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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> | |
c8e043e6 | 20 | |
894acb2f | 21 | #include <asm/iosf_mbi.h> |
c8e043e6 | 22 | |
894acb2f DB |
23 | #include "i2c-designware-core.h" |
24 | ||
25 | #define SEMAPHORE_TIMEOUT 100 | |
26 | #define PUNIT_SEMAPHORE 0x7 | |
9b5c9f04 AS |
27 | #define PUNIT_SEMAPHORE_BIT BIT(0) |
28 | #define PUNIT_SEMAPHORE_ACQUIRE BIT(1) | |
894acb2f DB |
29 | |
30 | static unsigned long acquired; | |
31 | ||
32 | static int get_sem(struct device *dev, u32 *sem) | |
33 | { | |
9b5c9f04 | 34 | u32 data; |
894acb2f DB |
35 | int ret; |
36 | ||
37 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE, | |
9b5c9f04 | 38 | &data); |
894acb2f DB |
39 | if (ret) { |
40 | dev_err(dev, "iosf failed to read punit semaphore\n"); | |
41 | return ret; | |
42 | } | |
43 | ||
9b5c9f04 | 44 | *sem = data & PUNIT_SEMAPHORE_BIT; |
894acb2f DB |
45 | |
46 | return 0; | |
47 | } | |
48 | ||
49 | static void reset_semaphore(struct device *dev) | |
50 | { | |
51 | u32 data; | |
52 | ||
53 | if (iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, | |
54 | PUNIT_SEMAPHORE, &data)) { | |
55 | dev_err(dev, "iosf failed to reset punit semaphore during read\n"); | |
56 | return; | |
57 | } | |
58 | ||
9b5c9f04 | 59 | data &= ~PUNIT_SEMAPHORE_BIT; |
894acb2f | 60 | if (iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE, |
9b5c9f04 | 61 | PUNIT_SEMAPHORE, data)) |
894acb2f DB |
62 | dev_err(dev, "iosf failed to reset punit semaphore during write\n"); |
63 | } | |
64 | ||
c8e043e6 | 65 | static int baytrail_i2c_acquire(struct dw_i2c_dev *dev) |
894acb2f | 66 | { |
c8e043e6 | 67 | u32 sem; |
894acb2f DB |
68 | int ret; |
69 | unsigned long start, end; | |
70 | ||
71 | if (!dev || !dev->dev) | |
72 | return -ENODEV; | |
73 | ||
30be774b | 74 | if (!dev->release_lock) |
894acb2f DB |
75 | return 0; |
76 | ||
9b5c9f04 | 77 | /* host driver writes to side band semaphore register */ |
894acb2f | 78 | ret = iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE, |
9b5c9f04 | 79 | PUNIT_SEMAPHORE, PUNIT_SEMAPHORE_ACQUIRE); |
894acb2f DB |
80 | if (ret) { |
81 | dev_err(dev->dev, "iosf punit semaphore request failed\n"); | |
82 | return ret; | |
83 | } | |
84 | ||
85 | /* host driver waits for bit 0 to be set in semaphore register */ | |
86 | start = jiffies; | |
87 | end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT); | |
88 | while (!time_after(jiffies, end)) { | |
89 | ret = get_sem(dev->dev, &sem); | |
90 | if (!ret && sem) { | |
91 | acquired = jiffies; | |
92 | dev_dbg(dev->dev, "punit semaphore acquired after %ums\n", | |
93 | jiffies_to_msecs(jiffies - start)); | |
94 | return 0; | |
95 | } | |
96 | ||
97 | usleep_range(1000, 2000); | |
98 | } | |
99 | ||
100 | dev_err(dev->dev, "punit semaphore timed out, resetting\n"); | |
101 | reset_semaphore(dev->dev); | |
102 | ||
103 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, | |
259aada4 AS |
104 | PUNIT_SEMAPHORE, &sem); |
105 | if (ret) | |
894acb2f DB |
106 | dev_err(dev->dev, "iosf failed to read punit semaphore\n"); |
107 | else | |
108 | dev_err(dev->dev, "PUNIT SEM: %d\n", sem); | |
109 | ||
110 | WARN_ON(1); | |
111 | ||
112 | return -ETIMEDOUT; | |
113 | } | |
894acb2f | 114 | |
c8e043e6 | 115 | static void baytrail_i2c_release(struct dw_i2c_dev *dev) |
894acb2f DB |
116 | { |
117 | if (!dev || !dev->dev) | |
118 | return; | |
119 | ||
120 | if (!dev->acquire_lock) | |
121 | return; | |
122 | ||
123 | reset_semaphore(dev->dev); | |
124 | dev_dbg(dev->dev, "punit semaphore held for %ums\n", | |
125 | jiffies_to_msecs(jiffies - acquired)); | |
126 | } | |
894acb2f DB |
127 | |
128 | int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev) | |
129 | { | |
130 | acpi_status status; | |
131 | unsigned long long shared_host = 0; | |
132 | acpi_handle handle; | |
133 | ||
134 | if (!dev || !dev->dev) | |
135 | return 0; | |
136 | ||
137 | handle = ACPI_HANDLE(dev->dev); | |
138 | if (!handle) | |
139 | return 0; | |
140 | ||
141 | status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host); | |
894acb2f DB |
142 | if (ACPI_FAILURE(status)) |
143 | return 0; | |
144 | ||
145 | if (shared_host) { | |
146 | dev_info(dev->dev, "I2C bus managed by PUNIT\n"); | |
147 | dev->acquire_lock = baytrail_i2c_acquire; | |
148 | dev->release_lock = baytrail_i2c_release; | |
149 | dev->pm_runtime_disabled = true; | |
150 | } | |
151 | ||
152 | if (!iosf_mbi_available()) | |
153 | return -EPROBE_DEFER; | |
154 | ||
155 | return 0; | |
156 | } | |
894acb2f DB |
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"); |