--- /dev/null
+/*
+ * TI tlc4541 ADC Driver
+ *
+ * Copyright (C) 2017 Phil Reid
+ *
+ * Datasheets can be found here:
+ * http://www.ti.com/lit/gpn/tlc3541
+ * http://www.ti.com/lit/gpn/tlc4541
+ *
+ * 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.
+ *
+ * The tlc4541 requires 24 clock cycles to start a transfer.
+ * Conversion then takes 2.94us to complete before data is ready
+ * Data is returned MSB first.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+
+struct tlc4541_state {
+ struct spi_device *spi;
+ struct regulator *reg;
+ struct spi_transfer scan_single_xfer[3];
+ struct spi_message scan_single_msg;
+
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ * 2 bytes data + 6 bytes padding + 8 bytes timestamp when
+ * call iio_push_to_buffers_with_timestamp.
+ */
+ __be16 rx_buf[8] ____cacheline_aligned;
+};
+
+struct tlc4541_chip_info {
+ const struct iio_chan_spec *channels;
+ unsigned int num_channels;
+};
+
+enum tlc4541_id {
+ TLC3541,
+ TLC4541,
+};
+
+#define TLC4541_V_CHAN(bits, bitshift) { \
+ .type = IIO_VOLTAGE, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = (bits), \
+ .storagebits = 16, \
+ .shift = (bitshift), \
+ .endianness = IIO_BE, \
+ }, \
+ }
+
+#define DECLARE_TLC4541_CHANNELS(name, bits, bitshift) \
+const struct iio_chan_spec name ## _channels[] = { \
+ TLC4541_V_CHAN(bits, bitshift), \
+ IIO_CHAN_SOFT_TIMESTAMP(1), \
+}
+
+static DECLARE_TLC4541_CHANNELS(tlc3541, 14, 2);
+static DECLARE_TLC4541_CHANNELS(tlc4541, 16, 0);
+
+static const struct tlc4541_chip_info tlc4541_chip_info[] = {
+ [TLC3541] = {
+ .channels = tlc3541_channels,
+ .num_channels = ARRAY_SIZE(tlc3541_channels),
+ },
+ [TLC4541] = {
+ .channels = tlc4541_channels,
+ .num_channels = ARRAY_SIZE(tlc4541_channels),
+ },
+};
+
+static irqreturn_t tlc4541_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct tlc4541_state *st = iio_priv(indio_dev);
+ int ret;
+
+ ret = spi_sync(st->spi, &st->scan_single_msg);
+ if (ret < 0)
+ goto done;
+
+ iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
+ iio_get_time_ns(indio_dev));
+
+done:
+ iio_trigger_notify_done(indio_dev->trig);
+ return IRQ_HANDLED;
+}
+
+static int tlc4541_get_range(struct tlc4541_state *st)
+{
+ int vref;
+
+ vref = regulator_get_voltage(st->reg);
+ if (vref < 0)
+ return vref;
+
+ vref /= 1000;
+
+ return vref;
+}
+
+static int tlc4541_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long m)
+{
+ int ret = 0;
+ struct tlc4541_state *st = iio_priv(indio_dev);
+
+ switch (m) {
+ case IIO_CHAN_INFO_RAW:
+ ret = iio_device_claim_direct_mode(indio_dev);
+ if (ret)
+ return ret;
+ ret = spi_sync(st->spi, &st->scan_single_msg);
+ iio_device_release_direct_mode(indio_dev);
+ if (ret < 0)
+ return ret;
+ *val = be16_to_cpu(st->rx_buf[0]);
+ *val = *val >> chan->scan_type.shift;
+ *val &= GENMASK(chan->scan_type.realbits - 1, 0);
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = tlc4541_get_range(st);
+ if (ret < 0)
+ return ret;
+ *val = ret;
+ *val2 = chan->scan_type.realbits;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+ return -EINVAL;
+}
+
+static const struct iio_info tlc4541_info = {
+ .read_raw = &tlc4541_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int tlc4541_probe(struct spi_device *spi)
+{
+ struct tlc4541_state *st;
+ struct iio_dev *indio_dev;
+ const struct tlc4541_chip_info *info;
+ int ret;
+ int8_t device_init = 0;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+
+ spi_set_drvdata(spi, indio_dev);
+
+ st->spi = spi;
+
+ info = &tlc4541_chip_info[spi_get_device_id(spi)->driver_data];
+
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = info->channels;
+ indio_dev->num_channels = info->num_channels;
+ indio_dev->info = &tlc4541_info;
+
+ /* perform reset */
+ spi_write(spi, &device_init, 1);
+
+ /* Setup default message */
+ st->scan_single_xfer[0].rx_buf = &st->rx_buf[0];
+ st->scan_single_xfer[0].len = 3;
+ st->scan_single_xfer[1].delay_usecs = 3;
+ st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
+ st->scan_single_xfer[2].len = 2;
+
+ spi_message_init_with_transfers(&st->scan_single_msg,
+ st->scan_single_xfer, 3);
+
+ st->reg = devm_regulator_get(&spi->dev, "vref");
+ if (IS_ERR(st->reg))
+ return PTR_ERR(st->reg);
+
+ ret = regulator_enable(st->reg);
+ if (ret)
+ return ret;
+
+ ret = iio_triggered_buffer_setup(indio_dev, NULL,
+ &tlc4541_trigger_handler, NULL);
+ if (ret)
+ goto error_disable_reg;
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto error_cleanup_buffer;
+
+ return 0;
+
+error_cleanup_buffer:
+ iio_triggered_buffer_cleanup(indio_dev);
+error_disable_reg:
+ regulator_disable(st->reg);
+
+ return ret;
+}
+
+static int tlc4541_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct tlc4541_state *st = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+ iio_triggered_buffer_cleanup(indio_dev);
+ regulator_disable(st->reg);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id tlc4541_dt_ids[] = {
+ { .compatible = "ti,tlc3541", },
+ { .compatible = "ti,tlc4541", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, tlc4541_dt_ids);
+#endif
+
+static const struct spi_device_id tlc4541_id[] = {
+ {"tlc3541", TLC3541},
+ {"tlc4541", TLC4541},
+ {}
+};
+MODULE_DEVICE_TABLE(spi, tlc4541_id);
+
+static struct spi_driver tlc4541_driver = {
+ .driver = {
+ .name = "tlc4541",
+ .of_match_table = of_match_ptr(tlc4541_dt_ids),
+ },
+ .probe = tlc4541_probe,
+ .remove = tlc4541_remove,
+ .id_table = tlc4541_id,
+};
+module_spi_driver(tlc4541_driver);
+
+MODULE_AUTHOR("Phil Reid <preid@electromag.com.au>");
+MODULE_DESCRIPTION("Texas Instruments TLC4541 ADC");
+MODULE_LICENSE("GPL v2");
projects / mirror_ubuntu-artful-kernel.git / commitdiff