RE: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver

From: Anand Ashok Dumbre
Date: Thu Jul 15 2021 - 03:48:35 EST

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> -----Original Message-----
> From: Jonathan Cameron <jic23@xxxxxxxxxx>
> Sent: Sunday 4 July 2021 7:31 PM
> To: Anand Ashok Dumbre <ANANDASH@xxxxxxxxxx>
> Cc: lars@xxxxxxxxxx; linux-iio@xxxxxxxxxxxxxxx; git-dev <git-
> dev@xxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>;
> pmeerw@xxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Manish Narani <MNARANI@xxxxxxxxxx>
> Subject: Re: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver
>
> On Thu, 24 Jun 2021 19:29:37 +0100
> Anand Ashok Dumbre <anand.ashok.dumbre@xxxxxxxxxx> 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 <manish.narani@xxxxxxxxxx>
> > Signed-off-by: Anand Ashok Dumbre <anand.ashok.dumbre@xxxxxxxxxx>

Hi Jonathan,

Thank you for the review.

My comments inline.

Thanks,
Anand
>
> Hi Anand,
>
> A few comments inline from a fresh read.
> Only significant one is that the use of separate masks and shifts differs from
> how they are normally done in the kernel these days.
> FIELD_PREP() and FIELD_GET() allow a single mask definition to be cleanly
> used for both the shift and masking in a nice clean way.
>
> Thanks,
>
> Jonathan
>
> > ---
> > drivers/iio/adc/Kconfig | 13 +
> > drivers/iio/adc/Makefile | 1 +
> > drivers/iio/adc/xilinx-ams.c | 1342
> > ++++++++++++++++++++++++++++++++++
> > 3 files changed, 1356 insertions(+)
> > create mode 100644 drivers/iio/adc/xilinx-ams.c
> >
> > diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index
> > c7946c439612..c011ab30ec9a 100644
> > --- a/drivers/iio/adc/Kconfig
> > +++ b/drivers/iio/adc/Kconfig
> > @@ -1256,4 +1256,17 @@ 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 supports Voltage and Temperature monitoring on Xilinx
> Ultrascale
> > + devices.
> > +
> > + The driver can also be built 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
> > a226657d19c0..99e031f44479 100644
> > --- a/drivers/iio/adc/Makefile
> > +++ b/drivers/iio/adc/Makefile
> > @@ -112,4 +112,5 @@ 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 000000000000..463e3162726c
> > --- /dev/null
> > +++ b/drivers/iio/adc/xilinx-ams.c
> > @@ -0,0 +1,1342 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Xilinx AMS driver
> > + *
> > + * Copyright (C) 2021 Xilinx, Inc.
> > + *
> > + * Manish Narani <mnarani@xxxxxxxxxx>
> > + * Rajnikant Bhojani <rajnikant.bhojani@xxxxxxxxxx> */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +#include <linux/iio/events.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/iio/sysfs.h>
> > +
> > +static const unsigned int AMS_UNMASK_TIMEOUT_MS = 500;
> > +
> > +/* AMS registers definitions */
> > +#define AMS_ISR_0 0x010
> > +#define AMS_ISR_1 0x014
> > +#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_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_CONFIG3 0x10C
> > +#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_PS_RESET_VALUE 0xFFFF
> > +#define AMS_PL_RESET_VALUE 0xFFFF
> > +
> > +#define AMS_CONF0_CHANNEL_NUM_MASK GENMASK(6, 0)
> > +
> > +#define AMS_CONF1_SEQ_MASK GENMASK(15, 12)
> > +#define AMS_CONF1_SEQ_DEFAULT (0 << 12)
> > +#define AMS_CONF1_SEQ_CONTINUOUS (2 << 12)
> > +#define AMS_CONF1_SEQ_SINGLE_CHANNEL (3 << 12)
>
> FIELD_PREP(AMS_CONFG1_SEQ_MASK, 0) or even better, define the values
> as not shifted and have
>
> FIELD_PREP(AMS_CONFIG1_SEQ_MASK, AMS_CONF1_SEQ_DEFAULT) etc in
> the relevant places inline.
>
Will fix this in next series.
>
> > +
> > +#define AMS_REG_SEQ0_MASK 0xFFFF
> > +#define AMS_REG_SEQ2_MASK 0x003F
> > +#define AMS_REG_SEQ1_MASK 0xFFFF
> > +#define AMS_REG_SEQ2_MASK_SHIFT 16
> > +#define AMS_REG_SEQ1_MASK_SHIFT 22
>
> As below, combine mask and shift into a shifted mask then you can use
> FIELD_PREP() to do the magic for you.

Will fix this in next series.
>
> > +
> > +#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_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_EOC_MASK 0x00000008U
> > +#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
>
> Can we handle these via a single mask that includes the shift and
> FIELD_PREP() etc? That tends to make it easier to review by ensuring we
> don't have multiple defines to deal with.
>

Will fix this in next series.

