G'day Jonathan,
On 14/01/2018 21:39, Jonathan Cameron wrote:
On Wed, 10 Jan 2018 14:17:31 +0800
Phil Reid <preid@xxxxxxxxxxxxxxxxx> wrote:
Add implementation for Analog Devices AD5272 and AD5274 digital
potentiometer devices.
Signed-off-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx>
Hi Phil,
A few minor comments inline, but looking pretty good.
Thanks for the review.
Jonathan
---
drivers/iio/potentiometer/Kconfig | 10 ++
drivers/iio/potentiometer/Makefile | 1 +
drivers/iio/potentiometer/ad5272.c | 219 +++++++++++++++++++++++++++++++++++++
3 files changed, 230 insertions(+)
create mode 100644 drivers/iio/potentiometer/ad5272.c
diff --git a/drivers/iio/potentiometer/Kconfig b/drivers/iio/potentiometer/Kconfig
index 8bf2825..0b04063 100644
--- a/drivers/iio/potentiometer/Kconfig
+++ b/drivers/iio/potentiometer/Kconfig
@@ -5,6 +5,16 @@
menu "Digital potentiometers"
+config AD5272
+ tristate "Analog Devices AD5272 Digital Potentiometer driver"
+ depends on I2C
+ help
+ Say yes here to build support for the Analog Devices AD5272
+ digital potentiometer chip.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ad5272.
+
config DS1803
tristate "Maxim Integrated DS1803 Digital Potentiometer driver"
depends on I2C
diff --git a/drivers/iio/potentiometer/Makefile b/drivers/iio/potentiometer/Makefile
index 2260d40..498bbb8 100644
--- a/drivers/iio/potentiometer/Makefile
+++ b/drivers/iio/potentiometer/Makefile
@@ -3,6 +3,7 @@
#
# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AD5272) += ad5272.o
obj-$(CONFIG_DS1803) += ds1803.o
obj-$(CONFIG_MAX5481) += max5481.o
obj-$(CONFIG_MAX5487) += max5487.o
diff --git a/drivers/iio/potentiometer/ad5272.c b/drivers/iio/potentiometer/ad5272.c
new file mode 100644
index 0000000..b9208c2
--- /dev/null
+++ b/drivers/iio/potentiometer/ad5272.c
@@ -0,0 +1,219 @@
+/*
+ * Analog Devices AD5372 digital potentiometer driver
+ * Copyright (C) 2018 Phil Reid <preid@xxxxxxxxxxxxxxxxx>
+ *
+ * Datasheet: http://www.analog.com/media/en/technical-documentation/data-sheets/AD5272_5274.pdf
+ *
+ * DEVID #Wipers #Positions Resistor Opts (kOhm) i2c address
+ * ad5272 1 1024 20, 50, 100 01011xx
+ * ad5274 1 256 20, 100 01011xx
+ *
+ * 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.
Could go all SPDX with the gpl part of this. Personally I don't mind
much but we'll probably end up converting it over soon anyway.
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+
+#define AD5272_RDAC_WR 1
+#define AD5272_RDAC_RD 2
+#define AD5272_CTL 7
+
+#define AD5272_RDAC_WR_EN BIT(1)
+
+struct ad5272_cfg {
+ int max_pos;
+ int kohms;
+ int shift;
+};
+
+enum ad5272_type {
+ AD5272_020,
+ AD5272_050,
+ AD5272_100,
+ AD5274_020,
+ AD5274_100,
+};
+
+static const struct ad5272_cfg ad5272_cfg[] = {
+ /* on-semiconductor parts */
+ [AD5272_020] = { .max_pos = 1024, .kohms = 20 },
+ [AD5272_050] = { .max_pos = 1024, .kohms = 50 },
+ [AD5272_100] = { .max_pos = 1024, .kohms = 100 },
+ [AD5274_020] = { .max_pos = 256, .kohms = 20, .shift = 2 },
+ [AD5274_100] = { .max_pos = 256, .kohms = 100, .shift = 2 },
+};
+
+struct ad5272_data {
+ struct i2c_client *client;
+ struct mutex lock;
+ const struct ad5272_cfg *cfg;
+};
+
+static const struct iio_chan_spec ad5272_channel = {
+ .type = IIO_RESISTANCE,
+ .output = 1,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+};
+
+static int ad5272_write(struct ad5272_data *data, int reg, int val)
+{
+ u8 buf[2];
+ int ret;
+
+ buf[0] = ((reg & 0xf) << 2) | ((val >> 8) & 0x3);
+ buf[1] = (u8)val;
again, could do as buf[2] = {...};
ok
+
+ mutex_lock(&data->lock);
+ ret = i2c_master_send(data->client, buf, 2);
sizeof(buf) preferred.
ok
+ mutex_unlock(&data->lock);
+ return ret < 0 ? ret : 0;
+}
+
+static int ad5272_read(struct ad5272_data *data, int reg, int *val)
+{
+ u8 buf[2];
Could assign value here for compactness.
u8 buf[2] = {(reg & 0xf) << 2, 0) >
It's a little paranoid to mask reg given you are controlling it entirely
in the driver and anything of more than 4 bits is a bug anyway.
