diff options
Diffstat (limited to 'drivers/staging/iio/iio_simple_dummy.c')
| -rw-r--r-- | drivers/staging/iio/iio_simple_dummy.c | 481 |
1 files changed, 481 insertions, 0 deletions
diff --git a/drivers/staging/iio/iio_simple_dummy.c b/drivers/staging/iio/iio_simple_dummy.c new file mode 100644 index 000000000000..314a4a6d3aea --- /dev/null +++ b/drivers/staging/iio/iio_simple_dummy.c @@ -0,0 +1,481 @@ +/** + * 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"); |