Subject: Re: [PATCH v4 21/21] pci/hotplug: PowerPC PowerNV PCI hotplug driver

From: Alexey Kardashevskiy <[email-masked]>
Date: Sun, 10 May 2015 01:54:31 +1000

On 05/01/2015 04:03 PM, Gavin Shan wrote:
> The patch intends to add standalone driver to support PCI hotplug
> for PowerPC PowerNV platform, which runs on top of skiboot firmware.
> The firmware identified hotpluggable slots and marked their device
> tree node with proper "ibm,slot-pluggable" and "ibm,reset-by-firmware".
> The driver simply scans device-tree to create/register PCI hotplug slot
> accordingly.
>
> If the skiboot firmware doesn't support slot status retrieval, the PCI
> slot device node shouldn't have property "ibm,reset-by-firmware". In
> that case, none of valid PCI slots will be detected from device tree.
> The skiboot firmware doesn't export the capability to access attention
> LEDs yet and it's something for TBD.
>
> Signed-off-by: Gavin Shan <[email-masked]>
> ---
>   drivers/pci/hotplug/Kconfig            |  12 +
>   drivers/pci/hotplug/Makefile           |   4 +
>   drivers/pci/hotplug/powernv_php.c      | 146 ++++++++
>   drivers/pci/hotplug/powernv_php.h      |  78 ++++
>   drivers/pci/hotplug/powernv_php_slot.c | 643 +++++++++++++++++++++++++++++++++
>   5 files changed, 883 insertions(+)
>   create mode 100644 drivers/pci/hotplug/powernv_php.c
>   create mode 100644 drivers/pci/hotplug/powernv_php.h
>   create mode 100644 drivers/pci/hotplug/powernv_php_slot.c
>
> diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
> index df8caec..ef55dae 100644
> --- a/drivers/pci/hotplug/Kconfig
> +++ b/drivers/pci/hotplug/Kconfig
> @@ -113,6 +113,18 @@ config HOTPLUG_PCI_SHPC
>
>   	  When in doubt, say N.
>
> +config HOTPLUG_PCI_POWERNV
> +	tristate "PowerPC PowerNV PCI Hotplug driver"
> +	depends on PPC_POWERNV && EEH
> +	help
> +	  Say Y here if you run PowerPC PowerNV platform that supports
> +          PCI Hotplug
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called powernv-php.
> +
> +	  When in doubt, say N.
> +
>   config HOTPLUG_PCI_RPA
>   	tristate "RPA PCI Hotplug driver"
>   	depends on PPC_PSERIES && EEH
> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
> index 4a9aa08..a69665e 100644
> --- a/drivers/pci/hotplug/Makefile
> +++ b/drivers/pci/hotplug/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_HOTPLUG_PCI_PCIE)		+= pciehp.o
>   obj-$(CONFIG_HOTPLUG_PCI_CPCI_ZT5550)	+= cpcihp_zt5550.o
>   obj-$(CONFIG_HOTPLUG_PCI_CPCI_GENERIC)	+= cpcihp_generic.o
>   obj-$(CONFIG_HOTPLUG_PCI_SHPC)		+= shpchp.o
> +obj-$(CONFIG_HOTPLUG_PCI_POWERNV)	+= powernv-php.o
>   obj-$(CONFIG_HOTPLUG_PCI_RPA)		+= rpaphp.o
>   obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR)	+= rpadlpar_io.o
>   obj-$(CONFIG_HOTPLUG_PCI_SGI)		+= sgi_hotplug.o
> @@ -50,6 +51,9 @@ ibmphp-objs		:=	ibmphp_core.o	\
>   acpiphp-objs		:=	acpiphp_core.o	\
>   				acpiphp_glue.o
>
> +powernv-php-objs	:=	powernv_php.o	\
> +				powernv_php_slot.o
> +
>   rpaphp-objs		:=	rpaphp_core.o	\
>   				rpaphp_pci.o	\
>   				rpaphp_slot.o
> diff --git a/drivers/pci/hotplug/powernv_php.c b/drivers/pci/hotplug/powernv_php.c
> new file mode 100644
> index 0000000..5cf9e717
> --- /dev/null
> +++ b/drivers/pci/hotplug/powernv_php.c
> @@ -0,0 +1,146 @@
> +/*
> + * PCI Hotplug Driver for PowerPC PowerNV platform.
> + *
> + * Copyright Gavin Shan, IBM Corporation 2015.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/sysfs.h>
> +#include <linux/pci.h>
> +#include <linux/pci_hotplug.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <asm/opal.h>
> +#include <asm/pnv-pci.h>
> +
> +#include "powernv_php.h"

Compiles without linux/kernel.h, linux/sysfs.h, linux/string.h, 
linux/slab.h. Sure you need all of these?

