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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 | */ | |
894acb2f DB |
14 | #include <linux/delay.h> |
15 | #include <linux/device.h> | |
16 | #include <linux/acpi.h> | |
17 | #include <linux/i2c.h> | |
18 | #include <linux/interrupt.h> | |
c8e043e6 | 19 | |
894acb2f | 20 | #include <asm/iosf_mbi.h> |
c8e043e6 | 21 | |
894acb2f DB |
22 | #include "i2c-designware-core.h" |
23 | ||
24 | #define SEMAPHORE_TIMEOUT 100 | |
25 | #define PUNIT_SEMAPHORE 0x7 | |
9b5c9f04 AS |
26 | #define PUNIT_SEMAPHORE_BIT BIT(0) |
27 | #define PUNIT_SEMAPHORE_ACQUIRE BIT(1) | |
894acb2f DB |
28 | |
29 | static unsigned long acquired; | |
30 | ||
31 | static int get_sem(struct device *dev, u32 *sem) | |
32 | { | |
9b5c9f04 | 33 | u32 data; |
894acb2f DB |
34 | int ret; |
35 | ||
4077a387 | 36 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &data); |
894acb2f DB |
37 | if (ret) { |
38 | dev_err(dev, "iosf failed to read punit semaphore\n"); | |
39 | return ret; | |
40 | } | |
41 | ||
9b5c9f04 | 42 | *sem = data & PUNIT_SEMAPHORE_BIT; |
894acb2f DB |
43 | |
44 | return 0; | |
45 | } | |
46 | ||
47 | static void reset_semaphore(struct device *dev) | |
48 | { | |
49 | u32 data; | |
50 | ||
4077a387 | 51 | if (iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &data)) { |
894acb2f DB |
52 | dev_err(dev, "iosf failed to reset punit semaphore during read\n"); |
53 | return; | |
54 | } | |
55 | ||
9b5c9f04 | 56 | data &= ~PUNIT_SEMAPHORE_BIT; |
4077a387 | 57 | if (iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, PUNIT_SEMAPHORE, data)) |
894acb2f DB |
58 | dev_err(dev, "iosf failed to reset punit semaphore during write\n"); |
59 | } | |
60 | ||
c8e043e6 | 61 | static int baytrail_i2c_acquire(struct dw_i2c_dev *dev) |
894acb2f | 62 | { |
4077a387 | 63 | u32 sem = PUNIT_SEMAPHORE_ACQUIRE; |
894acb2f DB |
64 | int ret; |
65 | unsigned long start, end; | |
66 | ||
ebf2ef8f AS |
67 | might_sleep(); |
68 | ||
894acb2f DB |
69 | if (!dev || !dev->dev) |
70 | return -ENODEV; | |
71 | ||
30be774b | 72 | if (!dev->release_lock) |
894acb2f DB |
73 | return 0; |
74 | ||
9b5c9f04 | 75 | /* host driver writes to side band semaphore register */ |
4077a387 | 76 | ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, PUNIT_SEMAPHORE, sem); |
894acb2f DB |
77 | if (ret) { |
78 | dev_err(dev->dev, "iosf punit semaphore request failed\n"); | |
79 | return ret; | |
80 | } | |
81 | ||
82 | /* host driver waits for bit 0 to be set in semaphore register */ | |
83 | start = jiffies; | |
84 | end = start + msecs_to_jiffies(SEMAPHORE_TIMEOUT); | |
ebf2ef8f | 85 | do { |
894acb2f DB |
86 | ret = get_sem(dev->dev, &sem); |
87 | if (!ret && sem) { | |
88 | acquired = jiffies; | |
89 | dev_dbg(dev->dev, "punit semaphore acquired after %ums\n", | |
90 | jiffies_to_msecs(jiffies - start)); | |
91 | return 0; | |
92 | } | |
93 | ||
94 | usleep_range(1000, 2000); | |
ebf2ef8f | 95 | } while (time_before(jiffies, end)); |
894acb2f DB |
96 | |
97 | dev_err(dev->dev, "punit semaphore timed out, resetting\n"); | |
98 | reset_semaphore(dev->dev); | |
99 | ||
4077a387 | 100 | ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, PUNIT_SEMAPHORE, &sem); |
259aada4 | 101 | if (ret) |
894acb2f DB |
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 | } | |
894acb2f | 110 | |
c8e043e6 | 111 | static void baytrail_i2c_release(struct dw_i2c_dev *dev) |
894acb2f DB |
112 | { |
113 | if (!dev || !dev->dev) | |
114 | return; | |
115 | ||
116 | if (!dev->acquire_lock) | |
117 | return; | |
118 | ||
119 | reset_semaphore(dev->dev); | |
120 | dev_dbg(dev->dev, "punit semaphore held for %ums\n", | |
121 | jiffies_to_msecs(jiffies - acquired)); | |
122 | } | |
894acb2f DB |
123 | |
124 | int i2c_dw_eval_lock_support(struct dw_i2c_dev *dev) | |
125 | { | |
126 | acpi_status status; | |
127 | unsigned long long shared_host = 0; | |
128 | acpi_handle handle; | |
129 | ||
130 | if (!dev || !dev->dev) | |
131 | return 0; | |
132 | ||
133 | handle = ACPI_HANDLE(dev->dev); | |
134 | if (!handle) | |
135 | return 0; | |
136 | ||
137 | status = acpi_evaluate_integer(handle, "_SEM", NULL, &shared_host); | |
894acb2f DB |
138 | if (ACPI_FAILURE(status)) |
139 | return 0; | |
140 | ||
141 | if (shared_host) { | |
142 | dev_info(dev->dev, "I2C bus managed by PUNIT\n"); | |
143 | dev->acquire_lock = baytrail_i2c_acquire; | |
144 | dev->release_lock = baytrail_i2c_release; | |
145 | dev->pm_runtime_disabled = true; | |
146 | } | |
147 | ||
148 | if (!iosf_mbi_available()) | |
149 | return -EPROBE_DEFER; | |
150 | ||
151 | return 0; | |
152 | } |