powerpc: add support for MPIC message register API

Some MPIC implementations contain one or more blocks of message registers
that are used to send messages between cores via IPIs.  A simple API has
been added to access (get/put, read, write, etc ...) these message registers.
The available message registers are initially discovered via nodes in the
device tree.  A separate commit contains a binding for the message register
nodes.

Signed-off-by: Meador Inge <meador_inge@mentor.com>
Signed-off-by: Jia Hongtao <B38951@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/sysdev/mpic_msgr.c

@@ -0,0 +1,282 @@
+/*
+ * Copyright 2011-2012, Meador Inge, Mentor Graphics Corporation.
+ *
+ * Some ideas based on un-pushed work done by Vivek Mahajan, Jason Jin, and
+ * Mingkai Hu from Freescale Semiconductor, Inc.
+ *
+ * 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; version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/list.h>
+#include <linux/of_platform.h>
+#include <linux/errno.h>
+#include <asm/prom.h>
+#include <asm/hw_irq.h>
+#include <asm/ppc-pci.h>
+#include <asm/mpic_msgr.h>
+
+#define MPIC_MSGR_REGISTERS_PER_BLOCK	4
+#define MPIC_MSGR_STRIDE		0x10
+#define MPIC_MSGR_MER_OFFSET		0x100
+#define MSGR_INUSE			0
+#define MSGR_FREE			1
+
+static struct mpic_msgr **mpic_msgrs;
+static unsigned int mpic_msgr_count;
+
+static inline void _mpic_msgr_mer_write(struct mpic_msgr *msgr, u32 value)
+{
+	out_be32(msgr->mer, value);
+}
+
+static inline u32 _mpic_msgr_mer_read(struct mpic_msgr *msgr)
+{
+	return in_be32(msgr->mer);
+}
+
+static inline void _mpic_msgr_disable(struct mpic_msgr *msgr)
+{
+	u32 mer = _mpic_msgr_mer_read(msgr);
+
+	_mpic_msgr_mer_write(msgr, mer & ~(1 << msgr->num));
+}
+
+struct mpic_msgr *mpic_msgr_get(unsigned int reg_num)
+{
+	unsigned long flags;
+	struct mpic_msgr *msgr;
+
+	/* Assume busy until proven otherwise.  */
+	msgr = ERR_PTR(-EBUSY);
+
+	if (reg_num >= mpic_msgr_count)
+		return ERR_PTR(-ENODEV);
+
+	raw_spin_lock_irqsave(&msgr->lock, flags);
+	if (mpic_msgrs[reg_num]->in_use == MSGR_FREE) {
+		msgr = mpic_msgrs[reg_num];
+		msgr->in_use = MSGR_INUSE;
+	}
+	raw_spin_unlock_irqrestore(&msgr->lock, flags);
+
+	return msgr;
+}
+EXPORT_SYMBOL_GPL(mpic_msgr_get);
+
+void mpic_msgr_put(struct mpic_msgr *msgr)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&msgr->lock, flags);
+	msgr->in_use = MSGR_FREE;
+	_mpic_msgr_disable(msgr);
+	raw_spin_unlock_irqrestore(&msgr->lock, flags);
+}
+EXPORT_SYMBOL_GPL(mpic_msgr_put);
+
+void mpic_msgr_enable(struct mpic_msgr *msgr)
+{
+	unsigned long flags;
+	u32 mer;
+
+	raw_spin_lock_irqsave(&msgr->lock, flags);
+	mer = _mpic_msgr_mer_read(msgr);
+	_mpic_msgr_mer_write(msgr, mer | (1 << msgr->num));
+	raw_spin_unlock_irqrestore(&msgr->lock, flags);
+}
+EXPORT_SYMBOL_GPL(mpic_msgr_enable);
+
+void mpic_msgr_disable(struct mpic_msgr *msgr)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&msgr->lock, flags);
+	_mpic_msgr_disable(msgr);
+	raw_spin_unlock_irqrestore(&msgr->lock, flags);
+}
+EXPORT_SYMBOL_GPL(mpic_msgr_disable);
+
+/* The following three functions are used to compute the order and number of
+ * the message register blocks.  They are clearly very inefficent.  However,
+ * they are called *only* a few times during device initialization.
+ */
+static unsigned int mpic_msgr_number_of_blocks(void)
+{
+	unsigned int count;
+	struct device_node *aliases;
+
+	count = 0;
+	aliases = of_find_node_by_name(NULL, "aliases");
+
+	if (aliases) {
+		char buf[32];
+
+		for (;;) {
+			snprintf(buf, sizeof(buf), "mpic-msgr-block%d", count);
+			if (!of_find_property(aliases, buf, NULL))
+				break;
+
+			count += 1;
+		}
+	}
+
+	return count;
+}
+
+static unsigned int mpic_msgr_number_of_registers(void)
+{
+	return mpic_msgr_number_of_blocks() * MPIC_MSGR_REGISTERS_PER_BLOCK;
+}
+
+static int mpic_msgr_block_number(struct device_node *node)
