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authorPaul Mackerras <paulus@samba.org>2006-05-03 09:04:37 -0400
committerPaul Mackerras <paulus@samba.org>2006-05-03 09:06:47 -0400
commitd205819e2346d20fee41297ea6cf789c591abccf (patch)
tree37698c88df06cb186026c9616d6d98405c72b161 /arch
parent6bfd93c32a5065d0e858780b3beb0b667081601c (diff)
[PATCH] powerpc: Use the ibm,pa-features property if available
Forthcoming IBM machines will have a "ibm,pa-features" property on CPU nodes, that contains bits indicating which optional architecture features are implemented by the CPU. This adds code to use the property, if present, to update our CPU feature bitmaps. Note that this means we can both set and clear feature bits based on what the firmware tells us. This is based on a patch by Will Schmidt <willschm@us.ibm.com>. Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch')
-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 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)
885 DBG(" <- unflatten_device_tree()\n"); 885 DBG(" <- unflatten_device_tree()\n");
886} 886}
887 887
888/*
889 * ibm,pa-features is a per-cpu property that contains a string of
890 * attribute descriptors, each of which has a 2 byte header plus up
891 * to 254 bytes worth of processor attribute bits. First header
892 * byte specifies the number of bytes following the header.
893 * Second header byte is an "attribute-specifier" type, of which
894 * zero is the only currently-defined value.
895 * Implementation: Pass in the byte and bit offset for the feature
896 * that we are interested in. The function will return -1 if the
897 * pa-features property is missing, or a 1/0 to indicate if the feature
898 * is supported/not supported. Note that the bit numbers are
899 * big-endian to match the definition in PAPR.
900 */
901static struct ibm_pa_feature {
902 unsigned long cpu_features; /* CPU_FTR_xxx bit */
903 unsigned int cpu_user_ftrs; /* PPC_FEATURE_xxx bit */
904 unsigned char pabyte; /* byte number in ibm,pa-features */
905 unsigned char pabit; /* bit number (big-endian) */
906 unsigned char invert; /* if 1, pa bit set => clear feature */
907} ibm_pa_features[] __initdata = {
908 {0, PPC_FEATURE_HAS_MMU, 0, 0, 0},
909 {0, PPC_FEATURE_HAS_FPU, 0, 1, 0},
910 {CPU_FTR_SLB, 0, 0, 2, 0},
911 {CPU_FTR_CTRL, 0, 0, 3, 0},
912 {CPU_FTR_NOEXECUTE, 0, 0, 6, 0},
913 {CPU_FTR_NODSISRALIGN, 0, 1, 1, 1},
914 {CPU_FTR_CI_LARGE_PAGE, 0, 1, 2, 0},
915};
916
917static void __init check_cpu_pa_features(unsigned long node)
918{
919 unsigned char *pa_ftrs;
920 unsigned long len, tablelen, i, bit;
921
922 pa_ftrs = of_get_flat_dt_prop(node, "ibm,pa-features", &tablelen);
923 if (pa_ftrs == NULL)
924 return;
925
926 /* find descriptor with type == 0 */
927 for (;;) {
928 if (tablelen < 3)
929 return;
930 len = 2 + pa_ftrs[0];
931 if (tablelen < len)
932 return; /* descriptor 0 not found */
933 if (pa_ftrs[1] == 0)
934 break;
935 tablelen -= len;
936 pa_ftrs += len;
937 }
938
939 /* loop over bits we know about */
940 for (i = 0; i < ARRAY_SIZE(ibm_pa_features); ++i) {
941 struct ibm_pa_feature *fp = &ibm_pa_features[i];
942
943 if (fp->pabyte >= pa_ftrs[0])
944 continue;
945 bit = (pa_ftrs[2 + fp->pabyte] >> (7 - fp->pabit)) & 1;
946 if (bit ^ fp->invert) {
947 cur_cpu_spec->cpu_features |= fp->cpu_features;
948 cur_cpu_spec->cpu_user_features |= fp->cpu_user_ftrs;
949 } else {
950 cur_cpu_spec->cpu_features &= ~fp->cpu_features;
951 cur_cpu_spec->cpu_user_features &= ~fp->cpu_user_ftrs;
952 }
953 }
954}
955
888static int __init early_init_dt_scan_cpus(unsigned long node, 956static int __init early_init_dt_scan_cpus(unsigned long node,
889 const char *uname, int depth, 957 const char *uname, int depth,
890 void *data) 958 void *data)
@@ -969,6 +1037,8 @@ static int __init early_init_dt_scan_cpus(unsigned long node,
969 } 1037 }
970#endif /* CONFIG_ALTIVEC */ 1038#endif /* CONFIG_ALTIVEC */
971 1039
1040 check_cpu_pa_features(node);
1041
972#ifdef CONFIG_PPC_PSERIES 1042#ifdef CONFIG_PPC_PSERIES
973 if (nthreads > 1) 1043 if (nthreads > 1)
974 cur_cpu_spec->cpu_features |= CPU_FTR_SMT; 1044 cur_cpu_spec->cpu_features |= CPU_FTR_SMT;