> +
> +#define DRIVER_VERSION	"0.1"
> +#define DRIVER_AUTHOR	"Gavin Shan, IBM Corporation"
> +#define DRIVER_DESC	"PowerPC PowerNV PCI Hotplug Driver"
> +
> +static struct notifier_block php_msg_nb = {
> +	.notifier_call	= powernv_php_msg_handler,
> +	.next		= NULL,
> +	.priority	= 0,
> +};
> +
> +static int powernv_php_register_one(struct device_node *dn)
> +{
> +	struct powernv_php_slot *slot;
> +	const __be32 *prop32;
> +	int ret;
> +
> +	/* Check if it's hotpluggable slot */
> +	prop32 = of_get_property(dn, "ibm,slot-pluggable", NULL);
> +	if (!prop32 || !of_read_number(prop32, 1))
> +		return 0;

Although nobody checks the return code, this should be -ENXIO or something 
but zero. And the check below too.

> +
> +	prop32 = of_get_property(dn, "ibm,reset-by-firmware", NULL);
> +	if (!prop32 || !of_read_number(prop32, 1))
> +		return 0;
> +
> +	/* Allocate slot */
> +	slot = powernv_php_slot_alloc(dn);
> +	if (!slot)
> +		return -ENODEV;
> +
> +	/* Register it */
> +	ret = powernv_php_slot_register(slot);
> +	if (ret) {
> +		powernv_php_slot_put(slot);
> +		return ret;
> +	}
> +
> +	return powernv_php_slot_enable(slot->php_slot, false, false);
> +}
> +
> +int powernv_php_register(struct device_node *dn)
> +{
> +	struct device_node *child;
> +	int ret = 0;
> +
> +	/*
> +	 * The parent slots should be registered before their
> +	 * child slots.
> +	 */
> +	for_each_child_of_node(dn, child) {
> +		ret = powernv_php_register_one(child);
> +		if (ret)
> +			break;
> +
> +		powernv_php_register(child);
> +	}
> +
> +	return ret;
> +}
> +
> +static void powernv_php_unregister_one(struct device_node *dn)
> +{
> +	struct powernv_php_slot *slot;
> +
> +	slot = powernv_php_slot_find(dn);
> +	if (!slot)
> +		return;
> +
> +	pci_hp_deregister(slot->php_slot);
> +}
> +
> +void powernv_php_unregister(struct device_node *dn)
> +{
> +	struct device_node *child;
> +
> +	/* The child slots should go before their parent slots */
> +	for_each_child_of_node(dn, child) {
> +		powernv_php_unregister(child);
> +		powernv_php_unregister_one(child);
> +	}
> +}
> +
> +static int __init powernv_php_init(void)
> +{
> +	struct device_node *dn;
> +
> +	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
> +
> +	/* Register hotplug message handler */
> +	if (pnv_pci_hotplug_notifier(&php_msg_nb, true)) {

If you called the function "pnv_pci_hotplug_notifier_register", you would 
not need the comment above.

> +		pr_warn("%s: Cannot register hotplug message notifier\n",
> +			__func__);
> +		return -EIO;
> +	}
> +
> +	/* Scan PHB nodes and their children */
> +	for_each_compatible_node(dn, NULL, "ibm,ioda-phb")
> +		powernv_php_register(dn);
> +	for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
> +		powernv_php_register(dn);
> +
> +	return 0;
> +}
> +
> +static void __exit powernv_php_exit(void)
> +{
> +	struct device_node *dn;
> +
> +	pnv_pci_hotplug_notifier(&php_msg_nb, false);
> +
> +	for_each_compatible_node(dn, NULL, "ibm,ioda-phb")
> +		powernv_php_unregister(dn);
> +	for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
> +		powernv_php_unregister(dn);
> +}
> +
> +module_init(powernv_php_init);
> +module_exit(powernv_php_exit);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> diff --git a/drivers/pci/hotplug/powernv_php.h b/drivers/pci/hotplug/powernv_php.h
> new file mode 100644
> index 0000000..87ba0d0
> --- /dev/null
> +++ b/drivers/pci/hotplug/powernv_php.h
> @@ -0,0 +1,78 @@
> +/*
> + * PCI Hotplug Driver for PowerPC PowerNV platform.
> + *
> + * Copyright Gavin Shan, IBM Corporation 2015.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#ifndef _POWERNV_PHP_H
> +#define _POWERNV_PHP_H

I would put these (and dependencies if any) here:

#include <linux/kref.h>
#include <linux/pci.h>
#include <linux/pci_hotplug.h>

and remove them from .c files.

