diff options
Diffstat (limited to 'arch/powerpc/kernel/prom.c')
| -rw-r--r-- | arch/powerpc/kernel/prom.c | 70 |
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; |