Re: [PATCH v8 RESEND] Introduce Cray ClusterStor E1000 NVMe slot LED driver

[Corey Minyard <corey@minyard.net>]

On Wed, Apr 29, 2026 at 04:22:55PM -0700, Tony Hutter wrote:
> Add driver to control the NVMe slot LEDs on the Cray ClusterStor E1000.
> The driver provides hotplug attention status callbacks for the 24 NVMe
> slots on the E1000.  This allows users to access the E1000's locate and
> fault LEDs via the normal /sys/bus/pci/slots/<slot>/attention sysfs
> entries.  This driver uses IPMI to communicate with the E1000 controller
> to toggle the LEDs.
> 
> Signed-off-by: Tony Hutter <hutter2@llnl.gov>

For the IPMI portions:
Reviewed-by: Corey Minyard <corey@minyard.net>

Have you tested removing and adding the IPMI interface while this is up?
You can do that with the hotmod interface on IPMI.  I didn't see any
issues, but it's always good to test.

-corey

> ---
> Changes in v8:
>  - Remove unused variable in craye1k_get_attention_status().
> 
> Changes in v7:
>  - Update sysfs-bus-pci text from feedback.
>  - Add DMI dependency to Kconfig.
>  - Refactor pciehp_core.c to remove CONFIG_HOTPLUG_PCI_PCIE_CRAY_E1000
>    code blocks.
>  - Move errno.h #include into correct alphabetical order.
>  - Add comment describing the reasoning for the debugfs counters.
>  - Move craye1k_init() call from pcie_hp_init() to init_slot().
>  - Make craye1k mutex global rather than in craye1k->lock.  This enables
>    handling of craye1k_[get|set]_attention_status() calls before the craye1k
>    driver is initialized.
>  - Do driver cleanup on craye1k_smi_gone().
> 
> Changes in v6:
>  - Change some dev_info_ratelimited() calls to dev_info().
>  - Don't call craye1k_init() if pcie_port_service_register() fails.
>  - Fix stray indent in #define CRAYE1K_POST_CMD_WAIT_MS
> 
> Changes in v5:
>  - Removed unnecessary ipmi_smi.h #include.
>  - Added WARN_ON() to craye1k_do_message() to sanity check that craye1k->lock
>    is held.
>  - Added additional comments for when craye1k->lock should be held.
> 
> Changes in v4:
>  - Fix typo in Kconfig: "is it" ->  "it is"
>  - Rename some #defines to CRAYE1K_SUBCMD_*
>  - Use IS_ERR() check in craye1k_debugfs_init()
>  - Return -EIO instead of -EINVAL when LED value check fails
> 
> Changes in v3:
>  - Add 'attention' values in Documentation/ABI/testing/sysfs-bus-pci.
>  - Remove ACPI_PCI_SLOT dependency.
>  - Cleanup craye1k_do_message() error checking.
>  - Skip unneeded memcpy() on failure in __craye1k_do_command().
>  - Merge craye1k_do_command_and_netfn() code into craye1k_do_command().
>  - Make craye1k_is_primary() return boolean.
>  - Return negative error code on failure in craye1k_set_primary().
> 
> Changes in v2:
>  - Integrated E1000 code into the pciehp driver as an built-in
>    extention rather than as a standalone module.
>  - Moved debug tunables and counters to debugfs.
>  - Removed forward declarations.
>  - Kept the /sys/bus/pci/slots/<slot>/attention interface rather
>    than using NPEM/_DSM or led_classdev as suggested.  The "attention"
>    interface is more beneficial for our site, since it allows us to
>    control the NVMe slot LEDs agnostically across different enclosure
>    vendors and kernel versions using the same scripts.  It is also
>    nice to use the same /sys/bus/pci/slots/<slot>/ sysfs directory for
>    both slot LED toggling ("attention") and slot power control
>    ("power").
> ---
>  Documentation/ABI/testing/sysfs-bus-pci |  21 +
>  MAINTAINERS                             |   5 +
>  drivers/pci/hotplug/Kconfig             |  10 +
>  drivers/pci/hotplug/Makefile            |   3 +
>  drivers/pci/hotplug/pciehp.h            |  20 +
>  drivers/pci/hotplug/pciehp_core.c       |  20 +-
>  drivers/pci/hotplug/pciehp_craye1k.c    | 687 ++++++++++++++++++++++++
>  7 files changed, 765 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/pci/hotplug/pciehp_craye1k.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
> index 92debe879ffb..8536d2ff30d1 100644
> --- a/Documentation/ABI/testing/sysfs-bus-pci
> +++ b/Documentation/ABI/testing/sysfs-bus-pci
> @@ -231,6 +231,27 @@ Description:
>  		    - scXX contains the device subclass;
>  		    - iXX contains the device class programming interface.
