> -----Original Message-----
> From: Que, Simon
> Sent: Thursday, August 12, 2010 6:00 AM
> To: Linux Omap; Tony Lindgren
> Cc: Cousson, Benoit; Shilimkar, Santosh; Premi, Sanjeev;
> Kanigeri, Hari
> Subject: [PATCH 3/4 v2] omap: hwspinlock: Created driver for
> OMAP hardware spinlock.
>
> Created driver for OMAP hardware spinlock.
>
> - Reserved spinlocks for internal use
> - Dynamic allocation of unreserved locks
> - Lock, unlock, and trylock functions, with or without
> disabling irqs/preempt
> - Registered as a platform device driver
>
> The device initialization uses hwmod to configure the devices.
> One device will be created for each IP. It will pass
> spinlock register offset info to the driver. The device
> initialization file is:
> arch/arm/mach-omap2/hwspinlocks.c
>
> The driver takes in register offset info passed in device
> initialization.
> It uses hwmod to obtain the base address of the hardware
> spinlock module.
> Then it reads info from the registers. The function
> hwspinlock_probe() initializes the array of spinlock
> structures, each containing a spinlock register address
> calculated from the base address and lock offsets.
> The device driver file is:
> arch/arm/plat-omap/hwspinlock.c
>
> Here's an API summary:
> int hwspinlock_lock(struct hwspinlock *);
> Attempt to lock a hardware spinlock. If it is busy,
> the function will
> keep trying until it succeeds. This is a blocking function.
> int hwspinlock_trylock(struct hwspinlock *);
> Attempt to lock a hardware spinlock. If it is busy,
> the function will
> return BUSY. If it succeeds in locking, the function
> will return
> ACQUIRED. This is a non-blocking function.
> int hwspinlock_unlock(struct hwspinlock *);
> Unlock a hardware spinlock.
>
> struct hwspinlock *hwspinlock_request(void);
> Provides for "dynamic allocation" of a hardware
> spinlock. It returns
> the handle to the next available (unallocated)
> spinlock. If no more
> locks are available, it returns NULL.
> struct hwspinlock *hwspinlock_request_specific(unsigned int);
> Provides for "static allocation" of a specific hardware
> spinlock. This
> allows the system to use a specific spinlock,
> identified by an ID. If
> the ID is invalid or if the desired lock is already
> allocated, this
> will return NULL. Otherwise it returns a spinlock handle.
> int hwspinlock_free(struct hwspinlock *);
> Frees an allocated hardware spinlock (either reserved
> or unreserved).
>
> Signed-off-by: Simon Que <[email protected]>
> Signed-off-by: Hari Kanigeri <[email protected]>
> Signed-off-by: Krishnamoorthy, Balaji T <[email protected]>
> ---
> arch/arm/mach-omap2/hwspinlocks.c | 65 +++++
> arch/arm/plat-omap/hwspinlock.c | 353
> ++++++++++++++++++++++++++
> arch/arm/plat-omap/include/plat/hwspinlock.h | 47 ++++
> 3 files changed, 465 insertions(+), 0 deletions(-)
> create mode 100644 arch/arm/mach-omap2/hwspinlocks.c
> create mode 100644 arch/arm/plat-omap/hwspinlock.c
> create mode 100644 arch/arm/plat-omap/include/plat/hwspinlock.h
>
> diff --git a/arch/arm/mach-omap2/hwspinlocks.c
> b/arch/arm/mach-omap2/hwspinlocks.c
> new file mode 100644
> index 0000000..154fc40
> --- /dev/null
> +++ b/arch/arm/mach-omap2/hwspinlocks.c
> @@ -0,0 +1,65 @@
> +/*
> + * OMAP hardware spinlock device initialization
> + *
> + * Copyright (C) 2010 Texas Instruments. All rights reserved.
