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#include <triscv/mmu.h>
struct tlb_map {
vm_t from;
pm_t to;
bool valid;
};
struct dev_map {
pm_t start;
struct dev dev;
};
/* completely arbitrary value */
#define MMU_SIZE 1024
#define MAX_DEVS 16
struct mmu {
/* virtual -> physical */
struct tlb_map tlb[MMU_SIZE];
/* physical to dev */
struct dev_map dev[MAX_DEVS];
size_t devs;
/* whether we should treat incoming addresses as virtual or physical */
bool translate;
};
struct mmu *mmu_create()
{
/** @todo map some backing memory as well */
return calloc(1, sizeof(struct mmu));
}
void mmu_destroy(struct mmu *mmu)
{
free(mmu);
}
static struct dev_map *mmu_find_dev_map(struct mmu *mmu, pm_t addr)
{
for (size_t i = 0; i < mmu->devs; ++i) {
struct dev_map *d = &mmu->dev[i];
if (d->start > addr)
continue;
/* slightly tricky off by one here */
if (d->dev.size <= (addr - d->start))
continue;
return d;
}
return NULL;
}
stat_t mmu_map_dev(struct mmu *mmu, pm_t start, struct dev dev)
{
/** @todo return status or something */
if (mmu->devs == MAX_DEVS)
return ERR_FULL;
if (mmu_find_dev_map(mmu, start))
return ERR_EXISTS;
struct dev_map *d = &mmu->dev[mmu->devs++];
d->dev = dev;
d->start = start;
return OK;
}
void mmu_enable(struct mmu *mmu)
{
mmu->translate = true;
}
void mmu_disable(struct mmu *mmu)
{
mmu->translate = false;
}
static bool mmu_translate(struct cpu *cpu, struct mmu *mmu, vm_t *addr)
{
(void)cpu;
(void)mmu;
(void)addr;
/** @todo raise segfault if addr is not allowed */
return true;
}
void mmu_write1(struct cpu *cpu, struct mmu *mmu, vm_t addr, tri_t t)
{
if (mmu->translate) {
if (!mmu_translate(cpu, mmu, &addr))
return;
}
struct dev_map *d = mmu_find_dev_map(mmu, addr);
if (!d || !d->dev.write1) {
/** @todo raise bus (?) error */
}
d->dev.write1(cpu, d->dev.dev, addr - d->start, t);
}
void mmu_write3(struct cpu *cpu, struct mmu *mmu, vm_t addr, tri_t t)
{
if (mmu->translate) {
if (!mmu_translate(cpu, mmu, &addr))
return;
}
struct dev_map *d = mmu_find_dev_map(mmu, addr);
if (!d || !d->dev.write3) {
/** @todo raise bus error */
}
d->dev.write3(cpu, d->dev.dev, addr - d->start, t);
}
tri_t mmu_read1(struct cpu *cpu, struct mmu *mmu, vm_t addr)
{
if (mmu->translate) {
if (!mmu_translate(cpu, mmu, &addr))
return 0;
}
struct dev_map *d = mmu_find_dev_map(mmu, addr);
if (!d || !d->dev.read1) {
/** @todo raise bus error */
return 0;
}
return d->dev.read1(cpu, d->dev.dev, addr - d->start);
}
tri_t mmu_read3(struct cpu *cpu, struct mmu *mmu, vm_t addr)
{
if (mmu->translate) {
if (!mmu_translate(cpu, mmu, &addr))
return 0;
}
struct dev_map *d = mmu_find_dev_map(mmu, addr);
if (!d || !d->dev.read3) {
/** @todo raise bus error */
return 0;
}
return d->dev.read3(cpu, d->dev.dev, addr - d->start);
}
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