Subject: Re: [PATCH v8 45/45] PCI/hotplug: PowerPC PowerNV PCI hotplug driver

From: Gavin Shan <[email-masked]>
Date: Tue, 3 May 2016 09:38:33 +1000

On Mon, May 02, 2016 at 04:11:53PM +1000, Alexey Kardashevskiy wrote:
>On 05/02/2016 01:44 PM, Gavin Shan wrote:
>>On Tue, Apr 19, 2016 at 08:36:48PM +1000, Alexey Kardashevskiy wrote:
>>>On 02/17/2016 02:44 PM, Gavin Shan wrote:
>>>>This adds standalone driver to support PCI hotplug for PowerPC PowerNV
>>>>platform that runs on top of skiboot firmware. The firmware identifies
>>>>hotpluggable slots and marked their device tree node with proper
>>>>"ibm,slot-pluggable" and "ibm,reset-by-firmware". The driver scans
>>>>device tree nodes to create/register PCI hotplug slot accordingly.
>>>>
>>>>The PCI slots are organized in fashion of tree, which means one
>>>>PCI slot might have parent PCI slot and parent PCI slot possibly
>>>>contains multiple child PCI slots. At the plugging time, the parent
>>>>PCI slot is populated before its children. The child PCI slots are
>>>>removed before their parent PCI slot can be removed from the system.
>>>>
>>>>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]>
>>>>Acked-by: Bjorn Helgaas <[email-masked]>
>>>>---
>>>> drivers/pci/hotplug/Kconfig   |  12 +
>>>> drivers/pci/hotplug/Makefile  |   3 +
>>>> drivers/pci/hotplug/pnv_php.c | 870 ++++++++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 885 insertions(+)
>>>> create mode 100644 drivers/pci/hotplug/pnv_php.c
>>>>
>>>>diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
>>>>index df8caec..167c8ce 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 pnv-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 b616e75..e33cdda 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-$(CONFIG_HOTPLUG_PCI_POWERNV)	+= pnv-php.o
>>>> obj-$(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 +51,8 @@ ibmphp-objs		:=	ibmphp_core.o	\
>>>> acpiphp-objs		:=	acpiphp_core.o	\
>>>> 				acpiphp_glue.o
>>>>
>>>>+pnv-php-objs		:=	pnv_php.o
>>>>+
>>>> rpaphp-objs		:=	rpaphp_core.o	\
>>>> 				rpaphp_pci.o	\
>>>> 				rpaphp_slot.o
>>>>diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
>>>>new file mode 100644
>>>>index 0000000..364ec36
>>>>--- /dev/null
>>>>+++ b/drivers/pci/hotplug/pnv_php.c
>>>>@@ -0,0 +1,870 @@
>>>>+/*
>>>>+ * 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/libfdt.h>
>>>>+#include <linux/module.h>
>>>>+#include <linux/pci.h>
>>>>+#include <linux/pci_hotplug.h>
>>>>+
>>>>+#include <asm/opal.h>
>>>>+#include <asm/pnv-pci.h>
>>>>+#include <asm/ppc-pci.h>
>>>>+
>>>>+#define DRIVER_VERSION	"0.1"
>>>>+#define DRIVER_AUTHOR	"Gavin Shan, IBM Corporation"
>>>>+#define DRIVER_DESC	"PowerPC PowerNV PCI Hotplug Driver"
>>>>+
>>>>+struct pnv_php_slot {
>>>>+	struct hotplug_slot		slot;
>>>>+	struct hotplug_slot_info	slot_info;
>>>>+	uint64_t			id;
>>>>+	char				*name;
>>>>+	int				slot_no;
>>>>+	struct kref			kref;
>>>>+#define PNV_PHP_STATE_INITIALIZED	0
>>>>+#define PNV_PHP_STATE_REGISTERED	1
>>>>+#define PNV_PHP_STATE_POPULATED		2
>>>>+	int				state;
>>>>+	struct device_node		*dn;
>>>>+	struct pci_dev			*pdev;
>>>>+	struct pci_bus			*bus;
>>>>+	bool				power_state_check;
>>>>+	int				power_state_confirmed;
>>>>+#define PNV_PHP_POWER_CONFIRMED_INVALID	0
>>>>+#define PNV_PHP_POWER_CONFIRMED_SUCCESS	1
>>>>+#define PNV_PHP_POWER_CONFIRMED_FAIL	2
>>>>+	struct opal_msg			*msg;
>>>>+	void				*fdt;
>>>>+	void				*dt;
>>>>+	struct of_changeset		ocs;
>>>>+	struct work_struct		work;
>>>>+	wait_queue_head_t		queue;
>>>>+	struct pnv_php_slot		*parent;
>>>>+	struct list_head		children;
>>>>+	struct list_head		link;
>>>>+};
>>>>+
>>>>+static LIST_HEAD(pnv_php_slot_list);
>>>>+static DEFINE_SPINLOCK(pnv_php_lock);
>>>>+
>>>>+static void pnv_php_register(struct device_node *dn);
>>>>+static void pnv_php_unregister_one(struct device_node *dn);
>>>>+static void pnv_php_unregister(struct device_node *dn);
>>>
>>>
>>>The names confused me. I'd suggest pnv_php_scan(), pnv_php_unregister(),
>>>pnv_php_unregister_children() instead.
