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
|
/*
* Intel BayTrail PMIC I2C bus semaphore implementaion
* Copyright (c) 2014, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*/
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <asm/iosf_mbi.h>
#include "i2c-designware-core.h"
#define SEMAPHORE_TIMEOUT 100
#define PUNIT_SEMAPHORE 0x7
#define PUNIT_SEMAPHORE_BIT BIT(0)
#define PUNIT_SEMAPHORE_ACQUIRE BIT(1)
static unsigned long acquired;
static int get_sem(struct device *dev, u32 *sem)
{
u32 data;
int ret;
ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &data);
if (ret) {
dev_err(dev, "iosf failed to read punit semaphore\n");
return ret;
}
*sem = data & PUNIT_SEMAPHORE_BIT;
return 0;
}
static void reset_semaphore(struct device *dev)
{
u32 data;
if (iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &data)) {
dev_err(dev, "iosf failed to reset punit semaphore during read\n");
return;
}
data &= ~PUNIT_SEMAPHORE_BIT;
if (iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, PUNIT_SEMAPHORE, data))
dev_err(dev, "iosf failed to reset punit semaphore during write\n");
}
static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
{
u32 sem = PUNIT_SEMAPHORE_ACQUIRE;
int ret;
unsigned long start, end;
might_sleep();
if (!dev || !dev->dev)
return -ENODEV;
if (!dev->release_lock)
return 0;
/* host driver writes to side band semaphore register */
ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, PUNIT_SEMAPHORE, sem);
if (ret) {
dev_err(dev->dev, "iosf punit semaphore request failed\n");
return ret;
}
/* host driver waits for bit 0 to be set in semaphore register */
start = jiffies;
end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT);
do {
ret = get_sem(dev->dev, &sem);
if (!ret && sem) {
acquired = jiffies;
dev_dbg(dev->dev, "punit semaphore acquired after %ums\n",
jiffies_to_msecs(jiffies - start));
return 0;
}
usleep_range(1000, 2000);
} while (time_before(jiffies, end));
dev_err(dev->dev, "punit semaphore timed out, resetting\n");
reset_semaphore(dev->dev);
ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &sem);
if (ret)
dev_err(dev->dev, "iosf failed to read punit semaphore\n");
else
dev_err(dev->dev, "PUNIT SEM: %d\n", sem);
WARN_ON(1);
return -ETIMEDOUT;
}
static void baytrail_i2c_release(struct dw_i2c_dev *dev)
{
if (!dev || !dev->dev)
return;
if (!dev->acquire_lock)
return;
reset_semaphore(dev->dev);
dev_dbg(dev->dev, "punit semaphore held for %ums\n",
jiffies_to_msecs(jiffies - acquired));
}
int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev)
{
acpi_status status;
unsigned long long shared_host = 0;
acpi_handle handle;
if (!dev || !dev->dev)
return 0;
handle = ACPI_HANDLE(dev->dev);
if (!handle)
return 0;
status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host);
if (ACPI_FAILURE(status))
return 0;
if (shared_host) {
dev_info(dev->dev, "I2C bus managed by PUNIT\n");
dev->acquire_lock = baytrail_i2c_acquire;
dev->release_lock = baytrail_i2c_release;
dev->pm_runtime_disabled = true;
}
if (!iosf_mbi_available())
return -EPROBE_DEFER;
return 0;
}
MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>");
MODULE_DESCRIPTION("Baytrail I2C Semaphore driver");
MODULE_LICENSE("GPL v2");
|
