1 // SPDX-License-Identifier: GPL-2.0
3 * OMAP hardware spinlock driver
5 * Copyright (C) 2010-2021 Texas Instruments Incorporated - https://www.ti.com
7 * Contact: Simon Que <sque@ti.com>
8 * Hari Kanigeri <h-kanigeri2@ti.com>
9 * Ohad Ben-Cohen <ohad@wizery.com>
10 * Suman Anna <s-anna@ti.com>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/device.h>
16 #include <linux/delay.h>
18 #include <linux/bitops.h>
19 #include <linux/pm_runtime.h>
20 #include <linux/slab.h>
21 #include <linux/spinlock.h>
22 #include <linux/hwspinlock.h>
24 #include <linux/platform_device.h>
26 #include "hwspinlock_internal.h"
28 /* Spinlock register offsets */
29 #define SYSSTATUS_OFFSET 0x0014
30 #define LOCK_BASE_OFFSET 0x0800
32 #define SPINLOCK_NUMLOCKS_BIT_OFFSET (24)
34 /* Possible values of SPINLOCK_LOCK_REG */
35 #define SPINLOCK_NOTTAKEN (0) /* free */
36 #define SPINLOCK_TAKEN (1) /* locked */
38 static int omap_hwspinlock_trylock(struct hwspinlock
*lock
)
40 void __iomem
*lock_addr
= lock
->priv
;
42 /* attempt to acquire the lock by reading its value */
43 return (SPINLOCK_NOTTAKEN
== readl(lock_addr
));
46 static void omap_hwspinlock_unlock(struct hwspinlock
*lock
)
48 void __iomem
*lock_addr
= lock
->priv
;
50 /* release the lock by writing 0 to it */
51 writel(SPINLOCK_NOTTAKEN
, lock_addr
);
55 * relax the OMAP interconnect while spinning on it.
57 * The specs recommended that the retry delay time will be
58 * just over half of the time that a requester would be
59 * expected to hold the lock.
61 * The number below is taken from an hardware specs example,
62 * obviously it is somewhat arbitrary.
64 static void omap_hwspinlock_relax(struct hwspinlock
*lock
)
69 static const struct hwspinlock_ops omap_hwspinlock_ops
= {
70 .trylock
= omap_hwspinlock_trylock
,
71 .unlock
= omap_hwspinlock_unlock
,
72 .relax
= omap_hwspinlock_relax
,
75 static int omap_hwspinlock_probe(struct platform_device
*pdev
)
77 struct device_node
*node
= pdev
->dev
.of_node
;
78 struct hwspinlock_device
*bank
;
79 struct hwspinlock
*hwlock
;
80 void __iomem
*io_base
;
81 int num_locks
, i
, ret
;
82 /* Only a single hwspinlock block device is supported */
88 io_base
= devm_platform_ioremap_resource(pdev
, 0);
90 return PTR_ERR(io_base
);
93 * make sure the module is enabled and clocked before reading
94 * the module SYSSTATUS register
96 pm_runtime_enable(&pdev
->dev
);
97 ret
= pm_runtime_get_sync(&pdev
->dev
);
99 pm_runtime_put_noidle(&pdev
->dev
);
103 /* Determine number of locks */
104 i
= readl(io_base
+ SYSSTATUS_OFFSET
);
105 i
>>= SPINLOCK_NUMLOCKS_BIT_OFFSET
;
108 * runtime PM will make sure the clock of this module is
109 * enabled again iff at least one lock is requested
111 ret
= pm_runtime_put(&pdev
->dev
);
115 /* one of the four lsb's must be set, and nothing else */
116 if (hweight_long(i
& 0xf) != 1 || i
> 8) {
121 num_locks
= i
* 32; /* actual number of locks in this device */
123 bank
= devm_kzalloc(&pdev
->dev
, struct_size(bank
, lock
, num_locks
),
130 platform_set_drvdata(pdev
, bank
);
132 for (i
= 0, hwlock
= &bank
->lock
[0]; i
< num_locks
; i
++, hwlock
++)
133 hwlock
->priv
= io_base
+ LOCK_BASE_OFFSET
+ sizeof(u32
) * i
;
135 ret
= hwspin_lock_register(bank
, &pdev
->dev
, &omap_hwspinlock_ops
,
140 dev_dbg(&pdev
->dev
, "Registered %d locks with HwSpinlock core\n",
146 pm_runtime_disable(&pdev
->dev
);
150 static int omap_hwspinlock_remove(struct platform_device
*pdev
)
152 struct hwspinlock_device
*bank
= platform_get_drvdata(pdev
);
155 ret
= hwspin_lock_unregister(bank
);
157 dev_err(&pdev
->dev
, "%s failed: %d\n", __func__
, ret
);
161 pm_runtime_disable(&pdev
->dev
);
166 static const struct of_device_id omap_hwspinlock_of_match
[] = {
167 { .compatible
= "ti,omap4-hwspinlock", },
168 { .compatible
= "ti,am64-hwspinlock", },
169 { .compatible
= "ti,am654-hwspinlock", },
172 MODULE_DEVICE_TABLE(of
, omap_hwspinlock_of_match
);
174 static struct platform_driver omap_hwspinlock_driver
= {
175 .probe
= omap_hwspinlock_probe
,
176 .remove
= omap_hwspinlock_remove
,
178 .name
= "omap_hwspinlock",
179 .of_match_table
= of_match_ptr(omap_hwspinlock_of_match
),
183 static int __init
omap_hwspinlock_init(void)
185 return platform_driver_register(&omap_hwspinlock_driver
);
187 /* board init code might need to reserve hwspinlocks for predefined purposes */
188 postcore_initcall(omap_hwspinlock_init
);
190 static void __exit
omap_hwspinlock_exit(void)
192 platform_driver_unregister(&omap_hwspinlock_driver
);
194 module_exit(omap_hwspinlock_exit
);
196 MODULE_LICENSE("GPL v2");
197 MODULE_DESCRIPTION("Hardware spinlock driver for OMAP");
198 MODULE_AUTHOR("Simon Que <sque@ti.com>");
199 MODULE_AUTHOR("Hari Kanigeri <h-kanigeri2@ti.com>");
200 MODULE_AUTHOR("Ohad Ben-Cohen <ohad@wizery.com>");