HI Jonathan Thanks for your review. I will make the changes and send it back to you after testing it on Monday on real hardware. Until then I have pushed my changes to https://github.com/ribalda/linux/tree/ribalda-iio-v3 in case you want to see it before I send it to the list. (I am still missing the dt-bindings) Some comments inline. Best regards! On Sat, Jan 26, 2019 at 9:42 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > > On Fri, 25 Jan 2019 11:00:55 +0100 > Ricardo Ribalda Delgado <ricardo@xxxxxxxxxxx> wrote: > > > It is a driver for Texas Instruments Dual, 12-Bit Serial Input > > Digital-to-Analog Converter. > > > > Datasheet of this chip: > > http://www.ti.com/lit/ds/sbas106/sbas106.pdf > > > > Signed-off-by: Ricardo Ribalda Delgado <ricardo@xxxxxxxxxxx> > Hi Ricardo, > > Various bits and pieces inline. > > Jonathan > > > --- > > > > v2: Fix range > > MAINTAINERS | 6 ++ > > drivers/iio/dac/Kconfig | 10 +++ > > drivers/iio/dac/Makefile | 1 + > > drivers/iio/dac/ti-dac7612.c | 169 +++++++++++++++++++++++++++++++++++ > > 4 files changed, 186 insertions(+) > > create mode 100644 drivers/iio/dac/ti-dac7612.c > > > > diff --git a/MAINTAINERS b/MAINTAINERS > > index d039f66a5cef..30ba5435906b 100644 > > --- a/MAINTAINERS > > +++ b/MAINTAINERS > > @@ -14877,6 +14877,12 @@ F: Documentation/devicetree/bindings/clock/ti,sci-clk.txt > > F: drivers/clk/keystone/sci-clk.c > > F: drivers/reset/reset-ti-sci.c > > > > +Texas Instruments' DAC7612 DAC Driver > > +M: Ricardo Ribalda <ricardo@xxxxxxxxxxx> > > +L: linux-iio@xxxxxxxxxxxxxxx > > +S: Supported > > +F: drivers/iio/dac/ti-dac7612.c > > + > > THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER > > M: Hans Verkuil <hverkuil@xxxxxxxxx> > > L: linux-media@xxxxxxxxxxxxxxx > > diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig > > index f28daf67db6a..fbef9107acad 100644 > > --- a/drivers/iio/dac/Kconfig > > +++ b/drivers/iio/dac/Kconfig > > @@ -375,6 +375,16 @@ config TI_DAC7311 > > > > If compiled as a module, it will be called ti-dac7311. > > > > +config TI_DAC7612 > > + tristate "Texas Instruments 12-bit 2-channel DAC driver" > > + depends on SPI_MASTER && GPIOLIB > > + help > > + Driver for the Texas Instruments DAC7612, DAC7612U, DAC7612UB > > + The driver hand drive the load pin automatically, otherwise > > + it needs to be toggled manually. > > Given the driver doesn't load without that pin, do we need to give > the otherwise? I would drop this comment entirely. I am probing the gpio with devm_gpiod_get_optional() so the driver can load without the pin > > > + > > + If compiled as a module, it will be called ti-dac7612. > > + > > config VF610_DAC > > tristate "Vybrid vf610 DAC driver" > > depends on OF > > diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile > > index f0a37c93de8e..1369fa1d2f0e 100644 > > --- a/drivers/iio/dac/Makefile > > +++ b/drivers/iio/dac/Makefile > > @@ -41,4 +41,5 @@ obj-$(CONFIG_STM32_DAC) += stm32-dac.o > > obj-$(CONFIG_TI_DAC082S085) += ti-dac082s085.o > > obj-$(CONFIG_TI_DAC5571) += ti-dac5571.o > > obj-$(CONFIG_TI_DAC7311) += ti-dac7311.o > > +obj-$(CONFIG_TI_DAC7612) += ti-dac7612.o > > obj-$(CONFIG_VF610_DAC) += vf610_dac.o > > diff --git a/drivers/iio/dac/ti-dac7612.c b/drivers/iio/dac/ti-dac7612.c > > new file mode 100644 > > index 000000000000..278406f69e0c > > --- /dev/null > > +++ b/drivers/iio/dac/ti-dac7612.c > > @@ -0,0 +1,169 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter > > + * > > + * Copyright 2019 Qtechnology A/S > > + * 2019 Ricardo Ribalda <ricardo@xxxxxxxxxxx> > > + * > > + * Licensed under the GPL-2. > > + */ > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > +#include <linux/spi/spi.h> > > +#include <linux/gpio/consumer.h> > > +#include <linux/iio/iio.h> > > + > > +#define NUM_CHANS 2 > > +#define RESOLUTION 12 > Please prefix any naming that is generic like this with > the driver name. Avoids potential redefined clashes in the future. > Where they are 'real numbers' rather than Magic numbers I would > generally look at using the actual number rather than a define. > > > + > > +struct dac7612 { > > + struct spi_device *spi; > > + struct gpio_desc *nld; > > + uint16_t cache[NUM_CHANS]; > > +}; > > + > > +static int dac7612_cmd_single(struct dac7612 *priv, int channel, u16 val) > > +{ > > + uint8_t buffer[2]; > > + int ret; > > + > > + if (channel >= NUM_CHANS) > Is there any way this can happen? Seems a little over paranoid. > > + return -EINVAL; > > + > > + buffer[0] = BIT(5) | (channel << 4) | (val >> 8); > BIT(5) is a magic number so should probably come from a define > as should the shifts of the other parts. > > > + buffer[1] = val & 0xff; > > + > > + priv->cache[channel] = val; > > + > > + ret = spi_write(priv->spi, buffer, sizeof(buffer)); > > spi write can potentially do a dma transfer so it needs > a dma safe buffer. This one isn't as it is on the stack. > Given it is a moderately fast path, best option is to put the > buffer in priv and use the __cacheline_aligned trick (plus the > fact private data is already cacheline aligned) to get it into > it's own cacheline. Wofram Sang's OSS talk on i2c dma is a good > tutorial on this and is on youtube if you have time. > > https://www.youtube.com/watch?v=JDwaMClvV-s > > > + if (ret) > > + return ret; > > + > > + gpiod_set_value(priv->nld, 0); > > + gpiod_set_value(priv->nld, 1); > > + > > + return 0; > > +} > > + > > +#define dac7612_CHANNEL(chan, name) { \ > > + .type = IIO_VOLTAGE, \ > > + .channel = (chan), \ > > + .address = (chan), \ > Not used, so don't set it. > > > + .indexed = true, \ > These are bit fields, so whilst this works, = 1 is more conventional. > > > + .output = true, \ > > + .datasheet_name = name, \ > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ > > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ > > + .scan_type = { \ > > + .sign = 'u', \ > > + .realbits = RESOLUTION, \ > > + .storagebits = RESOLUTION, \ > No need to provide scan_type as we don't have buffered output in > mainline. Also this would be wrong as storagebits needs to be > 8/16/32/64 etc. > > Would prefer a straight forward value like RESOLUTION was just > expressed as a number. > > > + }, \ > > +} > > + > > +static const struct iio_chan_spec dac7612_channels[] = { > > + dac7612_CHANNEL(0, "OUTA"), > > + dac7612_CHANNEL(1, "OUTB"), > > +}; > > + > > +static int dac7612_read_raw(struct iio_dev *iio_dev, > > + const struct iio_chan_spec *chan, > > + int *val, int *val2, long mask) > > +{ > > + struct dac7612 *priv; > > + > > + switch (mask) { > > + case IIO_CHAN_INFO_RAW: > > + priv = iio_priv(iio_dev); > > + *val = priv->cache[chan->channel]; > > + return IIO_VAL_INT; > > + > > + case IIO_CHAN_INFO_SCALE: > > + *val = 1000000; > > This makes me wonder. The