> > +#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_US 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 AMS_PS_SEQ_MAX AMS_SEQ_MAX
> > +#define PS_SEQ(x) (x)
> > +#define PL_SEQ(x) (AMS_PS_SEQ_MAX + (x))
> > +
> > +#define AMS_CHAN_TEMP(_scan_index, _addr) { \
> > + .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, \
>
> Currently these are only documentation i think as no support for using them
> in this driver (buffered modes). You could drop them until you need them in
> some future patch.

Makes sense, will remove the scan_type part, but will retain the scan index, since it
is used in some logic inside the rest of the code.

>
> > + }, \
> > +}
> > +
>
> ...
>
> > +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);
>
> nitpick: Blank line here.

Will fix this in next series.

>
> > + return 0;
> > +}
> > +
>
> ...
>
> > +static int ams_get_ext_chan(struct device_node *chan_node,
> > + struct iio_chan_spec *channels, int num_channels)
> {
> > + struct device_node *child;
> > + unsigned int reg;
> > + int ret;
> > +
> > + for_each_child_of_node(chan_node, child) {
> > + ret = of_property_read_u32(child, "reg", &reg);
> > + if (ret || reg > (AMS_PL_MAX_EXT_CHANNEL + 30))
> > + continue;
> > +
> > + memcpy(&channels[num_channels], &ams_pl_channels[reg
> +
> > + AMS_PL_MAX_FIXED_CHANNEL - 30], sizeof(*channels));
> > +
> > + if (of_property_read_bool(child,
> > + "xlnx,bipolar"))
>
> Above fits on one line easily.

Will fix this in next series.

>
> > + channels[num_channels].scan_type.sign = 's';
> > +
> > + num_channels++;
> > + }
> > +
> > + return num_channels;
> > +}
> > +
>
> ...
>
> > +
> > +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->lock);
> > +
> > + indio_dev->name = "xilinx-ams";
> > +
> > + indio_dev->info = &iio_ams_info;
> > + indio_dev->modes = INDIO_DIRECT_MODE;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + ams->base = devm_ioremap_resource(&pdev->dev, res);
>
> devm_platform_ioremap_resource()
> Slight reduction in boilerplate.

Will fix this in next series.

>
> > + if (IS_ERR(ams->base))
> > + return PTR_ERR(ams->base);
> > +
> > + ams->clk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(ams->clk))
> > + return PTR_ERR(ams->clk);
> > + clk_prepare_enable(ams->clk);
> > + devm_add_action_or_reset(&pdev->dev, (void
> *)clk_disable_unprepare,
> > + ams->clk);
> > +
> > + INIT_DELAYED_WORK(&ams->ams_unmask_work,
> ams_unmask_worker);
> > + devm_add_action_or_reset(&pdev->dev, (void
> *)cancel_delayed_work,
>
> I'm not keen on casting away the function pointer type. Normally we'd just
> wrap it in a local function, to make it clear it was deliberate and avoid
> potential nasty problems if the signature of the function ever changes.
>
> It's 3 lines of boilerplate, but will give me warm fuzzy feelings!
> Same for the other case above. The fact this isn't done in exising kernel code
> make this particularly risky.

Makes sense. I will revert the code back to its original and handle the cases using goto
and inside remove()

>
> > + &ams->ams_unmask_work);
> > +
> > + ret = ams_init_device(ams);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to initialize AMS\n");
> > + return ret;
> > + }
> > +
> > + ret = ams_parse_dt(indio_dev, pdev);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failure in parsing DT\n");
> > + return ret;
> > + }
> > +
> > + ams_enable_channel_sequence(indio_dev);
> > +
> > + ams->irq = platform_get_irq(pdev, 0);
>
> platform_get_irq () can return errors, in particular -EPROBE_DEFER so I'd
> check that and return before you call devm_request_irq() I'm not sure
> devm_request_irq() will not eat that error code.
>

Will fix this in next series.

>
> > + ret = devm_request_irq(&pdev->dev, ams->irq, &ams_irq, 0, "ams-
> irq",
> > + indio_dev);
> > + if (ret < 0) {
> > + dev_err(&pdev->dev, "failed to register interrupt\n");
> > + return ret;
> > + }
> > +
> > + platform_set_drvdata(pdev, indio_dev);
> > +
> > + return iio_device_register(indio_dev); }
> > +
> > +static int ams_remove(struct platform_device *pdev) {
> > + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > +
> > + iio_device_unregister(indio_dev);
>
> If this is all you have in remove, then you can use devm_iio_device_register()
> in probe() and not need an remove() callback at all.

I think remove will have more functions since I am getting rid of devm_add_action_or_reset()

>
> > +
> > + return 0;
> > +}
> > +
>
> ...

Next message: Guangbin Huang: "[PATCH V2 net-next 2/9] net: hns3: add support for registering devlink for PF"
Previous message: Maxime Ripard: "Re: [PATCH v6 1/2] ASoC: sunxi: Add Allwinner H6 Digital MIC driver"
Next in thread: Jonathan Cameron: "Re: [PATCH v6 2/4] iio: adc: Add Xilinx AMS driver"
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