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894acb2f DB |
1 | /* |
2 | * Intel BayTrail PMIC I2C bus semaphore implementaion | |
3 | * Copyright (c) 2014, Intel Corporation. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms and conditions of the GNU General Public License, | |
7 | * version 2, as published by the Free Software Foundation. | |
8 | * | |
9 | * This program is distributed in the hope it will be useful, but WITHOUT | |
10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
12 | * more details. | |
13 | */ | |
14 | #include <linux/module.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/device.h> | |
17 | #include <linux/acpi.h> | |
18 | #include <linux/i2c.h> | |
19 | #include <linux/interrupt.h> | |
20 | #include <asm/iosf_mbi.h> | |
21 | #include "i2c-designware-core.h" | |
22 | ||
23 | #define SEMAPHORE_TIMEOUT 100 | |
24 | #define PUNIT_SEMAPHORE 0x7 | |
25 | ||
26 | static unsigned long acquired; | |
27 | ||
28 | static int get_sem(struct device *dev, u32 *sem) | |
29 | { | |
30 | u32 reg_val; | |
31 | int ret; | |
32 | ||
33 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE, | |
34 | ®_val); | |
35 | if (ret) { | |
36 | dev_err(dev, "iosf failed to read punit semaphore\n"); | |
37 | return ret; | |
38 | } | |
39 | ||
40 | *sem = reg_val & 0x1; | |
41 | ||
42 | return 0; | |
43 | } | |
44 | ||
45 | static void reset_semaphore(struct device *dev) | |
46 | { | |
47 | u32 data; | |
48 | ||
49 | if (iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, | |
50 | PUNIT_SEMAPHORE, &data)) { | |
51 | dev_err(dev, "iosf failed to reset punit semaphore during read\n"); | |
52 | return; | |
53 | } | |
54 | ||
55 | data = data & 0xfffffffe; | |
56 | if (iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE, | |
57 | PUNIT_SEMAPHORE, data)) | |
58 | dev_err(dev, "iosf failed to reset punit semaphore during write\n"); | |
59 | } | |
60 | ||
61 | int baytrail_i2c_acquire(struct dw_i2c_dev *dev) | |
62 | { | |
63 | u32 sem = 0; | |
64 | int ret; | |
65 | unsigned long start, end; | |
66 | ||
67 | if (!dev || !dev->dev) | |
68 | return -ENODEV; | |
69 | ||
70 | if (!dev->acquire_lock) | |
71 | return 0; | |
72 | ||
73 | /* host driver writes 0x2 to side band semaphore register */ | |
74 | ret = iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE, | |
75 | PUNIT_SEMAPHORE, 0x2); | |
76 | if (ret) { | |
77 | dev_err(dev->dev, "iosf punit semaphore request failed\n"); | |
78 | return ret; | |
79 | } | |
80 | ||
81 | /* host driver waits for bit 0 to be set in semaphore register */ | |
82 | start = jiffies; | |
83 | end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT); | |
84 | while (!time_after(jiffies, end)) { | |
85 | ret = get_sem(dev->dev, &sem); | |
86 | if (!ret && sem) { | |
87 | acquired = jiffies; | |
88 | dev_dbg(dev->dev, "punit semaphore acquired after %ums\n", | |
89 | jiffies_to_msecs(jiffies - start)); | |
90 | return 0; | |
91 | } | |
92 | ||
93 | usleep_range(1000, 2000); | |
94 | } | |
95 | ||
96 | dev_err(dev->dev, "punit semaphore timed out, resetting\n"); | |
97 | reset_semaphore(dev->dev); | |
98 | ||
99 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, | |
100 | PUNIT_SEMAPHORE, &sem); | |
101 | if (!ret) | |
102 | dev_err(dev->dev, "iosf failed to read punit semaphore\n"); | |
103 | else | |
104 | dev_err(dev->dev, "PUNIT SEM: %d\n", sem); | |
105 | ||
106 | WARN_ON(1); | |
107 | ||
108 | return -ETIMEDOUT; | |
109 | } | |
110 | EXPORT_SYMBOL(baytrail_i2c_acquire); | |
111 | ||
112 | void baytrail_i2c_release(struct dw_i2c_dev *dev) | |
113 | { | |
114 | if (!dev || !dev->dev) | |
115 | return; | |
116 | ||
117 | if (!dev->acquire_lock) | |
118 | return; | |
119 | ||
120 | reset_semaphore(dev->dev); | |
121 | dev_dbg(dev->dev, "punit semaphore held for %ums\n", | |
122 | jiffies_to_msecs(jiffies - acquired)); | |
123 | } | |
124 | EXPORT_SYMBOL(baytrail_i2c_release); | |
125 | ||
126 | int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev) | |
127 | { | |
128 | acpi_status status; | |
129 | unsigned long long shared_host = 0; | |
130 | acpi_handle handle; | |
131 | ||
132 | if (!dev || !dev->dev) | |
133 | return 0; | |
134 | ||
135 | handle = ACPI_HANDLE(dev->dev); | |
136 | if (!handle) | |
137 | return 0; | |
138 | ||
139 | status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host); | |
140 | ||
141 | if (ACPI_FAILURE(status)) | |
142 | return 0; | |
143 | ||
144 | if (shared_host) { | |
145 | dev_info(dev->dev, "I2C bus managed by PUNIT\n"); | |
146 | dev->acquire_lock = baytrail_i2c_acquire; | |
147 | dev->release_lock = baytrail_i2c_release; | |
148 | dev->pm_runtime_disabled = true; | |
149 | } | |
150 | ||
151 | if (!iosf_mbi_available()) | |
152 | return -EPROBE_DEFER; | |
153 | ||
154 | return 0; | |
155 | } | |
156 | EXPORT_SYMBOL(i2c_dw_eval_lock_support); | |
157 | ||
158 | MODULE_AUTHOR("David E. Box <david.e.box@linux.intel.com>"); | |
159 | MODULE_DESCRIPTION("Baytrail I2C Semaphore driver"); | |
160 | MODULE_LICENSE("GPL v2"); |