Re: [PATCH V4 2/3] mfd: Intel Platform Monitoring Technology support
From: David E. Box
Date: Tue Jul 28 2020 - 16:35:40 EST
Hi Lee,
Thanks for this thorough review. Ack on all the comments with
particular thanks for spoting the missing continue.
David
On Tue, 2020-07-28 at 08:58 +0100, Lee Jones wrote:
> On Fri, 17 Jul 2020, David E. Box wrote:
>
> > Intel Platform Monitoring Technology (PMT) is an architecture for
> > enumerating and accessing hardware monitoring facilities. PMT
> > supports
> > multiple types of monitoring capabilities. This driver creates
> > platform
> > devices for each type so that they may be managed by capability
> > specific
> > drivers (to be introduced). Capabilities are discovered using PCIe
> > DVSEC
> > ids. Support is included for the 3 current capability types,
> > Telemetry,
> > Watcher, and Crashlog. The features are available on new Intel
> > platforms
> > starting from Tiger Lake for which support is added.
> >
> > Also add a quirk mechanism for several early hardware differences
> > and bugs.
> > For Tiger Lake, do not support Watcher and Crashlog capabilities
> > since they
> > will not be compatible with future product. Also, fix use a quirk
> > to fix
> > the discovery table offset.
> >
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> > Co-developed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx
> > >
> > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
> > Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
>
> This should be in chronological order.
>
> > ---
> > MAINTAINERS | 5 +
> > drivers/mfd/Kconfig | 10 ++
> > drivers/mfd/Makefile | 1 +
> > drivers/mfd/intel_pmt.c | 215
> > ++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 231 insertions(+)
> > create mode 100644 drivers/mfd/intel_pmt.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index b4a43a9e7fbc..2e42bf0c41ab 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8845,6 +8845,11 @@ F: drivers/mfd/intel_soc_pmic*
> > F: include/linux/mfd/intel_msic.h
> > F: include/linux/mfd/intel_soc_pmic*
> >
> > +INTEL PMT DRIVER
> > +M: "David E. Box" <david.e.box@xxxxxxxxxxxxxxx>
> > +S: Maintained
> > +F: drivers/mfd/intel_pmt.c
> > +
> > INTEL PRO/WIRELESS 2100, 2200BG, 2915ABG NETWORK CONNECTION
> > SUPPORT
> > M: Stanislav Yakovlev <stas.yakovlev@xxxxxxxxx>
> > L: linux-wireless@xxxxxxxxxxxxxxx
> > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> > index a37d7d171382..1a62ce2c68d9 100644
> > --- a/drivers/mfd/Kconfig
> > +++ b/drivers/mfd/Kconfig
> > @@ -670,6 +670,16 @@ config MFD_INTEL_PMC_BXT
> > Register and P-unit access. In addition this creates devices
> > for iTCO watchdog and telemetry that are part of the PMC.
> >
> > +config MFD_INTEL_PMT
> > + tristate "Intel Platform Monitoring Technology support"
>
> Nit: "Intel Platform Monitoring Technology (PMT) support"
>
> > + depends on PCI
> > + select MFD_CORE
> > + help
> > + The Intel Platform Monitoring Technology (PMT) is an
> > interface that
> > + provides access to hardware monitor registers. This driver
> > supports
> > + Telemetry, Watcher, and Crashlog PMT capabilities/devices for
> > + platforms starting from Tiger Lake.
> > +
> > config MFD_IPAQ_MICRO
> > bool "Atmel Micro ASIC (iPAQ h3100/h3600/h3700) Support"
> > depends on SA1100_H3100 || SA1100_H3600
> > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> > index 9367a92f795a..1961b4737985 100644
> > --- a/drivers/mfd/Makefile
> > +++ b/drivers/mfd/Makefile
> > @@ -216,6 +216,7 @@ obj-$(CONFIG_MFD_INTEL_LPSS_PCI) +=
> > intel-lpss-pci.o
> > obj-$(CONFIG_MFD_INTEL_LPSS_ACPI) += intel-lpss-acpi.o
> > obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o
> > obj-$(CONFIG_MFD_INTEL_PMC_BXT) += intel_pmc_bxt.o
> > +obj-$(CONFIG_MFD_INTEL_PMT) += intel_pmt.o
> > obj-$(CONFIG_MFD_PALMAS) += palmas.o
> > obj-$(CONFIG_MFD_VIPERBOARD) += viperboard.o
> > obj-$(CONFIG_MFD_RC5T583) += rc5t583.o rc5t583-irq.o
> > diff --git a/drivers/mfd/intel_pmt.c b/drivers/mfd/intel_pmt.c
> > new file mode 100644
> > index 000000000000..6857eaf4ff86
> > --- /dev/null
> > +++ b/drivers/mfd/intel_pmt.c
> > @@ -0,0 +1,215 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Intel Platform Monitoring Technology MFD driver
>
> s/MFD/(PMT)/
>
> > + * Copyright (c) 2020, Intel Corporation.
