On Fri, 12 Jan 2018 12:42:14 +0200 <alexandru.ardelean@xxxxxxxxxx> wrote: > From: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> > > On 10/01/2018 14:17, Phil Reid wrote: > > Add implementation for Analog Devices AD5272 and AD5274 digital > > potentiometer devices. > > > > Hey, > > Thanks for the patch. > Replies inline > > > Signed-off-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx> > > --- > > 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. > > + */ > > + > > +#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; > > Maybe this should be masked with 0xff, to avoid any potential > side-effects of downcasting. > So, buf[1] = (u8)(0xff & val). There are no sideeffects in down casting - it simply drops the bits. c99 spec gives me: 6.3.1.3 Signed and unsigned integers 1 When a value with integer type is converted to another integer type other than _Bool, if the value can be represented by the new type, it is unchanged. 2 Otherwise, if the new type is unsigned, the value is converted by repeatedly adding or subtracting one more than the maximum value that can be represented in the new type until the value is in the range of the new type.49) 3 Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised. So in this case we are down casting we basically end up subtracting all the higher bits (same as just cutting them off or masking as you did. Jonathan > > > + > > + mutex_lock(&data->lock); > > + ret = i2c_master_send(data->client, buf, 2); > > More of a preference from me. > But, I'd use sizeof(buf) instead of value '2'. > Same comment for other similar cases. > > > + mutex_unlock(&data->lock); > > + return ret < 0 ? ret : 0; > > +} > > + > > +static int ad5272_read(struct ad5272_data *data, int reg, int *val) > > +{ > > + u8 buf[2]; > > + 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; > > + > > + val = 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, > > +}; > > + > > +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); > > I think this may also need some more logic to perform a reset. > Maybe setting the value with `gpiod_set_value(reset_gpio, 1)` > Also, if `reset_gpio` is NULL, you could issue a software reset > with command 4. > > Something similar is done in `ad5592r-base.c` > > > + > > + 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]; > > + > > + 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] }, > > + { .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"); > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
