PCI/NPEM: Add Native PCIe Enclosure Management support

Native PCIe Enclosure Management (NPEM, PCIe r6.1 sec 6.28) allows managing
LEDs in storage enclosures. NPEM is indication oriented and it does not
give direct access to LEDs. Although each indication *could* represent an
individual LED, multiple indications could also be represented as a single,
multi-color LED or a single LED blinking in a specific interval.  The
specification leaves that open.

Each enabled indication (capability register bit on) is represented as a
ledclass_dev which can be controlled through sysfs. For every ledclass
device only 2 brightness states are allowed: LED_ON (1) or LED_OFF (0).
This corresponds to the NPEM control register (Indication bit on/off).

Ledclass devices appear in sysfs as child devices (subdirectory) of PCI
device which has an NPEM Extended Capability and indication is enabled in
NPEM capability register. For example, these are LEDs created for pcieport
"10000:02:05.0" on my setup:

  leds/
  ├── 10000:02:05.0:enclosure:fail
  ├── 10000:02:05.0:enclosure:locate
  ├── 10000:02:05.0:enclosure:ok
  └── 10000:02:05.0:enclosure:rebuild

They can be also found in "/sys/class/leds" directory. The parent PCIe
device domain/bus/device/function address is used to guarantee uniqueness
across leds subsystem.

To enable/disable a "fail" indication, the "brightness" file can be edited:

  echo 1 > ./leds/10000:02:05.0:enclosure:fail/brightness
  echo 0 > ./leds/10000:02:05.0:enclosure:fail/brightness

PCIe r6.1, sec 7.9.19.2 defines the possible indications.

Multiple indications for same parent PCIe device can conflict and hardware
may update them when processing new request. To avoid issues, driver
refresh all indications by reading back control register.

This driver expects to be the exclusive NPEM extended capability manager.
It waits up to 1 second after imposing new request, it doesn't verify if
controller is busy before write, and it assumes the mutex lock gives
protection from concurrent updates.

If _DSM LED management is available, we assume the platform may be using
NPEM for its own purposes (see PCI Firmware Spec r3.3 sec 4.7), so the
driver does not use NPEM. A future patch will add _DSM support; an info
message notes whether NPEM or _DSM is being used.

NPEM is a PCIe extended capability so it should be registered in
pcie_init_capabilities() but it is not possible due to LED dependency.  The
parent pci_device must be added earlier for led_classdev_register() to be
successful. NPEM does not require configuration on kernel side, so it is
safe to register LED devices later.

Link: https://lore.kernel.org/r/20240904104848.23480-3-mariusz.tkaczyk@linux.intel.com
Suggested-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
This commit is contained in:
Mariusz Tkaczyk 2024-09-04 12:48:47 +02:00 committed by Bjorn Helgaas
parent 78efa53e71
commit 4e893545ef
9 changed files with 546 additions and 0 deletions

