summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-designware-baytrail.c
blob: a2a275cfc1f694896bf112b2862f1bd8f2530ece (plain)
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
179
// SPDX-License-Identifier: GPL-2.0
/*
 * Intel BayTrail PMIC I2C bus semaphore implementaion
 * Copyright (c) 2014, Intel Corporation.
 */
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/acpi.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/pm_qos.h>

#include <asm/iosf_mbi.h>

#include "i2c-designware-core.h"

#define SEMAPHORE_TIMEOUT	500
#define PUNIT_SEMAPHORE		0x7
#define PUNIT_SEMAPHORE_CHT	0x10e
#define PUNIT_SEMAPHORE_BIT	BIT(0)
#define PUNIT_SEMAPHORE_ACQUIRE	BIT(1)

static unsigned long acquired;

static u32 get_sem_addr(struct dw_i2c_dev *dev)
{
	if (dev->flags & MODEL_CHERRYTRAIL)
		return PUNIT_SEMAPHORE_CHT;
	else
		return PUNIT_SEMAPHORE;
}

static int get_sem(struct dw_i2c_dev *dev, u32 *sem)
{
	u32 addr = get_sem_addr(dev);
	u32 data;
	int ret;

	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &data);
	if (ret) {
		dev_err(dev->dev, "iosf failed to read punit semaphore\n");
		return ret;
	}

	*sem = data & PUNIT_SEMAPHORE_BIT;

	return 0;
}

static void reset_semaphore(struct dw_i2c_dev *dev)
{
	if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_READ, get_sem_addr(dev),
			    0, PUNIT_SEMAPHORE_BIT))
		dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n");

	pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE);

	iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_END,
						     NULL);
	iosf_mbi_punit_release();
}

static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
{
	u32 addr;
	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;

	iosf_mbi_punit_acquire();
	iosf_mbi_call_pmic_bus_access_notifier_chain(MBI_PMIC_BUS_ACCESS_BEGIN,
						     NULL);

	/*
	 * Disallow the CPU to enter C6 or C7 state, entering these states
	 * requires the punit to talk to the pmic and if this happens while
	 * we're holding the semaphore, the SoC hangs.
	 */
	pm_qos_update_request(&dev->pm_qos, 0);

	addr = get_sem_addr(dev);

	/* host driver writes to side band semaphore register */
	ret = iosf_mbi_write(BT_MBI_UNIT_PMC, MBI_REG_WRITE, addr, sem);
	if (ret) {
		dev_err(dev->dev, "iosf punit semaphore request failed\n");
		goto out;
	}

	/* 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, &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");
out:
	reset_semaphore(dev);

	ret = iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_READ, addr, &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_dbg(dev->dev, "punit semaphore held for %ums\n",
		jiffies_to_msecs(jiffies - acquired));
}

int i2c_dw_probe_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)
		return 0;

	if (!iosf_mbi_available())
		return -EPROBE_DEFER;

	dev_info(dev->dev, "I2C bus managed by PUNIT\n");
	dev->acquire_lock = baytrail_i2c_acquire;
	dev->release_lock = baytrail_i2c_release;
	dev->pm_disabled = true;

	pm_qos_add_request(&dev->pm_qos, PM_QOS_CPU_DMA_LATENCY,
			   PM_QOS_DEFAULT_VALUE);

	return 0;
}

void i2c_dw_remove_lock_support(struct dw_i2c_dev *dev)
{
	if (dev->acquire_lock)
		pm_qos_remove_request(&dev->pm_qos);
}