[SPARC64]: Add hypervisor API negotiation and fix console bugs.

Hypervisor interfaces need to be negotiated in order to use
some API calls reliably.  So add a small set of interfaces
to request API versions and query current settings.

This allows us to fix some bugs in the hypervisor console:

1) If we can negotiate API group CORE of at least major 1
   minor 1 we can use con_read and con_write which can improve
   console performance quite a bit.

2) When we do a console write request, we should hold the
   spinlock around the whole request, not a byte at a time.
   What would happen is that it's easy for output from
   different cpus to get mixed with each other.

3) Use consistent udelay() based polling, udelay(1) each
   loop with a limit of 1000 polls to handle stuck hypervisor
   console.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 189 insertions, 0 deletions

diff --git a/arch/sparc64/kernel/hvapi.c b/arch/sparc64/kernel/hvapi.c
new file mode 100644
index 000000000000..f03ffc829c7a
--- /dev/null
+++ b/arch/sparc64/kernel/hvapi.c
@@ -0,0 +1,189 @@
+/* hvapi.c: Hypervisor API management.
+ *
+ * Copyright (C) 2007 David S. Miller <davem@davemloft.net>
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+
+#include <asm/hypervisor.h>
+#include <asm/oplib.h>
+
+/* If the hypervisor indicates that the API setting
+ * calls are unsupported, by returning HV_EBADTRAP or
+ * HV_ENOTSUPPORTED, we assume that API groups with the
+ * PRE_API flag set are major 1 minor 0.
+ */
+struct api_info {
+        unsigned long group;
+        unsigned long major;
+        unsigned long minor;
+        unsigned int refcnt;
+        unsigned int flags;
+#define FLAG_PRE_API            0x00000001
+};
+
+static struct api_info api_table[] = {
+        { .group = HV_GRP_SUN4V,        .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_CORE,         .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_INTR,                                 },
+        { .group = HV_GRP_SOFT_STATE,                           },
+        { .group = HV_GRP_PCI,          .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_LDOM,                                 },
+        { .group = HV_GRP_SVC_CHAN,     .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_NCS,          .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_NIAG_PERF,    .flags = FLAG_PRE_API   },
+        { .group = HV_GRP_FIRE_PERF,                            },
+        { .group = HV_GRP_DIAG,         .flags = FLAG_PRE_API   },
+};
+
+static DEFINE_SPINLOCK(hvapi_lock);
+
+static struct api_info *__get_info(unsigned long group)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(api_table); i++) {
+                if (api_table[i].group == group)
+                        return &api_table[i];
+        }
+        return NULL;
+}
+
+static void __get_ref(struct api_info *p)
+{
+        p->refcnt++;
+}
+
+static void __put_ref(struct api_info *p)
+{
+        if (--p->refcnt == 0) {
+                unsigned long ignore;
+
+                sun4v_set_version(p->group, 0, 0, &ignore);
+                p->major = p->minor = 0;
+        }
+}
+
+/* Register a hypervisor API specification.  It indicates the
+ * API group and desired major+minor.
+ *
+ * If an existing API registration exists '0' (success) will
+ * be returned if it is compatible with the one being registered.
+ * Otherwise a negative error code will be returned.
+ *
+ * Otherwise an attempt will be made to negotiate the requested
+ * API group/major/minor with the hypervisor, and errors returned
+ * if that does not succeed.
+ */
+int sun4v_hvapi_register(unsigned long group, unsigned long major,
+                         unsigned long *minor)
+{
+        struct api_info *p;
+        unsigned long flags;
+        int ret;
+
+        spin_lock_irqsave(&hvapi_lock, flags);
+        p = __get_info(group);
+        ret = -EINVAL;
+        if (p) {
+                if (p->refcnt) {
+                        ret = -EINVAL;
+                        if (p->major == major) {
+                                *minor = p->minor;
+                                ret = 0;
+                        }
+                } else {
+                        unsigned long actual_minor;
+                        unsigned long hv_ret;
+
+                        hv_ret = sun4v_set_version(group, major, *minor,
+                                                   &actual_minor);
+                        ret = -EINVAL;
+                        if (hv_ret == HV_EOK) {
+                                *minor = actual_minor;
+                                p->major = major;
+                                p->minor = actual_minor;
+                                ret = 0;
+                        } else if (hv_ret == HV_EBADTRAP ||
+                                   HV_ENOTSUPPORTED) {
+                                if (p->flags & FLAG_PRE_API) {
+                                        if (major == 1) {
+                                                p->major = 1;
+                                                p->minor = 0;
+                                                *minor = 0;
+                                                ret = 0;
+                                        }
+                                }
+                        }
+                }
+
+                if (ret == 0)
+                        __get_ref(p);
+        }
+        spin_unlock_irqrestore(&hvapi_lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL(sun4v_hvapi_register);
+
+void sun4v_hvapi_unregister(unsigned long group)
+{
+        struct api_info *p;
+        unsigned long flags;
+
+        spin_lock_irqsave(&hvapi_lock, flags);
+        p = __get_info(group);
+        if (p)
+                __put_ref(p);
+        spin_unlock_irqrestore(&hvapi_lock, flags);
+}
+EXPORT_SYMBOL(sun4v_hvapi_unregister);
+
+int sun4v_hvapi_get(unsigned long group,
+                    unsigned long *major,
+                    unsigned long *minor)
+{
+        struct api_info *p;
+        unsigned long flags;
+        int ret;
+
+        spin_lock_irqsave(&hvapi_lock, flags);
+        ret = -EINVAL;
+        p = __get_info(group);
+        if (p && p->refcnt) {
+                *major = p->major;
+                *minor = p->minor;
+                ret = 0;
+        }
+        spin_unlock_irqrestore(&hvapi_lock, flags);
+
+        return ret;
+}
+EXPORT_SYMBOL(sun4v_hvapi_get);
+
+void __init sun4v_hvapi_init(void)
+{
+        unsigned long group, major, minor;
+
+        group = HV_GRP_SUN4V;
+        major = 1;
+        minor = 0;
+        if (sun4v_hvapi_register(group, major, &minor))
+                goto bad;
+
+        group = HV_GRP_CORE;
+        major = 1;
+        minor = 1;
+        if (sun4v_hvapi_register(group, major, &minor))
+                goto bad;
+
+        return;
+
+bad:
+        prom_printf("HVAPI: Cannot register API group "
+                    "%lx with major(%u) minor(%u)\n",
+                    group, major, minor);
+        prom_halt();
+}