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Date: Tue, 22 Mar 2022 09:36:02 -0700
From: Won Chung <wonchung@...gle.com>
To: Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J . Wysocki" <rafael@...nel.org>,
Benson Leung <bleung@...omium.org>,
Prashant Malani <pmalani@...omium.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6] driver core: Add sysfs support for physical location
of a device
On Mon, Mar 14, 2022 at 12:55 PM Won Chung <wonchung@...gle.com> wrote:
>
> When ACPI table includes _PLD fields for a device, create a new
> directory (physical_location) in sysfs to share _PLD fields.
>
> Currently without PLD information, when there are multiple of same
> devices, it is hard to distinguish which device corresponds to which
> physical device at which location. For example, when there are two Type
> C connectors, it is hard to find out which connector corresponds to the
> Type C port on the left panel versus the Type C port on the right panel.
> With PLD information provided, we can determine which specific device at
> which location is doing what.
>
> _PLD output includes much more fields, but only generic fields are added
> and exposed to sysfs, so that non-ACPI devices can also support it in
> the future. The minimal generic fields needed for locating a device are
> the following.
> - panel
> - vertical_position
> - horizontal_position
> - dock
> - lid
>
> Signed-off-by: Won Chung <wonchung@...gle.com>
> ---
>
> Changes from v5
> - Remove physical_location directory only if physical_location is present.
> - Free memory for physical_location in device when device is removed.
>
> Changes from v4
> - Remove physical_location directory when device is deleted.
> - Correctly handle error from adding physical_location in
> device_add_attrs().
>
> Changes from v3
> - Move dev_add_physical_location() and dev_attr_physical_location_group
> to driver/base/physical_location.h.
> - Use pointer and reorder physical_location in struct device to pack its
> bytes. (checked using pahole)
> - Unify naming to physical_location since the name location is used in
> some places like USB port for different information.
>
> Changes from v2
> - Use sysfs_emit to create files.
> - Correct mix of spaces and tabs.
>
> Changes from v1
> - Correct directory names in Documentation.
> - Clarify namings in core.c
>
> .../testing/sysfs-devices-physical_location | 42 ++++++
> drivers/base/Makefile | 1 +
> drivers/base/core.c | 15 ++
> drivers/base/physical_location.c | 137 ++++++++++++++++++
> drivers/base/physical_location.h | 16 ++
> include/linux/device.h | 73 ++++++++++
> 6 files changed, 284 insertions(+)
> create mode 100644 Documentation/ABI/testing/sysfs-devices-physical_location
> create mode 100644 drivers/base/physical_location.c
> create mode 100644 drivers/base/physical_location.h
>
> diff --git a/Documentation/ABI/testing/sysfs-devices-physical_location b/Documentation/ABI/testing/sysfs-devices-physical_location
> new file mode 100644
> index 000000000000..202324b87083
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-devices-physical_location
> @@ -0,0 +1,42 @@
> +What: /sys/devices/.../physical_location
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + This directory contains information on physical location of
> + the device connection point with respect to the system's
> + housing.
> +
> +What: /sys/devices/.../physical_location/panel
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + Describes which panel surface of the system’s housing the
> + device connection point resides on.
> +
> +What: /sys/devices/.../physical_location/vertical_position
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + Describes vertical position of the device connection point on
> + the panel surface.
> +
> +What: /sys/devices/.../physical_location/horizontal_position
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + Describes horizontal position of the device connection point on
> + the panel surface.
> +
> +What: /sys/devices/.../physical_location/dock
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + "Yes" if the device connection point resides in a docking
> + station or a port replicator. "No" otherwise.
> +
> +What: /sys/devices/.../physical_location/lid
> +Date: March 2022
> +Contact: Won Chung <wonchung@...gle.com>
> +Description:
> + "Yes" if the device connection point resides on the lid of
> + laptop system. "No" otherwise.
