diff options
Diffstat (limited to 'drivers/hwspinlock/omap_hwspinlock.c')
| -rw-r--r-- | drivers/hwspinlock/omap_hwspinlock.c | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c new file mode 100644 index 000000000000..a8f02734c026 --- /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/bitops.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_internal.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; + + /* one of the four lsb's must be set, and nothing else */ + if (hweight_long(i & 0xf) != 1 || 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 = hwspin_lock_register(&omap_lock->lock); + if (ret) { + kfree(omap_lock); + goto free_locks; + } + } + + return 0; + +free_locks: + while (--i >= 0) { + lock = hwspin_lock_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(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 = hwspin_lock_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>"); |