diff mbox

[2/3,v3] omap: hwspinlock: Created driver for OMAP hardware spinlock

Message ID F39349C6FA641B4A831B7BF4EBF4D4E1481CCCB0@dlee03.ent.ti.com (mailing list archive)
State Superseded, archived
Delegated to: Tony Lindgren
Headers show

Commit Message

Que, Simon Aug. 13, 2010, 7:59 p.m. UTC
None
diff mbox

Patch

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 <sque@ti.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.
+ *
+ * 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..f4b0185
--- /dev/null
+++ b/arch/arm/plat-omap/hwspinlock.c
@@ -0,0 +1,347 @@ 
+/*
+ * OMAP hardware spinlock driver
+ *
+ * Copyright (C) 2010 Texas Instruments. All rights reserved.
+ *
+ * Contact: Simon Que <sque@ti.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.
+ *
+ * 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/list.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 {
+       struct list_head head;
+       bool is_init;
+       int id;
+       void __iomem *lock_reg;
+       bool is_allocated;
+       struct platform_device *pdev;
+};
+
+/* Array of spinlocks */
+static struct hwspinlock *hwspinlock_array;
+
+/* List for keeping track of free locks */
+static struct list_head free_locks;
+
+/* API functions */
+
+/* Busy loop to acquire a spinlock, with timeout */
+int hwspinlock_lock_timeout(struct hwspinlock *handle, int max_attempts)
+{
+       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 && (max_attempts > 0 &&
+                                       num_attempts < max_attempts));
+
+       /* If there was a timeout, put the device back */
+       if (num_attempts >= max_attempts)
+               pm_runtime_put_sync(&handle->pdev->dev);
+
+       return retval;
+}
+EXPORT_SYMBOL(hwspinlock_lock_timeout);
+
+/* 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)
+{
+       struct hwspinlock *handle = NULL;
+       unsigned long flags;
+
+       spin_lock_irqsave(&hwspinlock_state.local_lock, flags);
+
+       if (WARN_ON(!hwspinlock_state.is_init))
+               goto exit;
+
+       if (WARN_ON(list_empty(&free_locks)))
+               goto exit;
+
+       handle = (struct hwspinlock *) free_locks.next;
+       list_del(free_locks.next);
+       handle->is_allocated = true;
+
+exit:
+       spin_unlock_irqrestore(&hwspinlock_state.local_lock, flags);
+       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_state.is_init))
+               goto exit;
+
+       if (WARN_ON(id >= hwspinlock_state.num_locks))
+               goto exit;
+
+       if (WARN_ON(hwspinlock_array[id].is_allocated))
+               goto exit;
+
+       handle = &hwspinlock_array[id];
+       handle->is_allocated = true;
+
+       /* Remove from free lock list */
+       list_del(&handle->head);
+
+exit:
+       spin_unlock_irqrestore(&hwspinlock_state.local_lock, flags);
+       return handle;
+}
+EXPORT_SYMBOL(hwspinlock_request_specific);
+
+/* Release a claimed spinlock */
+int hwspinlock_free(struct hwspinlock *handle)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&hwspinlock_state.local_lock, flags);
+
+       if (WARN_ON(handle == NULL))
+               return -EINVAL;
+
+       if (WARN_ON(!handle->is_allocated))
+               return -ENOMEM;
+
+       list_add(&free_locks, &handle->head);
+       handle->is_allocated = false;
+
+       spin_unlock_irqrestore(&hwspinlock_state.local_lock, flags);
+       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;
+
+       /* 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;
+
+       /* Determine number of locks */
+       switch (readl(io_base + SYSSTATUS_OFFSET) >>
+                               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 */
+       }
+
+       /* 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);
+
+       /* Mark module as initialized */
+       hwspinlock_state.is_init = true;
+
+       /* Initialize lock lists */
+       INIT_LIST_HEAD(&free_locks);
+
+       /* 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;
+
+               /* Add it to the list of free locks */
+               list_add(&hwspinlock_array[id].head, &free_locks);
+       }
+       pm_runtime_enable(&pdev->dev);
+
+       return 0;
+}
+
+static struct platform_driver hwspinlock_driver = {
+       .probe          = hwspinlock_probe,
+       .driver         = {
+               .name   = "hwspinlock",
+       },
+};
+
+/* 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);
+
+       INIT_LIST_HEAD(&free_locks);    /* Clear free lock list */
+}
+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..3a38190
--- /dev/null
+++ b/arch/arm/plat-omap/include/plat/hwspinlock.h
@@ -0,0 +1,53 @@ 
+/*
+ * OMAP hardware spinlock driver header
+ *
+ * Copyright (C) 2010 Texas Instruments. All rights reserved.
+ *
+ * Contact: Simon Que <sque@ti.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.
+ *
+ * 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;
+
+/* Basic operations */
+int hwspinlock_lock_timeout(struct hwspinlock *handle, int max_attempts);
+int hwspinlock_unlock(struct hwspinlock *handle);
+
+/* Try locking once */
+#define hwspinlock_trylock(h) (hwspinlock_lock_timeout(h, 1))
+/* Lock without timeout */
+#define hwspinlock_lock(h) (hwspinlock_lock_timeout(h, -1))
+
+/* Allocation functions */
+struct hwspinlock *hwspinlock_request(void);
+struct hwspinlock *hwspinlock_request_specific(unsigned int id);
+int hwspinlock_free(struct hwspinlock *hwspinlock_ptr);
+
+#endif /* HWSPINLOCK_H */