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@ -500,3 +500,66 @@ Description:
console drivers from the device. Raw users of pci-sysfs
resourceN attributes must be terminated prior to resizing.
Success of the resizing operation is not guaranteed.
What: /sys/bus/pci/devices/.../leds/*:enclosure:*/brightness
What: /sys/class/leds/*:enclosure:*/brightness
Date: August 2024
KernelVersion: 6.12
Description:
LED indications on PCIe storage enclosures which are controlled
through the NPEM interface (Native PCIe Enclosure Management,
PCIe r6.1 sec 6.28) are accessible as led class devices, both
below /sys/class/leds and below NPEM-capable PCI devices.
Although these led class devices could be manipulated manually,
in practice they are typically manipulated automatically by an
application such as ledmon(8).
The name of a led class device is as follows:
<bdf>:enclosure:<indication>
where:
- <bdf> is the domain, bus, device and function number
(e.g. 10000:02:05.0)
- <indication> is a short description of the LED indication
Valid indications per PCIe r6.1 table 6-27 are:
- ok (drive is functioning normally)
- locate (drive is being identified by an admin)
- fail (drive is not functioning properly)
- rebuild (drive is part of an array that is rebuilding)
- pfa (drive is predicted to fail soon)
- hotspare (drive is marked to be used as a replacement)
- ica (drive is part of an array that is degraded)
- ifa (drive is part of an array that is failed)
- idt (drive is not the right type for the connector)
- disabled (drive is disabled, removal is safe)
- specific0 to specific7 (enclosure-specific indications)
Broadly, the indications fall into one of these categories:
- to signify drive state (ok, locate, fail, idt, disabled)
- to signify drive role or state in a software RAID array
(rebuild, pfa, hotspare, ica, ifa)
- to signify any other role or state (specific0 to specific7)
Mandatory indications per PCIe r6.1 sec 7.9.19.2 comprise:
ok, locate, fail, rebuild. All others are optional.
A led class device is only visible if the corresponding
indication is supported by the device.
To manipulate the indications, write 0 (LED_OFF) or 1 (LED_ON)
to the "brightness" file. Note that manipulating an indication
may implicitly manipulate other indications at the vendor's
discretion. E.g. when the user lights up the "ok" indication,
the vendor may choose to automatically turn off the "fail"
indication. The current state of an indication can be
retrieved by reading its "brightness" file.
The PCIe Base Specification allows vendors leeway to choose
different colors or blinking patterns for the indications,
but they typically follow the IBPI standard. E.g. the "locate"
indication is usually presented as one or two LEDs blinking at
4 Hz frequency:
https://en.wikipedia.org/wiki/International_Blinking_Pattern_Interpretation

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@ -143,6 +143,15 @@ config PCI_IOV
If unsure, say N.
config PCI_NPEM
bool "Native PCIe Enclosure Management"
depends on LEDS_CLASS=y
help
Support for Native PCIe Enclosure Management. It allows managing LED
indications in storage enclosures. Enclosure must support following
indications: OK, Locate, Fail, Rebuild, other indications are
optional.
config PCI_PRI
bool "PCI PRI support"
select PCI_ATS

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@ -35,6 +35,7 @@ obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o
obj-$(CONFIG_VGA_ARB) += vgaarb.o
obj-$(CONFIG_PCI_DOE) += doe.o
obj-$(CONFIG_PCI_DYNAMIC_OF_NODES) += of_property.o
obj-$(CONFIG_PCI_NPEM) += npem.o
# Endpoint library must be initialized before its users
obj-$(CONFIG_PCI_ENDPOINT) += endpoint/

