diff options
Diffstat (limited to 'drivers/hwspinlock/u8500_hsem.c')
| -rw-r--r-- | drivers/hwspinlock/u8500_hsem.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/drivers/hwspinlock/u8500_hsem.c b/drivers/hwspinlock/u8500_hsem.c new file mode 100644 index 000000000..67845c0c9 --- /dev/null +++ b/drivers/hwspinlock/u8500_hsem.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * u8500 HWSEM driver + * + * Copyright (C) 2010-2011 ST-Ericsson + * + * Implements u8500 semaphore handling for protocol 1, no interrupts. + * + * Author: Mathieu Poirier <mathieu.poirier@linaro.org> + * Heavily borrowed from the work of : + * Simon Que <sque@ti.com> + * Hari Kanigeri <h-kanigeri2@ti.com> + * Ohad Ben-Cohen <ohad@wizery.com> + */ + +#include <linux/module.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/hwspinlock.h> +#include <linux/platform_device.h> + +#include "hwspinlock_internal.h" + +/* + * Implementation of STE's HSem protocol 1 without interrutps. + * The only masterID we allow is '0x01' to force people to use + * HSems for synchronisation between processors rather than processes + * on the ARM core. + */ + +#define U8500_MAX_SEMAPHORE 32 /* a total of 32 semaphore */ +#define RESET_SEMAPHORE (0) /* free */ + +/* + * CPU ID for master running u8500 kernel. + * Hswpinlocks should only be used to synchonise operations + * between the Cortex A9 core and the other CPUs. Hence + * forcing the masterID to a preset value. + */ +#define HSEM_MASTER_ID 0x01 + +#define HSEM_REGISTER_OFFSET 0x08 + +#define HSEM_CTRL_REG 0x00 +#define HSEM_ICRALL 0x90 +#define HSEM_PROTOCOL_1 0x01 + +static int u8500_hsem_trylock(struct hwspinlock *lock) +{ + void __iomem *lock_addr = lock->priv; + + writel(HSEM_MASTER_ID, lock_addr); + + /* get only first 4 bit and compare to masterID. + * if equal, we have the semaphore, otherwise + * someone else has it. + */ + return (HSEM_MASTER_ID == (0x0F & readl(lock_addr))); +} + +static void u8500_hsem_unlock(struct hwspinlock *lock) +{ + void __iomem *lock_addr = lock->priv; + + /* release the lock by writing 0 to it */ + writel(RESET_SEMAPHORE, lock_addr); +} + +/* + * u8500: what value is recommended here ? + */ +static void u8500_hsem_relax(struct hwspinlock *lock) +{ + ndelay(50); +} + +static const struct hwspinlock_ops u8500_hwspinlock_ops = { + .trylock = u8500_hsem_trylock, + .unlock = u8500_hsem_unlock, + .relax = u8500_hsem_relax, +}; + +static int u8500_hsem_probe(struct platform_device *pdev) +{ + struct hwspinlock_pdata *pdata = pdev->dev.platform_data; + struct hwspinlock_device *bank; + struct hwspinlock *hwlock; + void __iomem *io_base; + int i, num_locks = U8500_MAX_SEMAPHORE; + ulong val; + + if (!pdata) + return -ENODEV; + + io_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(io_base)) + return PTR_ERR(io_base); + + /* make sure protocol 1 is selected */ + val = readl(io_base + HSEM_CTRL_REG); + writel((val & ~HSEM_PROTOCOL_1), io_base + HSEM_CTRL_REG); + + /* clear all interrupts */ + writel(0xFFFF, io_base + HSEM_ICRALL); + + bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks), + GFP_KERNEL); + if (!bank) + return -ENOMEM; + + platform_set_drvdata(pdev, bank); + + for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) + hwlock->priv = io_base + HSEM_REGISTER_OFFSET + sizeof(u32) * i; + + return devm_hwspin_lock_register(&pdev->dev, bank, + &u8500_hwspinlock_ops, + pdata->base_id, num_locks); +} + +static int u8500_hsem_remove(struct platform_device *pdev) +{ + struct hwspinlock_device *bank = platform_get_drvdata(pdev); + void __iomem *io_base = bank->lock[0].priv - HSEM_REGISTER_OFFSET; + + /* clear all interrupts */ + writel(0xFFFF, io_base + HSEM_ICRALL); + + return 0; +} + +static struct platform_driver u8500_hsem_driver = { + .probe = u8500_hsem_probe, + .remove = u8500_hsem_remove, + .driver = { + .name = "u8500_hsem", + }, +}; + +static int __init u8500_hsem_init(void) +{ + return platform_driver_register(&u8500_hsem_driver); +} +/* board init code might need to reserve hwspinlocks for predefined purposes */ +postcore_initcall(u8500_hsem_init); + +static void __exit u8500_hsem_exit(void) +{ + platform_driver_unregister(&u8500_hsem_driver); +} +module_exit(u8500_hsem_exit); + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Hardware Spinlock driver for u8500"); +MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>"); |