> + *
> + * Contact: Simon Que <[email protected]>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
> + * 02110-1301 USA
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/slab.h>
> +
> +#include <plat/hwspinlock.h>
> +#include <plat/omap_device.h>
> +#include <plat/omap_hwmod.h>
> +
> +
> +struct omap_device_pm_latency omap_spinlock_latency[] = {
> + {
> + .deactivate_func = omap_device_idle_hwmods,
> + .activate_func = omap_device_enable_hwmods,
> + .flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST,
> + }
> +};
> +
> +/* Initialization function */
> +int __init hwspinlocks_init(void)
> +{
> + int retval = 0;
> +
> + struct omap_hwmod *oh;
> + const char *oh_name, *pdev_name;
> +
> + oh_name = "spinlock";
> + oh = omap_hwmod_lookup(oh_name);
> + if (WARN_ON(oh == NULL))
> + return -EINVAL;
> +
> + pdev_name = "hwspinlock";
> +
> + /* Pass data to device initialization */
> + omap_device_build(pdev_name, 0, oh, NULL, 0,
> omap_spinlock_latency,
> +
> ARRAY_SIZE(omap_spinlock_latency), false);
> +
> + return retval;
> +}
> +postcore_initcall(hwspinlocks_init);
> diff --git a/arch/arm/plat-omap/hwspinlock.c
> b/arch/arm/plat-omap/hwspinlock.c
> new file mode 100644
> index 0000000..6f78658
> --- /dev/null
> +++ b/arch/arm/plat-omap/hwspinlock.c
> @@ -0,0 +1,353 @@
> +/*
> + * OMAP hardware spinlock driver
> + *
> + * Copyright (C) 2010 Texas Instruments. All rights reserved.
> + *
> + * Contact: Simon Que <[email protected]>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
> + * 02110-1301 USA
> + *
> + * This driver supports:
> + * - Reserved spinlocks for internal use
> + * - Dynamic allocation of unreserved locks
> + * - Lock, unlock, and trylock functions, with or without
> disabling irqs/preempt
> + * - Registered as a platform device driver
> + *
> + * The device initialization uses hwmod to configure the
> devices. One device
> + * will be created for each IP. It will pass spinlock
> register offset info to
> + * the driver. The device initialization file is:
> + * arch/arm/mach-omap2/hwspinlock_array.c
> + *
> + * The driver takes in register offset info passed in device
> initialization.
> + * It uses hwmod to obtain the base address of the hardware
> spinlock module.
> + * Then it reads info from the registers. The function
> hwspinlock_probe()
> + * initializes the array of spinlock structures, each
> containing a spinlock
> + * register address calculated from the base address and
> lock offsets.
> + *
> + * Here's an API summary:
> + *
> + * int hwspinlock_lock(struct hwspinlock *);
> + * Attempt to lock a hardware spinlock. If it is busy,
> the function will
> + * keep trying until it succeeds. This is a blocking function.
> + * int hwspinlock_trylock(struct hwspinlock *);
> + * Attempt to lock a hardware spinlock. If it is busy,
> the function will
> + * return BUSY. If it succeeds in locking, the
> function will return
> + * ACQUIRED. This is a non-blocking function
> + * int hwspinlock_unlock(struct hwspinlock *);
> + * Unlock a hardware spinlock.
> + *
> + * struct hwspinlock *hwspinlock_request(void);
> + * Provides for "dynamic allocation" of a hardware
> spinlock. It returns
> + * the handle to the next available (unallocated)
> spinlock. If no more
> + * locks are available, it returns NULL.
> + * struct hwspinlock *hwspinlock_request_specific(unsigned int);
> + * Provides for "static allocation" of a specific
> hardware spinlock. This
> + * allows the system to use a specific spinlock,
> identified by an ID. If
> + * the ID is invalid or if the desired lock is already
> allocated, this
> + * will return NULL. Otherwise it returns a spinlock handle.
> + * int hwspinlock_free(struct hwspinlock *);
> + * Frees an allocated hardware spinlock (either
> reserved or unreserved).