+{
+	struct device_node *aliases;
+	unsigned int index, number_of_blocks;
+	char buf[64];
+
+	number_of_blocks = mpic_msgr_number_of_blocks();
+	aliases = of_find_node_by_name(NULL, "aliases");
+	if (!aliases)
+		return -1;
+
+	for (index = 0; index < number_of_blocks; ++index) {
+		struct property *prop;
+
+		snprintf(buf, sizeof(buf), "mpic-msgr-block%d", index);
+		prop = of_find_property(aliases, buf, NULL);
+		if (node == of_find_node_by_path(prop->value))
+			break;
+	}
+
+	return index == number_of_blocks ? -1 : index;
+}
+
+/* The probe function for a single message register block.
+ */
+static __devinit int mpic_msgr_probe(struct platform_device *dev)
+{
+	void __iomem *msgr_block_addr;
+	int block_number;
+	struct resource rsrc;
+	unsigned int i;
+	unsigned int irq_index;
+	struct device_node *np = dev->dev.of_node;
+	unsigned int receive_mask;
+	const unsigned int *prop;
+
+	if (!np) {
+		dev_err(&dev->dev, "Device OF-Node is NULL");
+		return -EFAULT;
+	}
+
+	/* Allocate the message register array upon the first device
+	 * registered.
+	 */
+	if (!mpic_msgrs) {
+		mpic_msgr_count = mpic_msgr_number_of_registers();
+		dev_info(&dev->dev, "Found %d message registers\n",
+				mpic_msgr_count);
+
+		mpic_msgrs = kzalloc(sizeof(struct mpic_msgr) * mpic_msgr_count,
+							 GFP_KERNEL);
+		if (!mpic_msgrs) {
+			dev_err(&dev->dev,
+				"No memory for message register blocks\n");
+			return -ENOMEM;
+		}
+	}
+	dev_info(&dev->dev, "Of-device full name %s\n", np->full_name);
+
+	/* IO map the message register block. */
+	of_address_to_resource(np, 0, &rsrc);
+	msgr_block_addr = ioremap(rsrc.start, rsrc.end - rsrc.start);
+	if (!msgr_block_addr) {
+		dev_err(&dev->dev, "Failed to iomap MPIC message registers");
+		return -EFAULT;
+	}
+
+	/* Ensure the block has a defined order. */
+	block_number = mpic_msgr_block_number(np);
+	if (block_number < 0) {
+		dev_err(&dev->dev,
+			"Failed to find message register block alias\n");
+		return -ENODEV;
+	}
+	dev_info(&dev->dev, "Setting up message register block %d\n",
+			block_number);
+
+	/* Grab the receive mask which specifies what registers can receive
+	 * interrupts.
+	 */
+	prop = of_get_property(np, "mpic-msgr-receive-mask", NULL);
+	receive_mask = (prop) ? *prop : 0xF;
+
+	/* Build up the appropriate message register data structures. */
+	for (i = 0, irq_index = 0; i < MPIC_MSGR_REGISTERS_PER_BLOCK; ++i) {
+		struct mpic_msgr *msgr;
+		unsigned int reg_number;
+
+		msgr = kzalloc(sizeof(struct mpic_msgr), GFP_KERNEL);
+		if (!msgr) {
+			dev_err(&dev->dev, "No memory for message register\n");
+			return -ENOMEM;
+		}
+
+		reg_number = block_number * MPIC_MSGR_REGISTERS_PER_BLOCK + i;
+		msgr->base = msgr_block_addr + i * MPIC_MSGR_STRIDE;
+		msgr->mer = msgr->base + MPIC_MSGR_MER_OFFSET;
+		msgr->in_use = MSGR_FREE;
+		msgr->num = i;
+		raw_spin_lock_init(&msgr->lock);
+
+		if (receive_mask & (1 << i)) {
+			struct resource irq;
+
+			if (of_irq_to_resource(np, irq_index, &irq) == NO_IRQ) {
+				dev_err(&dev->dev,
+						"Missing interrupt specifier");
+				kfree(msgr);
+				return -EFAULT;
+			}
+			msgr->irq = irq.start;
+			irq_index += 1;
+		} else {
+			msgr->irq = NO_IRQ;
+		}
+
+		mpic_msgrs[reg_number] = msgr;
+		mpic_msgr_disable(msgr);
+		dev_info(&dev->dev, "Register %d initialized: irq %d\n",
+				reg_number, msgr->irq);
+
+	}
+
+	return 0;
+}
+
+static const struct of_device_id mpic_msgr_ids[] = {
+	{
+		.compatible = "fsl,mpic-v3.1-msgr",
+		.data = NULL,
+	},
+	{}
+};
+
+static struct platform_driver mpic_msgr_driver = {
+	.driver = {
+		.name = "mpic-msgr",
+		.owner = THIS_MODULE,
+		.of_match_table = mpic_msgr_ids,
+	},
+	.probe = mpic_msgr_probe,
+};
+
+static __init int mpic_msgr_init(void)
+{
+	return platform_driver_register(&mpic_msgr_driver);
+}
+subsys_initcall(mpic_msgr_init);