>  
> +What:		/sys/bus/pci/slots/.../attention
> +Date:		February 2025
> +Contact:	linux-pci@vger.kernel.org
> +Description:
> +		The attention attribute is used to read or write the attention
> +		status for an enclosure slot.  This is often used to set the
> +		slot LED value on a NVMe storage enclosure.
> +
> +		Common values:
> +		0 = OFF
> +		1 = ON
> +		2 = blink
> +
> +		Using the Cray ClusterStor E1000 extensions:
> +		0 = fault LED OFF, locate LED OFF
> +		1 = fault LED ON,  locate LED OFF
> +		2 = fault LED OFF, locate LED ON
> +		3 = fault LED ON,  locate LED ON
> +
> +		Other values are no-op, OFF, or ON depending on the driver.
> +
>  What:		/sys/bus/pci/slots/.../module
>  Date:		June 2009
>  Contact:	linux-pci@vger.kernel.org
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9ac254f4ec41..861576d60a36 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6543,6 +6543,11 @@ S:	Maintained
>  F:	Documentation/filesystems/cramfs.rst
>  F:	fs/cramfs/
>  
> +CRAY CLUSTERSTOR E1000 NVME SLOT LED DRIVER EXTENSIONS
> +M:	Tony Hutter <hutter2@llnl.gov>
> +S:	Maintained
> +F:	drivers/pci/hotplug/pciehp_craye1k.c
> +
>  CRC LIBRARY
>  M:	Eric Biggers <ebiggers@kernel.org>
>  R:	Ard Biesheuvel <ardb@kernel.org>
> diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
> index 3207860b52e4..3cb84e5e13e9 100644
> --- a/drivers/pci/hotplug/Kconfig
> +++ b/drivers/pci/hotplug/Kconfig
> @@ -183,4 +183,14 @@ config HOTPLUG_PCI_S390
>  
>  	  When in doubt, say Y.
>  
> +config HOTPLUG_PCI_PCIE_CRAY_E1000
> +	bool "PCIe Hotplug extensions for Cray ClusterStor E1000"
> +	depends on DMI && HOTPLUG_PCI_PCIE && IPMI_HANDLER=y
> +	help
> +	  Say Y here if you have a Cray ClusterStor E1000 and want to control
> +	  your NVMe slot LEDs.  Without this driver it is not possible
> +	  to control the fault and locate LEDs on the E1000's 24 NVMe slots.
> +
> +	  When in doubt, say N.
> +
>  endif # HOTPLUG_PCI
> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
> index 40aaf31fe338..82a1f0592d0a 100644
> --- a/drivers/pci/hotplug/Makefile
> +++ b/drivers/pci/hotplug/Makefile
> @@ -66,6 +66,9 @@ pciehp-objs		:=	pciehp_core.o	\
>  				pciehp_ctrl.o	\
>  				pciehp_pci.o	\
>  				pciehp_hpc.o
> +ifdef CONFIG_HOTPLUG_PCI_PCIE_CRAY_E1000
> +pciehp-objs		+=	pciehp_craye1k.o
> +endif
>  
>  shpchp-objs		:=	shpchp_core.o	\
>  				shpchp_ctrl.o	\
> diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
> index debc79b0adfb..3a8173f3e159 100644
> --- a/drivers/pci/hotplug/pciehp.h
> +++ b/drivers/pci/hotplug/pciehp.h
> @@ -199,6 +199,17 @@ int pciehp_get_raw_indicator_status(struct hotplug_slot *h_slot, u8 *status);
>  
>  int pciehp_slot_reset(struct pcie_device *dev);
>  
> +#ifdef CONFIG_HOTPLUG_PCI_PCIE_CRAY_E1000
> +int craye1k_init(void);
> +bool is_craye1k_board(void);
> +int craye1k_get_attention_status(struct hotplug_slot *hotplug_slot, u8 *status);
> +int craye1k_set_attention_status(struct hotplug_slot *hotplug_slot, u8 status);
> +#else
> +#define craye1k_init() (0)
> +#define craye1k_get_attention_status NULL
> +#define craye1k_set_attention_status NULL
> +#endif
> +
>  static inline const char *slot_name(struct controller *ctrl)
>  {
>  	return hotplug_slot_name(&ctrl->hotplug_slot);
> @@ -209,4 +220,13 @@ static inline struct controller *to_ctrl(struct hotplug_slot *hotplug_slot)
>  	return container_of(hotplug_slot, struct controller, hotplug_slot);
>  }
>  
> +static inline bool is_craye1k_slot(struct controller *ctrl)
> +{
> +#ifdef CONFIG_HOTPLUG_PCI_PCIE_CRAY_E1000
> +	return (PSN(ctrl) >= 1 && PSN(ctrl) <= 24 && is_craye1k_board());
> +#else
> +	return false;
> +#endif
> +}
> +
>  #endif				/* _PCIEHP_H */
> diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
> index f59baa912970..3e8e2b3069bf 100644
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -72,6 +72,22 @@ static int init_slot(struct controller *ctrl)
>  	} else if (ctrl->pcie->port->hotplug_user_indicators) {
>  		ops->get_attention_status = pciehp_get_raw_indicator_status;
>  		ops->set_attention_status = pciehp_set_raw_indicator_status;
> +	} else if (is_craye1k_slot(ctrl)) {
> +		/*
> +		 * The Cray E1000 driver controls slots 1-24.  Initialize the
> +		 * Cray E1000 driver when slot 1 is seen.