423
drivers/pci/npem.c Normal file
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@ -0,0 +1,423 @@
// SPDX-License-Identifier: GPL-2.0
/*
* PCIe Enclosure management driver created for LED interfaces based on
* indications. It says *what indications* blink but does not specify *how*
* they blink - it is hardware defined.
*
* The driver name refers to Native PCIe Enclosure Management. It is
* first indication oriented standard with specification.
*
* Native PCIe Enclosure Management (NPEM)
* PCIe Base Specification r6.1 sec 6.28, 7.9.19
*
* Copyright (c) 2023-2024 Intel Corporation
* Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
*/
#include <linux/acpi.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/iopoll.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/types.h>
#include <linux/uleds.h>
#include "pci.h"
struct indication {
u32 bit;
const char *name;
};
static const struct indication npem_indications[] = {
{PCI_NPEM_IND_OK, "enclosure:ok"},
{PCI_NPEM_IND_LOCATE, "enclosure:locate"},
{PCI_NPEM_IND_FAIL, "enclosure:fail"},
{PCI_NPEM_IND_REBUILD, "enclosure:rebuild"},
{PCI_NPEM_IND_PFA, "enclosure:pfa"},
{PCI_NPEM_IND_HOTSPARE, "enclosure:hotspare"},
{PCI_NPEM_IND_ICA, "enclosure:ica"},
{PCI_NPEM_IND_IFA, "enclosure:ifa"},
{PCI_NPEM_IND_IDT, "enclosure:idt"},
{PCI_NPEM_IND_DISABLED, "enclosure:disabled"},
{PCI_NPEM_IND_SPEC_0, "enclosure:specific_0"},
{PCI_NPEM_IND_SPEC_1, "enclosure:specific_1"},
{PCI_NPEM_IND_SPEC_2, "enclosure:specific_2"},
{PCI_NPEM_IND_SPEC_3, "enclosure:specific_3"},
{PCI_NPEM_IND_SPEC_4, "enclosure:specific_4"},
{PCI_NPEM_IND_SPEC_5, "enclosure:specific_5"},
{PCI_NPEM_IND_SPEC_6, "enclosure:specific_6"},
{PCI_NPEM_IND_SPEC_7, "enclosure:specific_7"},
{0, NULL}
};
#define for_each_indication(ind, inds) \
for (ind = inds; ind->bit; ind++)
/*
* The driver has internal list of supported indications. Ideally, the driver
* should not touch bits that are not defined and for which LED devices are
* not exposed but in reality, it needs to turn them off.
*
* Otherwise, there will be no possibility to turn off indications turned on by
* other utilities or turned on by default and it leads to bad user experience.
*
* Additionally, it excludes NPEM commands like RESET or ENABLE.
*/
static u32 reg_to_indications(u32 caps, const struct indication *inds)
{
const struct indication *ind;
u32 supported_indications = 0;
for_each_indication(ind, inds)
supported_indications |= ind->bit;
return caps & supported_indications;
}
/**
* struct npem_led - LED details
* @indication: indication details
* @npem: NPEM device
* @name: LED name
* @led: LED device
*/
struct npem_led {
const struct indication *indication;
struct npem *npem;
char name[LED_MAX_NAME_SIZE];
struct led_classdev led;
};
/**
* struct npem_ops - backend specific callbacks
* @get_active_indications: get active indications
* npem: NPEM device
* inds: response buffer
* @set_active_indications: set new indications
* npem: npem device
* inds: bit mask to set
* @inds: supported indications array, set of indications is backend specific
* @name: backend name
*/
struct npem_ops {
int (*get_active_indications)(struct npem *npem, u32 *inds);
int (*set_active_indications)(struct npem *npem, u32 inds);
const struct indication *inds;
const char *name;
};
/**
* struct npem - NPEM device properties
* @dev: PCI device this driver is attached to
* @ops: backend specific callbacks
* @lock: serializes concurrent access to NPEM device by multiple LED devices
* @pos: cached offset of NPEM Capability Register in Configuration Space;