> +
> +/* Slot power status */
> +#define POWERNV_PHP_SLOT_POWER_OFF	0
> +#define POWERNV_PHP_SLOT_POWER_ON	1
> +
> +/* Slot presence status */
> +#define POWERNV_PHP_SLOT_EMPTY		0
> +#define POWERNV_PHP_SLOT_PRESENT	1
> +
> +/* Slot attention status */
> +#define POWERNV_PHP_SLOT_ATTEN_OFF	0
> +#define POWERNV_PHP_SLOT_ATTEN_ON	1
> +#define POWERNV_PHP_SLOT_ATTEN_IND	2
> +#define POWERNV_PHP_SLOT_ATTEN_ACT	3
> +
> +struct powernv_php_slot {
> +	struct kref		kref;
> +	int			state;
> +#define POWERNV_PHP_SLOT_STATE_INIT		0x0
> +#define POWERNV_PHP_SLOT_STATE_REGISTER		0x1
> +#define POWERNV_PHP_SLOT_STATE_POPULATED	0x2

I believe these are not bitmasks but bit numbers, right? Decimal values are 
normally used for them.

> +	char			*name;
> +	struct device_node	*dn;
> +	struct pci_bus		*bus;
> +	uint64_t		id;
> +	int			slot_no;
> +	int			check_power_status;
> +	int			status_confirmed;
> +	struct opal_msg		*msg;
> +	struct work_struct	work;
> +	wait_queue_head_t	queue;
> +	struct hotplug_slot	*php_slot;
> +	struct powernv_php_slot	*parent;
> +	void (*release)(struct kref *kref);

What is the point in this? Just use php_slot_free() directly in 
powernv_php_slot_put, no?

> +	struct list_head	children;
> +	struct list_head	link;
> +};
> +
> +#define to_powernv_php_slot(kref) container_of(kref, struct powernv_php_slot, kref)
> +
> +static inline void powernv_php_slot_get(struct powernv_php_slot *slot)
> +{
> +	if (slot)
> +		kref_get(&slot->kref);
> +}
> +
> +static inline int powernv_php_slot_put(struct powernv_php_slot *slot)
> +{
> +	if (slot)
> +		return kref_put(&slot->kref, slot->release);
> +
> +	return 0;
> +}
> +
> +int powernv_php_msg_handler(struct notifier_block *nb,
> +			    unsigned long type, void *message);
> +struct powernv_php_slot *powernv_php_slot_find(struct device_node *dn);
> +struct powernv_php_slot *powernv_php_slot_alloc(struct device_node *dn);
> +int powernv_php_slot_register(struct powernv_php_slot *slot);
> +int powernv_php_slot_enable(struct hotplug_slot *php_slot,
> +			    bool rescan_bus, bool rescan_slot);

Just an observation - rescan_bus and rescan_slot are both true or both 
false and never different. And the only caller requesting rescan is in the 
same file as powernv_php_slot_enable() and it could do this rescan if 
powernv_php_slot_enable() could signal that rescan is needed (return 1?).

And no "goto" in powernv_php_slot_enable would be needed. Do not insist though.

> +int powernv_php_register(struct device_node *dn);
> +void powernv_php_unregister(struct device_node *dn);
> +
> +#endif /* !_POWERNV_PHP_H */
> diff --git a/drivers/pci/hotplug/powernv_php_slot.c b/drivers/pci/hotplug/powernv_php_slot.c
> new file mode 100644
> index 0000000..fc82355
> --- /dev/null
> +++ b/drivers/pci/hotplug/powernv_php_slot.c
> @@ -0,0 +1,643 @@
> +/*
> + * PCI Hotplug Driver for PowerPC PowerNV platform.
> + *
> + * Copyright Gavin Shan, IBM Corporation 2015.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/sysfs.h>
> +#include <linux/pci.h>
> +#include <linux/pci_hotplug.h>
> +#include <linux/string.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/wait.h>
> +#include <linux/workqueue.h>
> +
> +#include <asm/opal.h>
> +#include <asm/pnv-pci.h>
> +#include <asm/ppc-pci.h>
> +
> +#include "powernv_php.h"

