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 <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 264 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
index b0e46dede1a9..13e9e63a7266 100644
--- a/drivers/pci/hotplug/Kconfig
+++ b/drivers/pci/hotplug/Kconfig
@@ -151,4 +151,15 @@ config HOTPLUG_PCI_SGI
 
           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
diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
index c459cd4e39c2..47ec8c80e16d 100644
--- a/drivers/pci/hotplug/Makefile
+++ b/drivers/pci/hotplug/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_HOTPLUG_PCI_RPA)		+= rpaphp.o
 obj-$(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.
 
diff --git a/drivers/pci/hotplug/s390_pci_hpc.c b/drivers/pci/hotplug/s390_pci_hpc.c
new file mode 100644
index 000000000000..dee68e0698e1
--- /dev/null
+++ b/drivers/pci/hotplug/s390_pci_hpc.c
@@ -0,0 +1,252 @@
+/*
+ * PCI Hot Plug Controller Driver for System z
+ *
+ * Copyright 2012 IBM Corp.
+ *
+ * Author(s):
+ *   Jan Glauber <jang@linux.vnet.ibm.com>
+ */
+
+#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 <jang@linux.vnet.ibm.com");
+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);