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Date:   Fri, 12 Apr 2019 10:50:19 +0800
From:   Wu Hao <hao.wu@intel.com>
To:     Alan Tull <atull@kernel.org>
Cc:     Moritz Fischer <mdf@kernel.org>, linux-fpga@vger.kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-api@vger.kernel.org, Luwei Kang <luwei.kang@intel.com>,
        Xu Yilun <yilun.xu@intel.com>
Subject: Re: [PATCH 15/17] fpga: dfl: fme: add power management support
Message-ID: <20190412025019.GA27997@hao-dev>
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On Thu, Apr 11, 2019 at 03:07:35PM -0500, Alan Tull wrote:
> On Sun, Mar 24, 2019 at 10:24 PM Wu Hao <hao.wu@intel.com> wrote:
> 
> Hi Hao,
> 
> >
> > This patch adds support for power management private feature under
> > FPGA Management Engine (FME), sysfs interfaces are introduced for
> > different power management functions, users could use these sysfs
> > interface to get current number of consumed power, throttling
> 
> How about
> s/number/measurement/
> ?

Sounds better. : )

> 
> > thresholds, threshold status and other information, and configure
> > different value for throttling thresholds too.
> >
> > Signed-off-by: Luwei Kang <luwei.kang@intel.com>
> > Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> > Signed-off-by: Wu Hao <hao.wu@intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-platform-dfl-fme |  56 +++++
> >  drivers/fpga/dfl-fme-main.c                      | 257 +++++++++++++++++++++++
> >  2 files changed, 313 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-platform-dfl-fme b/Documentation/ABI/testing/sysfs-platform-dfl-fme
> > index d3aeb88..4b6448f 100644
> > --- a/Documentation/ABI/testing/sysfs-platform-dfl-fme
> > +++ b/Documentation/ABI/testing/sysfs-platform-dfl-fme
> > @@ -100,3 +100,59 @@ Description:       Read-only. Read this file to get the policy of temperature
> >                 threshold1. It only supports two value (policy):
> >                     0 - AP2 state (90% throttling)
> >                     1 - AP1 state (50% throttling)
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/consumed
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. It returns current power consumed by FPGA.
> 
> What are the units?
> 
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/threshold1
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-Write. Read/Write this file to get/set current power
> > +               threshold1 in Watts.
> 
> Perhaps document error codes here and for threshold2 below.
> 
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/threshold2
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-Write. Read/Write this file to get/set current power
> > +               threshold2 in Watts.
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/threshold1_status
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. It returns 1 if power consumption reaches the
> > +               threshold1, otherwise 0.
> 
> I'm used to things like this requiring user to reset the status, so it
> may be worth making it explicit that it will return to zero if
> consumption drops below threshold if that's what's happening here.
> If it's correct, perhaps could just say something like 'returns 1 if
> power consumption is currently at or above threshold1, otherwise 0'
> 
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/threshold2_status
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. It returns 1 if power consumption reaches the
> > +               threshold2, otherwise 0.
> 
> Same here.

Sure, will fix all above comments in this sysfs doc.

> 
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/ltr
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. Read this file to get current Latency Tolerance
> > +               Reporting (ltr) value, it's only valid for integrated
> > +               solution as it blocks CPU on low power state.
> 
> If we're not on the integrated solution, it returns a value but it is
> not really real?

Currently only integrated solution is implementing this private feature, other
devices e.g. Intel PAC card is not using this private feature, so user will
not see these sysfs interfaces at all.