> + */
> +
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +#include <plat/hwspinlock.h>
> +
> +/* Spinlock register offsets */
> +#define SYSSTATUS_OFFSET 0x0014
> +#define LOCK_BASE_OFFSET 0x0800
> +
> +/* Spinlock count code */
> +#define SPINLOCK_32_REGS 1
> +#define SPINLOCK_64_REGS 2
> +#define SPINLOCK_128_REGS 4
> +#define SPINLOCK_256_REGS 8
> +#define SPINLOCK_NUMLOCKS_BIT_OFFSET 24
> +
> +/* Number of attempts to try locking */
> +#define MAX_LOCK_ATTEMPTS 1000
> +
> +/* for managing a hardware spinlock module */
> +struct hwspinlock_module_state {
> + bool is_init; /* For first-time
> initialization */
> + int num_locks; /* Total number of
> locks in system */
> + spinlock_t local_lock; /* Local protection */
> + void __iomem *io_base; /* Mapped base address */
> +};
> +
> +/* Points to the hardware spinlock module */
> +static struct hwspinlock_module_state hwspinlock_state;
> +
> +/* Spinlock object */
> +struct hwspinlock {
> + bool is_init;
> + int id;
> + void __iomem *lock_reg;
> + bool is_allocated;
> + struct platform_device *pdev;
> +};
> +
> +/* Array of spinlocks */
> +static struct hwspinlock *hwspinlock_array;
> +
> +/* API functions */
> +
> +/* Busy loop to acquire a spinlock */
> +int hwspinlock_lock(struct hwspinlock *handle)
> +{
> + int retval;
> + int num_attempts = 0;
> +
> + if (WARN_ON(handle == NULL))
> + return -EINVAL;
> +
> + /* This is not permitted in IRQ because we do not want
> a context */
> + /* switch while the lock is being held */
> + if (WARN_ON(in_irq()))
> + return -EPERM;
> +
> + if (pm_runtime_get_sync(&handle->pdev->dev) < 0)
> + return -ENODEV;
> +
> + /* Attempt to acquire the lock by reading from it */
> + do {
> + retval = readl(handle->lock_reg);
> + num_attempts++; /* Increment the
> timeout counter */
> + } while (retval == HWSPINLOCK_BUSY &&
> + num_attempts <
> MAX_LOCK_ATTEMPTS);
> +
> + /* If there was a timeout, put the device back */
> + if (num_attempts >= MAX_LOCK_ATTEMPTS)
> + pm_runtime_put_sync(&handle->pdev->dev);
> +
> + return retval;
> +}
> +EXPORT_SYMBOL(hwspinlock_lock);
> +
> +/* Attempt to acquire a spinlock once */
> +int hwspinlock_trylock(struct hwspinlock *handle)
> +{
> + int retval = 0;
> +
> + if (WARN_ON(handle == NULL))
> + return -EINVAL;
> +
> + /* This is not permitted in IRQ because we do not want
> a context */
> + /* switch while the lock is being held */
> + if (WARN_ON(in_irq()))
> + return -EPERM;
> +
> + if ((retval = pm_runtime_get_sync(&handle->pdev->dev)) < 0)
> + return -ENODEV;
> +
> + /* Attempt to acquire the lock by reading from it */
> + retval = readl(handle->lock_reg);
> +
> + if (retval == HWSPINLOCK_BUSY)
> + pm_runtime_put_sync(&handle->pdev->dev);
> +
> + return retval;
> +}
> +EXPORT_SYMBOL(hwspinlock_trylock);
[sp] The code is almost duplicated in the functions hwspinlock_trylock()
and hwspinlock_lock(). The difference being try-once/ try-multiple.
I believe one function with additional arg - say limit - should be
sufficient.
If there is need to abstract additional arg, you can define macros
for the same.
