text: /**
   * @file  kernel/misc/pci.c
   * @brief PCI configuration and scanning.
   *
   * Functions for dealing with PCI devices through configuration mode #1
   * (CPU port I/O methods), including scanning and modifying device
   * configuration bytes.
   *
   * This used to have methods for dealing with ISA bridge IRQ remapping,
   * but it has been removed for the moment.
   *
   * TODO: Implement MSI configuration?
   */
  #include <stdint.h>
  #include <kernel/string.h>
  #include <kernel/pci.h>
  #include <kernel/printf.h>
  
  /* TODO: PCI is sufficiently generic this shouldn't depend
   *       directly on x86-64 hardware... */
  #include <kernel/arch/x86_64/ports.h>
  
  /**
   * @brief Write to a PCI device configuration space field.
   */
  void pci_write_field(uint32_t device, int field, int size, uint32_t value) {
  	outportl(PCI_ADDRESS_PORT, pci_get_addr(device, field));
  	outportl(PCI_VALUE_PORT, value);
  }
  
  /**
   * @brief Read from a PCI device configuration space field.
   */
  uint32_t pci_read_field(uint32_t device, int field, int size) {
  	outportl(PCI_ADDRESS_PORT, pci_get_addr(device, field));
  
  	if (size == 4) {
  		uint32_t t = inportl(PCI_VALUE_PORT);
  		return t;
  	} else if (size == 2) {
  		uint16_t t = inports(PCI_VALUE_PORT + (field & 2));
  		return t;
  	} else if (size == 1) {
  		uint8_t t = inportb(PCI_VALUE_PORT + (field & 3));
  		return t;
  	}
  	return 0xFFFF;
  }
  
  /**
   * @brief Obtain the device type from the class and subclass fields.
   */
  uint16_t pci_find_type(uint32_t dev) {
  	return (pci_read_field(dev, PCI_CLASS, 1) << 8) | pci_read_field(dev, PCI_SUBCLASS, 1);
  }
  
  static void pci_scan_hit(pci_func_t f, uint32_t dev, void * extra) {
  	int dev_vend = (int)pci_read_field(dev, PCI_VENDOR_ID, 2);
  	int dev_dvid = (int)pci_read_field(dev, PCI_DEVICE_ID, 2);
  
  	f(dev, dev_vend, dev_dvid, extra);
  }
  
  void pci_scan_func(pci_func_t f, int type, int bus, int slot, int func, void * extra) {
  	uint32_t dev = pci_box_device(bus, slot, func);
  	if (type == -1 || type == pci_find_type(dev)) {
  		pci_scan_hit(f, dev, extra);
  	}
  	if (pci_find_type(dev) == PCI_TYPE_BRIDGE) {
  		pci_scan_bus(f, type, pci_read_field(dev, PCI_SECONDARY_BUS, 1), extra);
  	}
  }
  
  void pci_scan_slot(pci_func_t f, int type, int bus, int slot, void * extra) {
  	uint32_t dev = pci_box_device(bus, slot, 0);
  	if (pci_read_field(dev, PCI_VENDOR_ID, 2) == PCI_NONE) {
  		return;
  	}
  	pci_scan_func(f, type, bus, slot, 0, extra);
  	if (!pci_read_field(dev, PCI_HEADER_TYPE, 1)) {
  		return;
  	}
  	for (int func = 1; func < 8; func++) {
  		uint32_t dev = pci_box_device(bus, slot, func);
  		if (pci_read_field(dev, PCI_VENDOR_ID, 2) != PCI_NONE) {
  			pci_scan_func(f, type, bus, slot, func, extra);
  		}
  	}
  }
  
  void pci_scan_bus(pci_func_t f, int type, int bus, void * extra) {
  	for (int slot = 0; slot < 32; ++slot) {
  		pci_scan_slot(f, type, bus, slot, extra);
  	}
  }
  
  /**
   * @brief Scan PCI buses for devices, calling the given function for each device.
   *
   * Used by drivers to implement device discovery, runs a callback function for ever
   * device found. A device consists of a bus, slot, and function. Also performs
   * recursive scans of bridges.
   */
  void pci_scan(pci_func_t f, int type, void * extra) {
  	if ((pci_read_field(0, PCI_HEADER_TYPE, 1) & 0x80) == 0) {
  		pci_scan_bus(f,type,0,extra);
  		return;
  	}
  
  	int hit = 0;
  	for (int func = 0; func < 8; ++func) {
  		uint32_t dev = pci_box_device(0, 0, func);
  		if (pci_read_field(dev, PCI_VENDOR_ID, 2) != PCI_NONE) {
  			hit = 1;
  			pci_scan_bus(f, type, func, extra);
  		} else {
  			break;
  		}
  	}
  
  	if (!hit) {
  		for (int bus = 0; bus < 256; ++bus) {
  			for (int slot = 0; slot < 32; ++slot) {
  				pci_scan_slot(f,type,bus,slot,extra);
  			}
  		}
  	}
  }
  
  int pci_get_interrupt(uint32_t device) {
  	return pci_read_field(device, PCI_INTERRUPT_LINE, 1);
  }
  