* only used if NPEM registers are accessed directly and not through _DSM
* @supported_indications: cached bit mask of supported indications;
* non-indication and reserved bits in the NPEM Capability Register are
* cleared in this bit mask
* @active_indications: cached bit mask of active indications;
* non-indication and reserved bits in the NPEM Control Register are
* cleared in this bit mask
* @led_cnt: size of @leds array
* @leds: array containing LED class devices of all supported LEDs
*/
struct npem {
struct pci_dev *dev;
const struct npem_ops *ops;
struct mutex lock;
u16 pos;
u32 supported_indications;
u32 active_indications;
int led_cnt;
struct npem_led leds[];
};
static int npem_read_reg(struct npem *npem, u16 reg, u32 *val)
{
int ret = pci_read_config_dword(npem->dev, npem->pos + reg, val);
return pcibios_err_to_errno(ret);
}
static int npem_write_ctrl(struct npem *npem, u32 reg)
{
int pos = npem->pos + PCI_NPEM_CTRL;
int ret = pci_write_config_dword(npem->dev, pos, reg);
return pcibios_err_to_errno(ret);
}
static int npem_get_active_indications(struct npem *npem, u32 *inds)
{
u32 ctrl;
int ret;
ret = npem_read_reg(npem, PCI_NPEM_CTRL, &ctrl);
if (ret)
return ret;
/* If PCI_NPEM_CTRL_ENABLE is not set then no indication should blink */
if (!(ctrl & PCI_NPEM_CTRL_ENABLE)) {
*inds = 0;
return 0;
}
*inds = ctrl & npem->supported_indications;
return 0;
}
static int npem_set_active_indications(struct npem *npem, u32 inds)
{
int ctrl, ret, ret_val;
u32 cc_status;
lockdep_assert_held(&npem->lock);
/* This bit is always required */
ctrl = inds | PCI_NPEM_CTRL_ENABLE;
ret = npem_write_ctrl(npem, ctrl);
if (ret)
return ret;
/*
* For the case where a NPEM command has not completed immediately,
* it is recommended that software not continuously "spin" on polling
* the status register, but rather poll under interrupt at a reduced
* rate; for example at 10 ms intervals.
*
* PCIe r6.1 sec 6.28 "Implementation Note: Software Polling of NPEM
* Command Completed"
*/
ret = read_poll_timeout(npem_read_reg, ret_val,
ret_val || (cc_status & PCI_NPEM_STATUS_CC),
10 * USEC_PER_MSEC, USEC_PER_SEC, false, npem,
PCI_NPEM_STATUS, &cc_status);
if (ret)
return ret;
if (ret_val)
return ret_val;
/*
* All writes to control register, including writes that do not change
* the register value, are NPEM commands and should eventually result
* in a command completion indication in the NPEM Status Register.
*
* PCIe Base Specification r6.1 sec 7.9.19.3
*
* Register may not be updated, or other conflicting bits may be
* cleared. Spec is not strict here. Read NPEM Control register after
* write to keep cache in-sync.
*/
return npem_get_active_indications(npem, &npem->active_indications);
}
static const struct npem_ops npem_ops = {
.get_active_indications = npem_get_active_indications,
.set_active_indications = npem_set_active_indications,
.name = "Native PCIe Enclosure Management",
.inds = npem_indications,
};
#define DSM_GUID GUID_INIT(0x5d524d9d, 0xfff9, 0x4d4b, 0x8c, 0xb7, 0x74, 0x7e,\
0xd5, 0x1e, 0x19, 0x4d)
#define GET_SUPPORTED_STATES_DSM 1
#define GET_STATE_DSM 2
#define SET_STATE_DSM 3
static const guid_t dsm_guid = DSM_GUID;
static bool npem_has_dsm(struct pci_dev *pdev)
{
acpi_handle handle;
handle = ACPI_HANDLE(&pdev->dev);
if (!handle)
return false;
return acpi_check_dsm(handle, &dsm_guid, 0x1,
BIT(GET_SUPPORTED_STATES_DSM) |
BIT(GET_STATE_DSM) | BIT(SET_STATE_DSM));
}
/*
* The status of each indicator is cached on first brightness_ get/set time
* and updated at write time. brightness_get() is only responsible for
