Subject: [PATCH 2/3] iio: adc: Add Xilinx AMS driver

From: [email-masked] (Jonathan Cameron)
Date: Sun, 2 Sep 2018 20:56:32 +0100

On Thu, 30 Aug 2018 15:52:18 +0530
Manish Narani <[email-masked]> wrote:

> The AMS includes an ADC as well as on-chip sensors that can be used to
> sample external voltages and monitor on-die operating conditions, such
> as temperature and supply voltage levels. The AMS has two SYSMON blocks.
> PL-SYSMON block is capable of monitoring off chip voltage and
> temperature.
> PL-SYSMON block has DRP, JTAG and I2C interface to enable monitoring
> from external master. Out of these interface currently only DRP is
> supported.
> Other block PS-SYSMON is memory mapped to PS.
> The AMS can use internal channels to monitor voltage and temperature as
> well as one primary and up to 16 auxiliary channels for measuring
> external voltages.
> The voltage and temperature monitoring channels also have event
> capability which allows to generate an interrupt when their value falls
> below or raises above a set threshold.
> 
> Signed-off-by: Manish Narani <[email-masked]>

Given the use of extended_name in here, there is a whole lot of
undocumented userspace ABI. Please add to 

Documentation/ABI/testing/sysfs-bus-iio-xilinx-ams or similar.

I am a little concerned at introducing quite so many of these.
Perhaps we need to revisit how we represent this sort of information...

Otherwise, a few minor things inline but looking fairly good overall.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/Kconfig      |   10 +
>  drivers/iio/adc/Makefile     |    1 +
>  drivers/iio/adc/xilinx-ams.c | 1081 ++++++++++++++++++++++++++++++++++++++++++
>  drivers/iio/adc/xilinx-ams.h |  281 +++++++++++
>  4 files changed, 1373 insertions(+)
>  create mode 100644 drivers/iio/adc/xilinx-ams.c
>  create mode 100644 drivers/iio/adc/xilinx-ams.h
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 4a75492..405ea00 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -941,4 +941,14 @@ config XILINX_XADC
>  	  The driver can also be build as a module. If so, the module will be called
>  	  xilinx-xadc.
>  
> +config XILINX_AMS
> +	tristate "Xilinx AMS driver"
> +	depends on ARCH_ZYNQMP || COMPILE_TEST
> +	depends on HAS_IOMEM
> +	help
> +	  Say yes here to have support for the Xilinx AMS.
> +
> +	  The driver can also be build as a module. If so, the module will be called
> +	  xilinx-ams.
> +
>  endmenu
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 03db7b5..fbfcc45 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -85,4 +85,5 @@ obj-$(CONFIG_VF610_ADC) += vf610_adc.o
>  obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
>  xilinx-xadc-y := xilinx-xadc-core.o xilinx-xadc-events.o
>  obj-$(CONFIG_XILINX_XADC) += xilinx-xadc.o
> +obj-$(CONFIG_XILINX_AMS) += xilinx-ams.o
>  obj-$(CONFIG_SD_ADC_MODULATOR) += sd_adc_modulator.o
> diff --git a/drivers/iio/adc/xilinx-ams.c b/drivers/iio/adc/xilinx-ams.c
> new file mode 100644
> index 0000000..10bcc52
> --- /dev/null
> +++ b/drivers/iio/adc/xilinx-ams.c
> @@ -0,0 +1,1081 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Xilinx AMS driver
> + *
> + *  Copyright (C) 2017-2018 Xilinx, Inc.
> + *
> + *  Manish Narani <[email-masked]>
> + *  Rajnikant Bhojani <[email-masked]>
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/clk.h>
> +#include <linux/of_address.h>
> +#include <linux/iopoll.h>
> +#include <linux/delay.h>
There is a rough convention of alphabetical order if there isn't
a reason to do otherwise. 

Here you might keep the iio headers for their own block at the end, but
the rest should be in order.

> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
> +#include <linux/io.h>
> +
> +#include "xilinx-ams.h"
> +
> +static const unsigned int AMS_UNMASK_TIMEOUT_MS = 500;
> +
> +static inline void ams_ps_update_reg(struct ams *ams, unsigned int offset,
> +				     u32 mask, u32 data)
> +{
> +	u32 val;
> +
> +	val = readl(ams->ps_base + offset);
> +	writel((val & ~mask) | (data & mask), ams->ps_base + offset);
> +}
> +
> +static inline void ams_pl_write_reg(struct ams *ams, unsigned int offset,
> +					u32 data)
> +{
> +	writel(data, ams->pl_base + offset);
> +}
I'm always anti wrappers that don't add much.  In this driver you also
only use them 'sometimes'.

I'd prefer just having the writel inline all the time.  The update
functions have a little more purpose and given they are called
quite often, perhaps are worth keeping.

Another option is to use regmap for the whole thing getting you update
functions and caching etc.  Might not be worth it here. Up to you.

