drivers: hwspinlock: add framework

Add a platform-independent hwspinlock framework.

Hardware spinlock devices are needed, e.g., in order to access data
that is shared between remote processors, that otherwise have no
alternative mechanism to accomplish synchronization and mutual exclusion
operations.
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Hari Kanigeri <h-kanigeri2@ti.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/Kconfig

@@ -117,4 +117,6 @@ source "drivers/staging/Kconfig"
 source "drivers/platform/Kconfig"
 
 source "drivers/clk/Kconfig"
+
+source "drivers/hwspinlock/Kconfig"
 endmenu

drivers/Makefile

@@ -117,3 +117,5 @@ obj-y				+= platform/
 obj-y				+= ieee802154/
 #common clk code
 obj-y				+= clk/
+
+obj-$(CONFIG_HWSPINLOCK)	+= hwspinlock/

drivers/hwspinlock/Kconfig

+#
+# Generic HWSPINLOCK framework
+#
+
+config HWSPINLOCK
+	tristate "Generic Hardware Spinlock framework"
+	help
+	  Say y here to support the generic hardware spinlock framework.
+	  You only need to enable this if you have hardware spinlock module
+	  on your system (usually only relevant if your system has remote slave
+	  coprocessors).
+
+	  If unsure, say N.

drivers/hwspinlock/Makefile

+#
+# Generic Hardware Spinlock framework
+#
+
+obj-$(CONFIG_HWSPINLOCK)		+= hwspinlock_core.o

drivers/hwspinlock/hwspinlock_internal.h

+/*
+ * Hardware spinlocks internal header
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Ohad Ben-Cohen <ohad@wizery.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __HWSPINLOCK_HWSPINLOCK_H
+#define __HWSPINLOCK_HWSPINLOCK_H
+
+#include <linux/spinlock.h>
+#include <linux/device.h>
+
+/**
+ * struct hwspinlock_ops - platform-specific hwspinlock handlers
+ *
+ * @trylock: make a single attempt to take the lock. returns 0 on
+ *	     failure and true on success. may _not_ sleep.
+ * @unlock:  release the lock. always succeed. may _not_ sleep.
+ * @relax:   optional, platform-specific relax handler, called by hwspinlock
+ *	     core while spinning on a lock, between two successive
+ *	     invocations of @trylock. may _not_ sleep.
+ */
+struct hwspinlock_ops {
+	int (*trylock)(struct hwspinlock *lock);
+	void (*unlock)(struct hwspinlock *lock);
+	void (*relax)(struct hwspinlock *lock);
+};
+
+/**
+ * struct hwspinlock - this struct represents a single hwspinlock instance
+ *
+ * @dev: underlying device, will be used to invoke runtime PM api
+ * @ops: platform-specific hwspinlock handlers
+ * @id: a global, unique, system-wide, index of the lock.
+ * @lock: initialized and used by hwspinlock core
+ * @owner: underlying implementation module, used to maintain module ref count
+ *
+ * Note: currently simplicity was opted for, but later we can squeeze some
+ * memory bytes by grouping the dev, ops and owner members in a single
+ * per-platform struct, and have all hwspinlocks point at it.
+ */
+struct hwspinlock {
+	struct device *dev;
+	const struct hwspinlock_ops *ops;
+	int id;
+	spinlock_t lock;
+	struct module *owner;
+};
+
+#endif /* __HWSPINLOCK_HWSPINLOCK_H */