> diff --git a/drivers/base/Makefile b/drivers/base/Makefile
> index 02f7f1358e86..83217d243c25 100644
> --- a/drivers/base/Makefile
> +++ b/drivers/base/Makefile
> @@ -25,6 +25,7 @@ obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
> obj-$(CONFIG_GENERIC_MSI_IRQ_DOMAIN) += platform-msi.o
> obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
> obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
> +obj-$(CONFIG_ACPI) += physical_location.o
>
> obj-y += test/
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 7bb957b11861..64d4d8646c12 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -32,6 +32,7 @@
> #include <linux/dma-map-ops.h> /* for dma_default_coherent */
>
> #include "base.h"
> +#include "physical_location.h"
> #include "power/power.h"
>
> #ifdef CONFIG_SYSFS_DEPRECATED
> @@ -2649,8 +2650,17 @@ static int device_add_attrs(struct device *dev)
> goto err_remove_dev_waiting_for_supplier;
> }
>
> + if (dev_add_physical_location(dev)) {
> + error = device_add_group(dev,
> + &dev_attr_physical_location_group);
> + if (error)
> + goto err_remove_dev_removable;
> + }
> +
> return 0;
>
> + err_remove_dev_removable:
> + device_remove_file(dev, &dev_attr_removable);
> err_remove_dev_waiting_for_supplier:
> device_remove_file(dev, &dev_attr_waiting_for_supplier);
> err_remove_dev_online:
> @@ -2672,6 +2682,11 @@ static void device_remove_attrs(struct device *dev)
> struct class *class = dev->class;
> const struct device_type *type = dev->type;
>
> + if (dev->physical_location) {
> + device_remove_group(dev, &dev_attr_physical_location_group);
> + kfree(dev->physical_location);
> + }
> +
> device_remove_file(dev, &dev_attr_removable);
> device_remove_file(dev, &dev_attr_waiting_for_supplier);
> device_remove_file(dev, &dev_attr_online);
> diff --git a/drivers/base/physical_location.c b/drivers/base/physical_location.c
> new file mode 100644
> index 000000000000..4c1a52ecd7f6
> --- /dev/null
> +++ b/drivers/base/physical_location.c
> @@ -0,0 +1,137 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Device physical location support
> + *
> + * Author: Won Chung <wonchung@...gle.com>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/sysfs.h>
> +
> +#include "physical_location.h"
> +
> +bool dev_add_physical_location(struct device *dev)
> +{
> + struct acpi_pld_info *pld;
> + acpi_status status;
> +
> + if (!has_acpi_companion(dev))
> + return false;
> +
> + status = acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld);
> + if (ACPI_FAILURE(status))
> + return false;
> +
> + dev->physical_location =
> + kzalloc(sizeof(*dev->physical_location), GFP_KERNEL);
> + dev->physical_location->panel = pld->panel;
> + dev->physical_location->vertical_position = pld->vertical_position;
> + dev->physical_location->horizontal_position = pld->horizontal_position;
> + dev->physical_location->dock = pld->dock;
> + dev->physical_location->lid = pld->lid;
> +
> + return true;
> +}
> +
> +static ssize_t panel_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + const char *panel;
> +
> + switch (dev->physical_location->panel) {
> + case DEVICE_PANEL_TOP:
> + panel = "top";
> + break;
> + case DEVICE_PANEL_BOTTOM:
> + panel = "bottom";
> + break;
> + case DEVICE_PANEL_LEFT:
> + panel = "left";
> + break;
> + case DEVICE_PANEL_RIGHT:
> + panel = "right";
> + break;
> + case DEVICE_PANEL_FRONT:
> + panel = "front";
> + break;
> + default:
> + panel = "unknown";
> + }
> + return sysfs_emit(buf, "%s\n", panel);
> +}
> +static DEVICE_ATTR_RO(panel);
> +
> +static ssize_t vertical_position_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + const char *vertical_position;
> +
> + switch (dev->physical_location->vertical_position) {
> + case DEVICE_VERT_POS_UPPER:
> + vertical_position = "upper";
> + break;
> + case DEVICE_VERT_POS_CENTER:
> + vertical_position = "center";
> + break;
> + case DEVICE_VERT_POS_LOWER:
> + vertical_position = "lower";
> + break;
> + default:
> + vertical_position = "unknown";
> + }
> + return sysfs_emit(buf, "%s\n", vertical_position);
> +}
> +static DEVICE_ATTR_RO(vertical_position);
> +
> +static ssize_t horizontal_position_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + const char *horizontal_position;
> +
> + switch (dev->physical_location->horizontal_position) {
> + case DEVICE_HORI_POS_LEFT:
> + horizontal_position = "left";
> + break;
> + case DEVICE_HORI_POS_CENTER:
> + horizontal_position = "center";
> + break;
> + case DEVICE_HORI_POS_RIGHT:
> + horizontal_position = "right";
> + break;
> + default:
> + horizontal_position = "unknown";
> + }
> + return sysfs_emit(buf, "%s\n", horizontal_position);
> +}
> +static DEVICE_ATTR_RO(horizontal_position);
> +
> +static ssize_t dock_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + return sysfs_emit(buf, "%s\n",
> + dev->physical_location->dock ? "yes" : "no");
> +}
> +static DEVICE_ATTR_RO(dock);
> +
> +static ssize_t lid_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + return sysfs_emit(buf, "%s\n",
> + dev->physical_location->lid ? "yes" : "no");
> +}
> +static DEVICE_ATTR_RO(lid);
> +
> +static struct attribute *dev_attr_physical_location[] = {
> + &dev_attr_panel.attr,
> + &dev_attr_vertical_position.attr,
> + &dev_attr_horizontal_position.attr,
> + &dev_attr_dock.attr,
> + &dev_attr_lid.attr,
> + NULL,
> +};
> +
> +const struct attribute_group dev_attr_physical_location_group = {
> + .name = "physical_location",
> + .attrs = dev_attr_physical_location,
> +};
> +
> diff --git a/drivers/base/physical_location.h b/drivers/base/physical_location.h
> new file mode 100644
> index 000000000000..82cde9f1b161
> --- /dev/null
> +++ b/drivers/base/physical_location.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Device physical location support
> + *
> + * Author: Won Chung <wonchung@...gle.com>
> + */
> +
> +#include <linux/device.h>
> +
> +#ifdef CONFIG_ACPI
> +extern bool dev_add_physical_location(struct device *dev);
> +extern const struct attribute_group dev_attr_physical_location_group;
> +#else
> +static inline bool dev_add_physical_location(struct device *dev) { return false; };
> +static const struct attribute_group dev_attr_physical_location_group = {};
> +#endif
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 93459724dcde..766fbea6ca83 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -386,6 +386,75 @@ struct dev_msi_info {
> #endif
> };
>
> +/**
> + * enum device_physical_location_panel - Describes which panel surface of the
> + * system's housing the device connection point resides on.
