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1/*
2 * Intel Low Power Subsystem PWM controller driver
3 *
4 * Copyright (C) 2014, Intel Corporation
5 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
6 * Author: Chew Kean Ho <kean.ho.chew@intel.com>
7 * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com>
8 * Author: Chew Chiau Ee <chiau.ee.chew@intel.com>
9 * Author: Alan Cox <alan@linux.intel.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15
16#include <linux/io.h>
17#include <linux/kernel.h>
18#include <linux/module.h>
19
20#include "pwm-lpss.h"
21
22#define PWM				0x00000000
23#define PWM_ENABLE			BIT(31)
24#define PWM_SW_UPDATE			BIT(30)
25#define PWM_BASE_UNIT_SHIFT		8
26#define PWM_BASE_UNIT_MASK		0x00ffff00
27#define PWM_ON_TIME_DIV_MASK		0x000000ff
28#define PWM_DIVISION_CORRECTION		0x2
29#define PWM_LIMIT			(0x8000 + PWM_DIVISION_CORRECTION)
30#define NSECS_PER_SEC			1000000000UL
31
32struct pwm_lpss_chip {
33	struct pwm_chip chip;
34	void __iomem *regs;
35	unsigned long clk_rate;
36};
37
38/* BayTrail */
39const struct pwm_lpss_boardinfo pwm_lpss_byt_info = {
40	.clk_rate = 25000000
41};
42EXPORT_SYMBOL_GPL(pwm_lpss_byt_info);
43
44/* Braswell */
45const struct pwm_lpss_boardinfo pwm_lpss_bsw_info = {
46	.clk_rate = 19200000
47};
48EXPORT_SYMBOL_GPL(pwm_lpss_bsw_info);
49
50static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip)
51{
52	return container_of(chip, struct pwm_lpss_chip, chip);
53}
54
55static int pwm_lpss_config(struct pwm_chip *chip, struct pwm_device *pwm,
56			   int duty_ns, int period_ns)
57{
58	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
59	u8 on_time_div;
60	unsigned long c;
61	unsigned long long base_unit, freq = NSECS_PER_SEC;
62	u32 ctrl;
63
64	do_div(freq, period_ns);
65
66	/* The equation is: base_unit = ((freq / c) * 65536) + correction */
67	base_unit = freq * 65536;
68
69	c = lpwm->clk_rate;
70	if (!c)
71		return -EINVAL;
72
73	do_div(base_unit, c);
74	base_unit += PWM_DIVISION_CORRECTION;
75	if (base_unit > PWM_LIMIT)
76		return -EINVAL;
77
78	if (duty_ns <= 0)
79		duty_ns = 1;
80	on_time_div = 255 - (255 * duty_ns / period_ns);
81
82	ctrl = readl(lpwm->regs + PWM);
83	ctrl &= ~(PWM_BASE_UNIT_MASK | PWM_ON_TIME_DIV_MASK);
84	ctrl |= (u16) base_unit << PWM_BASE_UNIT_SHIFT;
85	ctrl |= on_time_div;
86	/* request PWM to update on next cycle */
87	ctrl |= PWM_SW_UPDATE;
88	writel(ctrl, lpwm->regs + PWM);
89
90	return 0;
91}
92
93static int pwm_lpss_enable(struct pwm_chip *chip, struct pwm_device *pwm)
94{
95	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
96	u32 ctrl;
97
98	ctrl = readl(lpwm->regs + PWM);
99	writel(ctrl | PWM_ENABLE, lpwm->regs + PWM);
100
101	return 0;
102}
103
104static void pwm_lpss_disable(struct pwm_chip *chip, struct pwm_device *pwm)
105{
106	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
107	u32 ctrl;
108
109	ctrl = readl(lpwm->regs + PWM);
110	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
111}
112
113static const struct pwm_ops pwm_lpss_ops = {
114	.config = pwm_lpss_config,
115	.enable = pwm_lpss_enable,
116	.disable = pwm_lpss_disable,
117	.owner = THIS_MODULE,
118};
119
120struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
121				     const struct pwm_lpss_boardinfo *info)
122{
123	struct pwm_lpss_chip *lpwm;
124	int ret;
125
126	lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL);
127	if (!lpwm)
128		return ERR_PTR(-ENOMEM);
129
130	lpwm->regs = devm_ioremap_resource(dev, r);
131	if (IS_ERR(lpwm->regs))
132		return ERR_CAST(lpwm->regs);
133
134	lpwm->clk_rate = info->clk_rate;
135	lpwm->chip.dev = dev;
136	lpwm->chip.ops = &pwm_lpss_ops;
137	lpwm->chip.base = -1;
138	lpwm->chip.npwm = 1;
139
140	ret = pwmchip_add(&lpwm->chip);
141	if (ret) {
142		dev_err(dev, "failed to add PWM chip: %d\n", ret);
143		return ERR_PTR(ret);
144	}
145
146	return lpwm;
147}
148EXPORT_SYMBOL_GPL(pwm_lpss_probe);
149
150int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
151{
152	u32 ctrl;
153
154	ctrl = readl(lpwm->regs + PWM);
155	writel(ctrl & ~PWM_ENABLE, lpwm->regs + PWM);
156
157	return pwmchip_remove(&lpwm->chip);
158}
159EXPORT_SYMBOL_GPL(pwm_lpss_remove);
160
161MODULE_DESCRIPTION("PWM driver for Intel LPSS");
162MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>");
163MODULE_LICENSE("GPL v2");
164