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-rw-r--r--arch/powerpc/kernel/prom.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 1cb69e8fb0b..9a07f97f071 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -885,6 +885,74 @@ void __init unflatten_device_tree(void)
DBG(" <- unflatten_device_tree()\n");
}
+/*
+ * ibm,pa-features is a per-cpu property that contains a string of
+ * attribute descriptors, each of which has a 2 byte header plus up
+ * to 254 bytes worth of processor attribute bits. First header
+ * byte specifies the number of bytes following the header.
+ * Second header byte is an "attribute-specifier" type, of which
+ * zero is the only currently-defined value.
+ * Implementation: Pass in the byte and bit offset for the feature
+ * that we are interested in. The function will return -1 if the
+ * pa-features property is missing, or a 1/0 to indicate if the feature
+ * is supported/not supported. Note that the bit numbers are
+ * big-endian to match the definition in PAPR.
+ */
+static struct ibm_pa_feature {
+ unsigned long cpu_features; /* CPU_FTR_xxx bit */
+ unsigned int cpu_user_ftrs; /* PPC_FEATURE_xxx bit */
+ unsigned char pabyte; /* byte number in ibm,pa-features */
+ unsigned char pabit; /* bit number (big-endian) */
+ unsigned char invert; /* if 1, pa bit set => clear feature */
+} ibm_pa_features[] __initdata = {
+ {0, PPC_FEATURE_HAS_MMU, 0, 0, 0},
+ {0, PPC_FEATURE_HAS_FPU, 0, 1, 0},
+ {CPU_FTR_SLB, 0, 0, 2, 0},
+ {CPU_FTR_CTRL, 0, 0, 3, 0},
+ {CPU_FTR_NOEXECUTE, 0, 0, 6, 0},
+ {CPU_FTR_NODSISRALIGN, 0, 1, 1, 1},
+ {CPU_FTR_CI_LARGE_PAGE, 0, 1, 2, 0},
+};
+
+static void __init check_cpu_pa_features(unsigned long node)
+{
+ unsigned char *pa_ftrs;
+ unsigned long len, tablelen, i, bit;
+
+ pa_ftrs = of_get_flat_dt_prop(node, "ibm,pa-features", &tablelen);
+ if (pa_ftrs == NULL)
+ return;
+
+ /* find descriptor with type == 0 */
+ for (;;) {
+ if (tablelen < 3)
+ return;
+ len = 2 + pa_ftrs[0];
+ if (tablelen < len)
+ return; /* descriptor 0 not found */
+ if (pa_ftrs[1] == 0)
+ break;
+ tablelen -= len;
+ pa_ftrs += len;
+ }
+
+ /* loop over bits we know about */
+ for (i = 0; i < ARRAY_SIZE(ibm_pa_features); ++i) {
+ struct ibm_pa_feature *fp = &ibm_pa_features[i];
+
+ if (fp->pabyte >= pa_ftrs[0])
+ continue;
+ bit = (pa_ftrs[2 + fp->pabyte] >> (7 - fp->pabit)) & 1;
+ if (bit ^ fp->invert) {
+ cur_cpu_spec->cpu_features |= fp->cpu_features;
+ cur_cpu_spec->cpu_user_features |= fp->cpu_user_ftrs;
+ } else {
+ cur_cpu_spec->cpu_features &= ~fp->cpu_features;
+ cur_cpu_spec->cpu_user_features &= ~fp->cpu_user_ftrs;
+ }
+ }
+}
+
static int __init early_init_dt_scan_cpus(unsigned long node,
const char *uname, int depth,
void *data)
@@ -969,6 +1037,8 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
}
#endif /* CONFIG_ALTIVEC */
+ check_cpu_pa_features(node);
+
#ifdef CONFIG_PPC_PSERIES
if (nthreads > 1)
cur_cpu_spec->cpu_features |= CPU_FTR_SMT;