>>>
>>>
>>>Alistair, what do you reckon?
>>>
>>>
>>>>+
>>>>+static void pnv_php_free_slot(struct kref *kref)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = container_of(kref,
>>>>+						     struct pnv_php_slot,
>>>>+						     kref);
>>>>+
>>>>+	WARN_ON(!list_empty(&php_slot->children));
>>>>+	kfree(php_slot->name);
>>>>+	kfree(php_slot);
>>>>+}
>>>>+
>>>>+static inline void pnv_php_put_slot(struct pnv_php_slot *php_slot)
>>>>+{
>>>>+	if (!php_slot)
>>>
>>>
>>>BUG_ON()?
>>>
>>
>>checkpatch.pl will report warning like below. Are you sure you need a BUG_ON()?
>
>
>No, I am not - this is why I asked. How possible is it to have here
>phb_slot==NULL? Can we recover from that? The options are -
>1) memory is corrupted (then we cannot and it has to be BUG_ON)
>2) broken/old OPAL returns unexpected error (then we can continue, I guess)
>3) there are ways (via sysfs in the userspace? no idea) to get
>pnv_php_put_slot() called with phb_slot.
>
>If only 1) is possible - then BUG_ON, if 2) - WARN_ON, if 3) - should be
>neither BUG_ON nor WARN_ON. You know the code better, you decide.
>

I will have a WARN_ON instead since it's not harmful.

>>
>>WARNING: Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()
>>#159: FILE: drivers/pci/hotplug/pnv_php.c:76:
>>+	BUG_ON(!php_slot);
>>
>>
>>>>+		return;
>>>>+
>>>>+	kref_put(&php_slot->kref, pnv_php_free_slot);
>>>>+}
>>>>+
>>>>+static struct pnv_php_slot *pnv_php_match(struct device_node *dn,
>>>>+					  struct pnv_php_slot *php_slot)
>>>>+{
>>>>+	struct pnv_php_slot *target, *tmp;
>>>>+
>>>>+	if (php_slot->dn == dn) {
>>>>+		kref_get(&php_slot->kref);
>>>>+		return php_slot;
>>>>+	}
>>>>+
>>>>+	list_for_each_entry(tmp, &php_slot->children, link) {
>>>>+		target = pnv_php_match(dn, tmp);
>>>>+		if (target)
>>>>+			return target;
>>>>+	}
>>>>+
>>>>+	return NULL;
>>>>+}
>>>>+
>>>>+static struct pnv_php_slot *pnv_php_find_slot(struct device_node *dn)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot, *tmp;
>>>>+	unsigned long flags;
>>>>+
>>>>+	spin_lock_irqsave(&pnv_php_lock, flags);
>>>>+	list_for_each_entry(tmp, &pnv_php_slot_list, link) {
>>>>+		php_slot = pnv_php_match(dn, tmp);
>>>>+		if (php_slot) {
>>>>+			spin_unlock_irqrestore(&pnv_php_lock, flags);
>>>>+			return php_slot;
>>>>+		}
>>>>+	}
>>>>+	spin_unlock_irqrestore(&pnv_php_lock, flags);
>>>>+
>>>>+	return NULL;
>>>>+}
>>>>+
>>>>+/*
>>>>+ * Remove pdn for all children of the indicated device node.
>>>>+ * The function should remove pdn in a depth-first manner.
>>>>+ */
>>>>+static void pnv_php_rmv_pdns(struct device_node *dn)
>>>>+{
>>>>+	struct device_node *child;
>>>>+
>>>>+	for_each_child_of_node(dn, child) {
>>>>+		pnv_php_rmv_pdns(child);
>>>>+
>>>>+		pci_remove_device_node_info(child);
>>>>+	}
>>>>+}
>>>>+
>>>>+/*
>>>>+ * Remove all child nodes of the indicated device nodes. The
>>>>+ * function should remove device nodes in depth-first manner.
>>>>+ */
>>>>+static int pnv_php_rmv_device_nodes(struct device_node *parent)
>>>>+{
>>>>+	struct device_node *dn, *child;
>>>>+	int ret = 0;
>>>>+
>>>>+	for_each_child_of_node(parent, dn) {
>>>>+		ret = pnv_php_rmv_device_nodes(dn);
>>>>+		if (ret)
>>>>+			return ret;
>>>>+
>>>>+		child = of_get_next_child(dn, NULL);
>>>>+		if (child) {
>>>>+			of_node_put(child);
>>>>+			of_node_put(dn);
>>>>+			pr_err("%s: Alive children of node <%s>\n",
>>>>+			       __func__, of_node_full_name(dn));
>>>>+			return -EBUSY;
>>>>+		}
>>>>+
>>>>+		of_detach_node(dn);
>
>
>While playing with compiler options, I hit this:
>
>  MODPOST 248 modules
>ERROR: "of_detach_node" [drivers/pci/hotplug/pnv-php.ko] undefined!
