1 files changed, 302 insertions, 0 deletions
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
new file mode 100644
index 000000000..a6b621ff0
--- /dev/null
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -0,0 +1,302 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Coherency fabric (Aurora) support for Armada 370, 375, 38x and XP
+ * platforms.
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Yehuda Yitschak <yehuday@marvell.com>
+ * Gregory Clement <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * The Armada 370, 375, 38x and XP SOCs have a coherency fabric which is
+ * responsible for ensuring hardware coherency between all CPUs and between
+ * CPUs and I/O masters. This file initializes the coherency fabric and
+ * supplies basic routines for configuring and controlling hardware coherency
+ */
+
+#define pr_fmt(fmt) "mvebu-coherency: " fmt
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/of_address.h>
+#include <linux/io.h>
+#include <linux/smp.h>
+#include <linux/dma-map-ops.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/mbus.h>
+#include <linux/pci.h>
+#include <asm/smp_plat.h>
+#include <asm/cacheflush.h>
+#include <asm/mach/map.h>
+#include <asm/dma-mapping.h>
+#include "coherency.h"
+#include "mvebu-soc-id.h"
+
+unsigned long coherency_phys_base;
+void __iomem *coherency_base;
+static void __iomem *coherency_cpu_base;
+static void __iomem *cpu_config_base;
+
+/* Coherency fabric registers */
+#define IO_SYNC_BARRIER_CTL_OFFSET		   0x0
+
+enum {
+	COHERENCY_FABRIC_TYPE_NONE,
+	COHERENCY_FABRIC_TYPE_ARMADA_370_XP,
+	COHERENCY_FABRIC_TYPE_ARMADA_375,
+	COHERENCY_FABRIC_TYPE_ARMADA_380,
+};
+
+static const struct of_device_id of_coherency_table[] = {
+	{.compatible = "marvell,coherency-fabric",
+	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_370_XP },
+	{.compatible = "marvell,armada-375-coherency-fabric",
+	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_375 },
+	{.compatible = "marvell,armada-380-coherency-fabric",
+	 .data = (void *) COHERENCY_FABRIC_TYPE_ARMADA_380 },
+	{ /* end of list */ },
+};
+
+/* Functions defined in coherency_ll.S */
+int ll_enable_coherency(void);
+void ll_add_cpu_to_smp_group(void);
+
+#define CPU_CONFIG_SHARED_L2 BIT(16)
+
+/*
+ * Disable the "Shared L2 Present" bit in CPU Configuration register
+ * on Armada XP.
+ *
+ * The "Shared L2 Present" bit affects the "level of coherence" value
+ * in the clidr CP15 register.  Cache operation functions such as
+ * "flush all" and "invalidate all" operate on all the cache levels
+ * that included in the defined level of coherence. When HW I/O
+ * coherency is used, this bit causes unnecessary flushes of the L2
+ * cache.
+ */
+static void armada_xp_clear_shared_l2(void)
+{
+	u32 reg;
+
+	if (!cpu_config_base)
+		return;
+
+	reg = readl(cpu_config_base);
+	reg &= ~CPU_CONFIG_SHARED_L2;
+	writel(reg, cpu_config_base);
+}
+
+static int mvebu_hwcc_notifier(struct notifier_block *nb,
+			       unsigned long event, void *__dev)
+{
+	struct device *dev = __dev;
+
+	if (event != BUS_NOTIFY_ADD_DEVICE)
+		return NOTIFY_DONE;
+	dev->dma_coherent = true;
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block mvebu_hwcc_nb = {
+	.notifier_call = mvebu_hwcc_notifier,
+};
+
+static struct notifier_block mvebu_hwcc_pci_nb __maybe_unused = {
+	.notifier_call = mvebu_hwcc_notifier,
+};
+
+static int armada_xp_clear_l2_starting(unsigned int cpu)
+{
+	armada_xp_clear_shared_l2();
+	return 0;
+}
+
+static void __init armada_370_coherency_init(struct device_node *np)
+{
+	struct resource res;
+	struct device_node *cpu_config_np;
+
+	of_address_to_resource(np, 0, &res);
+	coherency_phys_base = res.start;
+	/*
+	 * Ensure secondary CPUs will see the updated value,
+	 * which they read before they join the coherency
+	 * fabric, and therefore before they are coherent with
+	 * the boot CPU cache.
+	 */
+	sync_cache_w(&coherency_phys_base);
+	coherency_base = of_iomap(np, 0);
+	coherency_cpu_base = of_iomap(np, 1);
+
+	cpu_config_np = of_find_compatible_node(NULL, NULL,
+						"marvell,armada-xp-cpu-config");
+	if (!cpu_config_np)
+		goto exit;
+
+	cpu_config_base = of_iomap(cpu_config_np, 0);
+	if (!cpu_config_base) {
+		of_node_put(cpu_config_np);
+		goto exit;
+	}
+
+	of_node_put(cpu_config_np);
+
+	cpuhp_setup_state_nocalls(CPUHP_AP_ARM_MVEBU_COHERENCY,
+				  "arm/mvebu/coherency:starting",
+				  armada_xp_clear_l2_starting, NULL);
+exit:
+	set_cpu_coherent();
+}
+
+/*
+ * This ioremap hook is used on Armada 375/38x to ensure that all MMIO
+ * areas are mapped as MT_UNCACHED instead of MT_DEVICE. This is
+ * needed for the HW I/O coherency mechanism to work properly without
+ * deadlock.
