powerpc/powernv/vas: Define vas_init() and vas_exit()

Implement vas_init() and vas_exit() functions for a new VAS module.
This VAS module is essentially a library for other device drivers
and kernel users of the NX coprocessors like NX-842 and NX-GZIP.
In the future this will be extended to add support for user space
to access the NX coprocessors.

VAS is currently only supported with 64K page size.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Documentation/devicetree/bindings/powerpc/ibm,vas.txt

+* IBM Powerpc Virtual Accelerator Switchboard (VAS)
+
+VAS is a hardware mechanism that allows kernel subsystems and user processes
+to directly submit compression and other requests to Nest accelerators (NX)
+or other coprocessors functions.
+
+Required properties:
+- compatible : should be "ibm,vas".
+- ibm,vas-id : A unique identifier for each instance of VAS in the system
+- reg : Should contain 4 pairs of 64-bit fields specifying the Hypervisor
+  window context start and length, OS/User window context start and length,
+  "Paste address" start and length, "Paste window id" start bit and number
+  of bits)
+
+Example:
+
+	vas@6019100000000 {
+		compatible = "ibm,vas", "ibm,power9-vas";
+		reg = <0x6019100000000 0x2000000 0x6019000000000 0x100000000 0x8000000000000 0x100000000 0x20 0x10>;
+		name = "vas";
+		ibm,vas-id = <0x1>;
+	};

MAINTAINERS

@@ -6429,6 +6429,14 @@ L:	netdev@vger.kernel.org
 S:	Supported
 F:	drivers/net/ethernet/ibm/ibmvnic.*
 
+IBM Power Virtual Accelerator Switchboard
+M:	Sukadev Bhattiprolu
+L:	linuxppc-dev@lists.ozlabs.org
+S:	Supported
+F:	arch/powerpc/platforms/powernv/vas*
+F:	arch/powerpc/include/asm/vas.h
+F:	arch/powerpc/include/uapi/asm/vas.h
+
 IBM Power Virtual Ethernet Device Driver
 M:	Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
 L:	netdev@vger.kernel.org

arch/powerpc/platforms/powernv/Kconfig

@@ -38,3 +38,17 @@ config PPC_MEMTRACE
 	help
 	  Enabling this option allows for the removal of memory (RAM)
 	  from the kernel mappings to be used for hardware tracing.
+
+config PPC_VAS
+	bool "IBM Virtual Accelerator Switchboard (VAS)"
+	depends on PPC_POWERNV && PPC_64K_PAGES
+	default y
+	help
+	  This enables support for IBM Virtual Accelerator Switchboard (VAS).
+
+	  VAS allows accelerators in co-processors like NX-GZIP and NX-842
+	  to be accessible to kernel subsystems and user processes.
+
+	  VAS adapters are found in POWER9 based systems.
+
+	  If unsure, say N.

arch/powerpc/platforms/powernv/Makefile

@@ -14,3 +14,4 @@ obj-$(CONFIG_TRACEPOINTS)	+= opal-tracepoints.o
 obj-$(CONFIG_OPAL_PRD)	+= opal-prd.o
 obj-$(CONFIG_PERF_EVENTS) += opal-imc.o
 obj-$(CONFIG_PPC_MEMTRACE)	+= memtrace.o
+obj-$(CONFIG_PPC_VAS)	+= vas.o vas-window.o

arch/powerpc/platforms/powernv/vas-window.c

+/*
+ * Copyright 2016-17 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/types.h>
+#include <linux/mutex.h>
+
+#include "vas.h"
+
+/* stub for now */
+int vas_win_close(struct vas_window *window)
+{
+	return -1;
+}