>/home/aik/p/kernel-power8hp/scripts/Makefile.modpost:91: recipe for target
>'__modpost' failed
>make[2]: *** [__modpost] Error 1
>

It was a known issue and the patch has been piled there. I will include
it in next revision.

>
>I enabled pnv-php to compile as a module:
>CONFIG_HOTPLUG_PCI_POWERNV=m
>
>This is missing:
>
>diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
>index c647bd1..75ce30d 100644
>--- a/drivers/of/dynamic.c
>+++ b/drivers/of/dynamic.c
>@@ -311,6 +311,7 @@ int of_detach_node(struct device_node *np)
>
>        return rc;
> }
>+EXPORT_SYMBOL_GPL(of_detach_node);
>
>
>
>
>>>>+		of_node_put(dn);
>>>>+	}
>>>>+
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+/*
>>>>+ * The function processes the message sent by firmware
>>>>+ * to remove all device tree nodes beneath the slot's
>>>>+ * nodes and the associated auxiliary data.
>>>>+ */
>>>>+static void pnv_php_handle_poweroff(struct pnv_php_slot *php_slot)
>>>>+{
>>>>+	int ret;
>>>>+
>>>>+	pnv_php_rmv_pdns(php_slot->dn);
>>>>+
>>>>+	/*
>>>>+	 * If the device sub-tree was created from OF changeset, simply
>>>>+	 * to revert that. Otherwise, the device nodes in the sub-tree
>>>>+	 * need to be iterated and detached.
>>>>+	 */
>>>>+	if (php_slot->fdt) {
>>>>+		of_changeset_destroy(&php_slot->ocs);
>>>>+		kfree(php_slot->dt);
>>>>+		kfree(php_slot->fdt);
>>>>+		php_slot->dt        = NULL;
>>>>+		php_slot->dn->child = NULL;
>>>>+		php_slot->fdt       = NULL;
>>>>+		php_slot->power_state_confirmed =
>>>>+			PNV_PHP_POWER_CONFIRMED_SUCCESS;
>>>>+		wake_up_interruptible(&php_slot->queue);
>>>>+		return;
>>>>+	}
>>>>+
>>>>+	ret = pnv_php_rmv_device_nodes(php_slot->dn);
>>>>+	if (!ret) {
>>>>+		php_slot->power_state_confirmed =
>>>>+			PNV_PHP_POWER_CONFIRMED_SUCCESS;
>>>>+	} else {
>>>>+		php_slot->power_state_confirmed = PNV_PHP_POWER_CONFIRMED_FAIL;
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d freeing nodes\n", ret);
>>>>+	}
>>>>+
>>>>+	wake_up_interruptible(&php_slot->queue);
>>>
>>>
>>>I liked one wake_up_interruptible() better...
>>>
>>
>>Will fix in next revision.
>>
>>>>+}
>>>>+
>>>>+static int pnv_php_populate_changeset(struct of_changeset *ocs,
>>>>+				      struct device_node *dn)
>>>>+{
>>>>+	struct device_node *child;
>>>>+	int ret = 0;
>>>>+
>>>>+	for_each_child_of_node(dn, child) {
>>>>+		ret = of_changeset_attach_node(ocs, child);
>>>>+		if (ret)
>>>>+			break;
>>>>+
>>>>+		ret = pnv_php_populate_changeset(ocs, child);
>>>
>>>
>>>I asked in v7 - may be to add here "if (ret) break;"?
>>>
>>
>>Will add it in v9.
>>
>>>>+	}
>>>>+
>>>>+	return ret;
>>>>+}
>>>>+
>>>>+static void *pnv_php_add_one_pdn(struct device_node *dn, void *data)
>>>>+{
>>>>+	struct pci_controller *hose = (struct pci_controller *)data;
>>>>+	struct pci_dn *pdn;
>>>>+
>>>>+	pdn = pci_add_device_node_info(hose, dn);
>>>>+	if (!pdn)
>>>>+		return ERR_PTR(-ENOMEM);
>>>>+
>>>>+	return NULL;
>>>>+}
>>>>+
>>>>+static void pnv_php_add_pdns(struct pnv_php_slot *slot)
>>>>+{
>>>>+	struct pci_controller *hose = pci_bus_to_host(slot->bus);
>>>>+
>>>>+	pci_traverse_device_nodes(slot->dn, pnv_php_add_one_pdn, hose);
>>>>+}
>>>>+
>>>>+static void pnv_php_handle_poweron(struct pnv_php_slot *php_slot)
>>>>+{
>>>>+	void *fdt, *fdt1, *dt;
>>>>+	int confirm = PNV_PHP_POWER_CONFIRMED_SUCCESS;
>>>>+	int ret;
>>>>+
>>>>+	/* We don't know the FDT blob size. We try to get it through
>>>>+	 * maximal memory chunk and then copy it to another chunk that
>>>>+	 * fits the real size.