I have a suspicion you won't need all these headers here too ;)

> +
> +static LIST_HEAD(php_slot_list);
> +static DEFINE_SPINLOCK(php_slot_lock);
> +
> +/*
> + * Release firmware data for all child device nodes of the
> + * indicated one.
> + */
> +static void release_device_nodes_info(struct device_node *np)
> +{
> +	struct device_node *child;
> +
> +	for_each_child_of_node(np, child) {
> +		/* In depth first */
> +		release_device_nodes_info(child);

Why is this "release", not "remove" (as this is what it does - calling 
remove_lalala in a loop)?

> +
> +		remove_pci_device_node_info(child);
> +	}
> +}
> +
> +/*
> + * Release all subordinate device nodes of the indicated one.
> + * Those device nodes in deepest path should be released firstly.
> + */
> +static int release_device_nodes(struct device_node *parent)
> +{
> +	struct device_node *np, *child;
> +	int ret = 0;
> +
> +	/* If the device node has children, remove them firstly */
> +	for_each_child_of_node(parent, np) {
> +		ret = release_device_nodes(np);
> +		if (ret)
> +			return ret;
> +
> +		/* The device shouldn't have alive children */
> +		child = of_get_next_child(np, NULL);
> +		if (child) {
> +			of_node_put(child);
> +			of_node_put(np);
> +			pr_err("%s: Alive children of node <%s>\n",
> +			       __func__, of_node_full_name(np));
> +			return -EBUSY;
> +		}
> +
> +		/* Detach the device node */
> +		of_detach_node(np);
> +		of_node_put(np);
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * The function processes the message sent by firmware
> + * to remove all device tree nodes beneath the slot's
> + * nodes, and the associated auxillary data.
> + */
> +static void slot_power_off_handler(struct powernv_php_slot *slot)
> +{
> +	int ret;
> +
> +	/* Release the firmware data for the child device nodes */
> +	release_device_nodes_info(slot->dn);
> +
> +	/* Release the child device nodes */
> +	ret = release_device_nodes(slot->dn);
> +	if (ret)
> +		pr_warn("%s: Error %d releasing children of <%s>\n",
> +			__func__, ret, of_node_full_name(slot->dn));
> +
> +	/* Confirm status change */
> +	slot->status_confirmed = 1;
> +	wake_up_interruptible(&slot->queue);
> +}
> +
> +static void slot_power_on_handler(struct powernv_php_slot *slot)
> +{
> +	struct opal_msg *msg = slot->msg;
> +	unsigned long phys = be64_to_cpu(msg->params[2]);
> +	unsigned long len = be64_to_cpu(msg->params[3]);
> +	void *blob = (phys && len > 0) ? __va(phys) : NULL;
> +
> +	/* There might have nothing behind the slot yet */
> +	if (!blob || !len)

"!len" is redundand here - blob will be NULL if len<=0.

