summaryrefslogtreecommitdiffstats
path: root/drivers/pwm/pwm-vt8500.c
blob: f9de9b28e46e04121a8e7d42b36f6f613b11a228 (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
220
221
222
223
224
225
226
227
/*
 * drivers/pwm/pwm-vt8500.c
 *
 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

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

#include <asm/div64.h>

#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_address.h>

/*
 * SoC architecture allocates register space for 4 PWMs but only
 * 2 are currently implemented.
 */
#define VT8500_NR_PWMS	2

struct vt8500_chip {
	struct pwm_chip chip;
	void __iomem *base;
	struct clk *clk;
};

#define to_vt8500_chip(chip)	container_of(chip, struct vt8500_chip, chip)

#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)
static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask)
{
	int loops = msecs_to_loops(10);
	while ((readb(reg) & bitmask) && --loops)
		cpu_relax();

	if (unlikely(!loops))
		pr_warn("Waiting for status bits 0x%x to clear timed out\n",
			   bitmask);
}

static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
		int duty_ns, int period_ns)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	unsigned long long c;
	unsigned long period_cycles, prescale, pv, dc;
	int err;

	err = clk_enable(vt8500->clk);
	if (err < 0) {
		dev_err(chip->dev, "failed to enable clock\n");
		return err;
	}

	c = clk_get_rate(vt8500->clk);
	c = c * period_ns;
	do_div(c, 1000000000);
	period_cycles = c;

	if (period_cycles < 1)
		period_cycles = 1;
	prescale = (period_cycles - 1) / 4096;
	pv = period_cycles / (prescale + 1) - 1;
	if (pv > 4095)
		pv = 4095;

	if (prescale > 1023) {
		clk_disable(vt8500->clk);
		return -EINVAL;
	}

	c = (unsigned long long)pv * duty_ns;
	do_div(c, period_ns);
	dc = c;

	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 1));
	writel(prescale, vt8500->base + 0x4 + (pwm->hwpwm << 4));

	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 2));
	writel(pv, vt8500->base + 0x8 + (pwm->hwpwm << 4));

	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 3));
	writel(dc, vt8500->base + 0xc + (pwm->hwpwm << 4));

	clk_disable(vt8500->clk);
	return 0;
}

static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	int err;
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);

	err = clk_enable(vt8500->clk);
	if (err < 0) {
		dev_err(chip->dev, "failed to enable clock\n");
		return err;
	}

	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
	writel(5, vt8500->base + (pwm->hwpwm << 4));
	return 0;
}

static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);

	pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
	writel(0, vt8500->base + (pwm->hwpwm << 4));

	clk_disable(vt8500->clk);
}

static struct pwm_ops vt8500_pwm_ops = {
	.enable = vt8500_pwm_enable,
	.disable = vt8500_pwm_disable,
	.config = vt8500_pwm_config,
	.owner = THIS_MODULE,
};

static const struct of_device_id vt8500_pwm_dt_ids[] = {
	{ .compatible = "via,vt8500-pwm", },
	{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);

static int vt8500_pwm_probe(struct platform_device *pdev)
{
	struct vt8500_chip *chip;
	struct resource *r;
	struct device_node *np = pdev->dev.of_node;
	int ret;

	if (!np) {
		dev_err(&pdev->dev, "invalid devicetree node\n");
		return -EINVAL;
	}

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

	chip->chip.dev = &pdev->dev;
	chip->chip.ops = &vt8500_pwm_ops;
	chip->chip.base = -1;
	chip->chip.npwm = VT8500_NR_PWMS;

	chip->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(chip->clk)) {
		dev_err(&pdev->dev, "clock source not specified\n");
		return PTR_ERR(chip->clk);
	}

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (r == NULL) {
		dev_err(&pdev->dev, "no memory resource defined\n");
		return -ENODEV;
	}

	chip->base = devm_ioremap_resource(&pdev->dev, r);
	if (IS_ERR(chip->base))
		return PTR_ERR(chip->base);

	ret = clk_prepare(chip->clk);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to prepare clock\n");
		return ret;
	}

	ret = pwmchip_add(&chip->chip);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to add PWM chip\n");
		return ret;
	}

	platform_set_drvdata(pdev, chip);
	return ret;
}

static int vt8500_pwm_remove(struct platform_device *pdev)
{
	struct vt8500_chip *chip;

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

	clk_unprepare(chip->clk);

	return pwmchip_remove(&chip->chip);
}

static struct platform_driver vt8500_pwm_driver = {
	.probe		= vt8500_pwm_probe,
	.remove		= vt8500_pwm_remove,
	.driver		= {
		.name	= "vt8500-pwm",
		.owner	= THIS_MODULE,
		.of_match_table = vt8500_pwm_dt_ids,
	},
};
module_platform_driver(vt8500_pwm_driver);

MODULE_DESCRIPTION("VT8500 PWM Driver");
MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
MODULE_LICENSE("GPL v2");
OpenPOWER on IntegriCloud