+ */
+static void __iomem *
+armada_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
+			 unsigned int mtype, void *caller)
+{
+	mtype = MT_UNCACHED;
+	return __arm_ioremap_caller(phys_addr, size, mtype, caller);
+}
+
+static void __init armada_375_380_coherency_init(struct device_node *np)
+{
+	struct device_node *cache_dn;
+
+	coherency_cpu_base = of_iomap(np, 0);
+	arch_ioremap_caller = armada_wa_ioremap_caller;
+	pci_ioremap_set_mem_type(MT_UNCACHED);
+
+	/*
+	 * We should switch the PL310 to I/O coherency mode only if
+	 * I/O coherency is actually enabled.
+	 */
+	if (!coherency_available())
+		return;
+
+	/*
+	 * Add the PL310 property "arm,io-coherent". This makes sure the
+	 * outer sync operation is not used, which allows to
+	 * workaround the system erratum that causes deadlocks when
+	 * doing PCIe in an SMP situation on Armada 375 and Armada
+	 * 38x.
+	 */
+	for_each_compatible_node(cache_dn, NULL, "arm,pl310-cache") {
+		struct property *p;
+
+		p = kzalloc(sizeof(*p), GFP_KERNEL);
+		p->name = kstrdup("arm,io-coherent", GFP_KERNEL);
+		of_add_property(cache_dn, p);
+	}
+}
+
+static int coherency_type(void)
+{
+	struct device_node *np;
+	const struct of_device_id *match;
+	int type;
+
+	/*
+	 * The coherency fabric is needed:
+	 * - For coherency between processors on Armada XP, so only
+	 *   when SMP is enabled.
+	 * - For coherency between the processor and I/O devices, but
+	 *   this coherency requires many pre-requisites (write
+	 *   allocate cache policy, shareable pages, SMP bit set) that
+	 *   are only meant in SMP situations.
+	 *
+	 * Note that this means that on Armada 370, there is currently
+	 * no way to use hardware I/O coherency, because even when
+	 * CONFIG_SMP is enabled, is_smp() returns false due to the
+	 * Armada 370 being a single-core processor. To lift this
+	 * limitation, we would have to find a way to make the cache
+	 * policy set to write-allocate (on all Armada SoCs), and to
+	 * set the shareable attribute in page tables (on all Armada
+	 * SoCs except the Armada 370). Unfortunately, such decisions
+	 * are taken very early in the kernel boot process, at a point
+	 * where we don't know yet on which SoC we are running.
+
+	 */
+	if (!is_smp())
+		return COHERENCY_FABRIC_TYPE_NONE;
+
+	np = of_find_matching_node_and_match(NULL, of_coherency_table, &match);
+	if (!np)
+		return COHERENCY_FABRIC_TYPE_NONE;
+
+	type = (int) match->data;
+
+	of_node_put(np);
+
+	return type;
+}
+
+int set_cpu_coherent(void)
+{
+	int type = coherency_type();
+
+	if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP) {
+		if (!coherency_base) {
+			pr_warn("Can't make current CPU cache coherent.\n");
+			pr_warn("Coherency fabric is not initialized\n");
+			return 1;
+		}
+
+		armada_xp_clear_shared_l2();
+		ll_add_cpu_to_smp_group();
+		return ll_enable_coherency();
+	}
+
+	return 0;
+}
+
+int coherency_available(void)
+{
+	return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
+}
+
+int __init coherency_init(void)
+{
+	int type = coherency_type();
+	struct device_node *np;
+
+	np = of_find_matching_node(NULL, of_coherency_table);
+
+	if (type == COHERENCY_FABRIC_TYPE_ARMADA_370_XP)
+		armada_370_coherency_init(np);
+	else if (type == COHERENCY_FABRIC_TYPE_ARMADA_375 ||
+		 type == COHERENCY_FABRIC_TYPE_ARMADA_380)
+		armada_375_380_coherency_init(np);
+
+	of_node_put(np);
+
+	return 0;
+}
+
+static int __init coherency_late_init(void)
+{
+	if (coherency_available())
+		bus_register_notifier(&platform_bus_type,
+				      &mvebu_hwcc_nb);
+	return 0;
+}
+
+postcore_initcall(coherency_late_init);
+
+#if IS_ENABLED(CONFIG_PCI)
+static int __init coherency_pci_init(void)
+{
+	if (coherency_available())
+		bus_register_notifier(&pci_bus_type,
+				       &mvebu_hwcc_pci_nb);
+	return 0;
+}
+
+arch_initcall(coherency_pci_init);
+#endif