// SPDX-License-Identifier: GPL-2.0
/*
 * Numascale NumaConnect-specific PCI code
 *
 * Copyright (C) 2012 Numascale AS. All rights reserved.
 *
 * Send feedback to <support@numascale.com>
 *
 * PCI accessor functions derived from mmconfig_64.c
 *
 */

#include <linux/pci.h>
#include <asm/pci_x86.h>

static u8 limit __read_mostly;

static inline char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
{
	struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);

	if (cfg && cfg->virt)
		return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
	return NULL;
}

static int pci_mmcfg_read_numachip(unsigned int seg, unsigned int bus,
			  unsigned int devfn, int reg, int len, u32 *value)
{
	char __iomem *addr;

	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
err:		*value = -1;
		return -EINVAL;
	}

	/* Ensure AMD Northbridges don't decode reads to other devices */
	if (unlikely(bus == 0 && devfn >= limit)) {
		*value = -1;
		return 0;
	}

	rcu_read_lock();
	addr = pci_dev_base(seg, bus, devfn);
	if (!addr) {
		rcu_read_unlock();
		goto err;
	}

	switch (len) {
	case 1:
		*value = mmio_config_readb(addr + reg);
		break;
	case 2:
		*value = mmio_config_readw(addr + reg);
		break;
	case 4:
		*value = mmio_config_readl(addr + reg);
		break;
	}
	rcu_read_unlock();

	return 0;
}

static int pci_mmcfg_write_numachip(unsigned int seg, unsigned int bus,
			   unsigned int devfn, int reg, int len, u32 value)
{
	char __iomem *addr;

	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
		return -EINVAL;

	/* Ensure AMD Northbridges don't decode writes to other devices */
	if (unlikely(bus == 0 && devfn >= limit))
		return 0;

	rcu_read_lock();
	addr = pci_dev_base(seg, bus, devfn);
	if (!addr) {
		rcu_read_unlock();
		return -EINVAL;
	}

	switch (len) {
	case 1:
		mmio_config_writeb(addr + reg, value);
		break;
	case 2:
		mmio_config_writew(addr + reg, value);
		break;
	case 4:
		mmio_config_writel(addr + reg, value);
		break;
	}
	rcu_read_unlock();

	return 0;
}

static const struct pci_raw_ops pci_mmcfg_numachip = {
	.read = pci_mmcfg_read_numachip,
	.write = pci_mmcfg_write_numachip,
};

int __init pci_numachip_init(void)
{
	int ret = 0;
	u32 val;

	/* For remote I/O, restrict bus 0 access to the actual number of AMD
	   Northbridges, which starts at device number 0x18 */
	ret = raw_pci_read(0, 0, PCI_DEVFN(0x18, 0), 0x60, sizeof(val), &val);
	if (ret)
		goto out;

	/* HyperTransport fabric size in bits 6:4 */
	limit = PCI_DEVFN(0x18 + ((val >> 4) & 7) + 1, 0);

	/* Use NumaChip PCI accessors for non-extended and extended access */
	raw_pci_ops = raw_pci_ext_ops = &pci_mmcfg_numachip;
out:
	return ret;
}