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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
/*
* drivers/base/platform.cc — platform bus + FDT-driven device creation.
*
* Mirrors Linux drivers/base/platform.c. Provides:
* - platform_bus — the bus_type instance
* - platform_match — compatible-string matching via of_match_table
* - platform_dispatch — bus->probe forwarder that down-casts and calls
* platform_driver::probe(platform_device*)
* - driver_probe_all() — boot entry: register bus, register linker-set
* drivers, walk FDT, register platform_devices
*
* Reference: docs/specs/storage_stack.md §4.3
*/
#include <lume/platform_device.h>
#include <lume/driver.h>
#include <lume/device_node.h>
#include <lume/fdt.h>
#include <string.h>
/* kmalloc is declared extern "C" in <lume/slab.h>, but mm/slab.cc defines
* it WITHOUT extern "C" (i.e. C++-mangled). Declare locally with C++
* linkage so the symbol matches what mm/slab.o exports. */
void* kmalloc(uint32 size);
#include <lume/klog.h>
#include <lume/kprintf.h>
#include <lume/errno.h>
#include <lume/container_of.h>
/* ------------------------------------------------------------------ */
/* Linker-section registry */
/* ------------------------------------------------------------------ */
extern "C" {
extern platform_driver* __drivers_start[];
extern platform_driver* __drivers_end[];
}
/* ------------------------------------------------------------------ */
/* platform_bus_type */
/* ------------------------------------------------------------------ */
static int platform_match(device* dev, device_driver* drv)
{
platform_device* pdev = to_platform_device(dev);
platform_driver* pdrv = to_platform_driver(drv);
if (pdrv->of_match_table == nullptr || pdev->of_node == nullptr) {
return 0;
}
const FdtProperty* compat_prop = pdev->of_node->get_prop("compatible");
if (compat_prop == nullptr || compat_prop->value == nullptr ||
compat_prop->len == 0) {
return 0;
}
const char* compat_list = static_cast<const char*>(compat_prop->value);
const uint32 compat_len = static_cast<uint32>(compat_prop->len);
for (const of_device_id* id = pdrv->of_match_table;
id->compatible != nullptr; ++id) {
uint32 offset = 0;
while (offset < compat_len) {
const char* node_compat = compat_list + offset;
uint32 remaining = compat_len - offset;
uint32 length = 0;
while (length < remaining && node_compat[length] != '\0') {
++length;
}
if (length == remaining) {
break; /* malformed property without a terminating NUL */
}
if (strcmp(id->compatible, node_compat) == 0) {
return 1;
}
offset += length + 1;
}
}
return 0;
}
static int platform_dispatch(device* dev)
{
platform_device* pdev = to_platform_device(dev);
platform_driver* pdrv = to_platform_driver(dev->driver);
if (pdrv->probe == nullptr) {
return 0;
}
return pdrv->probe(pdev);
}
bus_type platform_bus = {
.name = "platform",
.match = platform_match,
.probe = platform_dispatch,
.devices = {},
.drivers = {},
.lock = {},
.registered = false,
};
void platform_bus_init()
{
bus_register(&platform_bus);
}
/* ------------------------------------------------------------------ */
/* platform_driver_register / platform_device_register */
/* ------------------------------------------------------------------ */
int platform_driver_register(platform_driver* pdrv)
{
if (pdrv == nullptr) {
return -EINVAL;
}
pdrv->driver.bus = &platform_bus;
/* driver.probe is unused — we route through bus->probe. Set name
* from the first of_match if not already provided. */
if (pdrv->driver.name == nullptr && pdrv->of_match_table != nullptr) {
pdrv->driver.name = pdrv->of_match_table[0].compatible;
}
return driver_register(&pdrv->driver);
}
int platform_device_register(platform_device* pdev)
{
if (pdev == nullptr) {
return -EINVAL;
}
pdev->dev.bus = &platform_bus;
if (pdev->dev.init_name == nullptr && pdev->of_node != nullptr) {
pdev->dev.init_name = pdev->of_node->get_prop_string("compatible");
}
device_initialize(&pdev->dev);
return device_register(&pdev->dev);
}
/* ------------------------------------------------------------------ */
/* FDT-driven device instantiation */
/* ------------------------------------------------------------------ */
static platform_device* alloc_platform_device_from_node(DeviceNode* node,
const char* compat)
{
auto* pdev = static_cast<platform_device*>(
kmalloc(static_cast<uint32>(sizeof(platform_device))));
if (pdev == nullptr) {
return nullptr;
}
memset(pdev, 0, sizeof(*pdev));
pdev->of_node = node;
pdev->mmio_base = node->get_prop_u64("reg", 0);
/* "reg" second cell is size — for now we don't bother parsing it
* separately; drivers that need it pull from of_node directly. */
pdev->mmio_size = 0;
pdev->irq = -1;
pdev->dev.init_name = compat;
return pdev;
}
/* For each registered platform_driver, walk its of_match_table and
* spawn a platform_device for each FDT compatible match found.
