iio: adc: ltc2309: add support for ltc2305

Add support for the LTC2305 ADC to the LTC2309 driver. The LTC2305 is
a 2-channel, 12-bit SAR ADC that is register-compatible with the
LTC2309 but has a different channel selection mapping and count.

To support multiple chips in this family, introduce ltc2309_chip_info
struct to store chip-specific channel specifications and names.
The probe function now uses i2c_get_match_data() to retrieve the
correct configuration for the detected device.

Specific channel addresses for LTC2305 (CH0, CH1, and differential
pairs) are added based on the datasheet.

Signed-off-by: Kyle Hsieh <kylehsieh1995@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ltc2309.c b/drivers/iio/adc/ltc2309.c
index 3f27ffc666687303d650164595b3e5eeb102f638..316256edf150ab07d13de66567b658e577e12ad4 100644 (file)
--- a/drivers/iio/adc/ltc2309.c
+++ b/drivers/iio/adc/ltc2309.c
@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
+ * The LTC2305 is a  2-Channel, 12-Bit SAR ADC with an I2C Interface.
  * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
  *
  * Datasheet:
+ * https://www.analog.com/media/en/technical-documentation/data-sheets/23015fb.pdf
  * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
  *
  * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
@@ -41,6 +43,13 @@ struct ltc2309 {
 };
 
 /* Order matches expected channel address, See datasheet Table 1. */
+enum ltc2305_channels {
+       LTC2305_CH0_CH1 = 0x0,
+       LTC2305_CH1_CH0 = 0x4,
+       LTC2305_CH0     = 0x8,
+       LTC2305_CH1     = 0xc,
+};
+
 enum ltc2309_channels {
        LTC2309_CH0_CH1 = 0x0,
        LTC2309_CH2_CH3 = 0x1,
@@ -80,6 +89,13 @@ enum ltc2309_channels {
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
 }
 
+static const struct iio_chan_spec ltc2305_channels[] = {
+       LTC2309_CHAN(0, LTC2305_CH0),
+       LTC2309_CHAN(1, LTC2305_CH1),
+       LTC2309_DIFF_CHAN(0, 1, LTC2305_CH0_CH1),
+       LTC2309_DIFF_CHAN(1, 0, LTC2305_CH1_CH0),
+};
+
 static const struct iio_chan_spec ltc2309_channels[] = {
        LTC2309_CHAN(0, LTC2309_CH0),
        LTC2309_CHAN(1, LTC2309_CH1),
@@ -99,6 +115,24 @@ static const struct iio_chan_spec ltc2309_channels[] = {
        LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6),
 };
 
+struct ltc2309_chip_info {
+       const char *name;
+       const struct iio_chan_spec *channels;
+       int num_channels;
+};
+
+static const struct ltc2309_chip_info ltc2305_chip_info = {
+       .name = "ltc2305",
+       .channels = ltc2305_channels,
+       .num_channels = ARRAY_SIZE(ltc2305_channels),
+};
+
+static const struct ltc2309_chip_info ltc2309_chip_info = {
+       .name = "ltc2309",
+       .channels = ltc2309_channels,
+       .num_channels = ARRAY_SIZE(ltc2309_channels),
+};
+
 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309,
                                    unsigned long address, int *val)
 {
@@ -158,6 +192,7 @@ static const struct iio_info ltc2309_info = {
 
 static int ltc2309_probe(struct i2c_client *client)
 {
+       const struct ltc2309_chip_info *chip_info;
        struct iio_dev *indio_dev;
        struct ltc2309 *ltc2309;
        int ret;
@@ -167,13 +202,15 @@ static int ltc2309_probe(struct i2c_client *client)
                return -ENOMEM;
 
        ltc2309 = iio_priv(indio_dev);
+       chip_info = i2c_get_match_data(client);
+
        ltc2309->dev = &indio_dev->dev;
        ltc2309->client = client;
 
-       indio_dev->name = "ltc2309";
+       indio_dev->name = chip_info->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
-       indio_dev->channels = ltc2309_channels;
-       indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
+       indio_dev->channels = chip_info->channels;
+       indio_dev->num_channels = chip_info->num_channels;
        indio_dev->info = &ltc2309_info;
 
        ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref");
@@ -189,13 +226,15 @@ static int ltc2309_probe(struct i2c_client *client)
 }
 
 static const struct of_device_id ltc2309_of_match[] = {
-       { .compatible = "lltc,ltc2309" },
+       { .compatible = "lltc,ltc2305", .data = &ltc2305_chip_info },
+       { .compatible = "lltc,ltc2309", .data = &ltc2309_chip_info },
        { }
 };
 MODULE_DEVICE_TABLE(of, ltc2309_of_match);
 
 static const struct i2c_device_id ltc2309_id[] = {
-       { "ltc2309" },
+       { "ltc2305", (kernel_ulong_t)&ltc2305_chip_info },
+       { "ltc2309", (kernel_ulong_t)&ltc2309_chip_info },
        { }
 };
 MODULE_DEVICE_TABLE(i2c, ltc2309_id);