aboutsummaryrefslogtreecommitdiff
path: root/drivers/pwm/pwm-pxa.c
blob: a4d2164aaf55836cc662784f1e9a6f071e6d8be5 (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
/*
 * drivers/pwm/pwm-pxa.c
 *
 * simple driver for PWM (Pulse Width Modulator) controller
 *
 * 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.
 *
 * 2008-02-13	initial version
 * 		eric miao <eric.miao@marvell.com>
 */

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

#include <asm/div64.h>

#define HAS_SECONDARY_PWM	0x10

static const struct platform_device_id pwm_id_table[] = {
	/*   PWM    has_secondary_pwm? */
	{ "pxa25x-pwm", 0 },
	{ "pxa27x-pwm", HAS_SECONDARY_PWM },
	{ "pxa168-pwm", 0 },
	{ "pxa910-pwm", 0 },
	{ },
};
MODULE_DEVICE_TABLE(platform, pwm_id_table);

/* PWM registers and bits definitions */
#define PWMCR		(0x00)
#define PWMDCR		(0x04)
#define PWMPCR		(0x08)

#define PWMCR_SD	(1 << 6)
#define PWMDCR_FD	(1 << 10)

struct pxa_pwm_chip {
	struct pwm_chip	chip;
	struct device	*dev;

	struct clk	*clk;
	void __iomem	*mmio_base;
};

static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip)
{
	return container_of(chip, struct pxa_pwm_chip, chip);
}

/*
 * period_ns = 10^9 * (PRESCALE + 1) * (PV + 1) / PWM_CLK_RATE
 * duty_ns   = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
 */
static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
			  int duty_ns, int period_ns)
{
	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);
	unsigned long long c;
	unsigned long period_cycles, prescale, pv, dc;
	unsigned long offset;
	int rc;

	offset = pwm->hwpwm ? 0x10 : 0;

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

	if (period_cycles < 1)
		period_cycles = 1;
	prescale = (period_cycles - 1) / 1024;
	pv = period_cycles / (prescale + 1) - 1;

	if (prescale > 63)
		return -EINVAL;

	if (duty_ns == period_ns)
		dc = PWMDCR_FD;
	else
		dc = (pv + 1) * duty_ns / period_ns;

	/* NOTE: the clock to PWM has to be enabled first
	 * before writing to the registers
	 */
	rc = clk_prepare_enable(pc->clk);
	if (rc < 0)
		return rc;

	writel(prescale, pc->mmio_base + offset + PWMCR);
	writel(dc, pc->mmio_base + offset + PWMDCR);
	writel(pv, pc->mmio_base + offset + PWMPCR);

	clk_disable_unprepare(pc->clk);
	return 0;
}

static int pxa_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);

	return clk_prepare_enable(pc->clk);
}

static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip);

	clk_disable_unprepare(pc->clk);
}

static struct pwm_ops pxa_pwm_ops = {
	.config = pxa_pwm_config,
	.enable = pxa_pwm_enable,
	.disable = pxa_pwm_disable,
	.owner = THIS_MODULE,
};

static int pwm_probe(struct platform_device *pdev)
{
	const struct platform_device_id *id = platform_get_device_id(pdev);
	struct pxa_pwm_chip *pwm;
	struct resource *r;
	int ret = 0;

	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
	if (pwm == NULL) {
		dev_err(&pdev->dev, "failed to allocate memory\n");
		return -ENOMEM;
	}

	pwm->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(pwm->clk))
		return PTR_ERR(pwm->clk);

	pwm->chip.dev = &pdev->dev;
	pwm->chip.ops = &pxa_pwm_ops;
	pwm->chip.base = -1;
	pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(pwm->mmio_base))
		return PTR_ERR(pwm->mmio_base);

	ret = pwmchip_add(&pwm->chip);
	if (ret < 0) {
		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
		return ret;
	}

	platform_set_drvdata(pdev, pwm);
	return 0;
}

static int pwm_remove(struct platform_device *pdev)
{
	struct pxa_pwm_chip *chip;

	chip = platform_get_drvdata(pdev);
	if (chip == NULL)
		return -ENODEV;

	return pwmchip_remove(&chip->chip);
}

static struct platform_driver pwm_driver = {
	.driver		= {
		.name	= "pxa25x-pwm",
		.owner	= THIS_MODULE,
	},
	.probe		= pwm_probe,
	.remove		= pwm_remove,
	.id_table	= pwm_id_table,
};

module_platform_driver(pwm_driver);

MODULE_LICENSE("GPL v2");