> +
> +static inline void ams_pl_update_reg(struct ams *ams, unsigned int offset,
> +					 u32 mask, u32 data)
> +{
> +	u32 val;
> +
> +	val = readl(ams->pl_base + offset);
> +	writel((val & ~mask) | (data & mask), ams->pl_base + offset);
> +}
> +
> +static void ams_update_intrmask(struct ams *ams, u64 mask, u64 val)
> +{
> +	ams->intr_mask &= ~mask;
> +	ams->intr_mask |= (val & mask);
> +
> +	writel(~(ams->intr_mask | ams->masked_alarm), ams->base + AMS_IER_0);
> +	writel(~(ams->intr_mask >> AMS_ISR1_INTR_MASK_SHIFT),
> +			ams->base + AMS_IER_1);
> +	writel(ams->intr_mask | ams->masked_alarm, ams->base + AMS_IDR_0);
> +	writel(ams->intr_mask >> AMS_ISR1_INTR_MASK_SHIFT,
> +			ams->base + AMS_IDR_1);
> +}
> +
> +static void ams_disable_all_alarms(struct ams *ams)
> +{
> +	/* disable PS module alarm */
> +	if (ams->ps_base) {
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_REGCFG1_ALARM_MASK,
> +				  AMS_REGCFG1_ALARM_MASK);
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG3, AMS_REGCFG3_ALARM_MASK,
> +				  AMS_REGCFG3_ALARM_MASK);
> +	}
> +
> +	/* disable PL module alarm */
> +	if (ams->pl_base) {
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> +				    AMS_REGCFG1_ALARM_MASK,
> +				    AMS_REGCFG1_ALARM_MASK);
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG3,
> +				    AMS_REGCFG3_ALARM_MASK,
> +				    AMS_REGCFG3_ALARM_MASK);
> +	}
> +}
> +
> +static void iio_ams_update_alarm(struct ams *ams, unsigned long alarm_mask)
> +{
> +	u32 cfg;
> +	unsigned long flags;
> +	unsigned long pl_alarm_mask;
> +
> +	if (ams->ps_base) {
> +		/* Configuring PS alarm enable */
> +		cfg = ~((alarm_mask & AMS_ISR0_ALARM_2_TO_0_MASK) <<
> +			       AMS_CONF1_ALARM_2_TO_0_SHIFT);
> +		cfg &= ~((alarm_mask & AMS_ISR0_ALARM_6_TO_3_MASK) <<
> +				AMS_CONF1_ALARM_6_TO_3_SHIFT);
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_REGCFG1_ALARM_MASK,
> +				  cfg);
> +
> +		cfg = ~((alarm_mask >> AMS_CONF3_ALARM_12_TO_7_SHIFT) &
> +				AMS_ISR0_ALARM_12_TO_7_MASK);
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG3, AMS_REGCFG3_ALARM_MASK,
> +				  cfg);
> +	}
> +
> +	if (ams->pl_base) {
> +		pl_alarm_mask = (alarm_mask >> AMS_PL_ALARM_START);
> +		/* Configuring PL alarm enable */
> +		cfg = ~((pl_alarm_mask & AMS_ISR0_ALARM_2_TO_0_MASK) <<
> +			       AMS_CONF1_ALARM_2_TO_0_SHIFT);
> +		cfg &= ~((pl_alarm_mask & AMS_ISR0_ALARM_6_TO_3_MASK) <<
> +				AMS_CONF1_ALARM_6_TO_3_SHIFT);
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG1,
> +				AMS_REGCFG1_ALARM_MASK, cfg);
> +
> +		cfg = ~((pl_alarm_mask >> AMS_CONF3_ALARM_12_TO_7_SHIFT) &
> +				AMS_ISR0_ALARM_12_TO_7_MASK);
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG3,
> +				AMS_REGCFG3_ALARM_MASK, cfg);
> +	}
> +
> +	spin_lock_irqsave(&ams->lock, flags);
> +	ams_update_intrmask(ams, AMS_ISR0_ALARM_MASK, ~alarm_mask);
> +	spin_unlock_irqrestore(&ams->lock, flags);
> +}
> +
> +static void ams_enable_channel_sequence(struct ams *ams)
> +{
> +	int i;
> +	unsigned long long scan_mask;
> +	struct iio_dev *indio_dev = iio_priv_to_dev(ams);
> +
> +	/*
> +	 * Enable channel sequence. First 22 bit of scan_mask represent
> +	 * PS channels, and next remaining bit represents PL channels.
> +	 */
> +
> +	/* Run calibration of PS & PL as part of the sequence */
> +	scan_mask = 0x1 | BIT(PS_SEQ_MAX);
> +	for (i = 0; i < indio_dev->num_channels; i++)
> +		scan_mask |= BIT(indio_dev->channels[i].scan_index);
> +
> +	if (ams->ps_base) {
> +		/* put sysmon in a soft reset to change the sequence */
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				  AMS_CONF1_SEQ_DEFAULT);
> +
> +		/* configure basic channels */
> +		writel(scan_mask & AMS_REG_SEQ0_MASK,
> +				ams->ps_base + AMS_REG_SEQ_CH0);
> +		writel(AMS_REG_SEQ2_MASK &
> +			(scan_mask >> AMS_REG_SEQ2_MASK_SHIFT),
> +			ams->ps_base + AMS_REG_SEQ_CH2);
> +
> +		/* set continuous sequence mode */
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				  AMS_CONF1_SEQ_CONTINUOUS);
> +	}
> +
> +	if (ams->pl_base) {
> +		/* put sysmon in a soft reset to change the sequence */
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				    AMS_CONF1_SEQ_DEFAULT);
> +
> +		/* configure basic channels */
> +		scan_mask = scan_mask >> PS_SEQ_MAX;
> +		writel(scan_mask & AMS_REG_SEQ0_MASK,
> +				ams->pl_base + AMS_REG_SEQ_CH0);
> +		writel(AMS_REG_SEQ2_MASK &
> +				(scan_mask >> AMS_REG_SEQ2_MASK_SHIFT),
> +				ams->pl_base + AMS_REG_SEQ_CH2);
> +		writel(AMS_REG_SEQ1_MASK &
> +				(scan_mask >> AMS_REG_SEQ1_MASK_SHIFT),
> +				ams->pl_base + AMS_REG_SEQ_CH1);
> +
> +		/* set continuous sequence mode */
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				AMS_CONF1_SEQ_CONTINUOUS);
> +	}
> +}
> +
> +static int iio_ams_init_device(struct ams *ams)
> +{
> +	u32 reg;
> +	int ret;
> +
> +	/* reset AMS */
> +	if (ams->ps_base) {
> +		writel(AMS_PS_RESET_VALUE, ams->ps_base + AMS_VP_VN);
> +
> +		ret = readl_poll_timeout(ams->base + AMS_PS_CSTS, reg,
> +					 (reg & AMS_PS_CSTS_PS_READY) ==
> +					 AMS_PS_CSTS_PS_READY, 0,
> +					 AMS_INIT_TIMEOUT);
> +		if (ret)
> +			return ret;
> +
> +		/* put sysmon in a default state */
> +		ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				  AMS_CONF1_SEQ_DEFAULT);
> +	}
> +
> +	if (ams->pl_base) {
> +		writel(AMS_PL_RESET_VALUE, ams->pl_base + AMS_VP_VN);
> +
> +		ret = readl_poll_timeout(ams->base + AMS_PL_CSTS, reg,
> +					 (reg & AMS_PL_CSTS_ACCESS_MASK) ==
> +					 AMS_PL_CSTS_ACCESS_MASK, 0,
> +					 AMS_INIT_TIMEOUT);
> +		if (ret)
> +			return ret;
> +
> +		/* put sysmon in a default state */
> +		ams_pl_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +				    AMS_CONF1_SEQ_DEFAULT);
> +	}
> +
> +	ams_disable_all_alarms(ams);
> +
> +	/* Disable interrupt */
> +	ams_update_intrmask(ams, ~0, ~0);
> +
> +	/* Clear any pending interrupt */
> +	writel(AMS_ISR0_ALARM_MASK, ams->base + AMS_ISR_0);
> +	writel(AMS_ISR1_ALARM_MASK, ams->base + AMS_ISR_1);
> +
> +	return 0;
> +}
> +
> +static int ams_enable_single_channel(struct ams *ams, unsigned int offset)
> +{
> +	u8 channel_num = 0;
> +
> +	switch (offset) {
> +	case AMS_VCC_PSPLL0:
> +		channel_num = AMS_VCC_PSPLL0_CH;
> +		break;
> +	case AMS_VCC_PSPLL3:
> +		channel_num = AMS_VCC_PSPLL3_CH;
> +		break;
> +	case AMS_VCCINT:
> +		channel_num = AMS_VCCINT_CH;
> +		break;
> +	case AMS_VCCBRAM:
> +		channel_num = AMS_VCCBRAM_CH;
> +		break;
> +	case AMS_VCCAUX:
> +		channel_num = AMS_VCCAUX_CH;
> +		break;
> +	case AMS_PSDDRPLL:
> +		channel_num = AMS_PSDDRPLL_CH;
> +		break;
> +	case AMS_PSINTFPDDR:
> +		channel_num = AMS_PSINTFPDDR_CH;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* set single channel, sequencer off mode */
> +	ams_ps_update_reg(ams, AMS_REG_CONFIG1, AMS_CONF1_SEQ_MASK,
> +			AMS_CONF1_SEQ_SINGLE_CHANNEL);
> +
> +	/* write the channel number */
> +	ams_ps_update_reg(ams, AMS_REG_CONFIG0, AMS_CONF0_CHANNEL_NUM_MASK,
> +			channel_num);
> +	mdelay(1);
This delay should be documented..  Preferably with a reference to the datasheet
to justify the particular value.

> +
> +	return 0;
> +}
> +
> +static int ams_read_vcc_reg(struct ams *ams, unsigned int offset, u32 *data)
> +{
> +	int ret;
> +
> +	ret = ams_enable_single_channel(ams, offset);
> +	if (ret)
> +		return ret;
> +
> +	*data = readl(ams->base + offset);
> +	ams_enable_channel_sequence(ams);
> +
> +	return 0;
> +}
> +
> +static int ams_read_raw(struct iio_dev *indio_dev,
> +			struct iio_chan_spec const *chan,
> +			int *val, int *val2, long mask)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&ams->mutex);
> +		if (chan->scan_index >= (PS_SEQ_MAX * 3)) {
> +			ret = ams_read_vcc_reg(ams, chan->address, val);
> +			if (ret)
> +				goto read_raw_err;

Missing mutex_unlock?

