diff options
Diffstat (limited to 'drivers/iio/dac/stx104.c')
| -rw-r--r-- | drivers/iio/dac/stx104.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/drivers/iio/dac/stx104.c b/drivers/iio/dac/stx104.c new file mode 100644 index 000000000..174f4b75c --- /dev/null +++ b/drivers/iio/dac/stx104.c @@ -0,0 +1,152 @@ +/* + * DAC driver for the Apex Embedded Systems STX104 + * Copyright (C) 2016 William Breathitt Gray + * + * 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. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include <linux/bitops.h> +#include <linux/device.h> +#include <linux/errno.h> +#include <linux/iio/iio.h> +#include <linux/iio/types.h> +#include <linux/io.h> +#include <linux/ioport.h> +#include <linux/isa.h> +#include <linux/module.h> +#include <linux/moduleparam.h> + +#define STX104_NUM_CHAN 2 + +#define STX104_CHAN(chan) { \ + .type = IIO_VOLTAGE, \ + .channel = chan, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .indexed = 1, \ + .output = 1 \ +} + +#define STX104_EXTENT 16 +/** + * The highest base address possible for an ISA device is 0x3FF; this results in + * 1024 possible base addresses. Dividing the number of possible base addresses + * by the address extent taken by each device results in the maximum number of + * devices on a system. + */ +#define MAX_NUM_STX104 (1024 / STX104_EXTENT) + +static unsigned base[MAX_NUM_STX104]; +static unsigned num_stx104; +module_param_array(base, uint, &num_stx104, 0); +MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses"); + +/** + * struct stx104_iio - IIO device private data structure + * @chan_out_states: channels' output states + * @base: base port address of the IIO device + */ +struct stx104_iio { + unsigned chan_out_states[STX104_NUM_CHAN]; + unsigned base; +}; + +static int stx104_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, int *val2, long mask) +{ + struct stx104_iio *const priv = iio_priv(indio_dev); + + if (mask != IIO_CHAN_INFO_RAW) + return -EINVAL; + + *val = priv->chan_out_states[chan->channel]; + + return IIO_VAL_INT; +} + +static int stx104_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int val, int val2, long mask) +{ + struct stx104_iio *const priv = iio_priv(indio_dev); + const unsigned chan_addr_offset = 2 * chan->channel; + + if (mask != IIO_CHAN_INFO_RAW) + return -EINVAL; + + priv->chan_out_states[chan->channel] = val; + outw(val, priv->base + 4 + chan_addr_offset); + + return 0; +} + +static const struct iio_info stx104_info = { + .driver_module = THIS_MODULE, + .read_raw = stx104_read_raw, + .write_raw = stx104_write_raw +}; + +static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = { + STX104_CHAN(0), + STX104_CHAN(1) +}; + +static int stx104_probe(struct device *dev, unsigned int id) +{ + struct iio_dev *indio_dev; + struct stx104_iio *priv; + + indio_dev = devm_iio_device_alloc(dev, sizeof(*priv)); + if (!indio_dev) + return -ENOMEM; + + if (!devm_request_region(dev, base[id], STX104_EXTENT, + dev_name(dev))) { + dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n", + base[id], base[id] + STX104_EXTENT); + return -EBUSY; + } + + indio_dev->info = &stx104_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = stx104_channels; + indio_dev->num_channels = STX104_NUM_CHAN; + indio_dev->name = dev_name(dev); + + priv = iio_priv(indio_dev); + priv->base = base[id]; + + /* initialize DAC output to 0V */ + outw(0, base[id] + 4); + outw(0, base[id] + 6); + + return devm_iio_device_register(dev, indio_dev); +} + +static struct isa_driver stx104_driver = { + .probe = stx104_probe, + .driver = { + .name = "stx104" + } +}; + +static void __exit stx104_exit(void) +{ + isa_unregister_driver(&stx104_driver); +} + +static int __init stx104_init(void) +{ + return isa_register_driver(&stx104_driver, num_stx104); +} + +module_init(stx104_init); +module_exit(stx104_exit); + +MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>"); +MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver"); +MODULE_LICENSE("GPL v2"); |