summaryrefslogtreecommitdiffstats
path: root/drivers/iio/adc/ltc2497.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--drivers/iio/adc/ltc2497.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c
new file mode 100644
index 000000000..e1e14f5d2
--- /dev/null
+++ b/drivers/iio/adc/ltc2497.c
@@ -0,0 +1,174 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ *
+ * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
+ */
+
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/property.h>
+
+#include <asm/unaligned.h>
+
+#include "ltc2497.h"
+
+enum ltc2497_chip_type {
+ TYPE_LTC2497,
+ TYPE_LTC2499,
+};
+
+struct ltc2497_driverdata {
+ /* this must be the first member */
+ struct ltc2497core_driverdata common_ddata;
+ struct i2c_client *client;
+ u32 recv_size;
+ /*
+ * DMA (thus cache coherency maintenance) may require the
+ * transfer buffers to live in their own cache lines.
+ */
+ union {
+ __be32 d32;
+ u8 d8[3];
+ } data __aligned(IIO_DMA_MINALIGN);
+};
+
+static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
+ u8 address, int *val)
+{
+ struct ltc2497_driverdata *st =
+ container_of(ddata, struct ltc2497_driverdata, common_ddata);
+ int ret;
+
+ if (val) {
+ if (st->recv_size == 3)
+ ret = i2c_master_recv(st->client, (char *)&st->data.d8,
+ st->recv_size);
+ else
+ ret = i2c_master_recv(st->client, (char *)&st->data.d32,
+ st->recv_size);
+ if (ret < 0) {
+ dev_err(&st->client->dev, "i2c_master_recv failed\n");
+ return ret;
+ }
+
+ /*
+ * The data format is 16/24 bit 2s complement, but with an upper sign bit on the
+ * resolution + 1 position, which is set for positive values only. Given this
+ * bit's value, subtracting BIT(resolution + 1) from the ADC's result is
+ * equivalent to a sign extension.
+ */
+ if (st->recv_size == 3) {
+ *val = (get_unaligned_be24(st->data.d8) >> 6)
+ - BIT(ddata->chip_info->resolution + 1);
+ } else {
+ *val = (be32_to_cpu(st->data.d32) >> 6)
+ - BIT(ddata->chip_info->resolution + 1);
+ }
+
+ /*
+ * The part started a new conversion at the end of the above i2c
+ * transfer, so if the address didn't change since the last call
+ * everything is fine and we can return early.
+ * If not (which should only happen when some sort of bulk
+ * conversion is implemented) we have to program the new
+ * address. Note that this probably fails as the conversion that
+ * was triggered above is like not complete yet and the two
+ * operations have to be done in a single transfer.
+ */
+ if (ddata->addr_prev == address)
+ return 0;
+ }
+
+ ret = i2c_smbus_write_byte(st->client,
+ LTC2497_ENABLE | address);
+ if (ret)
+ dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
+ ERR_PTR(ret));
+ return ret;
+}
+
+static int ltc2497_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ const struct ltc2497_chip_info *chip_info;
+ struct iio_dev *indio_dev;
+ struct ltc2497_driverdata *st;
+ struct device *dev = &client->dev;
+ u32 resolution;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+ I2C_FUNC_SMBUS_WRITE_BYTE))
+ return -EOPNOTSUPP;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ i2c_set_clientdata(client, indio_dev);
+ st->client = client;
+ st->common_ddata.result_and_measure = ltc2497_result_and_measure;
+
+ chip_info = device_get_match_data(dev);
+ if (!chip_info)
+ chip_info = (const struct ltc2497_chip_info *)id->driver_data;
+ st->common_ddata.chip_info = chip_info;
+
+ resolution = chip_info->resolution;
+ st->recv_size = BITS_TO_BYTES(resolution) + 1;
+
+ return ltc2497core_probe(dev, indio_dev);
+}
+
+static void ltc2497_remove(struct i2c_client *client)
+{
+ struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+ ltc2497core_remove(indio_dev);
+}
+
+static const struct ltc2497_chip_info ltc2497_info[] = {
+ [TYPE_LTC2497] = {
+ .resolution = 16,
+ .name = NULL,
+ },
+ [TYPE_LTC2499] = {
+ .resolution = 24,
+ .name = "ltc2499",
+ },
+};
+
+static const struct i2c_device_id ltc2497_id[] = {
+ { "ltc2497", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2497] },
+ { "ltc2499", (kernel_ulong_t)&ltc2497_info[TYPE_LTC2499] },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ltc2497_id);
+
+static const struct of_device_id ltc2497_of_match[] = {
+ { .compatible = "lltc,ltc2497", .data = &ltc2497_info[TYPE_LTC2497] },
+ { .compatible = "lltc,ltc2499", .data = &ltc2497_info[TYPE_LTC2499] },
+ {},
+};
+MODULE_DEVICE_TABLE(of, ltc2497_of_match);
+
+static struct i2c_driver ltc2497_driver = {
+ .driver = {
+ .name = "ltc2497",
+ .of_match_table = ltc2497_of_match,
+ },
+ .probe = ltc2497_probe,
+ .remove = ltc2497_remove,
+ .id_table = ltc2497_id,
+};
+module_i2c_driver(ltc2497_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
+MODULE_LICENSE("GPL v2");