Hey, Thanks for the comments! I'll make the changes that you suggested! I did run checkpatch.pl -- the only thing it complained about was that the length of a line in the commit message was too long, and I don't think I can do anything about it because the line in question is a file path :-). otoh I definitely didn't do dt_binding_check, I had no idea that was a thing. I'll run it and integrate any necessary changes in the revised version. Thanks! Best regards, Alex On Wed, Mar 18, 2020 at 06:50:41AM +0000, Ardelean, Alexandru wrote: > On Tue, 2020-03-17 at 22:17 +0200, Alexandru Lazar wrote: > > [External] > > > > Add driver for the Maxim MAX1241 12-bit, single-channel ADC. The driver > > includes support for this device's low-power operation mode. > > hey, > > overall looks good; > > i'd run ./scripts/checpatch.pl on the patches a bit; > you can run it on the patch file, or on the git commit with > ./scripts/checpatch.pl -g <git-commits> > > i usually do ./scripts/checpatch.pl -g HEAD~2.. [or something like that] before > generating patches; > i sometimes forget to do that; > > some more comments inline > > > > > > Signed-off-by: Alexandru Lazar <alazar@xxxxxxxxxxxxx> > > --- > > drivers/iio/adc/Kconfig | 12 +++ > > drivers/iio/adc/Makefile | 1 + > > drivers/iio/adc/max1241.c | 215 ++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 228 insertions(+) > > create mode 100644 drivers/iio/adc/max1241.c > > > > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig > > index 5d8540b7b427..3a55beec69c9 100644 > > --- a/drivers/iio/adc/Kconfig > > +++ b/drivers/iio/adc/Kconfig > > @@ -566,6 +566,18 @@ config MAX1118 > > To compile this driver as a module, choose M here: the module will be > > called max1118. > > > > +config MAX1241 > > + tristate "Maxim max1241 ADC driver" > > + depends on SPI > > + select IIO_BUFFER > > + select IIO_TRIGGERED_BUFFER > > + help > > + Say yes here to build support for Maxim max1241 12-bit, single-channel > > + ADC. > > nitpick: this looks inconsistently indented > > > + > > + To compile this driver as a module, choose M here: the module will be > > + called max1118. > > + > > config MAX1363 > > tristate "Maxim max1363 ADC driver" > > depends on I2C > > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile > > index a1f1fbec0f87..37d6f17559dc 100644 > > --- a/drivers/iio/adc/Makefile > > +++ b/drivers/iio/adc/Makefile > > @@ -54,6 +54,7 @@ obj-$(CONFIG_LTC2497) += ltc2497.o > > obj-$(CONFIG_MAX1027) += max1027.o > > obj-$(CONFIG_MAX11100) += max11100.o > > obj-$(CONFIG_MAX1118) += max1118.o > > +obj-$(CONFIG_MAX1241) += max1241.o > > obj-$(CONFIG_MAX1363) += max1363.o > > obj-$(CONFIG_MAX9611) += max9611.o > > obj-$(CONFIG_MCP320X) += mcp320x.o > > diff --git a/drivers/iio/adc/max1241.c b/drivers/iio/adc/max1241.c > > new file mode 100644 > > index 000000000000..2bd31f22fb2c > > --- /dev/null > > +++ b/drivers/iio/adc/max1241.c > > @@ -0,0 +1,215 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * MAX1241 low-power, 12-bit serial ADC > > + * > > + * Copyright (c) 2020 Ioan-Alexandru Lazar <alazar@xxxxxxxxxxxxx> > > + * > > + * This file is subject to the terms and conditions of version 2 of > > + * the GNU General Public License. See the file COPYING in the main > > + * directory of this archive for more details. > > This license text is no longer needed. > The SPDX-License-Identifier header should handle that. > > > + * > > + * Datasheet: > > https://datasheets.maximintegrated.com/en/ds/MAX1240-MAX1241.pdf > > + */ > > + > > +#include <linux/regulator/consumer.h> > > +#include <linux/delay.h> > > +#include <linux/gpio/consumer.h> > > +#include <linux/gpio/driver.h> > > +#include <linux/gpio.h> > > +#include <linux/iio/iio.h> > > +#include <linux/module.h> > > +#include <linux/spi/spi.h> > > + > > +#define MAX1241_VAL_MASK 0xFFF > > +#define MAX1241_SHDN_DELAY_USEC 4 > > + > > +enum max1241_id { > > + max1241, > > +}; > > + > > +struct max1241 { > > + struct spi_device *spi; > > + struct mutex lock; > > + struct regulator *reg; > > + struct gpio_desc *shdn; > > + > > + __be16 data ____cacheline_aligned; > > Jonathan may know better than me here, but you could technically avoid needing > to explicitly use the __be16 datatype; and just use u16; > > i think the SPI framework should have some handling for that; > maybe using the 'bits_per_word' field; > you'd probably still need to do the shifting though; > i remember some discussion about this on ad7949.c > though there may be other drivers doing this as well > > though, this isn't a big deal; and i don't feel strongly about doing like this > or some other way; > this comment tries to be more informative [or just noisy] > > > > +}; > > + > > +static const struct iio_chan_spec max1241_channels[] = { > > + { > > + .type = IIO_VOLTAGE, > > + .indexed = 1, > > + .channel = 0, > > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > > + BIT(IIO_CHAN_INFO_SCALE), > > + .scan_index = 0, > > + .scan_type = { > > + .sign = 'u', > > + .realbits = 12, > > + .storagebits = 16, > > + }, > > + }, > > +}; > > + > > +static int max1241_read(struct max1241 *adc) > > +{ > > + int ret; > > + struct spi_device *spi = adc->spi; > > + struct spi_transfer xfers[] = { > > + /* > > + * Begin conversion by bringing /CS low for at least > > + * tconv us. > > + */ > > + { > > + .len = 0, > > + .delay_usecs = 8, > > 'delay_usecs' is going to go away. > Can you change this to? > .delay.value = 8, > .delay.unit = SPI_DELAY_UNIT_USECS. > > SPI_DELAY_UNIT_USECS is 0, so if you don't assign it's fine, but it's a good > idea to assign it, to make it clear it's usecs > > > > > + }, > > + /* > > + * Then read two bytes of data in our RX buffer. > > + */ > > + { > > + .rx_buf = &adc->data, > > + .len = 2, > > + }, > > + }; > > + > > + ret = spi_sync_transfer(spi, xfers, 2); > > + > > + return ret; > > +} > > + > > +static int max1241_read_raw(struct iio_dev *indio_dev, > > + struct iio_chan_spec const *chan, > > + int *val, int *val2, long mask) > > +{ > > + int ret, vref_uV; > > + struct max1241 *adc = iio_priv(indio_dev); > > + > > + switch (mask) { > > + case IIO_CHAN_INFO_RAW: > > + mutex_lock(&adc->lock); > > + > > + if (adc->shdn) { > > + gpiod_set_value(adc->shdn, 0); > > + udelay(MAX1241_SHDN_DELAY_USEC); > > + } > > + > > + ret = max1241_read(adc); > > + > > + if (adc->shdn) > > + gpiod_set_value(adc->shdn, 1); > > + > > + if (ret) { > > + mutex_unlock(&adc->lock); > > + return ret; > > + } > > + > > + *val = (be16_to_cpu(adc->data) >> 3) & MAX1241_VAL_MASK; > > + > > + mutex_unlock(&adc->lock); > > + return IIO_VAL_INT; > > + case IIO_CHAN_INFO_SCALE: > > + vref_uV = regulator_get_voltage(adc->reg); > > + > > + if (vref_uV < 0) > > + return vref_uV; > > + > > + *val = vref_uV / 1000; > > + *val2 = 12; > > + > > + return IIO_VAL_FRACTIONAL_LOG2; > > + default: > > + return -EINVAL; > > + } > > +} > > + > > +static const struct iio_info max1241_info = { > > + .read_raw = max1241_read_raw, > > +}; > > + > > +static int max1241_probe(struct spi_device *spi) > > +{ > > + struct iio_dev *indio_dev; > > + struct max1241 *adc; > > + int ret = 0; > > + > > + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); > > + if (!indio_dev) > > + return -ENOMEM; > > + > > + adc = iio_priv(indio_dev); > > + adc->spi = spi; > > + mutex_init(&adc->lock); > > + > > + spi_set_drvdata(spi, indio_dev); > > + > > + adc->reg = devm_regulator_get(&spi->dev, "vref"); > > + if (IS_ERR(adc->reg)) { > > + dev_err(&spi->dev, "failed to get vref regulator\n"); > > + return PTR_ERR(adc->reg); > > + } > > + > > + ret = regulator_enable(adc->reg); > > + if (ret) > > + return ret; > > + > > [1] > > > + adc->shdn = devm_gpiod_get_optional(&spi->dev, "shdn", GPIOD_OUT_HIGH); > > + if (!adc->shdn) > > + dev_info(&spi->dev, "no shdn pin passed, low-power mode > > disabled"); > > + else > > + dev_info(&spi->dev, "shdn pin passed, low-power mode enabled"); > > + > > + indio_dev->name = spi_get_device_id(spi)->name; > > + indio_dev->dev.parent = &spi->dev; > > + indio_dev->info = &max1241_info; > > + indio_dev->modes = INDIO_DIRECT_MODE; > > + indio_dev->channels = max1241_channels; > > + indio_dev->num_channels = ARRAY_SIZE(max1241_channels); > > + > > + ret = iio_device_register(indio_dev); > > This should disable the regulator on the error path. > if (ret) { > regulator_disable(adc->reg); > return ret; > } > > return 0; > > Though, I would argue in favor of adding a devm_add_action_or_reset() callback > to disable the regulator on error & remove. > This should be placed at [1] > > Example: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iio/light/isl29018.c#n762 > > I've started to grow quite fond of these type of callbacks. > For one part, you can remove the 'remove' part of the driver. > On another part you can do neat stuff to simplify/reduce error paths in probe. > We typically suggest these during our internal reviews. > > > > + > > + return ret; > > +} > > + > > +static int max1241_remove(struct spi_device *spi) > > +{ > > + struct iio_dev *indio_dev = spi_get_drvdata(spi); > > + struct max1241 *adc = iio_priv(indio_dev); > > + int ret = 0; > > + > > + iio_device_unregister(indio_dev); > > + ret = regulator_disable(adc->reg); > > + > > + return ret; > > +} > > + > > +static const struct spi_device_id max1241_id[] = { > > + { "max1241", max1241 }, > > + {}, > > +}; > > + > > +#ifdef CONFIG_OF > > i'd remove this CONFIG_OF > i guess this was copied from max1118.c > see [2] > > > + > > +static const struct of_device_id max1241_dt_ids[] = { > > + { .compatible = "maxim,max1241" }, > > the datasheet mentions also max1240 > you could add that to the list as well > typically, it's a good idea, since some people get hung-up on the naming [which > is not a bad idea] > so, if you add max1240 to this list, the driver officially supports both max1240 > & max1241 > > > > + {}, > > +}; > > +MODULE_DEVICE_TABLE(of, max1241_dt_ids); > > + > > +#endif > > + > > +static struct spi_driver max1241_spi_driver = { > > + .driver = { > > + .name = "max1241", > > + .of_match_table = of_match_ptr(max1241_dt_ids), > > [2] > i'd remove of_match_ptr() and make it just > > .of_match_table = max1241_dt_ids, > > there's this code in the kernel that parses of_match_table for ACPI as well; > might as well allow it to work > > > + }, > > + .probe = max1241_probe, > > + .remove = max1241_remove, > > + .id_table = max1241_id, > > +}; > > +module_spi_driver(max1241_spi_driver); > > + > > +MODULE_AUTHOR("Alexandru Lazar <alazar@xxxxxxxxxxxxx>"); > > +MODULE_DESCRIPTION("MAX1241 ADC driver"); > > +MODULE_LICENSE("GPL v2");