> +		} else if (chan->scan_index >= PS_SEQ_MAX)
> +			*val = readl(ams->pl_base + chan->address);
> +		else
> +			*val = readl(ams->ps_base + chan->address);
> +		mutex_unlock(&ams->mutex);
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:
> +			switch (chan->address) {
> +			case AMS_SUPPLY1:
> +			case AMS_SUPPLY2:
> +			case AMS_SUPPLY3:
> +			case AMS_SUPPLY4:
> +				*val = AMS_SUPPLY_SCALE_3VOLT;
> +				break;
> +			case AMS_SUPPLY5:
> +			case AMS_SUPPLY6:
> +				if (chan->scan_index < PS_SEQ_MAX)
> +					*val = AMS_SUPPLY_SCALE_6VOLT;
> +				else
> +					*val = AMS_SUPPLY_SCALE_3VOLT;
> +				break;
> +			case AMS_SUPPLY7:
> +			case AMS_SUPPLY8:
> +				*val = AMS_SUPPLY_SCALE_6VOLT;
> +				break;
> +			case AMS_SUPPLY9:
> +			case AMS_SUPPLY10:
> +				if (chan->scan_index < PS_SEQ_MAX)
> +					*val = AMS_SUPPLY_SCALE_3VOLT;
> +				else
> +					*val = AMS_SUPPLY_SCALE_6VOLT;
> +				break;
> +			case AMS_VCC_PSPLL0:
> +			case AMS_VCC_PSPLL3:
> +			case AMS_VCCINT:
> +			case AMS_VCCBRAM:
> +			case AMS_VCCAUX:
> +			case AMS_PSDDRPLL:
> +			case AMS_PSINTFPDDR:
> +				*val = AMS_SUPPLY_SCALE_3VOLT;
> +				break;
> +			default:
> +				*val = AMS_SUPPLY_SCALE_1VOLT;
> +				break;
> +			}
> +			*val2 = AMS_SUPPLY_SCALE_DIV_BIT;
> +			return IIO_VAL_FRACTIONAL_LOG2;
> +		case IIO_TEMP:
> +			*val = AMS_TEMP_SCALE;
> +			*val2 = AMS_TEMP_SCALE_DIV_BIT;
> +			return IIO_VAL_FRACTIONAL_LOG2;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_OFFSET:
> +		/* Only the temperature channel has an offset */
> +		*val = AMS_TEMP_OFFSET;
> +		return IIO_VAL_INT;
> +	}
> +
> +read_raw_err:

Given we only return an error code here, are we not better just doing
that inline?