> +		goto out;
> +
> +	/* Copy the FDT blob and parse it */
> +	of_fdt_add_subtree(slot->dn, blob);
> +
> +	/* Add device node firmware data */
> +	traverse_pci_device_nodes(slot->dn,
> +				  add_pci_device_node_info,
> +				  pci_bus_to_host(slot->bus));
> +
> +out:
> +	/* Confirm status change */
> +	slot->status_confirmed = 1;
> +	wake_up_interruptible(&slot->queue);
> +}
> +
> +static void powernv_php_slot_work(struct work_struct *data)
> +{
> +	struct powernv_php_slot *slot = container_of(data,
> +						     struct powernv_php_slot,
> +						     work);
> +	uint64_t php_event = be64_to_cpu(slot->msg->params[0]);
> +
> +	switch (php_event) {
> +	case 0: /* Slot power off */
> +		slot_power_off_handler(slot);
> +		break;
> +	case 1: /* Slot power on */
> +		slot_power_on_handler(slot);
> +		break;
> +	default:
> +		pr_warn("%s: Unsupported hotplug event %lld\n",
> +			__func__, php_event);
> +	}
> +
> +	of_node_put(slot->dn);
> +}
> +
> +int powernv_php_msg_handler(struct notifier_block *nb,
> +			    unsigned long type, void *message)
> +{
> +	phandle h;
> +	struct device_node *np;
> +	struct powernv_php_slot *slot;
> +	struct opal_msg *msg = message;
> +
> +	/* Check the message type */
> +	if (type != OPAL_MSG_PCI_HOTPLUG) {
> +		pr_warn("%s: Wrong message type %ld received!\n",
> +			__func__, type);
> +		return 0;
> +	}
> +
> +	/* Find the device node */
> +	h = (phandle)be64_to_cpu(msg->params[1]);
> +	np = of_find_node_by_phandle(h);
> +	if (!np) {
> +		pr_warn("%s: No device node for phandle 0x%08x\n",
> +			__func__, h);
> +		return 0;
> +	}
> +
> +	/* Find the slot */
> +	slot = powernv_php_slot_find(np);
> +	if (!slot) {
> +		pr_warn("%s: No slot found for node <%s>\n",
> +			__func__, of_node_full_name(np));
> +		of_node_put(np);
> +		return 0;
> +	}
> +
> +	/* Schedule the work */
> +	slot->msg = msg;
> +	schedule_work(&slot->work);
> +	return 0;
> +}
> +
> +static int set_power_status(struct hotplug_slot *php_slot, u8 val)
> +{
> +	struct powernv_php_slot *slot = php_slot->private;
> +	int ret;
> +
> +	/* Set power status */
> +	slot->status_confirmed = 0;
> +	ret = pnv_pci_set_power_status(slot->id, val);
> +	if (ret) {
> +		pr_warn("%s: Error %d powering %s slot %016llx\n",
> +			__func__, ret, val ? "on" : "off", slot->id);
> +		return ret;
> +	}
> +
> +	/* Waiting until the device tree is updated */
> +	ret = wait_event_timeout(slot->queue,
> +				 !slot->status_confirmed,
> +				 10 * HZ);
> +	if (ret) {
> +		pr_warn("%s: Error %d completing power-%s slot %016llx\n",
> +			__func__, ret, val ? "on" : "off", slot->id);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int get_power_status(struct hotplug_slot *php_slot, u8 *val)
> +{
> +	struct powernv_php_slot *slot = php_slot->private;
> +	uint8_t state;
> +	int ret;
> +
> +	/*
> +	 * Retrieve power status from firmware. If we fail
> +	 * getting that, the power status fails back to
> +	 * be on.
> +	 */
> +	ret = pnv_pci_get_power_status(slot->id, &state);
> +	if (ret) {
> +		*val = POWERNV_PHP_SLOT_POWER_ON;
> +		pr_warn("%s: Error %d getting power status of slot %016llx\n",
> +			__func__, ret, slot->id);
> +	} else {
> +		*val = state ? POWERNV_PHP_SLOT_POWER_ON :
> +			       POWERNV_PHP_SLOT_POWER_OFF;
> +		php_slot->info->power_status = *val;
> +	}
> +
> +	return 0;
> +}
> +
> +static int get_adapter_status(struct hotplug_slot *php_slot, u8 *val)
> +{
> +	struct powernv_php_slot *slot = php_slot->private;
> +	uint8_t state;
> +	int ret;
> +
> +	/*
> +	 * Retrieve presence status from firmware. If we can't
> +	 * get that, it will fail back to be empty.
> +	 */
> +	ret = pnv_pci_get_presence_status(slot->id, &state);
> +	if (ret >= 0) {
> +                *val = state ? POWERNV_PHP_SLOT_PRESENT :
> +                               POWERNV_PHP_SLOT_EMPTY;
> +                php_slot->info->adapter_status = *val;

ret = 0;

> +	} else {
> +		*val = POWERNV_PHP_SLOT_EMPTY;
> +		pr_warn("%s: Error %d getting presence of slot %016llx\n",
> +			__func__, ret, slot->id);
> +	}
> +
> +	return ret < 0 ? ret : 0;

return ret;

> +}
> +
> +static int set_attention_status(struct hotplug_slot *php_slot, u8 val)
> +{
> +	/* The default operation would to turn on the attention */
> +	switch (val) {
> +	case POWERNV_PHP_SLOT_ATTEN_OFF:
> +	case POWERNV_PHP_SLOT_ATTEN_ON:
> +	case POWERNV_PHP_SLOT_ATTEN_IND:
> +	case POWERNV_PHP_SLOT_ATTEN_ACT:
> +		break;
> +	default:
> +		val = POWERNV_PHP_SLOT_ATTEN_ON;

Is not @val a garbage in this case?