> +
> +/* Release a spinlock */
> +int hwspinlock_unlock(struct hwspinlock *handle)
> +{
> + if (WARN_ON(handle == NULL))
> + return -EINVAL;
> +
> + /* Release it by writing 0 to it */
> + writel(0, handle->lock_reg);
> +
> + pm_runtime_put_sync(&handle->pdev->dev);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(hwspinlock_unlock);
> +
> +/* Request an unclaimed spinlock */
> +struct hwspinlock *hwspinlock_request(void)
> +{
> + int i;
> + bool found = false;
> + struct hwspinlock *handle = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&hwspinlock_state.local_lock, flags);
> + /* Search for an unclaimed, unreserved lock */
> + for (i = 0; i < hwspinlock_state.num_locks && !found; i++) {
> + if (!hwspinlock_array[i].is_allocated) {
> + found = true;
> + handle = &hwspinlock_array[i];
> + }
[sp] Starting from index 0 every time can be quite time consuming
esp. in the situations where we need spinlocks. IRQs being
disabled for long can impact the performance.
Wouldn't a used and free list be better alternative?
> + }
> + spin_unlock_irqrestore(&hwspinlock_state.local_lock, flags);
> +
> + /* Return error if no more locks available */
> + if (!found)
> + return NULL;
> +
> + handle->is_allocated = true;
> +
> + return handle;
> +}
> +EXPORT_SYMBOL(hwspinlock_request);
> +
> +/* Request an unclaimed spinlock by ID */
> +struct hwspinlock *hwspinlock_request_specific(unsigned int id)
> +{
> + struct hwspinlock *handle = NULL;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&hwspinlock_state.local_lock, flags);
> +
> + if (WARN_ON(hwspinlock_array[id].is_allocated))
> + goto exit;
> +
[sp] if (id > hwspinlock_state.num_locks) then ??
> + handle = &hwspinlock_array[id];
> + handle->is_allocated = true;
> +
> +exit:
> + spin_unlock_irqrestore(&hwspinlock_state.local_lock, flags);
> + return handle;
> +}
> +EXPORT_SYMBOL(hwspinlock_request_specific);
[sp] What if either of the "request" funcs are called before
hwspinlock_probe() gets executed?
> +
> +/* Release a claimed spinlock */
> +int hwspinlock_free(struct hwspinlock *handle)
> +{
> + if (WARN_ON(handle == NULL))
> + return -EINVAL;
> +
> + if (WARN_ON(!handle->is_allocated))
> + return -ENOMEM;
> +
> + handle->is_allocated = false;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(hwspinlock_free);
> +
> +/* Probe function */
> +static int __devinit hwspinlock_probe(struct platform_device *pdev)
> +{
> + struct resource *res;
> + void __iomem *io_base;
> + int id;
> +
[sp] Extra line?
> + void __iomem *sysstatus_reg;
[sp] can be combined with op_base declaration.
