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SubjectRe: [PATCH 1/3] iio: Add ADM1177 Hot Swap Controller and Digital Power Monitor driver
On Tue, Nov 12, 2019 at 05:37:57PM +0000, Jonathan Cameron wrote:
> On Tue, 12 Nov 2019 17:35:50 +0200
> Beniamin Bia <beniamin.bia@analog.com> wrote:
>
> > From: Michael Hennerich <michael.hennerich@analog.com>
> >
> > ADM1177 is a Hot Swap Controller and Digital Power Monitor with
> > Soft Start Pin.
> >
> > Datasheet:
> > Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ADM1177.pdf
> >
> > Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
> > Co-developed-by: Beniamin Bia <beniamin.bia@analog.com>
> > Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
>
> Hi Beniamin,
>
> A couple immediate thoughts.
>
> 1. That cc list has some rather non obvious people on it. Unless something
> fairly surprising is going on, probably better to cut it back a bit.
>
> 2. Why IIO? Not entirely obvious to me. From first glance this is definitely
> doing hardware monitoring. If there is a reason there should be a clear
> statement here on why.
>

I don't see why this is implemented as iio driver. I think it should be implemented
as hardware monitoring driver.

Some more comments below.

Guenter

> +CC Guenter and Jean as hwmon maintainers.
>
> Whilst I'm here, a very quick review below.
>
> > ---
> > drivers/iio/adc/Kconfig | 12 ++
> > drivers/iio/adc/Makefile | 1 +
> > drivers/iio/adc/adm1177.c | 257 ++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 270 insertions(+)
> > create mode 100644 drivers/iio/adc/adm1177.c
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> > index 9554890a3200..4db8c6dcb595 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -228,6 +228,18 @@ config ASPEED_ADC
> > To compile this driver as a module, choose M here: the module will be
> > called aspeed_adc.
> >
> > +config ADM1177
> > + tristate "Analog Devices ADM1177 Digital Power Monitor driver"
> > + depends on I2C
> > + help
> > + Say yes here to build support for Analog Devices:
> > + ADM1177 Hot Swap Controller and Digital Power Monitor
> > + with Soft Start Pin. Provides direct access
> > + via sysfs.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called adm1177.
> > +
> > config AT91_ADC
> > tristate "Atmel AT91 ADC"
> > depends on ARCH_AT91
> > diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> > index 5ecc481c2967..7899d6a158f3 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -24,6 +24,7 @@ obj-$(CONFIG_AD7887) += ad7887.o
> > obj-$(CONFIG_AD7949) += ad7949.o
> > obj-$(CONFIG_AD799X) += ad799x.o
> > obj-$(CONFIG_ASPEED_ADC) += aspeed_adc.o
> > +obj-$(CONFIG_ADM1177) += adm1177.o
> > obj-$(CONFIG_AT91_ADC) += at91_adc.o
> > obj-$(CONFIG_AT91_SAMA5D2_ADC) += at91-sama5d2_adc.o
> > obj-$(CONFIG_AXP20X_ADC) += axp20x_adc.o
> > diff --git a/drivers/iio/adc/adm1177.c b/drivers/iio/adc/adm1177.c
> > new file mode 100644
> > index 000000000000..daec34566a65
> > --- /dev/null
> > +++ b/drivers/iio/adc/adm1177.c
> > @@ -0,0 +1,257 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * ADM1177 Hot Swap Controller and Digital Power Monitor with Soft Start Pin
> > + *
> > + * Copyright 2015-2019 Analog Devices Inc.
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/i2c.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/mutex.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/slab.h>
> > +#include <linux/sysfs.h>
> > +
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +#include <linux/iio/events.h>
> > +
> > +/* Command Byte Operations */
> > +#define ADM1177_CMD_V_CONT BIT(0)
> > +#define ADM1177_CMD_V_ONCE BIT(1)
> > +#define ADM1177_CMD_I_CONT BIT(2)
> > +#define ADM1177_CMD_I_ONCE BIT(3)
> > +#define ADM1177_CMD_VRANGE BIT(4)
> > +#define ADM1177_CMD_STATUS_RD BIT(6)
> > +
> > +/* Extended Register */
> > +#define ADM1177_REG_ALERT_EN 1
> > +#define ADM1177_REG_ALERT_TH 2
> > +#define ADM1177_REG_CONTROL 3
> > +
> > +/* ADM1177_REG_ALERT_EN */
> > +#define ADM1177_EN_ADC_OC1 BIT(0)
> > +#define ADM1177_EN_ADC_OC4 BIT(1)
> > +#define ADM1177_EN_HS_ALERT BIT(2)
> > +#define ADM1177_EN_OFF_ALERT BIT(3)
> > +#define ADM1177_CLEAR BIT(4)
> > +
> > +/* ADM1177_REG_CONTROL */
> > +#define ADM1177_SWOFF BIT(0)
> > +
> > +#define ADM1177_BITS 12
> > +
> > +/**
> > + * struct adm1177_state - driver instance specific data
> > + * @client pointer to i2c client
> > + * @reg regulator info for the the power supply of the device
> > + * @command internal control register
> > + * @r_sense_uohm current sense resistor value
> > + * @alert_threshold_ua current limit for shutdown
> > + * @vrange_high internal voltage divider
> > + */
> > +struct adm1177_state {
> > + struct i2c_client *client;
> > + struct regulator *reg;
> > + u8 command;
> > + u32 r_sense_uohm;
> > + u32 alert_threshold_ua;
> > + bool vrange_high;
> > +};
> > +
> > +static int adm1177_read(struct adm1177_state *st, u8 num, u8 *data)
> > +{
> > + struct i2c_client *client = st->client;
> > + int ret = 0;
> > +
> > + ret = i2c_master_recv(client, data, num);
> > + if (ret < 0) {
> > + dev_err(&client->dev, "I2C read error\n");
Seems a bit noisy (and inconsistent). It would make much more sense to
report the error to userspace instead of ignoring it and reporting a random
value (ie the stack content).

> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int adm1177_write_cmd(struct adm1177_state *st, u8 cmd)
> > +{
> > + st->command = cmd;
> > + return i2c_smbus_write_byte(st->client, cmd);
> > +}
> > +
> > +static int adm1177_write_reg(struct adm1177_state *st, u8 reg, u8 val)
> > +{
> > + return i2c_smbus_write_byte_data(st->client, reg, val);
>
> These wrappers don't really add anything. I'd just make the i2c
> calls directly inline. They will be self explanatory.
>

Plus, their return value is never checked.

> > +}
> > +
> > +static int adm1177_read_raw(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val,
> > + int *val2,
> > + long mask)
> > +{
> > + struct adm1177_state *st = iio_priv(indio_dev);
> > + u8 data[3];
> > +
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + adm1177_read(st, 3, data);
> > + switch (chan->type) {
> > + case IIO_VOLTAGE:
> > + *val = (data[0] << 4) | (data[2] >> 4);
> > + return IIO_VAL_INT;
> > + case IIO_CURRENT:
> > + *val = (data[1] << 4) | (data[2] & 0xF);
> > + return IIO_VAL_INT;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + case IIO_CHAN_INFO_SCALE:
> > + switch (chan->type) {
> > + case IIO_VOLTAGE:
> > + if (st->command & ADM1177_CMD_VRANGE)
> > + *val = 6650;
> > + else
> > + *val = 26350;
> > +
> > + *val2 = ADM1177_BITS;
> > + return IIO_VAL_FRACTIONAL_LOG2;
> > + case IIO_CURRENT:
> > + *val = 105840 / st->r_sense_uohm;
> > +
> > + *val2 = ADM1177_BITS;
> > + return IIO_VAL_FRACTIONAL_LOG2;
> > + default:
> > + return -EINVAL;
> > + }
> > + default:
> > + return -EINVAL;
> > + }
> > +}
> > +
> > +static const struct iio_chan_spec adm1177_channels[] = {
> > + {
> > + .type = IIO_VOLTAGE,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > + BIT(IIO_CHAN_INFO_SCALE),
> > + .indexed = 1,
> > + .channel = 0,
> > + },
> > + {
> > + .type = IIO_CURRENT,
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> > + BIT(IIO_CHAN_INFO_SCALE),
> > + .indexed = 1,
> > + .channel = 0,
> > + },
> > +};
> > +
> > +static const struct iio_info adm1177_info = {
> > + .read_raw = &adm1177_read_raw,
> > +};
>
> blank line here.
>
> > +static void adm1177_remove(void *data)
> > +{
> > + struct adm1177_state *st = data;
> > +
> > + if (st->reg)
> > + regulator_disable(st->reg);
>
> Probe and remove should be mirror images of each other.
> As you have a mixture of managed and non managed calls that
> isn't the case here.
>
> devm_add_action_or_reset will sort this out for you if
> used to turn off the regulator at the right point on removal.
>