>>>>+	 */
>>>>+	fdt1 = kzalloc(0x10000, GFP_KERNEL);
>>>>+	if (!fdt1)
>>>>+		goto error;
>>>>+
>>>>+	ret = pnv_pci_get_device_tree(php_slot->dn->phandle, fdt1, 0x10000);
>>>>+	if (ret)
>>>>+		goto free_fdt1;
>>>>+
>>>>+	fdt = kzalloc(fdt_totalsize(fdt1), GFP_KERNEL);
>>>>+	if (!fdt)
>>>>+		goto free_fdt1;
>>>>+
>>>>+	/* Unflatten device tree blob */
>>>>+	memcpy(fdt, fdt1, fdt_totalsize(fdt1));
>>>>+	dt = of_fdt_unflatten_tree(fdt, php_slot->dn, NULL);
>>>>+	if (!dt) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Cannot unflatten FDT\n");
>>>>+		goto free_fdt;
>>>>+	}
>>>>+
>>>>+	/* Initialize and apply the changeset */
>>>>+	of_changeset_init(&php_slot->ocs);
>>>>+	ret = pnv_php_populate_changeset(&php_slot->ocs, php_slot->dn);
>>>>+	if (ret) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d populating changeset\n",
>>>>+			 ret);
>>>>+		goto free_dt;
>>>>+	}
>>>>+
>>>>+	php_slot->dn->child = NULL;
>>>>+	ret = of_changeset_apply(&php_slot->ocs);
>>>>+	if (ret) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d applying changeset\n",
>>>>+			 ret);
>>>>+		goto destroy_changeset;
>>>>+	}
>>>>+
>>>>+	/* Add device node firmware data */
>>>>+	pnv_php_add_pdns(php_slot);
>>>>+	php_slot->fdt = fdt;
>>>>+	php_slot->dt  = dt;
>>>>+	goto out;
>>>>+
>>>>+destroy_changeset:
>>>>+	of_changeset_destroy(&php_slot->ocs);
>>>>+free_dt:
>>>>+	kfree(dt);
>>>>+	php_slot->dn->child = NULL;
>>>>+free_fdt:
>>>>+	kfree(fdt);
>>>>+free_fdt1:
>>>>+	kfree(fdt1);
>>>>+error:
>>>>+	confirm = PNV_PHP_POWER_CONFIRMED_FAIL;
>>>>+out:
>>>>+	/* Confirm status change */
>>>>+	php_slot->power_state_confirmed = confirm;
>>>>+	wake_up_interruptible(&php_slot->queue);
>>>>+}
>>>>+
>>>>+static void pnv_php_work(struct work_struct *data)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = container_of(data,
>>>>+						     struct pnv_php_slot,
>>>>+						     work);
>>>>+	uint64_t event = be64_to_cpu(php_slot->msg->params[0]);
>>>>+
>>>>+	if (event == OPAL_PCI_SLOT_POWER_OFF)
>>>>+		pnv_php_handle_poweroff(php_slot);
>>>>+	else
>>>>+		pnv_php_handle_poweron(php_slot);
>>>>+
>>>>+	pnv_php_put_slot(php_slot);
>>>>+}
>>>>+
>>>>+static int pnv_php_handle_msg(struct notifier_block *nb,
>>>>+			      unsigned long type,
>>>>+			      void *message)
>>>>+{
>>>>+	phandle h;
>>>>+	struct device_node *dn;
>>>>+	struct pnv_php_slot *php_slot;
>>>>+	struct opal_msg *msg = message;
>>>>+
>>>>+	if (type != OPAL_MSG_PCI_HOTPLUG) {
>>>>+		pr_warn("%s: Invalid message %ld received!\n",
>>>>+			__func__, type);
>>>>+		return NOTIFY_DONE;
>>>>+	}
>>>>+
>>>>+	h = (phandle)be64_to_cpu(msg->params[1]);
>>>>+	dn = of_find_node_by_phandle(h);
>>>>+	if (!dn) {
>>>>+		pr_warn("%s: No device node for phandle 0x%x\n",
>>>>+			__func__, h);
>>>>+		return NOTIFY_DONE;
>>>>+	}
>>>>+
>>>>+	php_slot = pnv_php_find_slot(dn);
>>>>+	if (!php_slot) {
>>>>+		pr_warn("%s: No slot found for node <%s>\n",
>>>>+			__func__, of_node_full_name(dn));
>>>>+		of_node_put(dn);
>>>>+		return NOTIFY_DONE;
>>>>+	}
>>>>+
>>>>+	of_node_put(dn);
>>>>+	php_slot->msg = msg;
>>>>+	schedule_work(&php_slot->work);
>>>>+	return NOTIFY_OK;
>>>>+}
>>>>+
>>>>+static int pnv_php_set_power_state(struct hotplug_slot *slot, u8 state)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = slot->private;
>>>>+	int ret;
>>>>+
>>>>+	php_slot->power_state_confirmed = PNV_PHP_POWER_CONFIRMED_INVALID;
>>>>+	ret = pnv_pci_set_power_state(php_slot->id, state);
>>>>+	if (ret) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d powering %s slot\n",
>>>>+			 ret, state ? "on" : "off");
>>>>+		return ret;
>>>>+	}
>>>>+
>>>>+	/* Continue to PCI probing after finalized device-tree. The
>>>>+	 * device-tree might have been updated completely at this
>>>>+	 * point. Thus we don't have to wait forever.