* reflecting the last written/cached value.
*/
static enum led_brightness brightness_get(struct led_classdev *led)
{
struct npem_led *nled = container_of(led, struct npem_led, led);
struct npem *npem = nled->npem;
int ret, val = 0;
ret = mutex_lock_interruptible(&npem->lock);
if (ret)
return ret;
if (npem->active_indications & nled->indication->bit)
val = 1;
mutex_unlock(&npem->lock);
return val;
}
static int brightness_set(struct led_classdev *led,
enum led_brightness brightness)
{
struct npem_led *nled = container_of(led, struct npem_led, led);
struct npem *npem = nled->npem;
u32 indications;
int ret;
ret = mutex_lock_interruptible(&npem->lock);
if (ret)
return ret;
if (brightness == 0)
indications = npem->active_indications & ~(nled->indication->bit);
else
indications = npem->active_indications | nled->indication->bit;
ret = npem->ops->set_active_indications(npem, indications);
mutex_unlock(&npem->lock);
return ret;
}
static void npem_free(struct npem *npem)
{
struct npem_led *nled;
int cnt;
if (!npem)
return;
for (cnt = 0; cnt < npem->led_cnt; cnt++) {
nled = &npem->leds[cnt];
if (nled->name[0])
led_classdev_unregister(&nled->led);
}
mutex_destroy(&npem->lock);
kfree(npem);
}
static int pci_npem_set_led_classdev(struct npem *npem, struct npem_led *nled)
{
struct led_classdev *led = &nled->led;
struct led_init_data init_data = {};
char *name = nled->name;
int ret;
init_data.devicename = pci_name(npem->dev);
init_data.default_label = nled->indication->name;
ret = led_compose_name(&npem->dev->dev, &init_data, name);
if (ret)
return ret;
led->name = name;
led->brightness_set_blocking = brightness_set;
led->brightness_get = brightness_get;
led->max_brightness = 1;
led->default_trigger = "none";
led->flags = 0;
ret = led_classdev_register(&npem->dev->dev, led);
if (ret)
/* Clear the name to indicate that it is not registered. */
name[0] = 0;
return ret;
}
static int pci_npem_init(struct pci_dev *dev, const struct npem_ops *ops,
int pos, u32 caps)
{
u32 supported = reg_to_indications(caps, ops->inds);
int supported_cnt = hweight32(supported);
const struct indication *indication;
struct npem_led *nled;
struct npem *npem;
int led_idx = 0;
int ret;
npem = kzalloc(struct_size(npem, leds, supported_cnt), GFP_KERNEL);
if (!npem)
return -ENOMEM;
npem->supported_indications = supported;
npem->led_cnt = supported_cnt;
npem->pos = pos;
npem->dev = dev;
npem->ops = ops;
ret = npem->ops->get_active_indications(npem,
&npem->active_indications);
if (ret)
return ret;
mutex_init(&npem->lock);
for_each_indication(indication, npem_indications) {
if (!(npem->supported_indications & indication->bit))
continue;
nled = &npem->leds[led_idx++];
nled->indication = indication;
nled->npem = npem;
ret = pci_npem_set_led_classdev(npem, nled);
if (ret) {
npem_free(npem);
return ret;
}
}
dev->npem = npem;
return 0;
}
void pci_npem_remove(struct pci_dev *dev)
{
npem_free(dev->npem);
}
void pci_npem_create(struct pci_dev *dev)
{
const struct npem_ops *ops = &npem_ops;
int pos = 0, ret;
u32 cap;
if (npem_has_dsm(dev)) {
/*
* OS should use the DSM for LED control if it is available
* PCI Firmware Spec r3.3 sec 4.7.
*/
pci_info(dev, "Not configuring %s because _DSM is present\n",
ops->name);
return;
} else {
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_NPEM);
if (pos == 0)
return;
if (pci_read_config_dword(dev, pos + PCI_NPEM_CAP, &cap) != 0 ||
(cap & PCI_NPEM_CAP_CAPABLE) == 0)
return;
}
pci_info(dev, "Configuring %s\n", ops->name);
ret = pci_npem_init(dev, ops, pos, cap);
if (ret)
pci_err(dev, "Failed to register %s, err: %d\n", ops->name,
ret);
}