> +
> + /* Determine number of locks */
> + sysstatus_reg = ioremap(OMAP44XX_SPINLOCK_BASE +
> SYSSTATUS_OFFSET,
> +
> sizeof(u32));
> + if (sysstatus_reg == NULL)
> + return -EFAULT;
> +
> + switch (readl(sysstatus_reg) >> SPINLOCK_NUMLOCKS_BIT_OFFSET) {
> + case SPINLOCK_32_REGS:
> + hwspinlock_state.num_locks = 32;
> + break;
> + case SPINLOCK_64_REGS:
> + hwspinlock_state.num_locks = 64;
> + break;
> + case SPINLOCK_128_REGS:
> + hwspinlock_state.num_locks = 128;
> + break;
> + case SPINLOCK_256_REGS:
> + hwspinlock_state.num_locks = 256;
> + break;
> + default:
> + return -EINVAL; /* Invalid spinlock count code */
> + }
> + iounmap(sysstatus_reg);
> +
> + /* Allocate spinlock device objects */
> + hwspinlock_array = kmalloc(sizeof(struct hwspinlock) *
> + hwspinlock_state.num_locks, GFP_KERNEL);
> + if (WARN_ON(hwspinlock_array == NULL))
> + return -ENOMEM;
> +
> + /* Initialize local lock */
> + spin_lock_init(&hwspinlock_state.local_lock);
> +
> + /* Get address info */
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> + /* Map spinlock module address space */
> + io_base = ioremap(res->start, resource_size(res));
> + hwspinlock_state.io_base = io_base;
> +
> + /* Set up each individual lock handle */
> + for (id = 0; id < hwspinlock_state.num_locks; id++) {
> + hwspinlock_array[id].id = id;
> + hwspinlock_array[id].pdev = pdev;
> + hwspinlock_array[id].is_init = true;
> + hwspinlock_array[id].is_allocated = false;
> +
> + hwspinlock_array[id].lock_reg = io_base +
> LOCK_BASE_OFFSET +
> +
> sizeof(u32) * id;
> + }
> + pm_runtime_enable(&pdev->dev);
> +
> + return 0;
> +}
> +
> +static struct platform_driver hwspinlock_driver = {
> + .probe = hwspinlock_probe,
> + .driver = {
> + .name = "hwspinlock",
[sp] Extra TAB?
> + },
> +};
> +
> +/* Initialization function */
> +static int __init hwspinlock_init(void)
> +{
> + int retval = 0;
> +
> + /* Register spinlock driver */
> + retval = platform_driver_register(&hwspinlock_driver);
> +
> + return retval;
> +}
> +postcore_initcall(hwspinlock_init);
> +
> +/* Cleanup function */
> +static void __exit hwspinlock_exit(void)
> +{
> + int id;
> +
> + platform_driver_unregister(&hwspinlock_driver);
> +
> + for (id = 0; id < hwspinlock_state.num_locks; id++)
> + hwspinlock_array[id].is_init = false;
> + iounmap(hwspinlock_state.io_base);
> +
> + /* Free spinlock device objects */
> + if (hwspinlock_state.is_init)
> + kfree(hwspinlock_array);
> +}
> +module_exit(hwspinlock_exit);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Hardware spinlock driver");
> +MODULE_AUTHOR("Simon Que");
> +MODULE_AUTHOR("Hari Kanigeri");
> diff --git a/arch/arm/plat-omap/include/plat/hwspinlock.h
> b/arch/arm/plat-omap/include/plat/hwspinlock.h
> new file mode 100644
> index 0000000..ea64c48
> --- /dev/null
> +++ b/arch/arm/plat-omap/include/plat/hwspinlock.h
> @@ -0,0 +1,47 @@
> +/*
> + * OMAP hardware spinlock driver header
> + *
> + * Copyright (C) 2010 Texas Instruments. All rights reserved.
> + *
> + * Contact: Simon Que <[email protected]>
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
> + * 02110-1301 USA
> + *
> + */
> +
> +#ifndef HWSPINLOCK_H
> +#define HWSPINLOCK_H
> +
> +#include <linux/platform_device.h>
> +#include <plat/omap44xx.h>
> +
> +/* Values that are read from the spinlock register */
> +/* ACQUIRED means the lock was successfully acquired by the
> read operation */
> +/* BUSY means the lock was already acquired before the read
> operation, and */
> +/* thus the read operation was not successful */
> +#define HWSPINLOCK_ACQUIRED 0
> +#define HWSPINLOCK_BUSY 1
> +
> +struct hwspinlock;
> +
> +int hwspinlock_lock(struct hwspinlock *handle);
> +int hwspinlock_trylock(struct hwspinlock *handle);
> +int hwspinlock_unlock(struct hwspinlock *handle);
> +
> +struct hwspinlock *hwspinlock_request(void);
> +struct hwspinlock *hwspinlock_request_specific(unsigned int id);
> +int hwspinlock_free(struct hwspinlock *hwspinlock_ptr);
> +
> +#endif /* HWSPINLOCK_H */
> --
> 1.7.0
>
>
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