summaryrefslogtreecommitdiff
path: root/drivers/pwm/pwm-ep93xx.c
blob: c9fc6f223640b63e9a7bc0bd7ac01893c9baaee6 (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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PWM framework driver for Cirrus Logic EP93xx
 *
 * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
 * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
 *
 * EP9301/02 have only one channel:
 *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
 *
 * EP9307 has only one channel:
 *   platform device ep93xx-pwm.0 - PWMOUT
 *
 * EP9312/15 have two channels:
 *   platform device ep93xx-pwm.0 - PWMOUT
 *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/pwm.h>

#include <asm/div64.h>

#include <linux/soc/cirrus/ep93xx.h>	/* for ep93xx_pwm_{acquire,release}_gpio() */

#define EP93XX_PWMx_TERM_COUNT	0x00
#define EP93XX_PWMx_DUTY_CYCLE	0x04
#define EP93XX_PWMx_ENABLE	0x08
#define EP93XX_PWMx_INVERT	0x0c

struct ep93xx_pwm {
	void __iomem *base;
	struct clk *clk;
	struct pwm_chip chip;
};

static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
{
	return container_of(chip, struct ep93xx_pwm, chip);
}

static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct platform_device *pdev = to_platform_device(chip->dev);

	return ep93xx_pwm_acquire_gpio(pdev);
}

static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct platform_device *pdev = to_platform_device(chip->dev);

	ep93xx_pwm_release_gpio(pdev);
}

static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
			     int duty_ns, int period_ns)
{
	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
	void __iomem *base = ep93xx_pwm->base;
	unsigned long long c;
	unsigned long period_cycles;
	unsigned long duty_cycles;
	unsigned long term;
	int ret = 0;

	/*
	 * The clock needs to be enabled to access the PWM registers.
	 * Configuration can be changed at any time.
	 */
	if (!pwm_is_enabled(pwm)) {
		ret = clk_enable(ep93xx_pwm->clk);
		if (ret)
			return ret;
	}

	c = clk_get_rate(ep93xx_pwm->clk);
	c *= period_ns;
	do_div(c, 1000000000);
	period_cycles = c;

	c = period_cycles;
	c *= duty_ns;
	do_div(c, period_ns);
	duty_cycles = c;

	if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
		term = readw(base + EP93XX_PWMx_TERM_COUNT);

		/* Order is important if PWM is running */
		if (period_cycles > term) {
			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
		} else {
			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
		}
	} else {
		ret = -EINVAL;
	}

	if (!pwm_is_enabled(pwm))
		clk_disable(ep93xx_pwm->clk);

	return ret;
}

static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
			       enum pwm_polarity polarity)
{
	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
	int ret;

	/*
	 * The clock needs to be enabled to access the PWM registers.
	 * Polarity can only be changed when the PWM is disabled.
	 */
	ret = clk_enable(ep93xx_pwm->clk);
	if (ret)
		return ret;

	if (polarity == PWM_POLARITY_INVERSED)
		writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
	else
		writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);

	clk_disable(ep93xx_pwm->clk);

	return 0;
}

static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
	int ret;

	ret = clk_enable(ep93xx_pwm->clk);
	if (ret)
		return ret;

	writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);

	return 0;
}

static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);

	writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
	clk_disable(ep93xx_pwm->clk);
}

static const struct pwm_ops ep93xx_pwm_ops = {
	.request = ep93xx_pwm_request,
	.free = ep93xx_pwm_free,
	.config = ep93xx_pwm_config,
	.set_polarity = ep93xx_pwm_polarity,
	.enable = ep93xx_pwm_enable,
	.disable = ep93xx_pwm_disable,
	.owner = THIS_MODULE,
};

static int ep93xx_pwm_probe(struct platform_device *pdev)
{
	struct ep93xx_pwm *ep93xx_pwm;
	int ret;

	ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
	if (!ep93xx_pwm)
		return -ENOMEM;

	ep93xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(ep93xx_pwm->base))
		return PTR_ERR(ep93xx_pwm->base);

	ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
	if (IS_ERR(ep93xx_pwm->clk))
		return PTR_ERR(ep93xx_pwm->clk);

	ep93xx_pwm->chip.dev = &pdev->dev;
	ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
	ep93xx_pwm->chip.base = -1;
	ep93xx_pwm->chip.npwm = 1;

	ret = pwmchip_add(&ep93xx_pwm->chip);
	if (ret < 0)
		return ret;

	platform_set_drvdata(pdev, ep93xx_pwm);
	return 0;
}

static int ep93xx_pwm_remove(struct platform_device *pdev)
{
	struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);

	return pwmchip_remove(&ep93xx_pwm->chip);
}

static struct platform_driver ep93xx_pwm_driver = {
	.driver = {
		.name = "ep93xx-pwm",
	},
	.probe = ep93xx_pwm_probe,
	.remove = ep93xx_pwm_remove,
};
module_platform_driver(ep93xx_pwm_driver);

MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_ALIAS("platform:ep93xx-pwm");
MODULE_LICENSE("GPL");