>>>>+	 */
>>>>+	if (php_slot->power_state_confirmed == PNV_PHP_POWER_CONFIRMED_SUCCESS)
>>>>+		return 0;
>>>>+
>>>>+	if (php_slot->power_state_confirmed == PNV_PHP_POWER_CONFIRMED_FAIL)
>>>>+		return -EBUSY;
>>>>+
>>>>+	/* Wait for firmware to add or remove device sub-tree. When it's done,
>>>>+	 * one signal is received from firmware.
>>>>+	 */
>>>>+	ret = wait_event_timeout(php_slot->queue,
>>>>+				 php_slot->power_state_confirmed, 10 * HZ);
>>>>+	if (!ret) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d waiting for power-%s\n",
>>>>+			 ret, state ? "on" : "off");
>>>>+		return -EBUSY;
>>>>+	}
>>>>+
>>>>+	if (php_slot->power_state_confirmed == PNV_PHP_POWER_CONFIRMED_SUCCESS)
>>>>+		return 0;
>>>>+
>>>>+	dev_warn(&php_slot->pdev->dev, "Error status %d for power-%s\n",
>>>>+		 php_slot->power_state_confirmed, state ? "on" : "off");
>>>>+	return -EBUSY;
>>>>+}
>>>>+
>>>>+static int pnv_php_get_power_state(struct hotplug_slot *slot, u8 *state)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = slot->private;
>>>>+	uint8_t power_state;
>>>
>>>
>>>Uninitialized variable.
>>>
>>
>
>>When pnv_pci_get_power_state() fails to get the power state, it fails back to
>>default one (OPAL_PCI_SLOT_POWER_ON). Otherwise, it is set to the state returned
>>from pnv_pci_get_power_state(). The logic is complete.
>
>What does guarantee that if the corresponding OPAL call returned success,
>then all data pointers to which you passed to OPAL will point to correct
>values? For exampple, the new pnv_pci_poll() updates the state only in some
>cases.
>

Note that opal_pci_poll() is going to be replaced by opal_pci_poll2() as you
suggested in another thread. The later function accepts two arguments.

When the second argument to opal_pci_poll() isn't null, the result is returned.
Otherwise, the result won't be returned.

>
>> Also, I don't see building warning/error caused by this.
>
>You do not see them now with your current compiler which does not mean you
>will never see them.
>

hrm, I really don't catch the point. Obviously, I'm not able to know the
unpredictable thing. I will initialize @power_state to default (ON) in
next revision since you're insisting on it :)

>
>>>
>>>>+	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_state(php_slot->id, &power_state);
>>>>+	if (ret) {
>>>>+		*state = OPAL_PCI_SLOT_POWER_ON;
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d getting power status\n",
>>>>+			 ret);
>>>>+	} else {
>>>>+		*state = power_state;
>>>>+		slot->info->power_status = power_state;
>>>>+	}
>>>>+
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static int pnv_php_get_adapter_state(struct hotplug_slot *slot, u8 *state)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = slot->private;
>>>>+	uint8_t presence;
>>>
>>>Uninitialized variable.
>>>
>>
>>Same as above.
>>
>>>>+	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_state(php_slot->id, &presence);
>>>>+	if (ret >= 0) {
>>>>+		*state = presence;
>>>>+		slot->info->adapter_status = presence;
>>>>+		ret = 0;
>>>>+	} else {
>>>>+		*state = OPAL_PCI_SLOT_EMPTY;
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d getting presence\n",
>>>>+			 ret);
>>>>+	}
>>>>+
>>>>+	return ret;
>>>>+}
>>>>+
>>>>+static int pnv_php_set_attention_state(struct hotplug_slot *slot, u8 state)
>>>>+{
>>>>+	/* FIXME: Make it real once firmware supports it */
>>>
>>>It still does not?
>>>
>>>
>>>>+	slot->info->attention_status = state;
>>>>+
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static int pnv_php_enable(struct pnv_php_slot *php_slot, bool rescan)
>>>>+{
>>>>+	struct hotplug_slot *slot = &php_slot->slot;
>>>>+	uint8_t presence, power_status;
>>>
>>>
>>>Uninitialized variables.
>>>
>>>
>>
>>I will initialize them to default states in next revision.
