x86/PCI: Add NumaChip remote PCI support

Add NumaChip-specific PCI access mechanism via MMCONFIG cycles, but
preventing access to AMD Northbridges which shouldn't respond.

Signed-off-by: Daniel J Blueman <daniel@numascale-asia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 129 insertions, 0 deletions

diff --git a/arch/x86/pci/numachip.c b/arch/x86/pci/numachip.c
new file mode 100644
index 000000000000..7307d9d12d15
--- /dev/null
+++ b/arch/x86/pci/numachip.c
@@ -0,0 +1,129 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * 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;
+}
+
+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;
+}