> +	}
> +
> +	/* FIXME: Make it real once firmware supports it */
> +	php_slot->info->attention_status = val;
> +
> +	return 0;
> +}
> +
> +int powernv_php_slot_enable(struct hotplug_slot *php_slot,
> +			    bool rescan_bus, bool rescan_slot)
> +{
> +	struct powernv_php_slot *slot = php_slot->private;
> +	uint8_t presence, power_status;
> +	int ret;
> +
> +	/* Check if the slot has been configured */
> +	if (slot->state != POWERNV_PHP_SLOT_STATE_REGISTER)
> +		return 0;
> +
> +	/* Retrieve slot presence status */
> +	ret = php_slot->ops->get_adapter_status(php_slot, &presence);
> +	if (ret) {
> +		pr_warn("%s: Error %d getting presence of slot %016llx\n",
> +			__func__, ret, slot->id);
> +		return ret;
> +	}
> +
> +	/* Proceed if there have nothing behind the slot */
> +	if (presence == POWERNV_PHP_SLOT_EMPTY)
> +		goto scan;
> +
> +	/*
> +	 * If we don't detect something behind the slot, we need
> +	 * make sure the power suply to the slot is on. Otherwise,
> +	 * the slot downstream PCIe linkturn should be down.
> +	 *
> +	 * On the first time, we don't change the power status to
> +	 * boost system boot with assumption that the firmware
> +	 * supplies consistent slot power status: empty slot always
> +	 * has its power off and non-empty slot has its power on.
> +	 */
> +	if (!slot->check_power_status) {
> +		slot->check_power_status = 1;
> +		goto scan;
> +	}
> +
> +	/* Check the power status. Scan the slot if that's already on */
> +	ret = php_slot->ops->get_power_status(php_slot, &power_status);
> +	if (ret) {
> +		pr_warn("%s: Error %d getting power status of slot %016llx\n",
> +			__func__, ret, slot->id);
> +		return ret;
> +	}
> +	if (power_status == POWERNV_PHP_SLOT_POWER_ON)
> +		goto scan;
> +
> +	/* Power is off, turn it on and then scan the slot */
> +	ret = set_power_status(php_slot, POWERNV_PHP_SLOT_POWER_ON);
> +	if (ret) {
> +		pr_warn("%s: Error %d powering on slot %016llx\n",
> +			__func__, ret, slot->id);
> +		return ret;
> +	}
> +
> +scan:
> +	switch (presence) {
> +	case POWERNV_PHP_SLOT_PRESENT:
> +		if (rescan_bus) {
> +			pci_lock_rescan_remove();
> +			pcibios_add_pci_devices(slot->bus);
> +			pci_unlock_rescan_remove();
> +		}
> +
> +		/* Rescan for child hotpluggable slots */
> +		slot->state = POWERNV_PHP_SLOT_STATE_POPULATED;
> +		if (rescan_slot)
> +			powernv_php_register(slot->dn);
> +		break;
> +	case POWERNV_PHP_SLOT_EMPTY:
> +		slot->state = POWERNV_PHP_SLOT_STATE_POPULATED;
> +		break;
> +	default:
> +		pr_warn("%s: Invalid presence status %d of slot %016llx\n",
> +			__func__, presence, slot->id);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int enable_slot(struct hotplug_slot *php_slot)
> +{
> +	return powernv_php_slot_enable(php_slot, true, true);
> +}
> +
> +static int disable_slot(struct hotplug_slot *php_slot)
> +{
> +	struct powernv_php_slot *slot = php_slot->private;
> +	uint8_t power_status;
> +	int ret;
> +
> +	if (slot->state != POWERNV_PHP_SLOT_STATE_POPULATED)
> +		return 0;
> +
> +	/* Remove all devices behind the slot */
> +	pci_lock_rescan_remove();
> +	pcibios_remove_pci_devices(slot->bus);
> +	pci_unlock_rescan_remove();
> +
> +	/* Detach the child hotpluggable slots */
> +	powernv_php_unregister(slot->dn);
> +
> +	/*
> +	 * Check the power status and turn it off if necessary. If we