>
>Thanks :)
>
>
>>
>>>>+	int ret;
>>>>+
>>>>+	/* Check if the slot has been configured */
>>>>+	if (php_slot->state != PNV_PHP_STATE_REGISTERED)
>>>>+		return 0;
>>>>+
>>>>+	/* Retrieve slot presence status */
>>>>+	ret = pnv_php_get_adapter_state(slot, &presence);
>>>>+	if (ret)
>>>>+		return ret;
>>>>+
>>>>+	/* Proceed if there have nothing behind the slot */
>>>>+	if (presence == OPAL_PCI_SLOT_EMPTY)
>>>>+		goto scan;
>>>>+
>>>>+	/*
>>>>+	 * If the power suply to the slot is off, we can't detect
>>>
>>>s/suply/supply/
>>>
>>
>>Will fix in next revision.
>>
>>>>+	 * adapter presence state. That means we have to turn the
>>>>+	 * slot on before going to probe slot's presence state.
>>>>+	 *
>>>>+	 * 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 (!php_slot->power_state_check) {
>>>>+		php_slot->power_state_check = true;
>>>>+
>>>>+		ret = pnv_php_get_power_state(slot, &power_status);
>>>>+		if (ret)
>>>>+			return ret;
>>>>+
>>>>+		if (power_status != OPAL_PCI_SLOT_POWER_ON)
>>>>+			return 0;
>>>>+	}
>>>>+
>>>>+	/* Check the power status. Scan the slot if that's already on */
>>>
>>>
>>>s/that's/it is/
>>>
>>
>>I don't know the difference. Will fix it in next revision anyway.
>>
>>>
>>>>+	ret = pnv_php_get_power_state(slot, &power_status);
>>>>+	if (ret)
>>>>+		return ret;
>>>>+
>>>>+	if (power_status == OPAL_PCI_SLOT_POWER_ON)
>>>>+		goto scan;
>>>>+
>>>>+	/* Power is off, turn it on and then scan the slot */
>>>>+	ret = pnv_php_set_power_state(slot, OPAL_PCI_SLOT_POWER_ON);
>>>>+	if (ret)
>>>>+		return ret;
>>>>+
>>>>+scan:
>>>>+	if (presence == OPAL_PCI_SLOT_PRESENT) {
>>>>+		if (rescan) {
>>>>+			pci_lock_rescan_remove();
>>>>+			pci_add_pci_devices(php_slot->bus);
>>>>+			pci_unlock_rescan_remove();
>>>>+		}
>>>>+
>>>>+		/* Rescan for child hotpluggable slots */
>>>>+		php_slot->state = PNV_PHP_STATE_POPULATED;
>>>>+		if (rescan)
>>>>+			pnv_php_register(php_slot->dn);
>>>>+	} else {
>>>>+		php_slot->state = PNV_PHP_STATE_POPULATED;
>>>>+	}
>>>>+
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static int pnv_php_enable_slot(struct hotplug_slot *slot)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = container_of(slot,
>>>>+						     struct pnv_php_slot, slot);
>>>>+
>>>>+	return pnv_php_enable(php_slot, true);
>>>>+}
>>>>+
>>>>+static int pnv_php_disable_slot(struct hotplug_slot *slot)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = slot->private;
>>>>+	uint8_t power_state;
>>>>+	int ret;
>>>>+
>>>>+	if (php_slot->state != PNV_PHP_STATE_POPULATED)
>>>>+		return 0;
>>>>+
>>>>+	/* Remove all devices behind the slot */
>>>>+	pci_lock_rescan_remove();
>>>>+	pci_remove_pci_devices(php_slot->bus);
>>>>+	pci_unlock_rescan_remove();
>>>>+
>>>>+	/* Detach the child hotpluggable slots */
>>>>+	pnv_php_unregister(php_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 = pnv_php_get_power_state(slot, &power_state);
>>>>+	if (ret || power_state == OPAL_PCI_SLOT_POWER_ON) {
>>>>+		ret = pnv_php_set_power_state(slot, OPAL_PCI_SLOT_POWER_OFF);
>>>>+		if (ret)
>>>>+			dev_warn(&php_slot->pdev->dev, "Error %d powering off\n",
>>>
>>>
>>>Long line, checkpatch.pl should have warned :)
>>>
>>
>>I didn't see the warning from checkpatch.pl.
>
>
>Cool, then never mind.
>
>
>>
>>>>+				 ret);
>>>>+	}
>>>>+
>>>>+	/* Update slot state */
>>>>+	php_slot->state = PNV_PHP_STATE_REGISTERED;
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static struct hotplug_slot_ops php_slot_ops = {
>>>>+	.get_power_status	= pnv_php_get_power_state,
>>>>+	.get_adapter_status	= pnv_php_get_adapter_state,
>>>>+	.set_attention_status	= pnv_php_set_attention_state,
>>>>+	.enable_slot		= pnv_php_enable_slot,
>>>>+	.disable_slot		= pnv_php_disable_slot,
>>>>+};
>>>>+
>>>>+static void pnv_php_release(struct hotplug_slot *slot)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot = slot->private;
>>>>+	unsigned long flags;
>>>>+
>>>>+	/* Remove from global or child list */
>>>>+	spin_lock_irqsave(&pnv_php_lock, flags);
>>>>+	list_del(&php_slot->link);
>>>>+	spin_unlock_irqrestore(&pnv_php_lock, flags);
>>>>+
>>>>+	/* Detach from parent */
>>>>+	pnv_php_put_slot(php_slot);
>>>>+	pnv_php_put_slot(php_slot->parent);
>>>>+}
>>>>+
>>>>+static int pnv_php_get_slot_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);
>>>
>>>
>>>Is this bit from the same space as 1<<60 as in pnv_eeh_bridge_reset()? If so,
>>>it would be great to have all these id bits defined in one place.
