This adds the capability to DLPAR add and remove memory from the kernel.  The
patch registers handlers for the arch-specific probe and release memory callouts to handle addition/removal of memory to the system and the associated device tree updates. Signed-off-by: Nathan Fontenot <nfont at austin.ibm.com> ---

Index: powerpc/arch/powerpc/platforms/pseries/dlpar.c
===================================================================
--- powerpc.orig/arch/powerpc/platforms/pseries/dlpar.c 2009-10-28 
15:21:38.000000000 -0500
+++ powerpc/arch/powerpc/platforms/pseries/dlpar.c      2009-10-28 
15:21:49.000000000 -0500
@@ -16,6 +16,10 @@
#include <linux/notifier.h>
#include <linux/proc_fs.h>
#include <linux/spinlock.h>
+#include <linux/memory_hotplug.h>
+#include <linux/sysdev.h>
+#include <linux/sysfs.h>
+

#include <asm/prom.h>
#include <asm/machdep.h>
@@ -404,11 +408,189 @@
        return 0;
}

+#ifdef CONFIG_MEMORY_HOTPLUG
+
+static struct property *clone_property(struct property *old_prop)
+{
+       struct property *new_prop;
+
+       new_prop = kzalloc((sizeof *new_prop), GFP_KERNEL);
+       if (!new_prop)
+               return NULL;
+
+       new_prop->name = kstrdup(old_prop->name, GFP_KERNEL);
+       new_prop->value = kzalloc(old_prop->length + 1, GFP_KERNEL);
+       if (!new_prop->name || !new_prop->value) {
+               free_property(new_prop);
+               return NULL;
+       }
+
+       memcpy(new_prop->value, old_prop->value, old_prop->length);
+       new_prop->length = old_prop->length;
+
+       return new_prop;
+}
+
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+
+int memory_probe(u64 phys_addr)
+{
+       struct device_node *dn = NULL;
+       struct property *new_prop;
+       struct property *old_prop;
+       struct of_drconf_cell *drmem;
+       const u64 *lmb_size;
+       int num_entries, i;
+       int rc = -EINVAL;
+
+       if (!phys_addr)
+               goto memory_probe_exit;
+
+       dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+       if (!dn)
+               goto memory_probe_exit;
+
+       lmb_size = of_get_property(dn, "ibm,lmb-size", NULL);
+       if (!lmb_size)
+               goto memory_probe_exit;
+
+       old_prop = of_find_property(dn, "ibm,dynamic-memory", NULL);
+       if (!old_prop)
+               goto memory_probe_exit;
+
+       num_entries = *(u32 *)old_prop->value;
+       drmem = (struct of_drconf_cell *)
+                               ((char *)old_prop->value + sizeof(u32));
+
+       for (i = 0; i < num_entries; i++) {
+               u64 lmb_end_addr = drmem[i].base_addr + *lmb_size;
+               if (phys_addr >= drmem[i].base_addr
+                   && phys_addr < lmb_end_addr)
+                       break;
+       }
+
+       if (i >= num_entries)
+               goto memory_probe_exit;
+
+       if (drmem[i].flags & DRCONF_MEM_ASSIGNED) {
+               /* This lmb is already adssigned to the system, nothing to do */
+               rc = 0;
+               goto memory_probe_exit;
+       }
+
+       rc = acquire_drc(drmem[i].drc_index);
+       if (rc) {
+               rc = -EINVAL;
+               goto memory_probe_exit;
+       }
+
+       new_prop = clone_property(old_prop);
+       drmem = (struct of_drconf_cell *)
+                               ((char *)new_prop->value + sizeof(u32));
+
+       drmem[i].flags |= DRCONF_MEM_ASSIGNED;
+       rc = prom_update_property(dn, new_prop, old_prop);
+       if (rc) {
+               free_property(new_prop);
+               rc = -EINVAL;
+               goto memory_probe_exit;
+       }
+
+       rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
+                                         PSERIES_DRCONF_MEM_ADD,
+                                         &drmem[i].base_addr);
+       if (rc == NOTIFY_BAD) {
+               prom_update_property(dn, old_prop, new_prop);
+               release_drc(drmem[i].drc_index);
+               rc = -EINVAL;
+       } else
+               rc = 0;
+
+memory_probe_exit:
+       of_node_put(dn);
+       return rc;
+}
+
+#endif /* CONFIG_ARCH_MEMORY_PROBE */
+
+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+
+static int memory_release(const char *buf, size_t count)
+{
+       unsigned long drc_index;
+       struct device_node *dn;
+       struct property *new_prop, *old_prop;
+       struct of_drconf_cell *drmem;
+       int num_entries;
+       int i;
+       int rc = -EINVAL;
+
+       rc = strict_strtoul(buf, 0, &drc_index);
+       if (rc)
+               return rc;
+
+       dn = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+       if (!dn)
+               return rc;
+
+       old_prop = of_find_property(dn, "ibm,dynamic-memory", NULL);
+       if (!old_prop)
+               goto memory_release_exit;
+
+       num_entries = *(u32 *)old_prop->value;
+       drmem = (struct of_drconf_cell *)
+                               ((char *)old_prop->value + sizeof(u32));
+
+       for (i = 0; i < num_entries; i++) {
+               if (drmem[i].drc_index == drc_index)
+                       break;
+       }
+
+       if (i >= num_entries)
+               goto memory_release_exit;
+
+       new_prop = clone_property(old_prop);
+       drmem = (struct of_drconf_cell *)
+                               ((char *)new_prop->value + sizeof(u32));
+
+       drmem[i].flags &= ~DRCONF_MEM_ASSIGNED;
+       rc = prom_update_property(dn, new_prop, old_prop);
+       if (rc) {
+               free_property(new_prop);
+               rc = -EINVAL;
+               goto memory_release_exit;
+       }
+
+       rc = blocking_notifier_call_chain(&pSeries_reconfig_chain,
+                                         PSERIES_DRCONF_MEM_REMOVE,
+                                         &drmem[i].base_addr);
+       if (rc != NOTIFY_BAD)
+               rc = release_drc(drc_index);
+
+       if (rc) {
+               prom_update_property(dn, old_prop, new_prop);
+               rc = -EINVAL;
+       }
+
+memory_release_exit:
+       of_node_put(dn);
+       return rc ? rc : count;
+}
+#endif /* CONFIG_ARCH_MEMORY_RELEASE */
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
static int pseries_dlpar_init(void)
{
        if (!machine_is(pseries))
                return 0;

+#ifdef CONFIG_ARCH_MEMORY_RELEASE
+       ppc_md.memory_release = memory_release;
+#endif
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+       ppc_md.memory_probe = memory_probe;
+#endif
+
        return 0;
}
device_initcall(pseries_dlpar_init);
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