1 files changed, 70 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 1cb69e8fb0b1..9a07f97f0712 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;