> + * @DEVICE_PANEL_TOP: Device connection point is on the top panel.
> + * @DEVICE_PANEL_BOTTOM: Device connection point is on the bottom panel.
> + * @DEVICE_PANEL_LEFT: Device connection point is on the left panel.
> + * @DEVICE_PANEL_RIGHT: Device connection point is on the right panel.
> + * @DEVICE_PANEL_FRONT: Device connection point is on the front panel.
> + * @DEVICE_PANEL_BACK: Device connection point is on the back panel.
> + * @DEVICE_PANEL_UNKNOWN: The panel with device connection point is unknown.
> + */
> +enum device_physical_location_panel {
> + DEVICE_PANEL_TOP,
> + DEVICE_PANEL_BOTTOM,
> + DEVICE_PANEL_LEFT,
> + DEVICE_PANEL_RIGHT,
> + DEVICE_PANEL_FRONT,
> + DEVICE_PANEL_BACK,
> + DEVICE_PANEL_UNKNOWN,
> +};
> +
> +/**
> + * enum device_physical_location_vertical_position - Describes vertical
> + * position of the device connection point on the panel surface.
> + * @DEVICE_VERT_POS_UPPER: Device connection point is at upper part of panel.
> + * @DEVICE_VERT_POS_CENTER: Device connection point is at center part of panel.
> + * @DEVICE_VERT_POS_LOWER: Device connection point is at lower part of panel.
> + */
> +enum device_physical_location_vertical_position {
> + DEVICE_VERT_POS_UPPER,
> + DEVICE_VERT_POS_CENTER,
> + DEVICE_VERT_POS_LOWER,
> +};
> +
> +/**
> + * enum device_physical_location_horizontal_position - Describes horizontal
> + * position of the device connection point on the panel surface.
> + * @DEVICE_HORI_POS_LEFT: Device connection point is at left part of panel.
> + * @DEVICE_HORI_POS_CENTER: Device connection point is at center part of panel.
> + * @DEVICE_HORI_POS_RIGHT: Device connection point is at right part of panel.
> + */
> +enum device_physical_location_horizontal_position {
> + DEVICE_HORI_POS_LEFT,
> + DEVICE_HORI_POS_CENTER,
> + DEVICE_HORI_POS_RIGHT,
> +};
> +
> +/**
> + * struct device_physical_location - Device data related to physical location
> + * of the device connection point.
> + * @panel: Panel surface of the system's housing that the device connection
> + * point resides on.
> + * @vertical_position: Vertical position of the device connection point within
> + * the panel.
> + * @horizontal_position: Horizontal position of the device connection point
> + * within the panel.
> + * @dock: Set if the device connection point resides in a docking station or
> + * port replicator.
> + * @lid: Set if this device connection point resides on the lid of laptop
> + * system.
> + */
> +struct device_physical_location {
> + enum device_physical_location_panel panel;
> + enum device_physical_location_vertical_position vertical_position;
> + enum device_physical_location_horizontal_position horizontal_position;
> + bool dock;
> + bool lid;
> +};
> +
> /**
> * struct device - The basic device structure
> * @parent: The device's "parent" device, the device to which it is attached.
> @@ -453,6 +522,8 @@ struct dev_msi_info {
> * device (i.e. the bus driver that discovered the device).
> * @iommu_group: IOMMU group the device belongs to.
> * @iommu: Per device generic IOMMU runtime data
> + * @physical_location: Describes physical location of the device connection
> + * point in the system housing.
> * @removable: Whether the device can be removed from the system. This
> * should be set by the subsystem / bus driver that discovered
> * the device.
> @@ -567,6 +638,8 @@ struct device {
> struct iommu_group *iommu_group;
> struct dev_iommu *iommu;
>
> + struct device_physical_location *physical_location;
> +
> enum device_removable removable;
>
> bool offline_disabled:1;
> --
> 2.35.1.723.g4982287a31-goog
>
Hi Greg,
I am sorry to keep bothering you with this, but can you take a look at
this patch for a review when you have time? Thank you very much!
Won
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