arch/powerpc/platforms/powernv/vas.c

+/*
+ * Copyright 2016-17 IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#define pr_fmt(fmt) "vas: " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+
+#include "vas.h"
+
+static DEFINE_MUTEX(vas_mutex);
+static LIST_HEAD(vas_instances);
+
+static int init_vas_instance(struct platform_device *pdev)
+{
+	int rc, vasid;
+	struct resource *res;
+	struct vas_instance *vinst;
+	struct device_node *dn = pdev->dev.of_node;
+
+	rc = of_property_read_u32(dn, "ibm,vas-id", &vasid);
+	if (rc) {
+		pr_err("No ibm,vas-id property for %s?\n", pdev->name);
+		return -ENODEV;
+	}
+
+	if (pdev->num_resources != 4) {
+		pr_err("Unexpected DT configuration for [%s, %d]\n",
+				pdev->name, vasid);
+		return -ENODEV;
+	}
+
+	vinst = kzalloc(sizeof(*vinst), GFP_KERNEL);
+	if (!vinst)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&vinst->node);
+	ida_init(&vinst->ida);
+	mutex_init(&vinst->mutex);
+	vinst->vas_id = vasid;
+	vinst->pdev = pdev;
+
+	res = &pdev->resource[0];
+	vinst->hvwc_bar_start = res->start;
+
+	res = &pdev->resource[1];
+	vinst->uwc_bar_start = res->start;
+
+	res = &pdev->resource[2];
+	vinst->paste_base_addr = res->start;
+
+	res = &pdev->resource[3];
+	if (res->end > 62) {
+		pr_err("Bad 'paste_win_id_shift' in DT, %llx\n", res->end);
+		goto free_vinst;
+	}
+
+	vinst->paste_win_id_shift = 63 - res->end;
+
+	pr_devel("Initialized instance [%s, %d], paste_base 0x%llx, "
+			"paste_win_id_shift 0x%llx\n", pdev->name, vasid,
+			vinst->paste_base_addr, vinst->paste_win_id_shift);
+
+	mutex_lock(&vas_mutex);
+	list_add(&vinst->node, &vas_instances);
+	mutex_unlock(&vas_mutex);
+
+	dev_set_drvdata(&pdev->dev, vinst);
+
+	return 0;
+
+free_vinst:
+	kfree(vinst);
+	return -ENODEV;
+
+}
+
+/*
+ * Although this is read/used multiple times, it is written to only
+ * during initialization.
+ */
+struct vas_instance *find_vas_instance(int vasid)
+{
+	struct list_head *ent;
+	struct vas_instance *vinst;
+
+	mutex_lock(&vas_mutex);
+	list_for_each(ent, &vas_instances) {
+		vinst = list_entry(ent, struct vas_instance, node);
+		if (vinst->vas_id == vasid) {
+			mutex_unlock(&vas_mutex);
+			return vinst;
+		}
+	}
+	mutex_unlock(&vas_mutex);
+
+	pr_devel("Instance %d not found\n", vasid);
+	return NULL;
+}
+
+static int vas_probe(struct platform_device *pdev)
+{
+	return init_vas_instance(pdev);
+}
+
+static const struct of_device_id powernv_vas_match[] = {
+	{ .compatible = "ibm,vas",},
+	{},
+};
+
+static struct platform_driver vas_driver = {
+	.driver = {
+		.name = "vas",
+		.of_match_table = powernv_vas_match,
+	},
+	.probe = vas_probe,
+};
+
+static int __init vas_init(void)
+{
+	int found = 0;
+	struct device_node *dn;
+
+	platform_driver_register(&vas_driver);
+
+	for_each_compatible_node(dn, NULL, "ibm,vas") {
+		of_platform_device_create(dn, NULL, NULL);
+		found++;
+	}
+
+	if (!found)
+		return -ENODEV;
+
+	pr_devel("Found %d instances\n", found);
+
+	return 0;
+}
+device_initcall(vas_init);

arch/powerpc/platforms/powernv/vas.h

@@ -379,4 +379,6 @@ struct vas_winctx {
 	enum vas_notify_after_count notify_after_count;
 };
 
+extern struct vas_instance *find_vas_instance(int vasid);
+
 #endif /* _VAS_H */