>>>
>>
>>Will have a macro (PCI_SLOT_ID) to produce the PCI slot ID in next revision.
>>
>>>
>>>>+
>>>>+	/* Bus/Slot/Function number */
>>>>+	prop32 = of_get_property(dn, "reg", NULL);
>>>>+	if (!prop32)
>>>>+		return -ENXIO;
>>>>+	*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 -ENXIO;
>>>>+		}
>>>>+
>>>>+		*id |= be64_to_cpup(prop64);
>>>>+		of_node_put(parent);
>>>>+		return 0;
>>>>+	}
>>>>+
>>>>+	return -ENODEV;
>>>>+}
>>>>+
>>>>+static struct pnv_php_slot *pnv_php_alloc_slot(struct device_node *dn)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot;
>>>>+	struct pci_bus *bus;
>>>>+	const char *label;
>>>>+	uint64_t id;
>>>>+
>>>>+	label = of_get_property(dn, "ibm,slot-label", NULL);
>>>>+	if (!label)
>>>>+		return NULL;
>>>>+
>>>>+	if (pnv_php_get_slot_id(dn, &id))
>>>>+		return NULL;
>>>>+
>>>>+	bus = pci_find_bus_by_node(dn);
>>>>+	if (!bus)
>>>>+		return NULL;
>>>>+
>>>>+	php_slot = kzalloc(sizeof(*php_slot), GFP_KERNEL);
>>>>+	if (!php_slot)
>>>>+		return NULL;
>>>>+
>>>>+	php_slot->name = kstrdup(label, GFP_KERNEL);
>>>>+	if (!php_slot->name) {
>>>>+		kfree(php_slot);
>>>>+		return NULL;
>>>>+	}
>>>>+
>>>>+	if (dn->child && PCI_DN(dn->child))
>>>>+		php_slot->slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
>>>>+	else
>>>>+		php_slot->slot_no = -1;   /* Placeholder slot */
>>>>+
>>>>+	kref_init(&php_slot->kref);
>>>>+	php_slot->state	                = PNV_PHP_STATE_INITIALIZED;
>>>>+	php_slot->dn	                = dn;
>>>>+	php_slot->pdev	                = bus->self;
>>>>+	php_slot->bus	                = bus;
>>>>+	php_slot->id	                = id;
>>>>+	php_slot->power_state_check     = false;
>>>>+	php_slot->power_state_confirmed = PNV_PHP_POWER_CONFIRMED_INVALID;
>>>>+	php_slot->slot.ops              = &php_slot_ops;
>>>>+	php_slot->slot.info             = &php_slot->slot_info;
>>>>+	php_slot->slot.release          = pnv_php_release;
>>>>+	php_slot->slot.private          = php_slot;
>>>>+
>>>>+	INIT_WORK(&php_slot->work, pnv_php_work);
>>>>+	init_waitqueue_head(&php_slot->queue);
>>>>+	INIT_LIST_HEAD(&php_slot->children);
>>>>+	INIT_LIST_HEAD(&php_slot->link);
>>>>+
>>>>+	return php_slot;
>>>>+}
>>>>+
>>>>+static int pnv_php_register_slot(struct pnv_php_slot *php_slot)
>>>>+{
>>>>+	struct pnv_php_slot *parent;
>>>>+	struct device_node *dn = php_slot->dn;
>>>>+	unsigned long flags;
>>>>+	int ret;
>>>>+
>>>>+	/* Check if the slot is registered or not */
>>>>+	parent = pnv_php_find_slot(php_slot->dn);
>>>>+	if (parent) {
>>>>+		pnv_php_put_slot(parent);
>>>>+		return -EEXIST;
>>>>+	}
>>>>+
>>>>+	/* Register PCI slot */
>>>>+	ret = pci_hp_register(&php_slot->slot, php_slot->bus,
>>>>+			      php_slot->slot_no, php_slot->name);
>>>>+	if (ret) {
>>>>+		dev_warn(&php_slot->pdev->dev, "Error %d registering slot\n",
>>>>+			 ret);
>>>>+		return ret;
>>>>+	}
>>>>+
>>>>+	/* Attach to the parent's child list or global list */
>>>>+	while ((dn = of_get_parent(dn))) {
>>>>+		if (!PCI_DN(dn)) {
>>>>+			of_node_put(dn);
>>>>+			break;
>>>>+		}
>>>>+
>>>>+		parent = pnv_php_find_slot(dn);
>>>>+		if (parent) {
>>>>+			of_node_put(dn);
>>>>+			break;
>>>>+		}
>>>>+
>>>>+		of_node_put(dn);
>>>>+	}
>>>>+
>>>>+	spin_lock_irqsave(&pnv_php_lock, flags);
