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Subject[PATCH v2 2/4] drivers: hwspinlock: add OMAP implementation
Date
From: Simon Que <sque@ti.com>

Add hwspinlock support for the OMAP4 Hardware Spinlock device.

The Hardware Spinlock device on OMAP4 provides hardware assistance
for synchronization between the multiple processors in the system
(dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).

[ohad@wizery.com: adapt to generic hwspinlock api, tidy up]
Signed-off-by: Simon Que <sque@ti.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
Signed-off-by: Krishnamoorthy, Balaji T <balajitk@ti.com>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Tony Lindgren <tony@atomide.com>
---
drivers/hwspinlock/Kconfig | 9 ++
drivers/hwspinlock/Makefile | 1 +
drivers/hwspinlock/omap_hwspinlock.c | 231 ++++++++++++++++++++++++++++++++++
3 files changed, 241 insertions(+), 0 deletions(-)
create mode 100644 drivers/hwspinlock/omap_hwspinlock.c
diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index 9dd8db4..eb4af28 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -11,3 +11,12 @@ config HWSPINLOCK
coprocessors).

If unsure, say N.
+
+config HWSPINLOCK_OMAP
+ tristate "OMAP Hardware Spinlock device"
+ depends on HWSPINLOCK && ARCH_OMAP4
+ help
+ Say y here to support the OMAP Hardware Spinlock device (firstly
+ introduced in OMAP4).
+
+ If unsure, say N.
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index b9d2b9f..5729a3f 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -3,3 +3,4 @@
#