> +		 */
> +		if (PSN(ctrl) == 1) {
> +			retval = craye1k_init();
> +			if (retval) {
> +				ctrl_err(ctrl,
> +					 "Error loading Cray E1000 extensions");
> +				kfree(ops);
> +				return retval;
> +			}
> +		}
> +		ops->get_attention_status = craye1k_get_attention_status;
> +		ops->set_attention_status = craye1k_set_attention_status;
>  	}
>  
>  	/* register this slot with the hotplug pci core */
> @@ -376,8 +392,10 @@ int __init pcie_hp_init(void)
>  
>  	retval = pcie_port_service_register(&hpdriver_portdrv);
>  	pr_debug("pcie_port_service_register = %d\n", retval);
> -	if (retval)
> +	if (retval) {
>  		pr_debug("Failure to register service\n");
> +		return retval;
> +	}
>  
>  	return retval;
>  }
> diff --git a/drivers/pci/hotplug/pciehp_craye1k.c b/drivers/pci/hotplug/pciehp_craye1k.c
> new file mode 100644
> index 000000000000..9c5bee81fdf8
> --- /dev/null
> +++ b/drivers/pci/hotplug/pciehp_craye1k.c
> @@ -0,0 +1,687 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2022-2024 Lawrence Livermore National Security, LLC
> + */
> +/*
> + * Cray ClusterStor E1000 hotplug slot LED driver extensions
> + *
> + * This driver controls the NVMe slot LEDs on the Cray ClusterStore E1000.
> + * It provides hotplug attention status callbacks for the 24 NVMe slots on
> + * the E1000.  This allows users to access the E1000's locate and fault
> + * LEDs via the normal /sys/bus/pci/slots/<slot>/attention sysfs entries.
> + * This driver uses IPMI to communicate with the E1000 controller to toggle
> + * the LEDs.
> + *
> + * This driver is based off of ibmpex.c
> + */
> +
> +#include <linux/debugfs.h>
> +#include <linux/delay.h>
> +#include <linux/dmi.h>
> +#include <linux/errno.h>
> +#include <linux/ipmi.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/pci_hotplug.h>
> +#include <linux/random.h>
> +#include "pciehp.h"
> +
> +/* Cray E1000 commands */
> +#define CRAYE1K_CMD_NETFN       0x3c
> +#define CRAYE1K_CMD_PRIMARY     0x33
> +#define CRAYE1K_CMD_FAULT_LED   0x39
> +#define CRAYE1K_CMD_LOCATE_LED  0x22
> +
> +/* Subcommands */
> +#define CRAYE1K_SUBCMD_GET_LED		0x0
> +#define CRAYE1K_SUBCMD_SET_LED		0x1
> +#define CRAYE1K_SUBCMD_SET_PRIMARY	0x1
> +
> +/*
> + * Milliseconds to wait after get/set LED command.  200ms value found though
> + * experimentation
> + */
> +#define CRAYE1K_POST_CMD_WAIT_MS	200
> +
> +struct craye1k {
> +	struct device *dev;   /* BMC device */
> +	struct mutex lock;
> +	struct completion read_complete;
> +	struct ipmi_addr address;
> +	struct ipmi_user *user;
> +	int iface;
> +
> +	long tx_msg_id;
> +	struct kernel_ipmi_msg tx_msg;
> +	unsigned char tx_msg_data[IPMI_MAX_MSG_LENGTH];
> +	unsigned char rx_msg_data[IPMI_MAX_MSG_LENGTH];
> +	unsigned long rx_msg_len;
> +	unsigned char rx_result;	/* IPMI completion code */
> +
> +	/* Parent dir for all our debugfs entries */
> +	struct dentry *parent;
> +
> +	/* debugfs stats */
> +	u64 check_primary;
> +	u64 check_primary_failed;
> +	u64 was_already_primary;
> +	u64 was_not_already_primary;
> +	u64 set_primary;
> +	u64 set_initial_primary_failed;
> +	u64 set_primary_failed;
> +	u64 set_led_locate_failed;
> +	u64 set_led_fault_failed;
