diff options
Diffstat (limited to 'kernel/arch/x86/kernel/cpu/mtrr/amd.c')
-rw-r--r-- | kernel/arch/x86/kernel/cpu/mtrr/amd.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/kernel/arch/x86/kernel/cpu/mtrr/amd.c b/kernel/arch/x86/kernel/cpu/mtrr/amd.c new file mode 100644 index 000000000..92ba9cd31 --- /dev/null +++ b/kernel/arch/x86/kernel/cpu/mtrr/amd.c @@ -0,0 +1,124 @@ +#include <linux/init.h> +#include <linux/mm.h> +#include <asm/mtrr.h> +#include <asm/msr.h> + +#include "mtrr.h" + +static void +amd_get_mtrr(unsigned int reg, unsigned long *base, + unsigned long *size, mtrr_type *type) +{ + unsigned long low, high; + + rdmsr(MSR_K6_UWCCR, low, high); + /* Upper dword is region 1, lower is region 0 */ + if (reg == 1) + low = high; + /* The base masks off on the right alignment */ + *base = (low & 0xFFFE0000) >> PAGE_SHIFT; + *type = 0; + if (low & 1) + *type = MTRR_TYPE_UNCACHABLE; + if (low & 2) + *type = MTRR_TYPE_WRCOMB; + if (!(low & 3)) { + *size = 0; + return; + } + /* + * This needs a little explaining. The size is stored as an + * inverted mask of bits of 128K granularity 15 bits long offset + * 2 bits. + * + * So to get a size we do invert the mask and add 1 to the lowest + * mask bit (4 as its 2 bits in). This gives us a size we then shift + * to turn into 128K blocks. + * + * eg 111 1111 1111 1100 is 512K + * + * invert 000 0000 0000 0011 + * +1 000 0000 0000 0100 + * *128K ... + */ + low = (~low) & 0x1FFFC; + *size = (low + 4) << (15 - PAGE_SHIFT); +} + +/** + * amd_set_mtrr - Set variable MTRR register on the local CPU. + * + * @reg The register to set. + * @base The base address of the region. + * @size The size of the region. If this is 0 the region is disabled. + * @type The type of the region. + * + * Returns nothing. + */ +static void +amd_set_mtrr(unsigned int reg, unsigned long base, unsigned long size, mtrr_type type) +{ + u32 regs[2]; + + /* + * Low is MTRR0, High MTRR 1 + */ + rdmsr(MSR_K6_UWCCR, regs[0], regs[1]); + /* + * Blank to disable + */ + if (size == 0) { + regs[reg] = 0; + } else { + /* + * Set the register to the base, the type (off by one) and an + * inverted bitmask of the size The size is the only odd + * bit. We are fed say 512K We invert this and we get 111 1111 + * 1111 1011 but if you subtract one and invert you get the + * desired 111 1111 1111 1100 mask + * + * But ~(x - 1) == ~x + 1 == -x. Two's complement rocks! + */ + regs[reg] = (-size >> (15 - PAGE_SHIFT) & 0x0001FFFC) + | (base << PAGE_SHIFT) | (type + 1); + } + + /* + * The writeback rule is quite specific. See the manual. Its + * disable local interrupts, write back the cache, set the mtrr + */ + wbinvd(); + wrmsr(MSR_K6_UWCCR, regs[0], regs[1]); +} + +static int +amd_validate_add_page(unsigned long base, unsigned long size, unsigned int type) +{ + /* + * Apply the K6 block alignment and size rules + * In order + * o Uncached or gathering only + * o 128K or bigger block + * o Power of 2 block + * o base suitably aligned to the power + */ + if (type > MTRR_TYPE_WRCOMB || size < (1 << (17 - PAGE_SHIFT)) + || (size & ~(size - 1)) - size || (base & (size - 1))) + return -EINVAL; + return 0; +} + +static const struct mtrr_ops amd_mtrr_ops = { + .vendor = X86_VENDOR_AMD, + .set = amd_set_mtrr, + .get = amd_get_mtrr, + .get_free_region = generic_get_free_region, + .validate_add_page = amd_validate_add_page, + .have_wrcomb = positive_have_wrcomb, +}; + +int __init amd_init_mtrr(void) +{ + set_mtrr_ops(&amd_mtrr_ops); + return 0; +} |