summaryrefslogtreecommitdiffstats
path: root/drivers/pwm/pwm-lpss.c
blob: 7a7a934a7757e58426fe1fb81bc4ecdbb63cb3ab (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
/*
 * Intel Low Power Subsystem PWM controller driver
 *
 * Copyright (C) 2014, Intel Corporation
 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
 * Author: Chew Kean Ho <kean.ho.chew@intel.com>
 * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
 * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
 * Author: Alan Cox <alan@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include "pwm-lpss.h"

#define PWM				0x00000000
#define PWM_ENABLE			BIT(31)
#define PWM_SW_UPDATE			BIT(30)
#define PWM_BASE_UNIT_SHIFT		8
#define PWM_BASE_UNIT_MASK		0x00ffff00
#define PWM_ON_TIME_DIV_MASK		0x000000ff
#define PWM_DIVISION_CORRECTION		0x2
#define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
#define NSECS_PER_SEC			1000000000UL

struct pwm_lpss_chip {
	struct pwm_chip chip;
	void __iomem *regs;
	unsigned long clk_rate;
};

/* BayTrail */
const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
	25000000
};
EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);

/* Braswell */
const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
	19200000
};
EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);

static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
{
	return container_of(chip, struct pwm_lpss_chip, chip);
}

static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
			   int duty_ns, int period_ns)
{
	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
	u8 on_time_div;
	unsigned long c;
	unsigned long long base_unit, freq = NSECS_PER_SEC;
	u32 ctrl;

	do_div(freq, period_ns);

	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
	base_unit = freq * 65536;

	c = lpwm->clk_rate;
	if (!c)
		return -EINVAL;

	do_div(base_unit, c);
	base_unit += PWM_DIVISION_CORRECTION;
	if (base_unit > PWM_LIMIT)
		return -EINVAL;

	if (duty_ns <= 0)
		duty_ns = 1;
	on_time_div = 255 - (255 * duty_ns / period_ns);

	ctrl = readl(lpwm->regs + PWM);
	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
	ctrl |= on_time_div;
	/* request PWM to update on next cycle */
	ctrl |= PWM_SW_UPDATE;
	writel(ctrl, lpwm->regs + PWM);

	return 0;
}

static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
	u32 ctrl;

	ctrl = readl(lpwm->regs + PWM);
	writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);

	return 0;
}

static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
	u32 ctrl;

	ctrl = readl(lpwm->regs + PWM);
	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
}

static const struct pwm_ops pwm_lpss_ops = {
	.config = pwm_lpss_config,
	.enable = pwm_lpss_enable,
	.disable = pwm_lpss_disable,
	.owner = THIS_MODULE,
};

struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
				     const struct pwm_lpss_boardinfo *info)
{
	struct pwm_lpss_chip *lpwm;
	int ret;

	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
	if (!lpwm)
		return ERR_PTR(-ENOMEM);

	lpwm->regs = devm_ioremap_resource(dev, r);
	if (IS_ERR(lpwm->regs))
		return ERR_CAST(lpwm->regs);

	lpwm->clk_rate = info->clk_rate;
	lpwm->chip.dev = dev;
	lpwm->chip.ops = &pwm_lpss_ops;
	lpwm->chip.base = -1;
	lpwm->chip.npwm = 1;

	ret = pwmchip_add(&lpwm->chip);
	if (ret) {
		dev_err(dev, "failed to add PWM chip: %d\n", ret);
		return ERR_PTR(ret);
	}

	return lpwm;
}
EXPORT_SYMBOL_GPL(pwm_lpss_probe);

int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
{
	u32 ctrl;

	ctrl = readl(lpwm->regs + PWM);
	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);

	return pwmchip_remove(&lpwm->chip);
}
EXPORT_SYMBOL_GPL(pwm_lpss_remove);

MODULE_DESCRIPTION("PWM driver for Intel LPSS");
MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
MODULE_LICENSE("GPL v2");