On top of that, this function is added with devm_add_action_or_reset(),
and it is only ever called if st->reg is not NULL.

> > +}
> > +
> > +static int adm1177_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> > + int ret;
> > + struct device_node *np;
> > + struct adm1177_state *st;
> > + struct iio_dev *indio_dev;
> > +
> > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + st = iio_priv(indio_dev);
> > + i2c_set_clientdata(client, indio_dev);
> > + st->client = client;
> > +
> > + np = client->dev.of_node;
> > +
> > + st->reg = devm_regulator_get_optional(&client->dev, "vref");
> > + if (IS_ERR(st->reg)) {
> > + if (PTR_ERR(st->reg) == EPROBE_DEFER)
> > + return -EPROBE_DEFER;
> > +
> > + st->reg = NULL;
> > + } else {
> > + ret = regulator_enable(st->reg);
> > + if (ret)
> > + return ret;
> > + ret = devm_add_action_or_reset(&client->dev, adm1177_remove,
> > + st);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + of_property_read_u32(np, "adi,r-sense-micro-ohms", &st->r_sense_uohm);

shunt-resistor-micro-ohms

> > + of_property_read_u32(np, "adi,shutdown-threshold-microamp",
> > + &st->alert_threshold_ua);
> > + st->vrange_high = of_property_read_bool(np,
> > + "adi,vrange-high-enable");
> > + if (st->alert_threshold_ua) {
> > + unsigned int val;
> > +
> > + val = (st->alert_threshold_ua * st->r_sense_uohm * 0xFF);
> > + val /= 105840000U;
> > + if (val > 0xFF) {
> > + dev_err(&client->dev,
> > + "Requested shutdown current %d uA above limit\n",
> > + st->alert_threshold_ua);
> > +
> > + val = 0xFF;
> > + }
> > + adm1177_write_reg(st, ADM1177_REG_ALERT_TH, val);
> > + }
> > +
> > + adm1177_write_cmd(st, ADM1177_CMD_V_CONT |
> > + ADM1177_CMD_I_CONT |
> > + (st->vrange_high ? 0 : ADM1177_CMD_VRANGE));
> > +
> > + indio_dev->name = id->name;
> > + indio_dev->channels = adm1177_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(adm1177_channels);
> > +
> > + indio_dev->dev.parent = &client->dev;
> > + indio_dev->info = &adm1177_info;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > + return devm_iio_device_register(&client->dev, indio_dev);
> > +}
> > +
> > +static const struct i2c_device_id adm1177_ids[] = {
> > + { "adm1177", 0 },
> > + {}
> > +};
> > +MODULE_DEVICE_TABLE(i2c, adm1177_ids);
> > +
> > +static const struct of_device_id adm1177_dt_ids[] = {
> > + { .compatible = "adi,adm1177" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, adm1177_dt_ids);
> > +
> > +static struct i2c_driver adm1177_driver = {
> > + .driver = {
> > + .name = "adm1177",
> > + .of_match_table = adm1177_dt_ids,
> > + },
> > + .probe = adm1177_probe,
> > + .id_table = adm1177_ids,
> > +};
> > +module_i2c_driver(adm1177_driver);
> > +
> > +MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
> > +MODULE_DESCRIPTION("Analog Devices ADM1177 ADC driver");
> > +MODULE_LICENSE("GPL v2");
>
>

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