> +	return -EINVAL;
> +}
> +
> +static int ams_get_alarm_offset(int scan_index, enum iio_event_direction dir)
> +{
> +	int offset = 0;
> +
> +	if (scan_index >= PS_SEQ_MAX)
> +		scan_index -= PS_SEQ_MAX;
> +
> +	if (dir == IIO_EV_DIR_FALLING) {
> +		if (scan_index < AMS_SEQ_SUPPLY7)
> +			offset = AMS_ALARM_THRESHOLD_OFF_10;
> +		else
> +			offset = AMS_ALARM_THRESHOLD_OFF_20;
> +	}
> +
> +	switch (scan_index) {
> +	case AMS_SEQ_TEMP:
> +		return AMS_ALARM_TEMP + offset;
> +	case AMS_SEQ_SUPPLY1:
> +		return AMS_ALARM_SUPPLY1 + offset;
> +	case AMS_SEQ_SUPPLY2:
> +		return AMS_ALARM_SUPPLY2 + offset;
> +	case AMS_SEQ_SUPPLY3:
> +		return AMS_ALARM_SUPPLY3 + offset;
> +	case AMS_SEQ_SUPPLY4:
> +		return AMS_ALARM_SUPPLY4 + offset;
> +	case AMS_SEQ_SUPPLY5:
> +		return AMS_ALARM_SUPPLY5 + offset;
> +	case AMS_SEQ_SUPPLY6:
> +		return AMS_ALARM_SUPPLY6 + offset;
> +	case AMS_SEQ_SUPPLY7:
> +		return AMS_ALARM_SUPPLY7 + offset;
> +	case AMS_SEQ_SUPPLY8:
> +		return AMS_ALARM_SUPPLY8 + offset;
> +	case AMS_SEQ_SUPPLY9:
> +		return AMS_ALARM_SUPPLY9 + offset;
> +	case AMS_SEQ_SUPPLY10:
> +		return AMS_ALARM_SUPPLY10 + offset;
> +	case AMS_SEQ_VCCAMS:
> +		return AMS_ALARM_VCCAMS + offset;
> +	case AMS_SEQ_TEMP_REMOTE:
> +		return AMS_ALARM_TEMP_REMOTE + offset;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct iio_chan_spec *ams_event_to_channel(
> +		struct iio_dev *indio_dev, u32 event)
> +{
> +	int scan_index = 0, i;
> +
> +	if (event >= AMS_PL_ALARM_START) {
> +		event -= AMS_PL_ALARM_START;
> +		scan_index = PS_SEQ_MAX;
> +	}
> +
> +	switch (event) {
> +	case AMS_ALARM_BIT_TEMP:
> +		scan_index += AMS_SEQ_TEMP;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY1:
> +		scan_index += AMS_SEQ_SUPPLY1;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY2:
> +		scan_index += AMS_SEQ_SUPPLY2;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY3:
> +		scan_index += AMS_SEQ_SUPPLY3;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY4:
> +		scan_index += AMS_SEQ_SUPPLY4;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY5:
> +		scan_index += AMS_SEQ_SUPPLY5;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY6:
> +		scan_index += AMS_SEQ_SUPPLY6;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY7:
> +		scan_index += AMS_SEQ_SUPPLY7;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY8:
> +		scan_index += AMS_SEQ_SUPPLY8;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY9:
> +		scan_index += AMS_SEQ_SUPPLY9;
> +		break;
> +	case AMS_ALARM_BIT_SUPPLY10:
> +		scan_index += AMS_SEQ_SUPPLY10;
> +		break;
> +	case AMS_ALARM_BIT_VCCAMS:
> +		scan_index += AMS_SEQ_VCCAMS;
> +		break;
> +	case AMS_ALARM_BIT_TEMP_REMOTE:
> +		scan_index += AMS_SEQ_TEMP_REMOTE;
> +		break;
> +	}
> +
> +	for (i = 0; i < indio_dev->num_channels; i++)
> +		if (indio_dev->channels[i].scan_index == scan_index)
> +			break;
> +
> +	return &indio_dev->channels[i];
> +}
> +
> +static int ams_get_alarm_mask(int scan_index)
> +{
> +	int bit = 0;
> +
> +	if (scan_index >= PS_SEQ_MAX) {
> +		bit = AMS_PL_ALARM_START;
> +		scan_index -= PS_SEQ_MAX;
> +	}
> +
> +	switch (scan_index) {
> +	case AMS_SEQ_TEMP:
> +		return BIT(AMS_ALARM_BIT_TEMP + bit);
> +	case AMS_SEQ_SUPPLY1:
> +		return BIT(AMS_ALARM_BIT_SUPPLY1 + bit);
> +	case AMS_SEQ_SUPPLY2:
> +		return BIT(AMS_ALARM_BIT_SUPPLY2 + bit);
> +	case AMS_SEQ_SUPPLY3:
> +		return BIT(AMS_ALARM_BIT_SUPPLY3 + bit);
> +	case AMS_SEQ_SUPPLY4:
> +		return BIT(AMS_ALARM_BIT_SUPPLY4 + bit);
> +	case AMS_SEQ_SUPPLY5:
> +		return BIT(AMS_ALARM_BIT_SUPPLY5 + bit);
> +	case AMS_SEQ_SUPPLY6:
> +		return BIT(AMS_ALARM_BIT_SUPPLY6 + bit);
> +	case AMS_SEQ_SUPPLY7:
> +		return BIT(AMS_ALARM_BIT_SUPPLY7 + bit);
> +	case AMS_SEQ_SUPPLY8:
> +		return BIT(AMS_ALARM_BIT_SUPPLY8 + bit);
> +	case AMS_SEQ_SUPPLY9:
> +		return BIT(AMS_ALARM_BIT_SUPPLY9 + bit);
> +	case AMS_SEQ_SUPPLY10:
> +		return BIT(AMS_ALARM_BIT_SUPPLY10 + bit);
> +	case AMS_SEQ_VCCAMS:
> +		return BIT(AMS_ALARM_BIT_VCCAMS + bit);
> +	case AMS_SEQ_TEMP_REMOTE:
> +		return BIT(AMS_ALARM_BIT_TEMP_REMOTE + bit);
> +	}
> +
> +	return 0;
> +}
> +
> +static int ams_read_event_config(struct iio_dev *indio_dev,
> +				 const struct iio_chan_spec *chan,
> +				 enum iio_event_type type,
> +				 enum iio_event_direction dir)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +
> +	return (ams->alarm_mask & ams_get_alarm_mask(chan->scan_index)) ? 1 : 0;
> +}
> +
> +static int ams_write_event_config(struct iio_dev *indio_dev,
> +				  const struct iio_chan_spec *chan,
> +				  enum iio_event_type type,
> +				  enum iio_event_direction dir,
> +				  int state)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	unsigned int alarm;
> +
> +	alarm = ams_get_alarm_mask(chan->scan_index);
> +
> +	mutex_lock(&ams->mutex);
> +
> +	if (state)
> +		ams->alarm_mask |= alarm;
> +	else
> +		ams->alarm_mask &= ~alarm;
> +
> +	iio_ams_update_alarm(ams, ams->alarm_mask);
> +
> +	mutex_unlock(&ams->mutex);
> +
> +	return 0;
> +}
> +
> +static int ams_read_event_value(struct iio_dev *indio_dev,
> +				const struct iio_chan_spec *chan,
> +				enum iio_event_type type,
> +				enum iio_event_direction dir,
> +				enum iio_event_info info, int *val, int *val2)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	unsigned int offset = ams_get_alarm_offset(chan->scan_index, dir);
> +
> +	mutex_lock(&ams->mutex);
> +
> +	if (chan->scan_index >= PS_SEQ_MAX)
> +		*val = readl(ams->pl_base + offset);
> +	else
> +		*val = readl(ams->ps_base + offset);
> +
> +	mutex_unlock(&ams->mutex);
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int ams_write_event_value(struct iio_dev *indio_dev,
> +				 const struct iio_chan_spec *chan,
> +				 enum iio_event_type type,
> +				 enum iio_event_direction dir,
> +				 enum iio_event_info info, int val, int val2)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	unsigned int offset;
> +
> +	mutex_lock(&ams->mutex);
> +
> +	/* Set temperature channel threshold to direct threshold */
> +	if (chan->type == IIO_TEMP) {
> +		offset = ams_get_alarm_offset(chan->scan_index,
> +					      IIO_EV_DIR_FALLING);
> +
> +		if (chan->scan_index >= PS_SEQ_MAX)
> +			ams_pl_update_reg(ams, offset,
> +					    AMS_ALARM_THR_DIRECT_MASK,
> +					    AMS_ALARM_THR_DIRECT_MASK);
> +		else
> +			ams_ps_update_reg(ams, offset,
> +					  AMS_ALARM_THR_DIRECT_MASK,
> +					  AMS_ALARM_THR_DIRECT_MASK);
> +	}
> +
> +	offset = ams_get_alarm_offset(chan->scan_index, dir);
> +	if (chan->scan_index >= PS_SEQ_MAX)
> +		writel(val, ams->pl_base + offset);
> +	else
> +		writel(val, ams->ps_base + offset);
> +
> +	mutex_unlock(&ams->mutex);
> +
> +	return 0;
> +}
> +
> +static void ams_handle_event(struct iio_dev *indio_dev, u32 event)
> +{
> +	const struct iio_chan_spec *chan;
> +
> +	chan = ams_event_to_channel(indio_dev, event);
> +
> +	if (chan->type == IIO_TEMP) {
> +		/* The temperature channel only supports over-temperature
In IIO we use the standard kernel syntax for comments of
/*
 * The temperature...
 */

This form is only used in a few subsystems such as net.

It's minor but nice to be consistent...

> +		 * events
> +		 */
> +		iio_push_event(indio_dev,
> +			       IIO_UNMOD_EVENT_CODE(chan->type, chan->channel,
> +						    IIO_EV_TYPE_THRESH,
> +						    IIO_EV_DIR_RISING),
> +			iio_get_time_ns(indio_dev));
> +	} else {
> +		/* For other channels we don't know whether it is a upper or
> +		 * lower threshold event. Userspace will have to check the
> +		 * channel value if it wants to know.
> +		 */
> +		iio_push_event(indio_dev,
> +			       IIO_UNMOD_EVENT_CODE(chan->type, chan->channel,
> +						    IIO_EV_TYPE_THRESH,
> +						    IIO_EV_DIR_EITHER),
> +			iio_get_time_ns(indio_dev));
> +	}
> +}
> +
> +static void ams_handle_events(struct iio_dev *indio_dev, unsigned long events)
> +{
> +	unsigned int bit;
> +
> +	for_each_set_bit(bit, &events, AMS_NO_OF_ALARMS)
> +		ams_handle_event(indio_dev, bit);
> +}
> +
> +/**
> + * ams_unmask_worker - ams alarm interrupt unmask worker
> + * @work :		work to be done
> + *
> + * The ZynqMP threshold interrupts are level sensitive. Since we can't make the
> + * threshold condition go way from within the interrupt handler, this means as
> + * soon as a threshold condition is present we would enter the interrupt handler
> + * again and again. To work around this we mask all active threshold interrupts
> + * in the interrupt handler and start a timer. In this timer we poll the
> + * interrupt status and only if the interrupt is inactive we unmask it again.
> + */
> +static void ams_unmask_worker(struct work_struct *work)
> +{
> +	struct ams *ams = container_of(work, struct ams, ams_unmask_work.work);
> +	unsigned int status, unmask;
> +
> +	spin_lock_irq(&ams->lock);
> +
> +	status = readl(ams->base + AMS_ISR_0);
> +
> +	/* Clear those bits which are not active anymore */
> +	unmask = (ams->masked_alarm ^ status) & ams->masked_alarm;
> +
> +	/* clear status of disabled alarm */
> +	unmask |= ams->intr_mask;
> +
> +	ams->masked_alarm &= status;
> +
> +	/* Also clear those which are masked out anyway */
> +	ams->masked_alarm &= ~ams->intr_mask;
> +
> +	/* Clear the interrupts before we unmask them */
> +	writel(unmask, ams->base + AMS_ISR_0);
> +
> +	ams_update_intrmask(ams, 0, 0);
> +
> +	spin_unlock_irq(&ams->lock);
> +
> +	/* if still pending some alarm re-trigger the timer */
> +	if (ams->masked_alarm)
> +		schedule_delayed_work(&ams->ams_unmask_work,
> +				      msecs_to_jiffies(AMS_UNMASK_TIMEOUT_MS));
> +}
> +
> +static irqreturn_t ams_iio_irq(int irq, void *data)
> +{
> +	unsigned int isr0, isr1;
> +	struct iio_dev *indio_dev = data;
> +	struct ams *ams = iio_priv(indio_dev);
> +
> +	spin_lock(&ams->lock);

Do these need to be handled in interrupt context?  Would we be better
off doing it in an interrupt thread where we can sleep (and hence
not use a spin lock for example)?

