s390/pci: PCI hotplug support via SCLP

Add SCLP PCI configure/deconfigure and implement a PCI hotplug
controller (s390_pci_hpc). The hotplug controller creates a slot
for every PCI function in stand-by or configured state. The PCI
functions are named after the PCI function ID (fid). By writing to
the power attribute in /sys/bus/pci/slots/<fid>/power the PCI function
is moved to stand-by or configured state. If moved to the configured
state the device is automatically scanned by the s390 PCI layer.

Signed-off-by: Jan Glauber <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/include/asm/pci.h

···
 	enum pci_bus_speed max_bus_speed;
 };
 
+struct pci_hp_callback_ops {
+	int (*create_slot)	(struct zpci_dev *zdev);
+	void (*remove_slot)	(struct zpci_dev *zdev);
+};
+
 static inline bool zdev_enabled(struct zpci_dev *zdev)
 {
 	return (zdev->fh & (1UL << 31)) ? true : false;
···
 /* DMA */
 int zpci_dma_init(void);
 void zpci_dma_exit(void);
+
+/* Hotplug */
+extern struct mutex zpci_list_lock;
+extern struct list_head zpci_list;
+extern struct pci_hp_callback_ops hotplug_ops;
+extern unsigned int pci_probe;
 
 #endif

arch/s390/include/asm/sclp.h

···
 void sclp_get_ipl_info(struct sclp_ipl_info *info);
 bool sclp_has_linemode(void);
 bool sclp_has_vt220(void);
+int sclp_pci_configure(u32 fid);
+int sclp_pci_deconfigure(u32 fid);
 
 #endif /* _ASM_S390_SCLP_H */

arch/s390/pci/pci.c

···
 
 /* list of all detected zpci devices */
 LIST_HEAD(zpci_list);
+EXPORT_SYMBOL_GPL(zpci_list);
 DEFINE_MUTEX(zpci_list_lock);
+EXPORT_SYMBOL_GPL(zpci_list_lock);
+
+struct pci_hp_callback_ops hotplug_ops;
+EXPORT_SYMBOL_GPL(hotplug_ops);
 
 static DECLARE_BITMAP(zpci_domain, ZPCI_NR_DEVICES);
 static DEFINE_SPINLOCK(zpci_domain_lock);
···
 
 	mutex_lock(&zpci_list_lock);
 	list_add_tail(&zdev->entry, &zpci_list);
+	if (hotplug_ops.create_slot)
+		hotplug_ops.create_slot(zdev);
 	mutex_unlock(&zpci_list_lock);
 
 	if (zdev->state == ZPCI_FN_STATE_STANDBY)
···
 out_start:
 	mutex_lock(&zpci_list_lock);
 	list_del(&zdev->entry);
+	if (hotplug_ops.remove_slot)
+		hotplug_ops.remove_slot(zdev);
 	mutex_unlock(&zpci_list_lock);
 out_bus:
 	zpci_free_domain(zdev);

drivers/pci/hotplug/Kconfig

···
 
 	  When in doubt, say N.
 
+config HOTPLUG_PCI_S390
+	tristate "System z PCI Hotplug Support"
+	depends on S390 && 64BIT
+	help
+	  Say Y here if you want to use the System z PCI Hotplug
+	  driver for PCI devices. Without this driver it is not
+	  possible to access stand-by PCI functions nor to deconfigure
+	  PCI functions.
+
+	  When in doubt, say Y.
+
 endif # HOTPLUG_PCI

drivers/pci/hotplug/Makefile

···
 obj-$(CONFIG_HOTPLUG_PCI_RPA_DLPAR)	+= rpadlpar_io.o
 obj-$(CONFIG_HOTPLUG_PCI_SGI)		+= sgi_hotplug.o
 obj-$(CONFIG_HOTPLUG_PCI_ACPI)		+= acpiphp.o
+obj-$(CONFIG_HOTPLUG_PCI_S390)		+= s390_pci_hpc.o
 