> +	u64 set_led_readback_failed;
> +	u64 set_led_failed;
> +	u64 get_led_failed;
> +	u64 completion_timeout;
> +	u64 wrong_msgid;
> +	u64 request_failed;
> +
> +	/* debugfs configuration options */
> +
> +	/* Print info on spurious IPMI messages */
> +	bool print_errors;
> +
> +	/* Retries for kernel IPMI layer */
> +	u32 ipmi_retries;
> +
> +	/* Timeout in ms for IPMI (0 = use IPMI default_retry_ms) */
> +	u32 ipmi_timeout_ms;
> +
> +	/* Timeout in ms to wait for E1000 message completion */
> +	u32 completion_timeout_ms;
> +};
> +
> +/*
> + * Make our craye1k a global so get/set_attention_status() can access it.
> + * This is safe since there's only one node controller on the board, and so it's
> + * impossible to instantiate more than one craye1k.
> + */
> +static struct craye1k *craye1k_global;
> +static DEFINE_MUTEX(craye1k_lock);
> +
> +/*
> + * The E1000 command timeout and retry values were found though experimentation
> + * by looking at the error counters.  Keep the counters around to troubleshoot
> + * any issues with our current timeout/retry values.
> + */
> +static struct dentry *
> +craye1k_debugfs_init(struct craye1k *craye1k)
> +{
> +	umode_t mode = 0644;
> +	struct dentry *parent = debugfs_create_dir("pciehp_craye1k", NULL);
> +
> +	if (IS_ERR(parent))
> +		return NULL;
> +
> +	debugfs_create_x64("check_primary", mode, parent,
> +			   &craye1k->check_primary);
> +	debugfs_create_x64("check_primary_failed", mode, parent,
> +			   &craye1k->check_primary_failed);
> +	debugfs_create_x64("was_already_primary", mode, parent,
> +			   &craye1k->was_already_primary);
> +	debugfs_create_x64("was_not_already_primary", mode, parent,
> +			   &craye1k->was_not_already_primary);
> +	debugfs_create_x64("set_primary", mode, parent,
> +			   &craye1k->set_primary);
> +	debugfs_create_x64("set_initial_primary_failed", mode, parent,
> +			   &craye1k->set_initial_primary_failed);
> +	debugfs_create_x64("set_primary_failed", mode, parent,
> +			   &craye1k->set_primary_failed);
> +	debugfs_create_x64("set_led_locate_failed", mode, parent,
> +			   &craye1k->set_led_locate_failed);
> +	debugfs_create_x64("set_led_fault_failed", mode, parent,
> +			   &craye1k->set_led_fault_failed);
> +	debugfs_create_x64("set_led_readback_failed", mode, parent,
> +			   &craye1k->set_led_readback_failed);
> +	debugfs_create_x64("set_led_failed", mode, parent,
> +			   &craye1k->set_led_failed);
> +	debugfs_create_x64("get_led_failed", mode, parent,
> +			   &craye1k->get_led_failed);
> +	debugfs_create_x64("completion_timeout", mode, parent,
> +			   &craye1k->completion_timeout);
> +	debugfs_create_x64("wrong_msgid", mode, parent,
> +			   &craye1k->wrong_msgid);
> +	debugfs_create_x64("request_failed", mode, parent,
> +			   &craye1k->request_failed);
> +
> +	debugfs_create_x32("ipmi_retries", mode, parent,
> +			   &craye1k->ipmi_retries);
> +	debugfs_create_x32("ipmi_timeout_ms", mode, parent,
> +			   &craye1k->ipmi_timeout_ms);
> +	debugfs_create_x32("completion_timeout_ms", mode, parent,
> +			   &craye1k->completion_timeout_ms);
> +	debugfs_create_bool("print_errors", mode, parent,
> +			    &craye1k->print_errors);
> +
> +	/* Return parent dir dentry */