units of voltage are millivolts, so is > raw value * 1000000 = value in mv? I tried using IIO_VAL_FRACTIONAL, with val = 1 and val2=1000000, and it only returned -EINVAL. Then I discovered the PLUS_MICRO and I want to remember that cating the range sysfs file returned: 0,000001, but I will try again on Monday. > > That would make this a very high voltage device. > See Documentation/ABI/testing/sysfs-bus-iio* for > IIO ABI documentation. > > > + return IIO_VAL_INT_PLUS_MICRO; > > + > > + default: > > + return -EINVAL; > > + } > > +} > > + > > +static int dac7612_write_raw(struct iio_dev *iio_dev, > > + const struct iio_chan_spec *chan, > > + int val, int val2, long mask) > > +{ > > + struct dac7612 *priv; > > struct dac7612 *priv = iio_priv(iio_dev); > > (it's just macro magic to get the right point so normally considered > fine to be called like this). > > > > + int ret; > > + > > + if (mask != IIO_CHAN_INFO_RAW) > > + return -EINVAL; > > + > > + if ((val >= BIT(RESOLUTION)) || val < 0) > > + return -EINVAL; > > As not providing a write_fmt function (which is fine) > should also sanity check that val2 is 0. > > > + > > + priv = iio_priv(iio_dev); > > + if (val == priv->cache[chan->channel]) > > + return 0; > > + > > + mutex_lock(&iio_dev->mlock); > > + ret = dac7612_cmd_single(priv, chan->channel, val); > > + mutex_unlock(&iio_dev->mlock); > > + > > + return ret; > > +} > > + > > +static const struct iio_info dac7612_info = { > > + .read_raw = dac7612_read_raw, > > + .write_raw = dac7612_write_raw, > > +}; > > + > > +static int dac7612_probe(struct spi_device *spi) > > +{ > > + struct iio_dev *iio_dev; > > + struct dac7612 *priv; > > + int i; > > + int ret; > > + > > + iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv)); > > + if (!iio_dev) > > + return -ENOMEM; > > + > > + priv = iio_priv(iio_dev); > > + priv->nld = devm_gpiod_get_optional(&spi->dev, "nLD", GPIOD_OUT_HIGH); > > This isn't a particularly standard gpio name. Hence this driver definitely > needs a DT binding doc (remember to cc dt list and maintainers). Also > this should almost certainly be prefixed with a vendor prefix. > > It's also not the name I'm seeing on the datasheet, so needs some justifying > comments. > > > + if (IS_ERR(priv->nld)) > > + return PTR_ERR(priv->nld); > > + priv->spi = spi; > > + spi_set_drvdata(spi, iio_dev); > > + iio_dev->dev.parent = &spi->dev; > > + iio_dev->info = &dac7612_info; > > + iio_dev->modes = INDIO_DIRECT_MODE; > > + iio_dev->channels = dac7612_channels; > > + iio_dev->num_channels = NUM_CHANS; > ARRAY_SIZE. > > + iio_dev->name = spi_get_device_id(spi)->name; > > + > > + for (i = 0; i < NUM_CHANS; i++) { > ARRAY_SIZE > > + ret = dac7612_cmd_single(priv, i, 0); > > + if (ret) > > + return ret; > > + } > > + > > + return devm_iio_device_register(&spi->dev, iio_dev); > > +} > > + > > +static const struct spi_device_id dac7612_id[] = { > > + {"ti-dac7612"}, > > + {} > > +}; > > +MODULE_DEVICE_TABLE(spi, dac7612_id); > > + > > +static struct spi_driver dac7612_driver = { > > + .driver = { > > + .name = "ti-dac7612", > > + }, > > + .probe = dac7612_probe, > > + .id_table = dac7612_id, > > +}; > > +module_spi_driver(dac7612_driver); > > + > > +MODULE_AUTHOR("Ricardo Ribalda <ricardo@xxxxxxxxxxx>"); > > +MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver"); > > +MODULE_LICENSE("GPL v2"); > -- Ricardo Ribalda
