1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
// 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/pm_runtime.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, ret, 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 = kzalloc(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;
/* no pm needed for HSem but required to comply with hwspilock core */
pm_runtime_enable(&pdev->dev);
ret = hwspin_lock_register(bank, &pdev->dev, &u8500_hwspinlock_ops,
pdata->base_id, num_locks);
if (ret)
goto reg_fail;
return 0;
reg_fail:
pm_runtime_disable(&pdev->dev);
kfree(bank);
return ret;
}
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;
int ret;
/* clear all interrupts */
writel(0xFFFF, io_base + HSEM_ICRALL);
ret = hwspin_lock_unregister(bank);
if (ret) {
dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
return ret;
}
pm_runtime_disable(&pdev->dev);
kfree(bank);
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>");
|
