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>

arch/x86/Kconfig

@@ -374,6 +374,7 @@ config X86_NUMACHIP
 	depends on NUMA
 	depends on SMP
 	depends on X86_X2APIC
+	depends on PCI_MMCONFIG
 	---help---
 	  Adds support for Numascale NumaChip large-SMP systems. Needed to
 	  enable more than ~168 cores.

arch/x86/include/asm/numachip/numachip.h

+/*
+ * 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 header file
+ *
+ * Copyright (C) 2012 Numascale AS. All rights reserved.
+ *
+ * Send feedback to <support@numascale.com>
+ *
+ */
+
+#ifndef _ASM_X86_NUMACHIP_NUMACHIP_H
+#define _ASM_X86_NUMACHIP_NUMACHIP_H
+
+extern int __init pci_numachip_init(void);
+
+#endif /* _ASM_X86_NUMACHIP_NUMACHIP_H */

arch/x86/kernel/apic/apic_numachip.c

@@ -22,6 +22,7 @@
 #include <linux/hardirq.h>
 #include <linux/delay.h>
 
+#include <asm/numachip/numachip.h>
 #include <asm/numachip/numachip_csr.h>
 #include <asm/smp.h>
 #include <asm/apic.h>
@@ -179,6 +180,7 @@ static int __init numachip_system_init(void)
 		return 0;
 
 	x86_cpuinit.fixup_cpu_id = fixup_cpu_id;
+	x86_init.pci.arch_init = pci_numachip_init;
 
 	map_csrs();
 

arch/x86/pci/Makefile

@@ -16,6 +16,7 @@ obj-$(CONFIG_STA2X11)           += sta2x11-fixup.o
 obj-$(CONFIG_X86_VISWS)		+= visws.o
 
 obj-$(CONFIG_X86_NUMAQ)		+= numaq_32.o
+obj-$(CONFIG_X86_NUMACHIP)	+= numachip.o
 
 obj-$(CONFIG_X86_INTEL_MID)	+= mrst.o
 

arch/x86/pci/numachip.c

+/*
+ * 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;
+}