*
* NOTE: This is a simplified FDT walker — it only finds the FIRST FDT
* node matching each compatible string (delegating to
* fdt_find_compatible). Devices with multiple FDT instances of the
* same compatible will only see one bound here. A full FDT tree walk
* is left for when virtio-mmio or multi-instance UART arrives.
*/
static void instantiate_devices_for_driver(platform_driver* pdrv)
{
if (pdrv == nullptr || pdrv->of_match_table == nullptr) {
return;
}
for (const of_device_id* id = pdrv->of_match_table;
id->compatible != nullptr; ++id) {
DeviceNode* node = fdt_find_compatible(id->compatible);
if (node == nullptr) {
continue;
}
platform_device* pdev =
alloc_platform_device_from_node(node, id->compatible);
if (pdev == nullptr) {
kprintf("[platform] OOM allocating pdev for %s\n", id->compatible);
continue;
}
kprintf("[platform] instantiating '%s' -> pdev mmio=0x%llx\n",
id->compatible, pdev->mmio_base);
platform_device_register(pdev);
}
}
/* ------------------------------------------------------------------ */
/* Boot entry — replaces the old driver_probe_all() */
/* ------------------------------------------------------------------ */
void driver_probe_all()
{
kprintf("[dpa] step 1: &platform_bus=%p (link 0xffffffc08033a0a8)\n",
&platform_bus);
kprintf("[dpa] step 1: pre-touch platform_bus.name slot...\n");
const char** name_slot = &platform_bus.name;
kprintf("[dpa] step 1: name_slot=%p\n", name_slot);
kprintf("[dpa] step 1: about to deref *name_slot\n");
const char* nm = *name_slot;
kprintf("[dpa] step 1: *name_slot=%p\n", nm);
kprintf("[dpa] step 1: about to read first byte of nm\n");
char first = nm != nullptr ? nm[0] : '!';
kprintf("[dpa] step 1: nm[0]='%c'\n", first);
kprintf("[dpa] step 1: platform_bus_init enter\n");
platform_bus_init();
kprintf("[dpa] step 1: platform_bus_init done\n");
platform_driver** start = __drivers_start;
platform_driver** end = __drivers_end;
kprintf("[dpa] step 2: __drivers_start=%p __drivers_end=%p count=%lld\n",
start, end, (long long)(end - start));
for (platform_driver** slot = start; slot < end; ++slot) {
kprintf("[dpa] step 2: slot=%p *slot=%p\n", slot, *slot);
if (*slot != nullptr) {
platform_driver* pdrv = *slot;
kprintf("[dpa] step 2: pdrv->of_match_table=%p\n",
pdrv->of_match_table);
if (pdrv->of_match_table != nullptr) {
kprintf("[dpa] step 2: pdrv->of_match_table[0].compatible=%p\n",
pdrv->of_match_table[0].compatible);
if (pdrv->of_match_table[0].compatible != nullptr) {
kprintf("[dpa] step 2: compatible='%s'\n",
pdrv->of_match_table[0].compatible);
}
}
platform_driver_register(pdrv);
kprintf("[dpa] step 2: registered\n");
}
}
kprintf("[dpa] step 3: instantiate devices\n");
for (platform_driver** slot = start; slot < end; ++slot) {
if (*slot != nullptr) {
instantiate_devices_for_driver(*slot);
}
}
kprintf("[dpa] done\n");
}
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