pseries/drc-info: Provide parallel routines to convert between
drc_index and CPU numbers at runtime, using the older device-tree
properties ("ibm,drc-indexes", "ibm,drc-names", "ibm,drc-types"
and "ibm,drc-power-domains"), or the new property "ibm,drc-info".

[V2: Revise contant names.]
[V3: No change.]
[V4: No change.]
[V5: Resynchronize/resubmit]
[V6: No change]

Signed-off-by: Michael Bringmann <m...@linux.vnet.ibm.com>
---
diff --git a/arch/powerpc/platforms/pseries/pseries_energy.c 
b/arch/powerpc/platforms/pseries/pseries_energy.c
index 9276779..10c4200 100644
--- a/arch/powerpc/platforms/pseries/pseries_energy.c
+++ b/arch/powerpc/platforms/pseries/pseries_energy.c
@@ -35,10 +35,68 @@ static int sysfs_entries;
 
 /* Helper Routines to convert between drc_index to cpu numbers */
 
+void read_one_drc_info(int **info, char **dtype, char **dname,
+                       unsigned long int *fdi_p, unsigned long int *nsl_p,
+                       unsigned long int *si_p, unsigned long int *ldi_p)
+{
+       char *drc_type, *drc_name, *pc;
+       u32 fdi, nsl, si, ldi;
+
+       fdi = nsl = si = ldi = 0;
+
+       /* Get drc-type:encode-string */
+       pc = (char *)info;
+       drc_type = pc;
+       pc += (strlen(drc_type) + 1);
+
+       /* Get drc-name-prefix:encode-string */
+       drc_name = (char *)pc;
+       pc += (strlen(drc_name) + 1);
+
+       /* Get drc-index-start:encode-int */
+       memcpy(&fdi, pc, 4);
+       fdi = be32_to_cpu(fdi);
+       pc += 4;
+
+       /* Get/skip drc-name-suffix-start:encode-int */
+       pc += 4;
+
+       /* Get number-sequential-elements:encode-int */
+       memcpy(&nsl, pc, 4);
+       nsl = be32_to_cpu(nsl);
+       pc += 4;
+
+       /* Get sequential-increment:encode-int */
+       memcpy(&si, pc, 4);
+       si = be32_to_cpu(si);
+       pc += 4;
+
+       /* Get/skip drc-power-domain:encode-int */
+       pc += 4;
+
+       /* Should now know end of current entry */
+       ldi = fdi + ((nsl-1)*si);
+
+       (*info) = (int *)pc;
+
+       if (dtype)
+               *dtype = drc_type;
+       if (dname)
+               *dname = drc_name;
+       if (fdi_p)
+               *fdi_p = fdi;
+       if (nsl_p)
+               *nsl_p = nsl;
+       if (si_p)
+               *si_p = si;
+       if (ldi_p)
+               *ldi_p = ldi;
+}
+EXPORT_SYMBOL(read_one_drc_info);
+
 static u32 cpu_to_drc_index(int cpu)
 {
        struct device_node *dn = NULL;
-       const int *indexes;
        int i;
        int rc = 1;
        u32 ret = 0;
@@ -46,18 +104,54 @@ static u32 cpu_to_drc_index(int cpu)
        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;
-       indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
-       if (indexes == NULL)
-               goto err_of_node_put;
+
        /* Convert logical cpu number to core number */
        i = cpu_core_index_of_thread(cpu);
-       /*
-        * The first element indexes[0] is the number of drc_indexes
-        * returned in the list.  Hence i+1 will get the drc_index
-        * corresponding to core number i.
-        */
-       WARN_ON(i > indexes[0]);
-       ret = indexes[i + 1];
+
+       if (firmware_has_feature(FW_FEATURE_DRC_INFO)) {
+               int *info = (int *)4;
+               unsigned long int num_set_entries, j, iw = i, fdi = 0;
+               unsigned long int ldi = 0, nsl = 0, si = 0;
+               char *dtype;
+               char *dname;
+
+               info = (int *)of_get_property(dn, "ibm,drc-info", NULL);
+               if (info == NULL)
+                       goto err_of_node_put;
+
+               num_set_entries = be32_to_cpu(*info++);
+
+               for (j = 0; j < num_set_entries; j++) {
+
+                       read_one_drc_info(&info, &dtype, &dname, &fdi,
+                                       &nsl, &si, &ldi);
+                       if (strcmp(dtype, "CPU"))
+                               goto err;
+
+                       if (iw < ldi)
+                               break;
+
+                       WARN_ON(((iw-fdi)%si) != 0);
+               }
+               WARN_ON((nsl == 0) | (si == 0));
+
+               ret = ldi + (iw*si);
+       } else {
+               const int *indexes;
+
+               indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
+               if (indexes == NULL)
+                       goto err_of_node_put;
+
+               /*
+                * The first element indexes[0] is the number of drc_indexes
+                * returned in the list.  Hence i+1 will get the drc_index
+                * corresponding to core number i.
+                */
+               WARN_ON(i > indexes[0]);
+               ret = indexes[i + 1];
+       }
+
        rc = 0;
 
 err_of_node_put:
@@ -78,21 +172,51 @@ static int drc_index_to_cpu(u32 drc_index)
        dn = of_find_node_by_path("/cpus");
        if (dn == NULL)
                goto err;
-       indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
-       if (indexes == NULL)
-               goto err_of_node_put;
-       /*
-        * First element in the array is the number of drc_indexes
-        * returned.  Search through the list to find the matching
-        * drc_index and get the core number
-        */
-       for (i = 0; i < indexes[0]; i++) {
-               if (indexes[i + 1] == drc_index)
+
+       if (firmware_has_feature(FW_FEATURE_DRC_INFO)) {
+               int *info = (int *)dn;
+               unsigned long int num_set_entries, j, ret;
+               unsigned long int fdi = 0, ldi = 0, nsl = 0, si = 0;
+               char *dtype, *dname;
+
+               info = (int *)of_get_property(dn, "ibm,drc-info", NULL);
+               if (info == NULL)
+                       goto err_of_node_put;
+
+               num_set_entries = be32_to_cpu(*info++);
+
+               for (j = 0; j < num_set_entries; j++) {
+                       read_one_drc_info(&info, &dtype, &dname, &fdi,
+                                       &nsl, &si, &ldi);
+                       if (strcmp(dtype, "CPU"))
+                               goto err;
+
+                       WARN_ON(drc_index < fdi);
+                       if (drc_index > ldi)
+                               continue;
+
+                       WARN_ON(((drc_index-fdi)%si) != 0);
+
+                       ret = ((drc_index-fdi)/si);
                        break;
+               }
+       } else {
+               indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
+               if (indexes == NULL)
+                       goto err_of_node_put;
+               /*
+                * First element in the array is the number of drc_indexes
+                * returned.  Search through the list to find the matching
+                * drc_index and get the core number
+                */
+               for (i = 0; i < indexes[0]; i++) {
+                       if (indexes[i + 1] == drc_index)
+                               break;
+               }
+               /* Convert core number to logical cpu number */
+               cpu = cpu_first_thread_of_core(i);
+               rc = 0;
        }
-       /* Convert core number to logical cpu number */
-       cpu = cpu_first_thread_of_core(i);
-       rc = 0;
 
 err_of_node_put:
        of_node_put(dn);

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