If in the future, other devices want

> 
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/xeon_limit
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. Read this file to get power limit for xeon, it
> > +               is only valid for integrated solution.
> > +
> > +What:          /sys/bus/platform/devices/dfl-fme.0/power_mgmt/fpga_limit
> > +Date:          March 2019
> > +KernelVersion:  5.2
> > +Contact:       Wu Hao <hao.wu@intel.com>
> > +Description:   Read-only. Read this file to get power limit for fpga, it
> > +               is only valid for integrated solution.
> > diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
> > index 449a17d..dafa6580 100644
> > --- a/drivers/fpga/dfl-fme-main.c
> > +++ b/drivers/fpga/dfl-fme-main.c
> > @@ -415,6 +415,259 @@ static const struct dfl_feature_ops fme_thermal_mgmt_ops = {
> >         .uinit = fme_thermal_mgmt_uinit,
> >  };
> >
> > +#define FME_PWR_STATUS         0x8
> > +#define FME_LATENCY_TOLERANCE  BIT_ULL(18)
> > +#define PWR_CONSUMED           GENMASK_ULL(17, 0)
> > +
> > +#define FME_PWR_THRESHOLD      0x10
> > +#define PWR_THRESHOLD1         GENMASK_ULL(6, 0)       /* in Watts */
> > +#define PWR_THRESHOLD2         GENMASK_ULL(14, 8)      /* in Watts */
> > +#define PWR_THRESHOLD_MAX      0x7f
> > +#define PWR_THRESHOLD1_STATUS  BIT_ULL(16)
> > +#define PWR_THRESHOLD2_STATUS  BIT_ULL(17)
> > +
> > +#define FME_PWR_XEON_LIMIT     0x18
> > +#define XEON_PWR_LIMIT         GENMASK_ULL(14, 0)
> > +#define XEON_PWR_EN            BIT_ULL(15)
> > +#define FME_PWR_FPGA_LIMIT     0x20
> > +#define FPGA_PWR_LIMIT         GENMASK_ULL(14, 0)
> > +#define FPGA_PWR_EN            BIT_ULL(15)
> > +
> > +#define POWER_ATTR(_name, _mode, _show, _store)        \
> > +struct device_attribute power_attr_##_name =           \
> > +       __ATTR(_name, _mode, _show, _store)
> > +
> > +#define POWER_ATTR_RO(_name, _show)                    \
> > +       POWER_ATTR(_name, 0444, _show, NULL)
> > +
> > +#define POWER_ATTR_RW(_name, _show, _store)            \
> > +       POWER_ATTR(_name, 0644, _show, _store)
> 
> Are these #defines necessary?  Seems like you could just use DEVICE_ATTR*

Actually it adds a prefix power_attr_xxx there to avoid name conflicts with
other ones from different private features, e.g. for the thermal threshold.

> 
> > +
> > +static ssize_t pwr_consumed_show(struct device *dev,
> > +                                struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_STATUS);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(PWR_CONSUMED, v));
> > +}
> > +static POWER_ATTR_RO(consumed, pwr_consumed_show);
> > +
> > +static ssize_t pwr_threshold1_show(struct device *dev,
> > +                                  struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(PWR_THRESHOLD1, v));
> > +}
> > +
> > +static ssize_t pwr_threshold1_store(struct device *dev,
> > +                                   struct device_attribute *attr,
> > +                                   const char *buf, size_t count)
> > +{
> > +       struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
> > +       void __iomem *base;
> > +       u8 threshold;
> > +       int ret;
> > +       u64 v;
> > +
> > +       ret = kstrtou8(buf, 0, &threshold);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (threshold > PWR_THRESHOLD_MAX)
> > +               return -EINVAL;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       mutex_lock(&pdata->lock);
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +       v &= ~PWR_THRESHOLD1;
> > +       v |= FIELD_PREP(PWR_THRESHOLD1, threshold);
> > +       writeq(v, base + FME_PWR_THRESHOLD);
> > +       mutex_unlock(&pdata->lock);
> > +
> > +       return count;
> > +}
> > +static POWER_ATTR_RW(threshold1, pwr_threshold1_show, pwr_threshold1_store);
> > +
> > +static ssize_t pwr_threshold2_show(struct device *dev,
> > +                                  struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(PWR_THRESHOLD2, v));
> > +}
> > +
> > +static ssize_t pwr_threshold2_store(struct device *dev,
> > +                                   struct device_attribute *attr,
> > +                                   const char *buf, size_t count)
> > +{
> > +       struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
> > +       void __iomem *base;
> > +       u8 threshold;
> > +       int ret;
> > +       u64 v;
> > +
> > +       ret = kstrtou8(buf, 0, &threshold);
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (threshold > PWR_THRESHOLD_MAX)
> > +               return -EINVAL;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       mutex_lock(&pdata->lock);
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +       v &= ~PWR_THRESHOLD2;
> > +       v |= FIELD_PREP(PWR_THRESHOLD2, threshold);
> > +       writeq(v, base + FME_PWR_THRESHOLD);
> > +       mutex_unlock(&pdata->lock);
> > +
> > +       return count;
> > +}
> > +static POWER_ATTR_RW(threshold2, pwr_threshold2_show, pwr_threshold2_store);
> > +
> > +static ssize_t pwr_threshold1_status_show(struct device *dev,
> > +                                         struct device_attribute *attr,
> > +                                         char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(PWR_THRESHOLD1_STATUS, v));
> > +}
> > +static POWER_ATTR_RO(threshold1_status, pwr_threshold1_status_show);
> > +
> > +static ssize_t pwr_threshold2_status_show(struct device *dev,
> > +                                         struct device_attribute *attr,
> > +                                         char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_THRESHOLD);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(PWR_THRESHOLD2_STATUS, v));
> > +}
> > +static POWER_ATTR_RO(threshold2_status, pwr_threshold2_status_show);
> > +
> > +static ssize_t ltr_show(struct device *dev,
> > +                       struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_STATUS);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n",
> > +                        (unsigned int)FIELD_GET(FME_LATENCY_TOLERANCE, v));
> > +}
> > +static POWER_ATTR_RO(ltr, ltr_show);
> > +
> > +static ssize_t xeon_limit_show(struct device *dev,
> > +                              struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u16 xeon_limit = 0;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_XEON_LIMIT);
> > +
> > +       if (FIELD_GET(XEON_PWR_EN, v))
> > +               xeon_limit = FIELD_GET(XEON_PWR_LIMIT, v);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n", xeon_limit);
> > +}
> > +static POWER_ATTR_RO(xeon_limit, xeon_limit_show);
> > +
> > +static ssize_t fpga_limit_show(struct device *dev,
> > +                              struct device_attribute *attr, char *buf)
> > +{
> > +       void __iomem *base;
> > +       u16 fpga_limit = 0;
> > +       u64 v;
> > +
> > +       base = dfl_get_feature_ioaddr_by_id(dev, FME_FEATURE_ID_POWER_MGMT);
> > +
> > +       v = readq(base + FME_PWR_FPGA_LIMIT);
> > +
> > +       if (FIELD_GET(FPGA_PWR_EN, v))
> > +               fpga_limit = FIELD_GET(FPGA_PWR_LIMIT, v);
> > +
> > +       return scnprintf(buf, PAGE_SIZE, "%u\n", fpga_limit);
> > +}
> > +static POWER_ATTR_RO(fpga_limit, fpga_limit_show);
> > +
> > +static struct attribute *power_mgmt_attrs[] = {
> > +       &power_attr_consumed.attr,
> > +       &power_attr_threshold1.attr,
> > +       &power_attr_threshold2.attr,
> > +       &power_attr_threshold1_status.attr,
> > +       &power_attr_threshold2_status.attr,
> > +       &power_attr_xeon_limit.attr,
> > +       &power_attr_fpga_limit.attr,
> > +       &power_attr_ltr.attr,
> 
> This is a nit, but I would expect to see these listed in the same
> order as their show/store functions above.  So ltr_attr would come
> between threshold2_status_attr and xeon_limit_attr.