> > + * All Rights Reserved.
> > + *
> > + * Authors: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
>
> Looks odd to use a plural for a single author.
>
> > + */
> > +
> > +#include <linux/bits.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/pci.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm.h>
> > +#include <linux/pm_runtime.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/types.h>
>
> Alphabetical please.
>
> > +/* Intel DVSEC capability vendor space offsets */
> > +#define INTEL_DVSEC_ENTRIES 0xA
> > +#define INTEL_DVSEC_SIZE 0xB
> > +#define INTEL_DVSEC_TABLE 0xC
> > +#define INTEL_DVSEC_TABLE_BAR(x) ((x) & GENMASK(2, 0))
> > +#define INTEL_DVSEC_TABLE_OFFSET(x) ((x) & GENMASK(31, 3))
> > +#define INTEL_DVSEC_ENTRY_SIZE 4
> > +
> > +/* PMT capabilities */
> > +#define DVSEC_INTEL_ID_TELEMETRY 2
> > +#define DVSEC_INTEL_ID_WATCHER 3
> > +#define DVSEC_INTEL_ID_CRASHLOG 4
> > +
> > +#define TELEMETRY_DEV_NAME "pmt_telemetry"
> > +#define WATCHER_DEV_NAME "pmt_watcher"
> > +#define CRASHLOG_DEV_NAME "pmt_crashlog"
>
> Please don't define names of things. It makes grepping a pain, at
> the
> very least. Just use the 'raw' string in-place.
>
> > +struct intel_dvsec_header {
> > + u16 length;
> > + u16 id;
> > + u8 num_entries;
> > + u8 entry_size;
> > + u8 tbir;
> > + u32 offset;
> > +};
> > +
> > +enum pmt_quirks {
> > + /* Watcher capability not supported */
> > + PMT_QUIRK_NO_WATCHER = BIT(0),
> > +
> > + /* Crashlog capability not supported */
> > + PMT_QUIRK_NO_CRASHLOG = BIT(1),
> > +
> > + /* Use shift instead of mask to read discovery table offset */
> > + PMT_QUIRK_TABLE_SHIFT = BIT(2),
> > +};
> > +
> > +struct pmt_platform_info {
> > + unsigned long quirks;
> > +};
> > +
> > +static const struct pmt_platform_info tgl_info = {
> > + .quirks = PMT_QUIRK_NO_WATCHER | PMT_QUIRK_NO_CRASHLOG |
> > + PMT_QUIRK_TABLE_SHIFT,
> > +};
> > +
> > +static int
> > +pmt_add_dev(struct pci_dev *pdev, struct intel_dvsec_header
> > *header,
> > + struct pmt_platform_info *info)
>
> My personal preference is to a) only break when you have to and b) to
> align with the '('. Perhaps point b) is satisfied and it's just the
> patch format that's shifting the tab though?
>
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct resource *res, *tmp;
> > + struct mfd_cell *cell;
> > + const char *name;
> > + int count = header->num_entries;
> > + int size = header->entry_size;
> > + int i;
> > +
> > + switch (header->id) {
> > + case DVSEC_INTEL_ID_TELEMETRY:
> > + name = TELEMETRY_DEV_NAME;
> > + break;
> > + case DVSEC_INTEL_ID_WATCHER:
> > + if (info->quirks & PMT_QUIRK_NO_WATCHER) {
> > + dev_info(dev, "Watcher not supported\n");
> > + return 0;
> > + }
> > + name = WATCHER_DEV_NAME;
> > + break;
> > + case DVSEC_INTEL_ID_CRASHLOG:
> > + if (info->quirks & PMT_QUIRK_NO_CRASHLOG) {
> > + dev_info(dev, "Crashlog not supported\n");
> > + return 0;
> > + }
> > + name = CRASHLOG_DEV_NAME;
> > + break;
> > + default:
> > + return -EINVAL;
>
> Doesn't deserve an error message?
>
> > + }
> > +
> > + if (!header->num_entries || !header->entry_size) {
> > + dev_warn(dev, "Invalid count or size for %s header\n",
> > name);
> > + return -EINVAL;
>
> If you're returning an error, this should be dev_err().
>
> Even if you only handle it as a warning at the call site.
>
> > + }
> > +
> > + cell = devm_kzalloc(dev, sizeof(*cell), GFP_KERNEL);
> > + if (!cell)
> > + return -ENOMEM;
> > +
> > + res = devm_kcalloc(dev, count, sizeof(*res), GFP_KERNEL);
> > + if (!res)
> > + return -ENOMEM;
> > +
> > + if (info->quirks & PMT_QUIRK_TABLE_SHIFT)
> > + header->offset >>= 3;
> > +
> > + for (i = 0, tmp = res; i < count; i++, tmp++) {
> > + tmp->start = pdev->resource[header->tbir].start +
> > + header->offset + i * (size << 2);
>
> Deserves a comment I think.