Perhaps not, but this doesn't immediately feel time critical...

> +
> +	isr0 = readl(ams->base + AMS_ISR_0);
> +	isr1 = readl(ams->base + AMS_ISR_1);
> +
> +	/* only process alarms that are not masked */
> +	isr0 &= ~((ams->intr_mask & AMS_ISR0_ALARM_MASK) | ams->masked_alarm);
> +	isr1 &= ~(ams->intr_mask >> AMS_ISR1_INTR_MASK_SHIFT);
> +
> +	/* clear interrupt */
> +	writel(isr0, ams->base + AMS_ISR_0);
> +	writel(isr1, ams->base + AMS_ISR_1);

If we have interrupts here that aren't ours we should a) not be clearing them
b) be returning IRQ_NONE so it can be handled as an incorrect interrupt
and reported as such.

> +
> +	if (isr0) {
> +		/* Once the alarm interrupt occurred, mask until get cleared */
> +		ams->masked_alarm |= isr0;
> +		ams_update_intrmask(ams, 0, 0);
> +
> +		ams_handle_events(indio_dev, isr0);
> +
> +		schedule_delayed_work(&ams->ams_unmask_work,
> +				      msecs_to_jiffies(AMS_UNMASK_TIMEOUT_MS));
> +	}
> +
> +	spin_unlock(&ams->lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct iio_event_spec ams_temp_events[] = {
> +	{
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_RISING,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE) |
> +				BIT(IIO_EV_INFO_VALUE),
> +	},
> +};
> +
> +static const struct iio_event_spec ams_voltage_events[] = {
> +	{
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_RISING,
> +		.mask_separate = BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_FALLING,
> +		.mask_separate = BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_EITHER,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +	},
> +};
> +
> +static const struct iio_chan_spec ams_ps_channels[] = {
> +	AMS_PS_CHAN_TEMP(AMS_SEQ_TEMP, AMS_TEMP, "ps_temp"),
> +	AMS_PS_CHAN_TEMP(AMS_SEQ_TEMP_REMOTE, AMS_TEMP_REMOTE, "remote_temp"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY1, AMS_SUPPLY1, "vccpsintlp"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY2, AMS_SUPPLY2, "vccpsintfp"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY3, AMS_SUPPLY3, "vccpsaux"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY4, AMS_SUPPLY4, "vccpsddr"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY5, AMS_SUPPLY5, "vccpsio3"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY6, AMS_SUPPLY6, "vccpsio0"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY7, AMS_SUPPLY7, "vccpsio1"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY8, AMS_SUPPLY8, "vccpsio2"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY9, AMS_SUPPLY9, "psmgtravcc"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_SUPPLY10, AMS_SUPPLY10, "psmgtravtt"),
> +	AMS_PS_CHAN_VOLTAGE(AMS_SEQ_VCCAMS, AMS_VCCAMS, "vccams"),
> +};
> +
> +static const struct iio_chan_spec ams_pl_channels[] = {
> +	AMS_PL_CHAN_TEMP(AMS_SEQ_TEMP, AMS_TEMP, "pl_temp"),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY1, AMS_SUPPLY1, "vccint", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY2, AMS_SUPPLY2, "vccaux", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VREFP, AMS_VREFP, "vccvrefp", false),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VREFN, AMS_VREFN, "vccvrefn", false),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY3, AMS_SUPPLY3, "vccbram", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY4, AMS_SUPPLY4, "vccplintlp", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY5, AMS_SUPPLY5, "vccplintfp", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY6, AMS_SUPPLY6, "vccplaux", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VCCAMS, AMS_VCCAMS, "vccams", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_VP_VN, AMS_VP_VN, "vccvpvn", false),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY7, AMS_SUPPLY7, "vuser0", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY8, AMS_SUPPLY8, "vuser1", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY9, AMS_SUPPLY9, "vuser2", true),
> +	AMS_PL_CHAN_VOLTAGE(AMS_SEQ_SUPPLY10, AMS_SUPPLY10, "vuser3", true),
> +	AMS_PL_AUX_CHAN_VOLTAGE(0, "vccaux0"),

Extended_name is a two edged sword.  It lets you make nice specifically
named channels, but it also breaks almost all userspace code as it
doesn't know how to handle the extra bit on the end of the name.

As such we tend to only specify it for very special use non standard
channels (such as the power supplies)

For the aux channels, it has no particular meaning. So I would prefer
that you dropped it and just left them with the indexes.

> +	AMS_PL_AUX_CHAN_VOLTAGE(1, "vccaux1"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(2, "vccaux2"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(3, "vccaux3"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(4, "vccaux4"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(5, "vccaux5"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(6, "vccaux6"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(7, "vccaux7"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(8, "vccaux8"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(9, "vccaux9"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(10, "vccaux10"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(11, "vccaux11"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(12, "vccaux12"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(13, "vccaux13"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(14, "vccaux14"),
> +	AMS_PL_AUX_CHAN_VOLTAGE(15, "vccaux15"),
> +};
> +
> +static const struct iio_chan_spec ams_ctrl_channels[] = {
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCC_PSPLL, AMS_VCC_PSPLL0, "vcc_pspll0"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCC_PSBATT, AMS_VCC_PSPLL3, "vcc_psbatt"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCINT, AMS_VCCINT, "vccint"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCBRAM, AMS_VCCBRAM, "vccbram"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_VCCAUX, AMS_VCCAUX, "vccaux"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_PSDDRPLL, AMS_PSDDRPLL, "psddrpll"),
> +	AMS_CTRL_CHAN_VOLTAGE(AMS_SEQ_INTDDR, AMS_PSINTFPDDR, "psintfpddr"),
> +};
> +
> +static int ams_init_module(struct iio_dev *indio_dev, struct device_node *np,
> +			   struct iio_chan_spec *channels)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	struct device_node *chan_node, *child;
> +	int ret, num_channels = 0;
> +	unsigned int reg;
> +
> +	if (of_device_is_compatible(np, "xlnx,zynqmp-ams-ps")) {
> +		ams->ps_base = of_iomap(np, 0);
> +		if (!ams->ps_base)
> +			return -ENXIO;
> +
> +		/* add PS channels to iio device channels */
> +		memcpy(channels + num_channels, ams_ps_channels,
> +		       sizeof(ams_ps_channels));
> +		num_channels += ARRAY_SIZE(ams_ps_channels);
> +	} else if (of_device_is_compatible(np, "xlnx,zynqmp-ams-pl")) {
> +		ams->pl_base = of_iomap(np, 0);
> +		if (!ams->pl_base)
> +			return -ENXIO;
> +
> +		/* Copy only first 10 fix channels */
> +		memcpy(channels + num_channels, ams_pl_channels,
> +		       AMS_PL_MAX_FIXED_CHANNEL * sizeof(*channels));
> +		num_channels += AMS_PL_MAX_FIXED_CHANNEL;
> +
> +		chan_node = of_get_child_by_name(np, "xlnx,ext-channels");
> +		if (chan_node) {
> +			for_each_child_of_node(chan_node, child) {
> +				ret = of_property_read_u32(child, "reg", &reg);
> +				if (ret || reg > AMS_PL_MAX_EXT_CHANNEL)
> +					continue;
> +
> +				memcpy(&channels[num_channels],
> +				       &ams_pl_channels[reg +
> +				       AMS_PL_MAX_FIXED_CHANNEL],
> +				       sizeof(*channels));
> +
> +				if (of_property_read_bool(child,
> +							  "xlnx,bipolar"))
> +					channels[num_channels].scan_type.sign =
> +						's';
> +
> +				num_channels += 1;

num_channels++;