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@ -398,6 +398,14 @@ static inline void pci_doe_destroy(struct pci_dev *pdev) { }
static inline void pci_doe_disconnected(struct pci_dev *pdev) { }
#endif
#ifdef CONFIG_PCI_NPEM
void pci_npem_create(struct pci_dev *dev);
void pci_npem_remove(struct pci_dev *dev);
#else
static inline void pci_npem_create(struct pci_dev *dev) { }
static inline void pci_npem_remove(struct pci_dev *dev) { }
#endif
/**
* pci_dev_set_io_state - Set the new error state if possible.
*

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@ -2593,6 +2593,8 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
dev->match_driver = false;
ret = device_add(&dev->dev);
WARN_ON(ret < 0);
pci_npem_create(dev);
}
struct pci_dev *pci_scan_single_device(struct pci_bus *bus, int devfn)

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@ -34,6 +34,8 @@ static void pci_destroy_dev(struct pci_dev *dev)
if (!dev->dev.kobj.parent)
return;
pci_npem_remove(dev);
device_del(&dev->dev);
down_write(&pci_bus_sem);

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@ -516,6 +516,9 @@ struct pci_dev {
#endif
#ifdef CONFIG_PCI_DOE
struct xarray doe_mbs; /* Data Object Exchange mailboxes */
#endif
#ifdef CONFIG_PCI_NPEM
struct npem *npem; /* Native PCIe Enclosure Management */
#endif
u16 acs_cap; /* ACS Capability offset */
phys_addr_t rom; /* Physical address if not from BAR */

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@ -740,6 +740,7 @@
#define PCI_EXT_CAP_ID_DVSEC 0x23 /* Designated Vendor-Specific */
#define PCI_EXT_CAP_ID_DLF 0x25 /* Data Link Feature */
#define PCI_EXT_CAP_ID_PL_16GT 0x26 /* Physical Layer 16.0 GT/s */
#define PCI_EXT_CAP_ID_NPEM 0x29 /* Native PCIe Enclosure Management */
#define PCI_EXT_CAP_ID_PL_32GT 0x2A /* Physical Layer 32.0 GT/s */
#define PCI_EXT_CAP_ID_DOE 0x2E /* Data Object Exchange */
#define PCI_EXT_CAP_ID_MAX PCI_EXT_CAP_ID_DOE
@ -1121,6 +1122,40 @@
#define PCI_PL_16GT_LE_CTRL_USP_TX_PRESET_MASK 0x000000F0
#define PCI_PL_16GT_LE_CTRL_USP_TX_PRESET_SHIFT 4
/* Native PCIe Enclosure Management */
#define PCI_NPEM_CAP 0x04 /* NPEM capability register */
#define PCI_NPEM_CAP_CAPABLE 0x00000001 /* NPEM Capable */
#define PCI_NPEM_CTRL 0x08 /* NPEM control register */
#define PCI_NPEM_CTRL_ENABLE 0x00000001 /* NPEM Enable */
/*
* Native PCIe Enclosure Management indication bits and Reset command bit
* are corresponding for capability and control registers.
*/
#define PCI_NPEM_CMD_RESET 0x00000002 /* Reset Command */
#define PCI_NPEM_IND_OK 0x00000004 /* OK */
#define PCI_NPEM_IND_LOCATE 0x00000008 /* Locate */
#define PCI_NPEM_IND_FAIL 0x00000010 /* Fail */
#define PCI_NPEM_IND_REBUILD 0x00000020 /* Rebuild */
#define PCI_NPEM_IND_PFA 0x00000040 /* Predicted Failure Analysis */
#define PCI_NPEM_IND_HOTSPARE 0x00000080 /* Hot Spare */
#define PCI_NPEM_IND_ICA 0x00000100 /* In Critical Array */
#define PCI_NPEM_IND_IFA 0x00000200 /* In Failed Array */
#define PCI_NPEM_IND_IDT 0x00000400 /* Device Type */
#define PCI_NPEM_IND_DISABLED 0x00000800 /* Disabled */
#define PCI_NPEM_IND_SPEC_0 0x01000000
#define PCI_NPEM_IND_SPEC_1 0x02000000
#define PCI_NPEM_IND_SPEC_2 0x04000000
#define PCI_NPEM_IND_SPEC_3 0x08000000
#define PCI_NPEM_IND_SPEC_4 0x10000000
#define PCI_NPEM_IND_SPEC_5 0x20000000
#define PCI_NPEM_IND_SPEC_6 0x40000000
#define PCI_NPEM_IND_SPEC_7 0x80000000
#define PCI_NPEM_STATUS 0x0c /* NPEM status register */
#define PCI_NPEM_STATUS_CC 0x00000001 /* Command Completed */
/* Data Object Exchange */
#define PCI_DOE_CAP 0x04 /* DOE Capabilities Register */
#define PCI_DOE_CAP_INT_SUP 0x00000001 /* Interrupt Support */