ok
+ int ret;
+
+ buf[0] = (reg & 0xf) << 2;
+ buf[1] = 0;
+
+ mutex_lock(&data->lock);
+ ret = i2c_master_send(data->client, buf, 2);
+ if (ret < 0)
+ goto error;
+
+ ret = i2c_master_recv(data->client, buf, 2);
+ if (ret < 0)
+ goto error;
+
+ *val = ((buf[0] & 0x3) << 8) | buf[1];
+ ret = 0;
+error:
+ mutex_unlock(&data->lock);
+ return ret;
+}
+
+static int ad5272_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long mask)
+{
+ struct ad5272_data *data = iio_priv(indio_dev);
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW: {
+ ret = ad5272_read(data, AD5272_RDAC_RD, val);
+ *val = *val >> data->cfg->shift;
+ return ret ? ret : IIO_VAL_INT;
+ }
+ case IIO_CHAN_INFO_SCALE:
+ *val = 1000 * data->cfg->kohms;
+ *val2 = data->cfg->max_pos;
+ return IIO_VAL_FRACTIONAL;
+ }
+
+ return -EINVAL;
+}
+
+static int ad5272_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val, int val2, long mask)
+{
+ struct ad5272_data *data = iio_priv(indio_dev);
+
+ if (mask != IIO_CHAN_INFO_RAW)
+ return -EINVAL;
+
+ if (val >= data->cfg->max_pos || val < 0)
+ return -EINVAL;
Also verify that val2 = 0 as otherwise the classic
1.999999 evaluates to 1 rather surprises users.
yeap, that'd surprise me too.
+
+ val = val << data->cfg->shift;
I would role this into the next line.
ok
return ad5272_write(data, AD5272_RDAC_WR, val << data->cfg->shift);
+
+ return ad5272_write(data, AD5272_RDAC_WR, val);
+}
+
+static const struct iio_info ad5272_info = {
+ .read_raw = ad5272_read_raw,
+ .write_raw = ad5272_write_raw,
+ .driver_module = THIS_MODULE,
.driver_module no longer exists so just drop this.
We do the equivalent with some macro tricks to avoid having
to have this same line in every driver.
ok
+};
+
+static int ad5272_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct gpio_desc *reset_gpio;
+ struct iio_dev *indio_dev;
+ struct ad5272_data *data;
+ int ret;
+
+ reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(reset_gpio))
+ return PTR_ERR(reset_gpio);
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ i2c_set_clientdata(client, indio_dev);
+
+ data = iio_priv(indio_dev);
+ data->client = client;
+ mutex_init(&data->lock);
+ data->cfg = &ad5272_cfg[id->driver_data];
Calling it cfg kind of implies config to me whereas this is
chip type specific data.
I just followed what seemed to be the existing convention for the iio/potentmeters.
ds1803, mcp4531, max5481
Happy to change.
+
+ ret = ad5272_write(data, AD5272_CTL, AD5272_RDAC_WR_EN);
+ if (ret < 0)
+ return -ENODEV;
+
+ indio_dev->dev.parent = dev;
+ indio_dev->info = &ad5272_info;
+ indio_dev->channels = &ad5272_channel;
+ indio_dev->num_channels = 1;
+ indio_dev->name = client->name;
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id ad5272_dt_ids[] = {
+ { .compatible = "adi,ad5272-020", .data = &ad5272_cfg[AD5272_020] },
Why do this rather than stash the index in the data parameter and look up later
(more consistent with the i2c_device_id table below)?
Yeah I was a bit confused by this.
I was following how the ds1803.c driver was doing things.
To be honest I don't have a good grasp of how .data works here or how it gets referenced or if it's
even used...
+ { .compatible = "adi,ad5272-050", .data = &ad5272_cfg[AD5272_050] },
+ { .compatible = "adi,ad5272-100", .data = &ad5272_cfg[AD5272_100] },
+ { .compatible = "adi,ad5274-020", .data = &ad5272_cfg[AD5274_020] },
+ { .compatible = "adi,ad5274-100", .data = &ad5272_cfg[AD5274_100] },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ad5272_dt_ids);
+#endif /* CONFIG_OF */
+
+static const struct i2c_device_id ad5272_id[] = {
+ { "ad5272-020", AD5272_020 },
+ { "ad5272-050", AD5272_050 },
+ { "ad5272-100", AD5272_100 },
+ { "ad5274-020", AD5274_020 },
+ { "ad5274-100", AD5274_100 },
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, ad5272_id);
+
+static struct i2c_driver ad5272_driver = {
+ .driver = {
+ .name = "ad5272",
+ .of_match_table = of_match_ptr(ad5272_dt_ids),
+ },
+ .probe = ad5272_probe,
+ .id_table = ad5272_id,
+};
+
+module_i2c_driver(ad5272_driver);
+
+MODULE_AUTHOR("Phil Reid <preid@xxxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("AD5272 digital potentiometer");
+MODULE_LICENSE("GPL v2");
--
Regards
Phil Reid
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