> +			}
> +		}
> +		of_node_put(chan_node);
> +	} else if (of_device_is_compatible(np, "xlnx,zynqmp-ams")) {
> +		/* add AMS channels to iio device channels */
> +		memcpy(channels + num_channels, ams_ctrl_channels,
> +				sizeof(ams_ctrl_channels));
> +		num_channels += ARRAY_SIZE(ams_ctrl_channels);
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	return num_channels;
> +}
> +
> +static int ams_parse_dt(struct iio_dev *indio_dev, struct platform_device *pdev)
> +{
> +	struct ams *ams = iio_priv(indio_dev);
> +	struct iio_chan_spec *ams_channels, *dev_channels;
> +	struct device_node *child_node = NULL, *np = pdev->dev.of_node;
> +	int ret, chan_vol = 0, chan_temp = 0, i, rising_off, falling_off;

chan_vol and chan_temp are counts?  Perhaps their names can make that clearer.

> +	unsigned int num_channels = 0;
> +
> +	/* Initialize buffer for channel specification */
> +	ams_channels = kzalloc(sizeof(ams_ps_channels) +
> +			       sizeof(ams_pl_channels) +
> +			       sizeof(ams_ctrl_channels), GFP_KERNEL);
> +	if (!ams_channels)
> +		return -ENOMEM;
> +
> +	if (of_device_is_available(np)) {
> +		ret = ams_init_module(indio_dev, np, ams_channels);
> +		if (ret < 0) {
> +			kfree(ams_channels);
> +			return ret;
> +		}
> +
> +		num_channels += ret;
> +	}
> +
> +	for_each_child_of_node(np, child_node) {
> +		if (of_device_is_available(child_node)) {
> +			ret = ams_init_module(indio_dev, child_node,
> +					      ams_channels + num_channels);
> +			if (ret < 0) {
> +				kfree(ams_channels);
> +				return ret;
> +			}
> +
> +			num_channels += ret;
> +		}
> +	}
> +
> +	for (i = 0; i < num_channels; i++) {
> +		if (ams_channels[i].type == IIO_VOLTAGE)
> +			ams_channels[i].channel = chan_vol++;
> +		else
> +			ams_channels[i].channel = chan_temp++;
> +
> +		if (ams_channels[i].scan_index < (PS_SEQ_MAX * 3)) {
> +			/* set threshold to max and min for each channel */
> +			falling_off = ams_get_alarm_offset(
> +					ams_channels[i].scan_index,
> +					IIO_EV_DIR_FALLING);
> +			rising_off = ams_get_alarm_offset(
> +					ams_channels[i].scan_index,
> +					IIO_EV_DIR_RISING);
> +			if (ams_channels[i].scan_index >= PS_SEQ_MAX) {
> +				writel(AMS_ALARM_THR_MIN,
> +						ams->pl_base + falling_off);
> +				writel(AMS_ALARM_THR_MAX,
> +						ams->pl_base + rising_off);
> +			} else {
> +				writel(AMS_ALARM_THR_MIN,
> +						ams->ps_base + falling_off);
> +				writel(AMS_ALARM_THR_MAX,
> +						ams->ps_base + rising_off);
> +			}
> +		}
> +	}
> +
> +	dev_channels = devm_kzalloc(&pdev->dev, sizeof(*dev_channels) *
> +				    num_channels, GFP_KERNEL);
> +	if (!dev_channels) {
> +		kfree(ams_channels);
> +		return -ENOMEM;
> +	}
> +
> +	memcpy(dev_channels, ams_channels,
> +	       sizeof(*ams_channels) * num_channels);
> +	kfree(ams_channels);
If you were to reorder this so the ams_channels cleanup was last you could use
the nice clean pattern of

error:
	kfree(ams_channels);

	return ret;

To make it clear that the ams_channels gets freed in all paths.

> +	indio_dev->channels = dev_channels;
> +	indio_dev->num_channels = num_channels;
> +
> +	return 0;
> +}
> +
> +static const struct iio_info iio_pl_info = {
> +	.read_raw = &ams_read_raw,
> +	.read_event_config = &ams_read_event_config,
> +	.write_event_config = &ams_write_event_config,
> +	.read_event_value = &ams_read_event_value,
> +	.write_event_value = &ams_write_event_value,
> +};
> +
> +static const struct of_device_id ams_of_match_table[] = {
> +	{ .compatible = "xlnx,zynqmp-ams" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ams_of_match_table);
> +
> +static int ams_probe(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev;
> +	struct ams *ams;
> +	struct resource *res;
> +	int ret;
> +
> +	if (!pdev->dev.of_node)
> +		return -ENODEV;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*ams));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	ams = iio_priv(indio_dev);
> +	mutex_init(&ams->mutex);
> +	spin_lock_init(&ams->lock);
> +
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->name = "ams";
As names go, that one is a too little generic.  Particularly
with a common manufacturer of ADCs called Austrian
Micro Systems ;)  No possibility of confusion!

It's fine to use ams within the driver, but for external
interfaces, perhaps prefix with xilinx-?

> +
> +	indio_dev->info = &iio_pl_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ams-base");
> +	ams->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(ams->base))
> +		return PTR_ERR(ams->base);
> +
> +	INIT_DELAYED_WORK(&ams->ams_unmask_work, ams_unmask_worker);
> +
> +	ams->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(ams->clk))
> +		return PTR_ERR(ams->clk);
> +	clk_prepare_enable(ams->clk);
> +
> +	ret = iio_ams_init_device(ams);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to initialize AMS\n");
> +		goto clk_disable;
> +	}
> +
> +	ret = ams_parse_dt(indio_dev, pdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failure in parsing DT\n");
> +		goto clk_disable;
> +	}
> +
> +	ams_enable_channel_sequence(ams);
> +
> +	ams->irq = platform_get_irq_byname(pdev, "ams-irq");

Why store this in the ams structure?  It's not used anywhere other than in the
next line.

> +	ret = devm_request_irq(&pdev->dev, ams->irq, &ams_iio_irq, 0, "ams-irq",
> +			       indio_dev);
This mixing of devm and non devm functions makes it tricky to
be sure there aren't an races.

One easy solution is to use devm_add_action to put the
clk_disable_unprepare into the cleanup list.

> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to register interrupt\n");
> +		goto clk_disable;
> +	}
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	return iio_device_register(indio_dev);

What if device register returns an error?  You leave the clock enabled.

That way everything is using the managed cleanup and the ordering will
be correct.

The alternative is to not use devm forms for everything after the
clk_prepare_enable.