 # acpiphp_ibm extends acpiphp, so should be linked afterwards.
 

drivers/pci/hotplug/s390_pci_hpc.c

···
+/*
+ * PCI Hot Plug Controller Driver for System z
+ *
+ * Copyright 2012 IBM Corp.
+ *
+ * Author(s):
+ *   Jan Glauber <[e-mail]>
+ */
+
+#define COMPONENT "zPCI hpc"
+#define pr_fmt(fmt) COMPONENT ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/pci_hotplug.h>
+#include <linux/init.h>
+#include <asm/sclp.h>
+
+#define SLOT_NAME_SIZE	10
+static LIST_HEAD(s390_hotplug_slot_list);
+
+MODULE_AUTHOR("Jan Glauber <[e-mail]");
+MODULE_DESCRIPTION("Hot Plug PCI Controller for System z");
+MODULE_LICENSE("GPL");
+
+static int zpci_fn_configured(enum zpci_state state)
+{
+	return state == ZPCI_FN_STATE_CONFIGURED ||
+	       state == ZPCI_FN_STATE_ONLINE;
+}
+
+/*
+ * struct slot - slot information for each *physical* slot
+ */
+struct slot {
+	struct list_head slot_list;
+	struct hotplug_slot *hotplug_slot;
+	struct zpci_dev *zdev;
+};
+
+static int enable_slot(struct hotplug_slot *hotplug_slot)
+{
+	struct slot *slot = hotplug_slot->private;
+	int rc;
+
+	if (slot->zdev->state != ZPCI_FN_STATE_STANDBY)
+		return -EIO;
+
+	rc = sclp_pci_configure(slot->zdev->fid);
+	if (!rc) {
+		slot->zdev->state = ZPCI_FN_STATE_CONFIGURED;
+		/* automatically scan the device after is was configured */
+		zpci_enable_device(slot->zdev);
+		zpci_scan_device(slot->zdev);
+	}
+	return rc;
+}
+
+static int disable_slot(struct hotplug_slot *hotplug_slot)
+{
+	struct slot *slot = hotplug_slot->private;
+	int rc;
+
+	if (!zpci_fn_configured(slot->zdev->state))
+		return -EIO;
+
+	/* TODO: we rely on the user to unbind/remove the device, is that plausible
+	 *	 or do we need to trigger that here?
+	 */
+	rc = sclp_pci_deconfigure(slot->zdev->fid);
+	if (!rc) {
+		/* Fixme: better call List-PCI to find the disabled FH
+		   for the FID since the FH should be opaque... */
+		slot->zdev->fh &= 0x7fffffff;
+		slot->zdev->state = ZPCI_FN_STATE_STANDBY;
+	}
+	return rc;
+}
+
+static int get_power_status(struct hotplug_slot *hotplug_slot, u8 *value)
+{
+	struct slot *slot = hotplug_slot->private;
+
+	switch (slot->zdev->state) {
+	case ZPCI_FN_STATE_STANDBY:
+		*value = 0;
+		break;
+	default:
+		*value = 1;
+		break;
+	}
+	return 0;
+}
+
+static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
+{
+	/* if the slot exits it always contains a function */
+	*value = 1;
+	return 0;
+}
+
+static void release_slot(struct hotplug_slot *hotplug_slot)
+{
+	struct slot *slot = hotplug_slot->private;
+
+	pr_debug("%s - physical_slot = %s\n", __func__, hotplug_slot_name(hotplug_slot));
+	kfree(slot->hotplug_slot->info);
+	kfree(slot->hotplug_slot);
+	kfree(slot);
+}
+
+static struct hotplug_slot_ops s390_hotplug_slot_ops = {
+	.enable_slot =		enable_slot,
+	.disable_slot =		disable_slot,
+	.get_power_status =	get_power_status,
+	.get_adapter_status =	get_adapter_status,
+};
+
+static int init_pci_slot(struct zpci_dev *zdev)
+{
+	struct hotplug_slot *hotplug_slot;
+	struct hotplug_slot_info *info;
+	char name[SLOT_NAME_SIZE];
+	struct slot *slot;
+	int rc;
+
+	if (!zdev)
+		return 0;
+
+	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
+	if (!slot)
+		goto error;
+
+	hotplug_slot = kzalloc(sizeof(*hotplug_slot), GFP_KERNEL);
+	if (!hotplug_slot)
+		goto error_hp;
+	hotplug_slot->private = slot;
+
+	slot->hotplug_slot = hotplug_slot;
+	slot->zdev = zdev;
+
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		goto error_info;
+	hotplug_slot->info = info;
+
+	hotplug_slot->ops = &s390_hotplug_slot_ops;
+	hotplug_slot->release = &release_slot;
+
+	get_power_status(hotplug_slot, &info->power_status);
+	get_adapter_status(hotplug_slot, &info->adapter_status);
+
+	snprintf(name, SLOT_NAME_SIZE, "%08x", zdev->fid);
+	rc = pci_hp_register(slot->hotplug_slot, zdev->bus,
+			     ZPCI_DEVFN, name);
+	if (rc) {
+		pr_err("pci_hp_register failed with error %d\n", rc);
+		goto error_reg;
+	}
+	list_add(&slot->slot_list, &s390_hotplug_slot_list);
+	return 0;
+
+error_reg:
+	kfree(info);
+error_info:
+	kfree(hotplug_slot);
+error_hp:
+	kfree(slot);
+error:
+	return -ENOMEM;
+}
+
+static int __init init_pci_slots(void)
+{
+	struct zpci_dev *zdev;
+	int device = 0;
+
+	/*
+	 * Create a structure for each slot, and register that slot
+	 * with the pci_hotplug subsystem.
+	 */
+	mutex_lock(&zpci_list_lock);
+	list_for_each_entry(zdev, &zpci_list, entry) {
+		init_pci_slot(zdev);
+		device++;
+	}
+
+	mutex_unlock(&zpci_list_lock);
+	return (device) ? 0 : -ENODEV;
+}
+
+static void exit_pci_slot(struct zpci_dev *zdev)
+{
+	struct list_head *tmp, *n;
+	struct slot *slot;
+
+	list_for_each_safe(tmp, n, &s390_hotplug_slot_list) {
+		slot = list_entry(tmp, struct slot, slot_list);
+		if (slot->zdev != zdev)
+			continue;
+		list_del(&slot->slot_list);
+		pci_hp_deregister(slot->hotplug_slot);
+	}
+}
+
+static void __exit exit_pci_slots(void)
+{
+	struct list_head *tmp, *n;
+	struct slot *slot;
+
+	/*
+	 * Unregister all of our slots with the pci_hotplug subsystem.
+	 * Memory will be freed in release_slot() callback after slot's
+	 * lifespan is finished.
+	 */
+	list_for_each_safe(tmp, n, &s390_hotplug_slot_list) {
+		slot = list_entry(tmp, struct slot, slot_list);
+		list_del(&slot->slot_list);
+		pci_hp_deregister(slot->hotplug_slot);
+	}
+}
+
+static int __init pci_hotplug_s390_init(void)
+{
+	/*
+	 * Do specific initialization stuff for your driver here
+	 * like initializing your controller hardware (if any) and
+	 * determining the number of slots you have in the system
+	 * right now.
+	 */
+
+	if (!pci_probe)
+		return -EOPNOTSUPP;
+
+	/* register callbacks for slot handling from arch code */
+	mutex_lock(&zpci_list_lock);
+	hotplug_ops.create_slot = init_pci_slot;
+	hotplug_ops.remove_slot = exit_pci_slot;
+	mutex_unlock(&zpci_list_lock);
+	pr_info("registered hotplug slot callbacks\n");
+	return init_pci_slots();
+}
+
+static void __exit pci_hotplug_s390_exit(void)
+{
+	exit_pci_slots();
+}
+
+module_init(pci_hotplug_s390_init);
+module_exit(pci_hotplug_s390_exit);

