/* * 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 */ static int omap_hwspinlock_trylock(struct hwspinlock *lock) { void __iomem *lock_addr = lock->priv; /* attempt to acquire the lock by reading its value */ return (SPINLOCK_NOTTAKEN == readl(lock_addr)); } static void omap_hwspinlock_unlock(struct hwspinlock *lock) { void __iomem *lock_addr = lock->priv; /* release the lock by writing 0 to it */ writel(SPINLOCK_NOTTAKEN, 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 omap_hwspinlock_probe(struct platform_device *pdev) { struct hwspinlock_pdata *pdata = pdev->dev.platform_data; struct hwspinlock_device *bank; struct hwspinlock *hwlock; struct resource *res; void __iomem *io_base; int num_locks, i, ret; if (!pdata) return -ENODEV; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) return -ENODEV; io_base = ioremap(res->start, resource_size(res)); if (!io_base) return -ENOMEM; /* * make sure the module is enabled and clocked before reading * the module SYSSTATUS register */ pm_runtime_enable(&pdev->dev); ret = pm_runtime_get_sync(&pdev->dev); if (ret < 0) { pm_runtime_put_noidle(&pdev->dev); goto iounmap_base; } /* Determine number of locks */ i = readl(io_base + SYSSTATUS_OFFSET); i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET; /* * runtime PM will make sure the clock of this module is * enabled again iff at least one lock is requested */ ret = pm_runtime_put(&pdev->dev); if (ret < 0) goto iounmap_base; /* 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; } num_locks = i * 32; /* actual number of locks in this device */ bank = kzalloc(sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL); if (!bank) { ret = -ENOMEM; goto iounmap_base; } platform_set_drvdata(pdev, bank); for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i; ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops, pdata->base_id, num_locks); if (ret) goto reg_fail; return 0; reg_fail: kfree(bank); iounmap_base: pm_runtime_disable(&pdev->dev); iounmap(io_base); return ret; } static int omap_hwspinlock_remove(struct platform_device *pdev) { struct hwspinlock_device *bank = platform_get_drvdata(pdev); void __iomem *io_base = bank->lock[0].priv - LOCK_BASE_OFFSET; int ret; ret = hwspin_lock_unregister(bank); if (ret) { dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret); return ret; } pm_runtime_disable(&pdev->dev); iounmap(io_base); kfree(bank); 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>");