> +	return parent;
> +}
> +
> +/*
> + * craye1k_msg_handler() - IPMI message response handler
> + */
> +static void craye1k_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
> +{
> +	struct craye1k *craye1k = user_msg_data;
> +
> +	if (msg->msgid != craye1k->tx_msg_id) {
> +		craye1k->wrong_msgid++;
> +		if (craye1k->print_errors) {
> +			dev_warn_ratelimited(craye1k->dev,
> +					     "rx msgid %ld != %ld",
> +					     msg->msgid, craye1k->tx_msg_id);
> +		}
> +		ipmi_free_recv_msg(msg);
> +		return;
> +	}
> +
> +	/* Set rx_result to the IPMI completion code */
> +	if (msg->msg.data_len > 0)
> +		craye1k->rx_result = msg->msg.data[0];
> +	else
> +		craye1k->rx_result = IPMI_UNKNOWN_ERR_COMPLETION_CODE;
> +
> +	if (msg->msg.data_len > 1) {
> +		/* Exclude completion code from data bytes */
> +		craye1k->rx_msg_len = msg->msg.data_len - 1;
> +		memcpy(craye1k->rx_msg_data, msg->msg.data + 1,
> +		       craye1k->rx_msg_len);
> +	} else {
> +		craye1k->rx_msg_len = 0;
> +	}
> +
> +	ipmi_free_recv_msg(msg);
> +
> +	complete(&craye1k->read_complete);
> +}
> +
> +static const struct ipmi_user_hndl craye1k_user_hndl = {
> +	.ipmi_recv_hndl = craye1k_msg_handler
> +};
> +
> +static void craye1k_new_smi(int iface, struct device *dev)
> +{
> +	int rc;
> +	struct craye1k *craye1k;
> +
> +	craye1k = kzalloc(sizeof(*craye1k), GFP_KERNEL);
> +	if (!craye1k)
> +		return;
> +
> +	craye1k->address.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
> +	craye1k->address.channel = IPMI_BMC_CHANNEL;
> +	craye1k->iface = iface;
> +	craye1k->dev = dev;
> +	craye1k->tx_msg.data = craye1k->tx_msg_data;
> +	craye1k->ipmi_retries = 4;
> +	craye1k->ipmi_timeout_ms = 500;
> +	craye1k->completion_timeout_ms = 300;
> +
> +	init_completion(&craye1k->read_complete);
> +
> +	dev_set_drvdata(dev, craye1k);
> +
> +	rc = ipmi_create_user(craye1k->iface, &craye1k_user_hndl, craye1k,
> +			      &craye1k->user);
> +	if (rc < 0) {
> +		dev_err(dev, "Unable to register IPMI user, iface %d\n",
> +			craye1k->iface);
> +		kfree(craye1k);
> +		dev_set_drvdata(dev, NULL);
> +		return;
> +	}
> +
> +	mutex_lock(&craye1k_lock);
> +
> +	/* There's only one node controller so driver data should not be set */
> +	WARN_ON(craye1k_global);
> +
> +	craye1k_global = craye1k;
> +	craye1k->parent = craye1k_debugfs_init(craye1k);
> +	mutex_unlock(&craye1k_lock);
> +	if (!craye1k->parent)
> +		dev_warn(dev, "Cannot create debugfs");
> +
> +	dev_info(dev, "Cray ClusterStor E1000 slot LEDs registered");
> +}
> +
> +static void craye1k_smi_gone(int iface)
> +{
> +	pr_warn("craye1k: Got unexpected smi_gone, iface=%d", iface);
> +
> +	mutex_lock(&craye1k_lock);
> +	if (craye1k_global) {
> +		debugfs_remove_recursive(craye1k_global->parent);
> +		kfree(craye1k_global);
> +		craye1k_global = NULL;
> +	}
> +	mutex_unlock(&craye1k_lock);
> +}
> +
> +static struct ipmi_smi_watcher craye1k_smi_watcher = {
> +	.owner = THIS_MODULE,
> +	.new_smi = craye1k_new_smi,
> +	.smi_gone = craye1k_smi_gone
> +};
> +
> +/*
> + * craye1k_send_message() - Send the message already setup in 'craye1k'
> + *
> + * Context: craye1k_lock is already held.
> + * Return: 0 on success, non-zero on error.