drivers/s390/char/sclp.h

···
 /*
- * Copyright IBM Corp. 1999, 2009
+ * Copyright IBM Corp. 1999,2012
  *
  * Author(s): Martin Peschke <[e-mail]>
  *	      Martin Schwidefsky <[e-mail]>
···
 #define SCLP_HAS_CHP_RECONFIG	(sclp_facilities & 0x2000000000000000ULL)
 #define SCLP_HAS_CPU_INFO	(sclp_facilities & 0x0800000000000000ULL)
 #define SCLP_HAS_CPU_RECONFIG	(sclp_facilities & 0x0400000000000000ULL)
+#define SCLP_HAS_PCI_RECONFIG	(sclp_facilities & 0x0000000040000000ULL)
 
 
 struct gds_subvector {

drivers/s390/char/sclp_cmd.c

···
 /*
- * Copyright IBM Corp. 2007, 2009
+ * Copyright IBM Corp. 2007,2012
  *
  * Author(s): Heiko Carstens <[e-mail]>,
  *	      Peter Oberparleiter <[e-mail]>
···
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/err.h>
+#include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/mm.h>
···
 __initcall(sclp_detect_standby_memory);
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
+
+/*
+ * PCI I/O adapter configuration related functions.
+ */
+#define SCLP_CMDW_CONFIGURE_PCI			0x001a0001
+#define SCLP_CMDW_DECONFIGURE_PCI		0x001b0001
+
+#define SCLP_RECONFIG_PCI_ATPYE			2
+
+struct pci_cfg_sccb {
+	struct sccb_header header;
+	u8 atype;		/* adapter type */
+	u8 reserved1;
+	u16 reserved2;
+	u32 aid;		/* adapter identifier */
+} __packed;
+
+static int do_pci_configure(sclp_cmdw_t cmd, u32 fid)
+{
+	struct pci_cfg_sccb *sccb;
+	int rc;
+
+	if (!SCLP_HAS_PCI_RECONFIG)
+		return -EOPNOTSUPP;
+
+	sccb = (struct pci_cfg_sccb *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!sccb)
+		return -ENOMEM;
+
+	sccb->header.length = PAGE_SIZE;
+	sccb->atype = SCLP_RECONFIG_PCI_ATPYE;
+	sccb->aid = fid;
+	rc = do_sync_request(cmd, sccb);
+	if (rc)
+		goto out;
+	switch (sccb->header.response_code) {
+	case 0x0020:
+	case 0x0120:
+		break;
+	default:
+		pr_warn("configure PCI I/O adapter failed: cmd=0x%08x  response=0x%04x\n",
+			cmd, sccb->header.response_code);
+		rc = -EIO;
+		break;
+	}
+out:
+	free_page((unsigned long) sccb);
+	return rc;
+}
+
+int sclp_pci_configure(u32 fid)
+{
+	return do_pci_configure(SCLP_CMDW_CONFIGURE_PCI, fid);
+}
+EXPORT_SYMBOL(sclp_pci_configure);
+
+int sclp_pci_deconfigure(u32 fid)
+{
+	return do_pci_configure(SCLP_CMDW_DECONFIGURE_PCI, fid);
+}
+EXPORT_SYMBOL(sclp_pci_deconfigure);
 
 /*
  * Channel path configuration related functions.