are assumed to be IIO_INT_PLUS_MICRO unless the callback write_raw_get_fmt
+ * in struct iio_info is provided by the driver.
+ */
+static int iio_dummy_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val,
+ int val2,
+ long mask)
+{
+ int i;
+ int ret = 0;
+ struct iio_dummy_state *st = iio_priv(indio_dev);
+
+ switch (mask) {
+ case 0:
+ if (chan->output == 0)
+ return -EINVAL;
+
+ /* Locking not required as writing single value */
+ mutex_lock(&st->lock);
+ st->dac_val = val;
+ mutex_unlock(&st->lock);
+ return 0;
+ case (1 << IIO_CHAN_INFO_CALIBBIAS_SEPARATE):
+ mutex_lock(&st->lock);
+ /* Compare against table - hard matching here */
+ for (i = 0; i < ARRAY_SIZE(dummy_scales); i++)
+ if (val == dummy_scales[i].val &&
+ val2 == dummy_scales[i].val2)
+ break;
+ if (i == ARRAY_SIZE(dummy_scales))
+ ret = -EINVAL;
+ else
+ st->accel_calibscale = &dummy_scales[i];
+ mutex_unlock(&st->lock);
+ return ret;
+ default:
+ return -EINVAL;
+ }
+}
+
+/*
+ * Device type specific information.
+ */
+static const struct iio_info iio_dummy_info = {
+ .driver_module = THIS_MODULE,
+ .read_raw = &iio_dummy_read_raw,
+ .write_raw = &iio_dummy_write_raw,
+};
+
+/**
+ * iio_dummy_init_device() - device instance specific init
+ * @indio_dev: the iio device structure
+ *
+ * Most drivers have one of these to set up default values,
+ * reset the device to known state etc.
+ */
+static int iio_dummy_init_device(struct iio_dev *indio_dev)
+{
+ struct iio_dummy_state *st = iio_priv(indio_dev);
+
+ st->dac_val = 0;
+ st->single_ended_adc_val = 73;
+ st->differential_adc_val[0] = 33;
+ st->differential_adc_val[1] = -34;
+ st->accel_val = 34;
+ st->accel_calibbias = -7;
+ st->accel_calibscale = &dummy_scales[0];
+
+ return 0;
+}
+
+/**
+ * iio_dummy_probe() - device instance probe
+ * @index: an id number for this instance.
+ *
+ * Arguments are bus type specific.
+ * I2C: iio_dummy_probe(struct i2c_client *client,
+ * const struct i2c_device_id *id)
+ * SPI: iio_dummy_probe(struct spi_device *spi)
+ */
+static int __devinit iio_dummy_probe(int index)
+{
+ int ret;
+ struct iio_dev *indio_dev;
+ struct iio_dummy_state *st;
+
+ /*
+ * Allocate an IIO device.
+ *
+ * This structure contains all generic state
+ * information about the device instance.
+ * It also has a region (accessed by iio_priv()
+ * for chip specific state information.
+ */
+ indio_dev = iio_allocate_device(sizeof(*st));
+ if (indio_dev == NULL) {
+ ret = -ENOMEM;
+ goto error_ret;
+ }
+
+ st = iio_priv(indio_dev);
+ mutex_init(&st->lock);
+
+ iio_dummy_init_device(indio_dev);
+ /*
+ * With hardware: Set the parent device.
+ * indio_dev->dev.parent = &spi->dev;
+ * indio_dev->dev.parent = &client->dev;
+ */
+
+ /*
+ * Make the iio_dev struct available to remove function.
+ * Bus equivalents
+ * i2c_set_clientdata(client, indio_dev);
+ * spi_set_drvdata(spi, indio_dev);
+ */
+ iio_dummy_devs[index] = indio_dev;
+
+
+ /*
+ * Set the device name.
+ *
+ * This is typically a part number and obtained from the module
+ * id table.
+ * e.g. for i2c and spi:
+ * indio_dev->name = id->name;
+ * indio_dev->name = spi_get_device_id(spi)->name;
+ */
+ indio_dev->name = iio_dummy_part_number;
+
+ /* Provide description of available channels */
+ indio_dev->channels = iio_dummy_channels;
+ indio_dev->num_channels = ARRAY_SIZE(iio_dummy_channels);
+
+ /*
+ * Provide device type specific interface functions and
+ * constant data.
+ */
+ indio_dev->info = &iio_dummy_info;
+
+ /* Specify that device provides sysfs type interfaces */
+ indio_dev->modes = INDIO_DIRECT_MODE;
+
+ ret = iio_device_register(indio_dev);
+ if (ret < 0)
+ goto error_free_device;
+
+ return 0;
+error_free_device:
+ /* Note free device should only be called, before registration
+ * has succeeded. */
+ iio_free_device(indio_dev);
+error_ret:
+ return ret;
+}
+
+/**
+ * iio_dummy_remove() - device instance removal function
+ * @index: device index.
+ *
+ * Parameters follow those of iio_dummy_probe for buses.
+ */
+static int iio_dummy_remove(int index)
+{
+ /*
+ * Get a pointer to the device instance iio_dev structure
+ * from the bus subsystem. E.g.
+ * struct iio_dev *indio_dev = i2c_get_clientdata(client);
+ * struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ */
+ struct iio_dev *indio_dev = iio_dummy_devs[index];
+
+ /* Unregister the device */
+ iio_device_unregister(indio_dev);
+
+ /* Device specific code to power down etc */
+
+ /* Free all structures */
+ iio_free_device(indio_dev);
+
+ return 0;
+}
+
+/**
+ * iio_dummy_init() - device driver registration
+ *
+ * Varies depending on bus type of the device. As there is no device
+ * here, call probe directly. For information on device registration
+ * i2c:
+ * Documentation/i2c/writing-clients
+ * spi:
+ * Documentation/spi/spi-summary
+ */
+static __init int iio_dummy_init(void)
+{
+ int i, ret;
+ if (instances > 10) {
+ instances = 1;
+ return -EINVAL;
+ }
+ /* Fake a bus */
+ iio_dummy_devs = kzalloc(sizeof(*iio_dummy_devs)*instances, GFP_KERNEL);
+ /* Here we have no actual device so call probe */
+ for (i = 0; i < instances; i++) {
+ ret = iio_dummy_probe(i);
+ if (ret < 0)
+ return ret;
+ }
+ return 0;
+}
+module_init(iio_dummy_init);
+
+/**
+ * iio_dummy_exit() - device driver removal
+ *
+ * Varies depending on bus type of the device.
+ * As there is no device here, call remove directly.
+ */
+static __exit void iio_dummy_exit(void)
+{
+ int i;
+ for (i = 0; i < instances; i++)
+ iio_dummy_remove(i);
+ kfree(iio_dummy_devs);
+}
+module_exit(iio_dummy_exit);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
+MODULE_DESCRIPTION("IIO dummy driver");
+MODULE_LICENSE("GPL v2");
projects / GitHub / exynos8895 / android_kernel_samsung_universal8895.git / commitdiff