> + */
> +static int craye1k_send_message(struct craye1k *craye1k)
> +{
> +	int rc;
> +
> +	rc = ipmi_validate_addr(&craye1k->address, sizeof(craye1k->address));
> +	if (rc) {
> +		dev_err_ratelimited(craye1k->dev, "ipmi_validate_addr() = %d\n",
> +				    rc);
> +		return rc;
> +	}
> +
> +	craye1k->tx_msg_id++;
> +
> +	rc = ipmi_request_settime(craye1k->user, &craye1k->address,
> +				  craye1k->tx_msg_id, &craye1k->tx_msg, craye1k,
> +				  0, craye1k->ipmi_retries,
> +				  craye1k->ipmi_timeout_ms);
> +
> +	if (rc) {
> +		craye1k->request_failed++;
> +		return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * craye1k_do_message() - Send the message in 'craye1k' and wait for a response
> + *
> + * Context: craye1k_lock is already held.
> + * Return: 0 on success, non-zero on error.
> + */
> +static int craye1k_do_message(struct craye1k *craye1k)
> +{
> +	int rc;
> +	struct completion *read_complete = &craye1k->read_complete;
> +	unsigned long tout = msecs_to_jiffies(craye1k->completion_timeout_ms);
> +
> +	WARN_ON(!mutex_is_locked(&craye1k_lock));
> +
> +	rc = craye1k_send_message(craye1k);
> +	if (rc)
> +		return rc;
> +
> +	rc = wait_for_completion_killable_timeout(read_complete, tout);
> +	if (rc == 0) {
> +		/* timed out */
> +		craye1k->completion_timeout++;
> +		return -ETIME;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * __craye1k_do_command() - Do an IPMI command
> + *
> + * Send a command with optional data bytes, and read back response bytes.
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: 0 on success, non-zero on error.
> + */
> +static int __craye1k_do_command(struct craye1k *craye1k, u8 netfn, u8 cmd,
> +				u8 *send_data, u8 send_data_len, u8 *recv_data,
> +				u8 recv_data_len)
> +{
> +	int rc;
> +
> +	craye1k->tx_msg.netfn = netfn;
> +	craye1k->tx_msg.cmd = cmd;
> +
> +	if (send_data) {
> +		memcpy(&craye1k->tx_msg_data[0], send_data, send_data_len);
> +		craye1k->tx_msg.data_len = send_data_len;
> +	} else {
> +		craye1k->tx_msg_data[0] = 0;
> +		craye1k->tx_msg.data_len = 0;
> +	}
> +
> +	rc = craye1k_do_message(craye1k);
> +	if (rc == 0)
> +		memcpy(recv_data, craye1k->rx_msg_data, recv_data_len);
> +
> +	return rc;
> +}
> +
> +/*
> + * craye1k_do_command() - Do a Cray E1000 specific IPMI command.
> + * @cmd: Cray E1000 specific command
> + * @send_data:  Data to send after the command
> + * @send_data_len: Data length
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: the last byte from the response or 0 if response had no response
> + * data bytes, else -1 on error.
> + */
> +static int craye1k_do_command(struct craye1k *craye1k, u8 cmd, u8 *send_data,
> +			      u8 send_data_len)
> +{
> +	int rc;
> +
> +	rc = __craye1k_do_command(craye1k, CRAYE1K_CMD_NETFN, cmd, send_data,
> +				  send_data_len, NULL, 0);
> +	if (rc != 0) {
> +		/* Error attempting command */
> +		return -1;
> +	}
> +
> +	if (craye1k->tx_msg.data_len == 0)
> +		return 0;
> +
> +	/* Return last received byte value */
> +	return craye1k->rx_msg_data[craye1k->rx_msg_len - 1];
> +}
> +
> +/*
> + * __craye1k_set_primary() - Tell the BMC we want to be the primary server
> + *
> + * An E1000 board has two physical servers on it.  In order to set a slot
> + * NVMe LED, this server needs to first tell the BMC that it's the primary
> + * server.
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: 0 on success, non-zero on error.
> + */
> +static int __craye1k_set_primary(struct craye1k *craye1k)
> +{
> +	u8 bytes[2] = {CRAYE1K_SUBCMD_SET_PRIMARY, 1};	/* set primary to 1 */
> +
> +	craye1k->set_primary++;
> +	return craye1k_do_command(craye1k, CRAYE1K_CMD_PRIMARY, bytes, 2);
> +}
> +
> +/*
> + * craye1k_is_primary() - Are we the primary server?
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: true if we are the primary server, false otherwise.