obj-$(CONFIG_HWSPINLOCK) += hwspinlock_core.o
+obj-$(CONFIG_HWSPINLOCK_OMAP) += omap_hwspinlock.o
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c
new file mode 100644
index 0000000..0525d59
--- /dev/null
+++ b/drivers/hwspinlock/omap_hwspinlock.c
@@ -0,0 +1,231 @@
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Contact: Simon Que <sque@ti.com>
+ * Hari Kanigeri <h-kanigeri2@ti.com>
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/hwspinlock.h>
+#include <linux/platform_device.h>
+
+#include "hwspinlock.h"
+
+/* Spinlock register offsets */
+#define SYSSTATUS_OFFSET 0x0014
+#define LOCK_BASE_OFFSET 0x0800
+
+#define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
+
+/* Possible values of SPINLOCK_LOCK_REG */
+#define SPINLOCK_NOTTAKEN (0) /* free */
+#define SPINLOCK_TAKEN (1) /* locked */
+
+#define to_omap_hwspinlock(lock) \
+ container_of(lock, struct omap_hwspinlock, lock)
+
+struct omap_hwspinlock {
+ struct hwspinlock lock;
+ void __iomem *addr;
+};
+
+struct omap_hwspinlock_state {
+ int num_locks; /* Total number of locks in system */
+ void __iomem *io_base; /* Mapped base address */
+};
+
+static int omap_hwspinlock_trylock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* attempt to acquire the lock by reading its value */
+ return (SPINLOCK_NOTTAKEN == readl(omap_lock->addr));
+}
+
+static void omap_hwspinlock_unlock(struct hwspinlock *lock)
+{
+ struct omap_hwspinlock *omap_lock = to_omap_hwspinlock(lock);
+
+ /* release the lock by writing 0 to it */
+ writel(SPINLOCK_NOTTAKEN, omap_lock->addr);
+}
+
+/*
+ * relax the OMAP interconnect while spinning on it.
+ *
+ * The specs recommended that the retry delay time will be
+ * just over half of the time that a requester would be
+ * expected to hold the lock.
+ *
+ * The number below is taken from an hardware specs example,
+ * obviously it is somewhat arbitrary.
+ */
+static void omap_hwspinlock_relax(struct hwspinlock *lock)
+{
+ ndelay(50);
+}
+
+static const struct hwspinlock_ops omap_hwspinlock_ops = {
+ .trylock = omap_hwspinlock_trylock,
+ .unlock = omap_hwspinlock_unlock,
+ .relax = omap_hwspinlock_relax,
+};
+
+static int __devinit omap_hwspinlock_probe(struct platform_device *pdev)
+{
+ struct omap_hwspinlock *omap_lock;
+ struct omap_hwspinlock_state *state;
+ struct hwspinlock *lock;
+ struct resource *res;
+ void __iomem *io_base;
+ int i, ret;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ state = kzalloc(sizeof(*state), GFP_KERNEL);
+ if (!state)
+ return -ENOMEM;
+
+ io_base = ioremap(res->start, resource_size(res));
+ if (!io_base) {
+ ret = -ENOMEM;
+ goto free_state;
+ }
+
+ /* Determine number of locks */
+ i = readl(io_base + SYSSTATUS_OFFSET);
+ i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET;
+
+ /* exactly one of the four least significant bits must be 1 */
+ if (!i || !is_power_of_2(i) || i > 8) {
+ ret = -EINVAL;
+ goto iounmap_base;
+ }
+
+ state->num_locks = i * 32;
+ state->io_base = io_base;
+
+ platform_set_drvdata(pdev, state);
+
+ /*
+ * runtime PM will make sure the clock of this module is
+ * enabled iff at least one lock is requested
+ */
+ pm_runtime_enable(&pdev->dev);
+
+ for (i = 0; i < state->num_locks; i++) {
+ omap_lock = kzalloc(sizeof(*omap_lock), GFP_KERNEL);
+ if (!omap_lock) {
+ ret = -ENOMEM;
+ goto free_locks;
+ }
+
+ omap_lock->lock.dev = &pdev->dev;
+ omap_lock->lock.owner = THIS_MODULE;
+ omap_lock->lock.id = i;
+ omap_lock->lock.ops = &omap_hwspinlock_ops;
+ omap_lock->addr = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i;
+
+ ret = hwspinlock_register(&omap_lock->lock);
+ if (ret) {
+ kfree(omap_lock);
+ goto free_locks;
+ }
+ }
+
+ return 0;
+
+free_locks:
+ while (--i >= 0) {
+ lock = hwspinlock_unregister(i);
+ /* this should't happen, but let's give our best effort */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: cleanups failed\n", __func__);
+ continue;
+ }
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+ pm_runtime_disable(&pdev->dev);
+iounmap_base:
+ iounmap(state->io_base);
+free_state:
+ kfree(state);
+ return ret;
+}
+
+static int omap_hwspinlock_remove(struct platform_device *pdev)
+{
+ struct omap_hwspinlock_state *state = platform_get_drvdata(pdev);
+ struct hwspinlock *lock;
+ struct omap_hwspinlock *omap_lock;
+ int i;
+
+ for (i = 0; i < state->num_locks; i++) {
+ lock = hwspinlock_unregister(i);
+ /* this shouldn't happen at this point. if it does, at least
+ * don't continue with the remove */
+ if (!lock) {
+ dev_err(&pdev->dev, "%s: failed on %d\n", __func__, i);
+ return -EBUSY;
+ }
+
+ omap_lock = to_omap_hwspinlock(lock);
+ kfree(omap_lock);
+ }
+
+ pm_runtime_disable(&pdev->dev);
+ iounmap(state->io_base);
+ kfree(state);
+
+ return 0;
+}
+
+static struct platform_driver omap_hwspinlock_driver = {
+ .probe = omap_hwspinlock_probe,
+ .remove = omap_hwspinlock_remove,
+ .driver = {
+ .name = "omap_hwspinlock",
+ },
+};
+
+static int __init omap_hwspinlock_init(void)
+{
+ return platform_driver_register(&omap_hwspinlock_driver);
+}
+/* board init code might need to reserve hwspinlocks for predefined purposes */
+postcore_initcall(omap_hwspinlock_init);
+
+static void __exit omap_hwspinlock_exit(void)
+{
+ platform_driver_unregister(&omap_hwspinlock_driver);
+}
+module_exit(omap_hwspinlock_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
+MODULE_AUTHOR("Simon Que <sque@ti.com>");
+MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
+MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");
--
1.7.0.4


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