> +
> +clk_disable:
> +	clk_disable_unprepare(ams->clk);
> +
> +	return ret;
> +}
> +
> +static int ams_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct ams *ams = iio_priv(indio_dev);
> +
> +	cancel_delayed_work(&ams->ams_unmask_work);
> +
> +	/* Unregister the device */
> +	iio_device_unregister(indio_dev);
> +	clk_disable_unprepare(ams->clk);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused ams_suspend(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ams *ams = iio_priv(indio_dev);
> +
> +	clk_disable_unprepare(ams->clk);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused ams_resume(struct device *dev)
> +{
> +	struct iio_dev *indio_dev = dev_get_drvdata(dev);
> +	struct ams *ams = iio_priv(indio_dev);
You could streamline this without loss of clarity as.

struct ams *ams = iio_priv(dev_get_drvdata(dev));

(very minor point!)
> +
> +	clk_prepare_enable(ams->clk);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(ams_pm_ops, ams_suspend, ams_resume);
> +
> +static struct platform_driver ams_driver = {
> +	.probe = ams_probe,
> +	.remove = ams_remove,
> +	.driver = {
> +		.name = "ams",
> +		.pm	= &ams_pm_ops,

Spacing here seems a little odd.  Just have a single space after pm

> +		.of_match_table = ams_of_match_table,
> +	},
> +};
> +module_platform_driver(ams_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Xilinx, Inc.");
> diff --git a/drivers/iio/adc/xilinx-ams.h b/drivers/iio/adc/xilinx-ams.h
> new file mode 100644
> index 0000000..b9fa262
> --- /dev/null
> +++ b/drivers/iio/adc/xilinx-ams.h

I can't immediately see why a lot of this wants to be in a header.

Please move it inline with the C file.