> + */
> +static bool craye1k_is_primary(struct craye1k *craye1k)
> +{
> +	u8 byte = 0;
> +	int rc;
> +
> +	/* Response byte is 0x1 on success */
> +	rc = craye1k_do_command(craye1k, CRAYE1K_CMD_PRIMARY, &byte, 1);
> +	craye1k->check_primary++;
> +	if (rc == 0x1)
> +		return true;   /* success */
> +
> +	craye1k->check_primary_failed++;
> +	return false;   /* We are not the primary server node */
> +}
> +
> +/*
> + * craye1k_set_primary() - Attempt to set ourselves as the primary server
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: 0 on success, -1 otherwise.
> + */
> +static int craye1k_set_primary(struct craye1k *craye1k)
> +{
> +	int tries = 10;
> +
> +	if (craye1k_is_primary(craye1k)) {
> +		craye1k->was_already_primary++;
> +		return 0;
> +	}
> +	craye1k->was_not_already_primary++;
> +
> +	/* delay found through experimentation */
> +	msleep(300);
> +
> +	if (__craye1k_set_primary(craye1k) != 0) {
> +		craye1k->set_initial_primary_failed++;
> +		return -1;	/* error */
> +	}
> +
> +	/*
> +	 * It can take 2 to 3 seconds after setting primary for the controller
> +	 * to report that it is the primary.
> +	 */
> +	while (tries--) {
> +		msleep(500);
> +		if (craye1k_is_primary(craye1k))
> +			break;
> +	}
> +
> +	if (tries == 0) {
> +		craye1k->set_primary_failed++;
> +		return -1;	/* never reported that it's primary */
> +	}
> +
> +	/* Wait for primary switch to finish */
> +	msleep(1500);
> +
> +	return 0;
> +}
> +
> +/*
> + * craye1k_get_slot_led() - Get slot LED value
> + * @slot: Slot number (1-24)
> + * @is_locate_led: 0 = get fault LED value, 1 = get locate LED value
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: slot value on success, -1 on failure.
> + */
> +static int craye1k_get_slot_led(struct craye1k *craye1k, unsigned char slot,
> +				bool is_locate_led)
> +{
> +	u8 bytes[2];
> +	u8 cmd;
> +
> +	bytes[0] = CRAYE1K_SUBCMD_GET_LED;
> +	bytes[1] = slot;
> +
> +	cmd = is_locate_led ? CRAYE1K_CMD_LOCATE_LED : CRAYE1K_CMD_FAULT_LED;
> +
> +	return craye1k_do_command(craye1k, cmd, bytes, 2);
> +}
> +
> +/*
> + * craye1k_set_slot_led() - Attempt to set the locate/fault LED to a value
> + * @slot: Slot number (1-24)
> + * @is_locate_led: 0 = use fault LED, 1 = use locate LED
> + * @value: Value to set (0 or 1)
> + *
> + * Check the LED value after calling this function to ensure it has been set
> + * properly.
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: 0 on success, non-zero on failure.
> + */
> +static int craye1k_set_slot_led(struct craye1k *craye1k, unsigned char slot,
> +				unsigned char is_locate_led,
> +				unsigned char value)
> +{
> +	u8 bytes[3];
> +	u8 cmd;
> +
> +	bytes[0] = CRAYE1K_SUBCMD_SET_LED;
> +	bytes[1] = slot;
> +	bytes[2] = value;
> +
> +	cmd = is_locate_led ? CRAYE1K_CMD_LOCATE_LED : CRAYE1K_CMD_FAULT_LED;
> +
> +	return craye1k_do_command(craye1k, cmd, bytes, 3);
> +}
> +
> +/*
> + * __craye1k_get_attention_status() - Get LED value
> + *
> + * Context: craye1k_lock is already held.
> + * Returns: 0 on success, -EIO on failure.