Sure, it does make sense.

> 
> > +       NULL,
> > +};
> > +
> > +static struct attribute_group power_mgmt_attr_group = {
> > +       .attrs  = power_mgmt_attrs,
> > +       .name   = "power_mgmt",
> > +};
> > +
> > +static int fme_power_mgmt_init(struct platform_device *pdev,
> > +                              struct dfl_feature *feature)
> > +{
> > +       return sysfs_create_group(&pdev->dev.kobj, &power_mgmt_attr_group);
> > +}
> > +
> > +static void fme_power_mgmt_uinit(struct platform_device *pdev,
> > +                                struct dfl_feature *feature)
> > +{
> > +       sysfs_remove_group(&pdev->dev.kobj, &power_mgmt_attr_group);
> > +}
> > +
> > +static const struct dfl_feature_id fme_power_mgmt_id_table[] = {
> > +       {.id = FME_FEATURE_ID_POWER_MGMT,},
> > +       {0,}
> > +};
> > +
> > +static const struct dfl_feature_ops fme_power_mgmt_ops = {
> > +       .init = fme_power_mgmt_init,
> > +       .uinit = fme_power_mgmt_uinit,
> > +};
> > +
> >  static struct dfl_feature_driver fme_feature_drvs[] = {
> >         {
> >                 .id_table = fme_hdr_id_table,
> > @@ -429,6 +682,10 @@ static struct dfl_feature_driver fme_feature_drvs[] = {
> >                 .ops = &fme_thermal_mgmt_ops,
> >         },
> >         {
> > +               .id_table = fme_power_mgmt_id_table,
> > +               .ops = &fme_power_mgmt_ops,
> > +       },
> > +       {
> >                 .ops = NULL,
> >         },
> >  };
> > --
> > 2.7.4
> >

Thanks a lot for the review and comments. :)

Hao

> 
> Thanks,
> Alan