>
> > + tmp->end = tmp->start + (size << 2) - 1;
> > + tmp->flags = IORESOURCE_MEM;
> > + }
> > +
> > + cell->resources = res;
> > + cell->num_resources = count;
> > + cell->name = name;
> > +
> > + return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, cell, 1,
> > NULL, 0,
> > + NULL);
> > +}
> > +
> > +static int
> > +pmt_pci_probe(struct pci_dev *pdev, const struct pci_device_id
> > *id)
> > +{
> > + struct intel_dvsec_header header;
> > + struct pmt_platform_info *info;
> > + bool found_devices = false;
> > + int ret, pos = 0;
> > + u32 table;
> > + u16 vid;
> > +
> > + ret = pcim_enable_device(pdev);
> > + if (ret)
> > + return ret;
> > +
> > + info = devm_kmemdup(&pdev->dev, (void *)id->driver_data,
> > sizeof(*info),
> > + GFP_KERNEL);
> > + if (!info)
> > + return -ENOMEM;
> > +
> > + pos = pci_find_next_ext_capability(pdev, pos,
> > PCI_EXT_CAP_ID_DVSEC);
> > + while (pos) {
>
> If you do:
>
> do {
> int pos;
>
> pos = pci_find_next_ext_capability(pdev, pos,
> PCI_EXT_CAP_ID_DVSEC);
> if (!pos)
> break;
>
> Then you can invoke pci_find_next_ext_capability() once, no?
>
> > + pci_read_config_word(pdev, pos + PCI_DVSEC_HEADER1,
> > &vid);
> > + if (vid != PCI_VENDOR_ID_INTEL)
> > + continue;
> > +
> > + pci_read_config_word(pdev, pos + PCI_DVSEC_HEADER2,
> > + &header.id);
> > + pci_read_config_byte(pdev, pos + INTEL_DVSEC_ENTRIES,
> > + &header.num_entries);
> > + pci_read_config_byte(pdev, pos + INTEL_DVSEC_SIZE,
> > + &header.entry_size);
> > + pci_read_config_dword(pdev, pos + INTEL_DVSEC_TABLE,
> > + &table);
> > +
> > + header.tbir = INTEL_DVSEC_TABLE_BAR(table);
> > + header.offset = INTEL_DVSEC_TABLE_OFFSET(table);
> > +
> > + ret = pmt_add_dev(pdev, &header, info);
> > + if (ret)
> > + dev_warn(&pdev->dev,
> > + "Failed to add devices for DVSEC id
> > %d\n",
>
> "device", so not all devices, right?
>
> > + header.id);
>
> Don't you want to continue here?
>
> Else you're going to set found_devices for a failed device.
>
> > + found_devices = true;
> > +
> > + pos = pci_find_next_ext_capability(pdev, pos,
> > + PCI_EXT_CAP_ID_DVSEC
> > );
> > + }
> > +
> > + if (!found_devices) {
> > + dev_err(&pdev->dev, "No supported PMT capabilities
> > found.\n");
> > + return -ENODEV;
> > + }
> > +
> > + pm_runtime_put(&pdev->dev);
> > + pm_runtime_allow(&pdev->dev);
> > +
> > + return 0;
> > +}
> > +
> > +static void pmt_pci_remove(struct pci_dev *pdev)
> > +{
> > + pm_runtime_forbid(&pdev->dev);
> > + pm_runtime_get_sync(&pdev->dev);
> > +}
> > +
> > +#define PCI_DEVICE_ID_INTEL_PMT_TGL 0x9a0d
>
> What's this for?
>
> If this is PCI_DEVICE_DATA magic, it would be worth tying it to the
> struct i.e. remove the empty line between it and the table below.
>
> > +static const struct pci_device_id pmt_pci_ids[] = {
> > + { PCI_DEVICE_DATA(INTEL, PMT_TGL, &tgl_info) },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(pci, pmt_pci_ids);
> > +
> > +static struct pci_driver pmt_pci_driver = {
> > + .name = "intel-pmt",
> > + .id_table = pmt_pci_ids,
> > + .probe = pmt_pci_probe,
> > + .remove = pmt_pci_remove,
> > +};
> > +module_pci_driver(pmt_pci_driver);
> > +
> > +MODULE_AUTHOR("David E. Box <david.e.box@xxxxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("Intel Platform Monitoring Technology MFD
> > driver");
>
> s/MFD/(PMT)/
>
> > +MODULE_LICENSE("GPL v2");