> @@ -0,0 +1,281 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Xilinx AMS driver
> + *
> + *  Copyright (C) 2017-2018 Xilinx, Inc.
> + *
> + *  Manish Narani <[email-masked]>
> + *  Rajnikant Bhojani <[email-masked]>
> + */
> +
> +#ifndef __XILINX_AMS_H__
> +#define __XILINX_AMS_H__
> +
> +#define AMS_MISC_CTRL     0x000
> +#define AMS_ISR_0         0x010
> +#define AMS_ISR_1         0x014
> +#define AMS_IMR_0         0x018
> +#define AMS_IMR_1         0x01c
> +#define AMS_IER_0         0x020
> +#define AMS_IER_1         0x024
> +#define AMS_IDR_0         0x028
> +#define AMS_IDR_1         0x02c
> +#define AMS_PS_CSTS       0x040
> +#define AMS_PL_CSTS       0x044
> +#define AMS_MON_CSTS      0x050
> +
> +#define AMS_VCC_PSPLL0    0x060
> +#define AMS_VCC_PSPLL3    0x06C
> +#define AMS_VCCINT        0x078
> +#define AMS_VCCBRAM       0x07C
> +#define AMS_VCCAUX        0x080
> +#define AMS_PSDDRPLL      0x084
> +#define AMS_PSINTFPDDR    0x09C
> +
> +#define AMS_VCC_PSPLL0_CH 48
> +#define AMS_VCC_PSPLL3_CH 51
> +#define AMS_VCCINT_CH     54
> +#define AMS_VCCBRAM_CH    55
> +#define AMS_VCCAUX_CH     56
> +#define AMS_PSDDRPLL_CH   57
> +#define AMS_PSINTFPDDR_CH 63
> +
> +#define AMS_REG_CONFIG0   0x100
> +#define AMS_REG_CONFIG1   0x104
> +#define AMS_REG_CONFIG2   0x108
> +#define AMS_REG_CONFIG3   0x10C
> +#define AMS_REG_CONFIG4   0x110
> +#define AMS_REG_SEQ_CH0   0x120
> +#define AMS_REG_SEQ_CH1   0x124
> +#define AMS_REG_SEQ_CH2   0x118
> +
> +#define AMS_TEMP          0x000
> +#define AMS_SUPPLY1       0x004
> +#define AMS_SUPPLY2       0x008
> +#define AMS_VP_VN         0x00c
> +#define AMS_VREFP         0x010
> +#define AMS_VREFN         0x014
> +#define AMS_SUPPLY3       0x018
> +#define AMS_SUPPLY4       0x034
> +#define AMS_SUPPLY5       0x038
> +#define AMS_SUPPLY6       0x03c
> +#define AMS_SUPPLY7       0x200
> +#define AMS_SUPPLY8       0x204
> +#define AMS_SUPPLY9       0x208
> +#define AMS_SUPPLY10      0x20c
> +#define AMS_VCCAMS        0x210
> +#define AMS_TEMP_REMOTE   0x214
> +
> +#define AMS_REG_VAUX(x)   (0x40 + (4*(x)))
> +#define AMS_REG_VUSER(x)  (0x200 + (4*(x)))
> +
> +#define AMS_PS_RESET_VALUE   0xFFFFU
> +#define AMS_PL_RESET_VALUE   0xFFFFU
> +
> +#define AMS_CONF0_CHANNEL_NUM_MASK      (0x3f << 0)
> +
> +#define AMS_CONF1_SEQ_MASK              (0xf << 12)
> +#define AMS_CONF1_SEQ_DEFAULT           (0 << 12)
> +#define AMS_CONF1_SEQ_SINGLE_PASS       (1 << 12)
> +#define AMS_CONF1_SEQ_CONTINUOUS        (2 << 12)
> +#define AMS_CONF1_SEQ_SINGLE_CHANNEL    (3 << 12)
> +
> +#define AMS_REG_SEQ0_MASK        0xFFFF
> +#define AMS_REG_SEQ2_MASK        0x3F
> +#define AMS_REG_SEQ1_MASK        0xFFFF
> +#define AMS_REG_SEQ2_MASK_SHIFT  16
> +#define AMS_REG_SEQ1_MASK_SHIFT  22
> +
> +#define AMS_REGCFG1_ALARM_MASK   0xF0F
> +#define AMS_REGCFG3_ALARM_MASK   0x3F
> +
> +#define AMS_ALARM_TEMP            0x140
> +#define AMS_ALARM_SUPPLY1         0x144
> +#define AMS_ALARM_SUPPLY2         0x148
> +#define AMS_ALARM_OT              0x14c
> +
> +#define AMS_ALARM_SUPPLY3         0x160
> +#define AMS_ALARM_SUPPLY4         0x164
> +#define AMS_ALARM_SUPPLY5         0x168
> +#define AMS_ALARM_SUPPLY6         0x16c
> +#define AMS_ALARM_SUPPLY7         0x180
> +#define AMS_ALARM_SUPPLY8         0x184
> +#define AMS_ALARM_SUPPLY9         0x188
> +#define AMS_ALARM_SUPPLY10        0x18c
> +#define AMS_ALARM_VCCAMS          0x190
> +#define AMS_ALARM_TEMP_REMOTE     0x194
> +#define AMS_ALARM_THRESHOLD_OFF_10 0x10
> +#define AMS_ALARM_THRESHOLD_OFF_20 0x20
> +
> +#define AMS_ALARM_THR_DIRECT_MASK 0x01
> +#define AMS_ALARM_THR_MIN         0x0000
> +#define AMS_ALARM_THR_MAX         0xffff
> +
> +#define AMS_NO_OF_ALARMS             32
> +#define AMS_PL_ALARM_START           16
> +#define AMS_ISR0_ALARM_MASK          0xFFFFFFFFU
> +#define AMS_ISR1_ALARM_MASK          0xE000001FU
> +#define AMS_ISR1_INTR_MASK_SHIFT     32
> +#define AMS_ISR0_ALARM_2_TO_0_MASK     0x07
> +#define AMS_ISR0_ALARM_6_TO_3_MASK     0x78
> +#define AMS_ISR0_ALARM_12_TO_7_MASK    0x3F
> +#define AMS_CONF1_ALARM_2_TO_0_SHIFT   1
> +#define AMS_CONF1_ALARM_6_TO_3_SHIFT   5
> +#define AMS_CONF3_ALARM_12_TO_7_SHIFT  8
> +
> +#define AMS_PS_CSTS_PS_READY       0x08010000U
> +#define AMS_PL_CSTS_ACCESS_MASK    0x00000001U
> +
> +#define AMS_PL_MAX_FIXED_CHANNEL   10
> +#define AMS_PL_MAX_EXT_CHANNEL     20
> +
> +#define AMS_INIT_TIMEOUT	10000
> +
> +/*
> + * Following scale and offset value is derived from
> + * UG580 (v1.7) December 20, 2016
> + */
> +#define AMS_SUPPLY_SCALE_1VOLT     1000
> +#define AMS_SUPPLY_SCALE_3VOLT     3000
> +#define AMS_SUPPLY_SCALE_6VOLT     6000
> +#define AMS_SUPPLY_SCALE_DIV_BIT   16
> +
> +#define AMS_TEMP_SCALE             509314
> +#define AMS_TEMP_SCALE_DIV_BIT     16
> +#define AMS_TEMP_OFFSET            -((280230L << 16) / 509314)
> +
> +enum ams_alarm_bit {
> +	AMS_ALARM_BIT_TEMP,
> +	AMS_ALARM_BIT_SUPPLY1,
> +	AMS_ALARM_BIT_SUPPLY2,
> +	AMS_ALARM_BIT_SUPPLY3,
> +	AMS_ALARM_BIT_SUPPLY4,
> +	AMS_ALARM_BIT_SUPPLY5,
> +	AMS_ALARM_BIT_SUPPLY6,
> +	AMS_ALARM_BIT_RESERVED,
> +	AMS_ALARM_BIT_SUPPLY7,
> +	AMS_ALARM_BIT_SUPPLY8,
> +	AMS_ALARM_BIT_SUPPLY9,
> +	AMS_ALARM_BIT_SUPPLY10,
> +	AMS_ALARM_BIT_VCCAMS,
> +	AMS_ALARM_BIT_TEMP_REMOTE
> +};
> +
> +enum ams_seq {
> +	AMS_SEQ_VCC_PSPLL,
> +	AMS_SEQ_VCC_PSBATT,
> +	AMS_SEQ_VCCINT,
> +	AMS_SEQ_VCCBRAM,
> +	AMS_SEQ_VCCAUX,
> +	AMS_SEQ_PSDDRPLL,
> +	AMS_SEQ_INTDDR
> +};
> +
> +enum ams_ps_pl_seq {
> +	AMS_SEQ_CALIB,
> +	AMS_SEQ_RSVD_1,
> +	AMS_SEQ_RSVD_2,
> +	AMS_SEQ_TEST,
> +	AMS_SEQ_RSVD_4,
> +	AMS_SEQ_SUPPLY4,
> +	AMS_SEQ_SUPPLY5,
> +	AMS_SEQ_SUPPLY6,
> +	AMS_SEQ_TEMP,
> +	AMS_SEQ_SUPPLY2,
> +	AMS_SEQ_SUPPLY1,
> +	AMS_SEQ_VP_VN,
> +	AMS_SEQ_VREFP,
> +	AMS_SEQ_VREFN,
> +	AMS_SEQ_SUPPLY3,
> +	AMS_SEQ_CURRENT_MON,
> +	AMS_SEQ_SUPPLY7,
> +	AMS_SEQ_SUPPLY8,
> +	AMS_SEQ_SUPPLY9,
> +	AMS_SEQ_SUPPLY10,
> +	AMS_SEQ_VCCAMS,
> +	AMS_SEQ_TEMP_REMOTE,
> +	AMS_SEQ_MAX
> +};
> +
> +#define AMS_SEQ(x)          (AMS_SEQ_MAX + (x))
> +#define AMS_VAUX_SEQ(x)     (AMS_SEQ_MAX + (x))
> +
> +#define PS_SEQ_MAX          AMS_SEQ_MAX
> +#define PS_SEQ(x)           (x)
> +#define PL_SEQ(x)           (PS_SEQ_MAX + x)
> +
> +#define AMS_CHAN_TEMP(_scan_index, _addr, _ext) { \
> +	.type = IIO_TEMP, \
> +	.indexed = 1, \
> +	.address = (_addr), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> +		BIT(IIO_CHAN_INFO_SCALE) | \
> +		BIT(IIO_CHAN_INFO_OFFSET), \
> +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	.event_spec = ams_temp_events, \
> +	.num_event_specs = ARRAY_SIZE(ams_temp_events), \
> +	.scan_index = (_scan_index), \
> +	.scan_type = { \
> +		.sign = 'u', \
> +		.realbits = 12, \
> +		.storagebits = 16, \
> +		.shift = 4, \
> +		.endianness = IIO_CPU, \
> +	}, \
> +	.extend_name = _ext, \
> +}
> +
> +#define AMS_CHAN_VOLTAGE(_scan_index, _addr, _ext, _alarm) { \
> +	.type = IIO_VOLTAGE, \
> +	.indexed = 1, \
> +	.address = (_addr), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> +		BIT(IIO_CHAN_INFO_SCALE), \
> +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	.event_spec = (_alarm) ? ams_voltage_events : NULL, \
> +	.num_event_specs = (_alarm) ? ARRAY_SIZE(ams_voltage_events) : 0, \
> +	.scan_index = (_scan_index), \
> +	.scan_type = { \
> +		.realbits = 10, \
> +		.storagebits = 16, \
> +		.shift = 6, \
> +		.endianness = IIO_CPU, \
> +	}, \
> +	.extend_name = _ext, \
> +}
> +
> +#define AMS_PS_CHAN_TEMP(_scan_index, _addr, _ext) \
> +	AMS_CHAN_TEMP(PS_SEQ(_scan_index), _addr, _ext)
> +#define AMS_PS_CHAN_VOLTAGE(_scan_index, _addr, _ext) \
> +	AMS_CHAN_VOLTAGE(PS_SEQ(_scan_index), _addr, _ext, true)
> +
> +#define AMS_PL_CHAN_TEMP(_scan_index, _addr, _ext) \
> +	AMS_CHAN_TEMP(PL_SEQ(_scan_index), _addr, _ext)
> +#define AMS_PL_CHAN_VOLTAGE(_scan_index, _addr, _ext, _alarm) \
> +	AMS_CHAN_VOLTAGE(PL_SEQ(_scan_index), _addr, _ext, _alarm)
> +#define AMS_PL_AUX_CHAN_VOLTAGE(_auxno, _ext) \
> +	AMS_CHAN_VOLTAGE(PL_SEQ(AMS_VAUX_SEQ(_auxno)), \
> +			AMS_REG_VAUX(_auxno), _ext, false)
> +#define AMS_CTRL_CHAN_VOLTAGE(_scan_index, _addr, _ext) \
> +	AMS_CHAN_VOLTAGE(PL_SEQ(AMS_VAUX_SEQ(AMS_SEQ(_scan_index))), \
> +			_addr, _ext, false)
> +
> +struct ams {
> +	void __iomem *base;
> +	void __iomem *ps_base;
> +	void __iomem *pl_base;
> +	struct clk *clk;
> +	struct device *dev;
> +
> +	struct mutex mutex;
Pleases give clear comments on what these locks are protecting.
It's certainly curious to see a mutex and a spinlock with such
generic names right next to each other.

> +	spinlock_t lock;
> +
> +	unsigned int alarm_mask;
> +	unsigned int masked_alarm;
> +	u64 intr_mask;
> +	int irq;
As noted above, this is only used next to where it is first set.
No advantage in having it here.

> +
> +	struct delayed_work ams_unmask_work;
> +};
> +
> +#endif /* __XILINX_AMS_H__ */