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/* SPDX-License-Identifier: copyleft-next-0.3.1 */
/* Copyright 2023 Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
#include <threads.h>
#include <inttypes.h>
#include <stdlib.h>
#include <gran/common.h>
#include <gran/component.h>
#include <gran/bus/simple_bus.h>
struct mem_region {
uintptr_t addr;
size_t size;
struct component *component;
struct mem_region *next;
};
struct simple_bus {
struct component component;
mtx_t lock;
struct mem_region *mem_regions;
};
static struct mem_region *find_mem_region(struct simple_bus *bus,
uintptr_t addr)
{
if (!bus->mem_regions)
return NULL;
struct mem_region *cur = bus->mem_regions;
while (cur) {
/* address is within memory region */
if (addr >= cur->addr && addr < cur->addr + cur->size)
return cur;
cur = cur->next;
}
return NULL;
}
static stat add_mem_region(struct simple_bus *bus, struct mem_region *new)
{
if (!bus->mem_regions) {
bus->mem_regions = new;
return OK;
}
struct mem_region *found = NULL;
if ((found = find_mem_region(bus, new->addr))) {
error("%s overlaps with %s at %" PRIuPTR,
new->component->name,
found->component->name,
new->addr
);
return EEXISTS;
}
new->next = bus->mem_regions;
bus->mem_regions = new;
return OK;
}
static stat simple_bus_write(struct simple_bus *bus, struct packet *pkt)
{
/* only one device can drive the bus at one time */
if (mtx_trylock(&bus->lock) != thrd_success)
return EBUSY;
struct mem_region *mem_region = find_mem_region(bus, packet_addr(pkt));
if (!mem_region) {
warn("nothing to write on bus %s at %" PRIuPTR,
bus->component.name, packet_addr(pkt));
return EBUS;
}
stat ret = write(mem_region->component, pkt);
mtx_unlock(&bus->lock);
return ret;
}
static stat simple_bus_read(struct simple_bus *bus, struct packet *pkt)
{
/* only one device can drive the bus at one time */
if (mtx_trylock(&bus->lock) != thrd_success)
return EBUSY;
struct mem_region *mem_region = find_mem_region(bus, packet_addr(pkt));
if (!mem_region) {
warn("nothing to read on bus %s at %" PRIuPTR,
bus->component.name, packet_addr(pkt));
return EBUS;
}
stat ret = read(mem_region->component, pkt);
mtx_unlock(&bus->lock);
return ret;
}
static stat simple_bus_swap(struct simple_bus *bus, struct packet *pkt)
{
if (mtx_trylock(&bus->lock) != thrd_success)
return EBUSY;
struct mem_region *mem_region = find_mem_region(bus, packet_addr(pkt));
if (!mem_region) {
warn("nothing to swap on bus %s at %" PRIuPTR,
bus->component.name, packet_addr(pkt));
return EBUS;
}
stat ret = swap(mem_region->component, pkt);
mtx_unlock(&bus->lock);
return ret;
}
static stat simple_bus_snoop(struct simple_bus *bus, struct snoop *snoop)
{
struct mem_region *cur = bus->mem_regions;
while (cur) {
if (cur->component->snoop) {
stat ret = cur->component->snoop(cur->component, snoop);
if (ret)
return ret;
if (snoop_state(snoop) == SNOOP_ANSWERED)
return OK;
}
cur = cur->next;
}
return OK;
}
static void simple_bus_destroy(struct simple_bus *bus)
{
struct mem_region *cur = bus->mem_regions, *next = NULL;
if (cur)
do {
next = cur->next;
destroy(cur->component);
free(cur);
} while ((cur = next));
free(bus);
}
struct component *create_simple_bus()
{
struct simple_bus *bus = calloc(1, sizeof(struct simple_bus));
if (!bus)
return NULL;
bus->component.write = (write_callback)simple_bus_write;
bus->component.read = (read_callback)simple_bus_read;
bus->component.swap = (swap_callback)simple_bus_swap;
bus->component.snoop = (snoop_callback)simple_bus_snoop;
// actually, still not sure about what API I want to use for controls
// bus->component.ctrl = (ctrl_callback)simple_bus_ctrl;
bus->component.destroy = (destroy_callback)simple_bus_destroy;
mtx_init(&bus->lock, mtx_plain);
return (struct component *)bus;
}
stat simple_bus_add(struct component *bus, struct component *component,
uint64_t addr, uint64_t size)
{
struct mem_region *new = calloc(1, sizeof(struct mem_region));
if (!new)
return ENOMEM;
new->addr = addr;
new->size = size;
new->component = component;
if (add_mem_region((struct simple_bus *)bus, new)) {
free(new);
return EEXISTS;
}
return OK;
}
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