>>>>+	php_slot->parent = parent;
>>>>+	if (parent)
>>>>+		list_add_tail(&php_slot->link, &parent->children);
>>>>+	else
>>>>+		list_add_tail(&php_slot->link, &pnv_php_slot_list);
>>>>+	spin_unlock_irqrestore(&pnv_php_lock, flags);
>>>>+
>>>>+	php_slot->state = PNV_PHP_STATE_REGISTERED;
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static int pnv_php_register_one(struct device_node *dn)
>>>>+{
>>>>+	struct pnv_php_slot *php_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 -ENXIO;
>>>>+
>>>>+	prop32 = of_get_property(dn, "ibm,reset-by-firmware", NULL);
>>>>+	if (!prop32 || !of_read_number(prop32, 1))
>>>>+		return -ENXIO;
>>>>+
>>>>+	php_slot = pnv_php_alloc_slot(dn);
>>>>+	if (!php_slot)
>>>>+		return -ENODEV;
>>>>+
>>>>+	ret = pnv_php_register_slot(php_slot);
>>>>+	if (ret)
>>>>+		goto free_slot;
>>>>+
>>>>+	ret = pnv_php_enable(php_slot, false);
>>>>+	if (ret)
>>>>+		goto unregister_slot;
>>>>+
>>>>+	return 0;
>>>>+
>>>>+unregister_slot:
>>>>+	pnv_php_unregister_one(php_slot->dn);
>>>>+free_slot:
>>>>+	pnv_php_put_slot(php_slot);
>>>>+	return ret;
>>>>+}
>>>>+
>>>>+static void pnv_php_register(struct device_node *dn)
>>>>+{
>>>>+	struct device_node *child;
>>>>+
>>>>+	/*
>>>>+	 * The parent slots should be registered before their
>>>>+	 * child slots.
>>>>+	 */
>>>>+	for_each_child_of_node(dn, child) {
>>>>+		pnv_php_register_one(child);
>>>>+		pnv_php_register(child);
>>>>+	}
>>>>+}
>>>>+
>>>>+static void pnv_php_unregister_one(struct device_node *dn)
>>>>+{
>>>>+	struct pnv_php_slot *php_slot;
>>>>+
>>>>+	php_slot = pnv_php_find_slot(dn);
>>>>+	if (!php_slot)
>>>>+		return;
>>>>+
>>>>+	pnv_php_put_slot(php_slot);
>>>>+	pci_hp_deregister(&php_slot->slot);
>>>>+}
>>>>+
>>>>+static void pnv_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) {
>>>>+		pnv_php_unregister(child);
>>>>+		pnv_php_unregister_one(child);
>>>>+	}
>>>>+}
>>>>+
>>>>+static struct notifier_block php_msg_nb = {
>>>>+	.notifier_call	= pnv_php_handle_msg,
>>>>+	.next		= NULL,
>>>>+	.priority	= 0,
>>>>+};
>>>>+
>>>>+static int __init pnv_php_init(void)
>>>>+{
>>>>+	struct device_node *dn;
>>>>+	int ret;
>>>>+
>>>>+	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
>>>>+
>>>>+	/* Register hotplug message handler */
>>>>+	ret = pnv_pci_hotplug_notifier_register(&php_msg_nb);
>>>>+	if (ret) {
>>>>+		pr_warn("%s: Error %d registering hotplug notifier\n",
>>>>+			__func__, ret);
>>>>+		return ret;
>>>>+	}
>>>>+
>>>>+	/* Scan PHB nodes and their children */
>>>>+	for_each_compatible_node(dn, NULL, "ibm,ioda-phb")
>>>>+		pnv_php_register(dn);
>>>>+	for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
>>>>+		pnv_php_register(dn);
>>>>+
>>>>+	return 0;
>>>>+}
>>>>+
>>>>+static void __exit pnv_php_exit(void)
>>>>+{
>>>>+	struct device_node *dn;
>>>>+
>>>>+	for_each_compatible_node(dn, NULL, "ibm,ioda-phb")
>>>>+		pnv_php_unregister(dn);
>>>>+	for_each_compatible_node(dn, NULL, "ibm,ioda2-phb")
>>>>+		pnv_php_unregister(dn);
>>>>+
>>>>+	pnv_pci_hotplug_notifier_unregister(&php_msg_nb);
>>>>+}
>>>>+
>>>>+module_init(pnv_php_init);
>>>>+module_exit(pnv_php_exit);
>>>>+
>>>>+MODULE_VERSION(DRIVER_VERSION);
>>>>+MODULE_LICENSE("GPL v2");
>>>>+MODULE_AUTHOR(DRIVER_AUTHOR);
>>>>+MODULE_DESCRIPTION(DRIVER_DESC);
>>>>