> + */
> +static int __craye1k_get_attention_status(struct hotplug_slot *hotplug_slot,
> +					  u8 *status, bool set_primary)
> +{
> +	unsigned char slot;
> +	int locate, fault;
> +	struct craye1k *craye1k;
> +
> +	craye1k = craye1k_global;
> +	slot = PSN(to_ctrl(hotplug_slot));
> +
> +	if (set_primary) {
> +		if (craye1k_set_primary(craye1k) != 0) {
> +			craye1k->get_led_failed++;
> +			return -EIO;
> +		}
> +	}
> +
> +	locate = craye1k_get_slot_led(craye1k, slot, true);
> +	if (locate == -1) {
> +		craye1k->get_led_failed++;
> +		return -EIO;
> +	}
> +	msleep(CRAYE1K_POST_CMD_WAIT_MS);
> +
> +	fault = craye1k_get_slot_led(craye1k, slot, false);
> +	if (fault == -1) {
> +		craye1k->get_led_failed++;
> +		return -EIO;
> +	}
> +	msleep(CRAYE1K_POST_CMD_WAIT_MS);
> +
> +	*status = locate << 1 | fault;
> +
> +	return 0;
> +}
> +
> +int craye1k_get_attention_status(struct hotplug_slot *hotplug_slot,
> +				 u8 *status)
> +{
> +	int rc;
> +
> +	if (mutex_lock_interruptible(&craye1k_lock) != 0)
> +		return -EINTR;
> +
> +	if (!craye1k_global) {
> +		/* Driver isn't initialized yet */
> +		mutex_unlock(&craye1k_lock);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	rc =  __craye1k_get_attention_status(hotplug_slot, status, true);
> +
> +	mutex_unlock(&craye1k_lock);
> +	return rc;
> +}
> +
> +int craye1k_set_attention_status(struct hotplug_slot *hotplug_slot,
> +				 u8 status)
> +{
> +	unsigned char slot;
> +	int tries = 4;
> +	int rc;
> +	u8 new_status;
> +	struct craye1k *craye1k;
> +	bool locate, fault;
> +
> +	if (mutex_lock_interruptible(&craye1k_lock) != 0)
> +		return -EINTR;
> +
> +	if (!craye1k_global) {
> +		/* Driver isn't initialized yet */
> +		mutex_unlock(&craye1k_lock);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	craye1k = craye1k_global;
> +
> +	slot = PSN(to_ctrl(hotplug_slot));
> +
> +	/* Retry to ensure all LEDs are set */
> +	while (tries--) {
> +		/*
> +		 * The node must first set itself to be the primary node before
> +		 * setting the slot LEDs (each board has two nodes, or
> +		 * "servers" as they're called by the manufacturer).  This can
> +		 * lead to contention if both nodes are trying to set the LEDs
> +		 * at the same time.
> +		 */
> +		rc = craye1k_set_primary(craye1k);
> +		if (rc != 0) {
> +			/* Could not set as primary node.  Just retry again. */
> +			continue;
> +		}
> +
> +		/* Write value twice to increase success rate */
> +		locate = (status & 0x2) >> 1;
> +		craye1k_set_slot_led(craye1k, slot, 1, locate);
> +		if (craye1k_set_slot_led(craye1k, slot, 1, locate) != 0) {
> +			craye1k->set_led_locate_failed++;
> +			continue;	/* fail, retry */
> +		}
> +
> +		msleep(CRAYE1K_POST_CMD_WAIT_MS);
> +
> +		fault = status & 0x1;
> +		craye1k_set_slot_led(craye1k, slot, 0, fault);
> +		if (craye1k_set_slot_led(craye1k, slot, 0, fault) != 0) {
> +			craye1k->set_led_fault_failed++;
> +			continue;	/* fail, retry */
> +		}
> +
> +		msleep(CRAYE1K_POST_CMD_WAIT_MS);
> +
> +		rc = __craye1k_get_attention_status(hotplug_slot, &new_status,
> +						    false);
> +
> +		msleep(CRAYE1K_POST_CMD_WAIT_MS);
> +
> +		if (rc == 0 && new_status == status)
> +			break;	/* success */
> +
> +		craye1k->set_led_readback_failed++;
> +
> +		/*
> +		 * At this point we weren't successful in setting the LED and
> +		 * need to try again.
> +		 *
> +		 * Do a random back-off to reduce contention with other server
> +		 * node in the unlikely case that both server nodes are trying to
> +		 * trying to set a LED at the same time.
> +		 *
> +		 * The 500ms minimum in the back-off reduced the chance of this
> +		 * whole retry loop failing from 1 in 700 to none in 10000.
> +		 */
> +		msleep(500 + (get_random_long() % 500));
> +	}
> +	mutex_unlock(&craye1k_lock);
> +	if (tries == 0) {
> +		craye1k->set_led_failed++;
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +bool is_craye1k_board(void)
> +{
> +	return dmi_match(DMI_PRODUCT_NAME, "VSSEP1EC");
> +}
> +
> +int craye1k_init(void)
> +{
> +	return ipmi_smi_watcher_register(&craye1k_smi_watcher);
> +}
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Tony Hutter <hutter2@llnl.gov>");
> +MODULE_DESCRIPTION("Cray E1000 NVMe Slot LED driver");
> -- 
> 2.43.7
> 
>