> +	 * fail to get the power status, the power will be forced to
> +	 * be off.
> +	 */
> +	ret = php_slot->ops->get_power_status(php_slot, &power_status);
> +	if (ret || power_status == POWERNV_PHP_SLOT_POWER_ON) {
> +		ret = set_power_status(php_slot, POWERNV_PHP_SLOT_POWER_OFF);
> +		if (ret)
> +			pr_warn("%s: Error %d powering off slot %016llx\n",
> +				__func__, ret, slot->id);
> +	}
> +
> +	/* Update slot state */
> +	slot->state = POWERNV_PHP_SLOT_STATE_REGISTER;
> +	return 0;
> +}
> +
> +static struct hotplug_slot_ops php_slot_ops = {
> +	.get_power_status	= get_power_status,
> +	.get_adapter_status	= get_adapter_status,
> +	.set_attention_status	= set_attention_status,
> +	.enable_slot		= enable_slot,
> +	.disable_slot		= disable_slot,
> +};
> +
> +static struct powernv_php_slot *php_slot_match(struct device_node *dn,
> +					       struct powernv_php_slot *slot)
> +{
> +	struct powernv_php_slot *target, *tmp;
> +
> +	if (slot->dn == dn)
> +		return slot;
> +
> +	list_for_each_entry(tmp, &slot->children, link) {
> +		target = php_slot_match(dn, tmp);
> +		if (target)
> +			return target;
> +	}
> +
> +	return NULL;
> +}
> +
> +struct powernv_php_slot *powernv_php_slot_find(struct device_node *dn)
> +{
> +	struct powernv_php_slot *slot, *tmp;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&php_slot_lock, flags);
> +	list_for_each_entry(tmp, &php_slot_list, link) {
> +		slot = php_slot_match(dn, tmp);
> +		if (slot) {
> +			spin_unlock_irqrestore(&php_slot_lock, flags);
> +			return slot;
> +		}
> +	}
> +	spin_unlock_irqrestore(&php_slot_lock, flags);
> +
> +	return NULL;
> +}
> +
> +static void php_slot_free(struct kref *kref)
> +{
> +	struct powernv_php_slot *slot = to_powernv_php_slot(kref);
> +
> +	WARN_ON(!list_empty(&slot->children));
> +	kfree(slot->name);
> +	kfree(slot);
> +}
> +
> +static void php_slot_release(struct hotplug_slot *hp_slot)
> +{
> +	struct powernv_php_slot *slot = hp_slot->private;
> +	unsigned long flags;
> +
> +	/* Remove from global or child list */
> +	spin_lock_irqsave(&php_slot_lock, flags);
> +	list_del(&slot->link);
> +	spin_unlock_irqrestore(&php_slot_lock, flags);
> +
> +	/* Detach from parent */
> +	powernv_php_slot_put(slot);
> +	powernv_php_slot_put(slot->parent);
> +}
> +
> +static bool php_slot_get_id(struct device_node *dn,
> +			    uint64_t *id)
> +{
> +	struct device_node *parent = dn;
> +	const __be64 *prop64;
> +	const __be32 *prop32;
> +
> +	/*
> +	 * The hotpluggable slot always has a compound Id, which
> +	 * consists of 16-bits PHB Id, 16 bits bus/slot/function
> +	 * number, and compound indicator
> +	 */
> +	*id = (0x1ul << 63);
> +
> +	/* Bus/Slot/Function number */
> +	prop32 = of_get_property(dn, "reg", NULL);
> +	if (!prop32)
> +		return false;
> +	*id |= ((of_read_number(prop32, 1) & 0x00ffff00) << 8);
> +
> +	/* PHB Id */
> +	while ((parent = of_get_parent(parent))) {
> +		if (!PCI_DN(parent)) {
> +			of_node_put(parent);
> +			break;
> +		}
> +
> +		if (!of_device_is_compatible(parent, "ibm,ioda2-phb") &&
> +		    !of_device_is_compatible(parent, "ibm,ioda-phb")) {
> +			of_node_put(parent);
> +			continue;
> +		}
> +
> +		prop64 = of_get_property(parent, "ibm,opal-phbid", NULL);
> +		if (!prop64) {
> +			of_node_put(parent);
> +			return false;
> +		}
> +
> +		*id |= be64_to_cpup(prop64);
