2 * OMAP hardware spinlock driver
4 * Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com
6 * Contact: Simon Que <sque@ti.com>
7 * Hari Kanigeri <h-kanigeri2@ti.com>
8 * Ohad Ben-Cohen <ohad@wizery.com>
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * version 2 as published by the Free Software Foundation.
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/device.h>
23 #include <linux/delay.h>
25 #include <linux/bitops.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/slab.h>
28 #include <linux/spinlock.h>
29 #include <linux/hwspinlock.h>
30 #include <linux/platform_device.h>
32 #include "hwspinlock_internal.h"
34 /* Spinlock register offsets */
35 #define SYSSTATUS_OFFSET 0x0014
36 #define LOCK_BASE_OFFSET 0x0800
38 #define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
40 /* Possible values of SPINLOCK_LOCK_REG */
41 #define SPINLOCK_NOTTAKEN (0) /* free */
42 #define SPINLOCK_TAKEN (1) /* locked */
44 static int omap_hwspinlock_trylock(struct hwspinlock
*lock
)
46 void __iomem
*lock_addr
= lock
->priv
;
48 /* attempt to acquire the lock by reading its value */
49 return (SPINLOCK_NOTTAKEN
== readl(lock_addr
));
52 static void omap_hwspinlock_unlock(struct hwspinlock
*lock
)
54 void __iomem
*lock_addr
= lock
->priv
;
56 /* release the lock by writing 0 to it */
57 writel(SPINLOCK_NOTTAKEN
, lock_addr
);
61 * relax the OMAP interconnect while spinning on it.
63 * The specs recommended that the retry delay time will be
64 * just over half of the time that a requester would be
65 * expected to hold the lock.
67 * The number below is taken from an hardware specs example,
68 * obviously it is somewhat arbitrary.
70 static void omap_hwspinlock_relax(struct hwspinlock
*lock
)
75 static const struct hwspinlock_ops omap_hwspinlock_ops
= {
76 .trylock
= omap_hwspinlock_trylock
,
77 .unlock
= omap_hwspinlock_unlock
,
78 .relax
= omap_hwspinlock_relax
,
81 static int omap_hwspinlock_probe(struct platform_device
*pdev
)
83 struct hwspinlock_pdata
*pdata
= pdev
->dev
.platform_data
;
84 struct hwspinlock_device
*bank
;
85 struct hwspinlock
*hwlock
;
87 void __iomem
*io_base
;
88 int num_locks
, i
, ret
;
93 res
= platform_get_resource(pdev
, IORESOURCE_MEM
, 0);
97 io_base
= ioremap(res
->start
, resource_size(res
));
102 * make sure the module is enabled and clocked before reading
103 * the module SYSSTATUS register
105 pm_runtime_enable(&pdev
->dev
);
106 ret
= pm_runtime_get_sync(&pdev
->dev
);
108 pm_runtime_put_noidle(&pdev
->dev
);
112 /* Determine number of locks */
113 i
= readl(io_base
+ SYSSTATUS_OFFSET
);
114 i
>>= SPINLOCK_NUMLOCKS_BIT_OFFSET
;
117 * runtime PM will make sure the clock of this module is
118 * enabled again iff at least one lock is requested
120 ret
= pm_runtime_put(&pdev
->dev
);
124 /* one of the four lsb's must be set, and nothing else */
125 if (hweight_long(i
& 0xf) != 1 || i
> 8) {
130 num_locks
= i
* 32; /* actual number of locks in this device */
132 bank
= kzalloc(sizeof(*bank
) + num_locks
* sizeof(*hwlock
), GFP_KERNEL
);
138 platform_set_drvdata(pdev
, bank
);
140 for (i
= 0, hwlock
= &bank
->lock
[0]; i
< num_locks
; i
++, hwlock
++)
141 hwlock
->priv
= io_base
+ LOCK_BASE_OFFSET
+ sizeof(u32
) * i
;
143 ret
= hwspin_lock_register(bank
, &pdev
->dev
, &omap_hwspinlock_ops
,
144 pdata
->base_id
, num_locks
);
153 pm_runtime_disable(&pdev
->dev
);
158 static int omap_hwspinlock_remove(struct platform_device
*pdev
)
160 struct hwspinlock_device
*bank
= platform_get_drvdata(pdev
);
161 void __iomem
*io_base
= bank
->lock
[0].priv
- LOCK_BASE_OFFSET
;
164 ret
= hwspin_lock_unregister(bank
);
166 dev_err(&pdev
->dev
, "%s failed: %d\n", __func__
, ret
);
170 pm_runtime_disable(&pdev
->dev
);
177 static struct platform_driver omap_hwspinlock_driver
= {
178 .probe
= omap_hwspinlock_probe
,
179 .remove
= omap_hwspinlock_remove
,
181 .name
= "omap_hwspinlock",
182 .owner
= THIS_MODULE
,
186 static int __init
omap_hwspinlock_init(void)
188 return platform_driver_register(&omap_hwspinlock_driver
);
190 /* board init code might need to reserve hwspinlocks for predefined purposes */
191 postcore_initcall(omap_hwspinlock_init
);
193 static void __exit
omap_hwspinlock_exit(void)
195 platform_driver_unregister(&omap_hwspinlock_driver
);
197 module_exit(omap_hwspinlock_exit
);
199 MODULE_LICENSE("GPL v2");
200 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
201 MODULE_AUTHOR("Simon Que <sque@ti.com>");
202 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
203 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");