> +		of_node_put(parent);
> +		return true;
> +	}
> +
> +        return false;
> +}
> +
> +struct powernv_php_slot *powernv_php_slot_alloc(struct device_node *dn)
> +{
> +	struct pci_bus *bus;
> +	struct powernv_php_slot *slot;
> +	const char *label;
> +	uint64_t id;
> +	int slot_no;
> +	size_t size;
> +	void *pmem;
> +
> +	/* Slot name */
> +	label = of_get_property(dn, "ibm,slot-label", NULL);
> +	if (!label)
> +		return NULL;
> +
> +	/* Slot indentifier */
> +	if (!php_slot_get_id(dn, &id))
> +		return NULL;
> +
> +	/* PCI bus */
> +	bus = pcibios_find_pci_bus(dn);
> +	if (!bus)
> +		return NULL;
> +
> +	/* Slot number */
> +	if (dn->child && PCI_DN(dn->child))
> +		slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
> +	else
> +		slot_no = -1;
> +
> +	/* Allocate slot */
> +	size = sizeof(struct powernv_php_slot) +
> +	       sizeof(struct hotplug_slot) +
> +	       sizeof(struct hotplug_slot_info);
> +	pmem = kzalloc(size, GFP_KERNEL);
> +	if (!pmem) {
> +		pr_warn("%s: Cannot allocate slot for node %s\n",
> +			__func__, dn->full_name);
> +		return NULL;
> +	}
> +
> +	/* Assign memory blocks */
> +	slot = pmem;
> +	slot->php_slot = pmem + sizeof(struct powernv_php_slot);
> +	slot->php_slot->info = pmem + sizeof(struct powernv_php_slot) +
> +			      sizeof(struct hotplug_slot);
> +	slot->name = kstrdup(label, GFP_KERNEL);
> +	if (!slot->name) {
> +		pr_warn("%s: Cannot populate name for node %s\n",
> +			__func__, dn->full_name);
> +		kfree(pmem);
> +		return NULL;
> +	}
> +
> +	/* Initialize slot */
> +	kref_init(&slot->kref);
> +	slot->state = POWERNV_PHP_SLOT_STATE_INIT;
> +	slot->dn = dn;
> +	slot->bus = bus;
> +	slot->id = id;
> +	slot->slot_no = slot_no;
> +	INIT_WORK(&slot->work, powernv_php_slot_work);
> +	init_waitqueue_head(&slot->queue);
> +	slot->check_power_status = 0;
> +	slot->status_confirmed = 0;
> +	slot->release = php_slot_free;
> +	slot->php_slot->ops = &php_slot_ops;
> +	slot->php_slot->release = php_slot_release;
> +	slot->php_slot->private = slot;
> +	INIT_LIST_HEAD(&slot->children);
> +	INIT_LIST_HEAD(&slot->link);
> +
> +	return slot;
> +}
> +
> +int powernv_php_slot_register(struct powernv_php_slot *slot)
> +{
> +	struct powernv_php_slot *parent;
> +	struct device_node *dn = slot->dn;
> +	unsigned long flags;
> +	int ret;
> +
> +	/* Avoid register same slot for twice */
> +	if (powernv_php_slot_find(slot->dn))
> +		return -EEXIST;
> +
> +	/* Register slot */
> +	ret = pci_hp_register(slot->php_slot, slot->bus,
> +			      slot->slot_no, slot->name);
> +	if (ret) {
> +		pr_warn("%s: Cannot register slot %s (%d)\n",
> +			__func__, slot->name, ret);
> +		return ret;
> +	}
> +
> +	/* Put into global or parent list */
> +	while ((dn = of_get_parent(dn))) {
> +		if (!PCI_DN(dn)) {
> +			of_node_put(dn);
> +			break;
> +		}
> +
> +		parent = powernv_php_slot_find(dn);
> +		if (parent) {
> +			of_node_put(dn);
> +			break;
> +		}
> +	}
> +
> +	spin_lock_irqsave(&php_slot_lock, flags);
> +	if (parent) {
> +		powernv_php_slot_get(parent);
> +		slot->parent = parent;
> +		list_add_tail(&slot->link, &parent->children);
> +	} else {
> +		list_add_tail(&slot->link, &php_slot_list);
> +	}
> +	spin_unlock_irqrestore(&php_slot_lock, flags);
> +
> +	/* Update slot state */
> +	slot->state = POWERNV_PHP_SLOT_STATE_REGISTER;
> +	return 0;
> +}
>

-- 
Alexey