aboutsummaryrefslogtreecommitdiff
path: root/drivers/pwm/pwm-tegra.c
blob: a5402933001f9cf446192d79b1ddf204e748e2a1 (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
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
/*
 * drivers/pwm/pwm-tegra.c
 *
 * Tegra pulse-width-modulation controller driver
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

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

#define PWM_ENABLE	(1 << 31)
#define PWM_DUTY_WIDTH	8
#define PWM_DUTY_SHIFT	16
#define PWM_SCALE_WIDTH	13
#define PWM_SCALE_SHIFT	0

#define NUM_PWM 4

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

	struct clk		*clk;

	void __iomem		*mmio_base;
};

static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
{
	return container_of(chip, struct tegra_pwm_chip, chip);
}

static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
{
	return readl(chip->mmio_base + (num << 4));
}

static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
			     unsigned long val)
{
	writel(val, chip->mmio_base + (num << 4));
}

static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
			    int duty_ns, int period_ns)
{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	unsigned long long c;
	unsigned long rate, hz;
	u32 val = 0;
	int err;

	/*
	 * Convert from duty_ns / period_ns to a fixed number of duty ticks
	 * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
	 * nearest integer during division.
	 */
	c = duty_ns * ((1 << PWM_DUTY_WIDTH) - 1) + period_ns / 2;
	do_div(c, period_ns);

	val = (u32)c << PWM_DUTY_SHIFT;

	/*
	 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
	 * cycles at the PWM clock rate will take period_ns nanoseconds.
	 */
	rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
	hz = 1000000000ul / period_ns;

	rate = (rate + (hz / 2)) / hz;

	/*
	 * Since the actual PWM divider is the register's frequency divider
	 * field minus 1, we need to decrement to get the correct value to
	 * write to the register.
	 */
	if (rate > 0)
		rate--;

	/*
	 * Make sure that the rate will fit in the register's frequency
	 * divider field.
	 */
	if (rate >> PWM_SCALE_WIDTH)
		return -EINVAL;

	val |= rate << PWM_SCALE_SHIFT;

	/*
	 * If the PWM channel is disabled, make sure to turn on the clock
	 * before writing the register. Otherwise, keep it enabled.
	 */
	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
		err = clk_prepare_enable(pc->clk);
		if (err < 0)
			return err;
	} else
		val |= PWM_ENABLE;

	pwm_writel(pc, pwm->hwpwm, val);

	/*
	 * If the PWM is not enabled, turn the clock off again to save power.
	 */
	if (!test_bit(PWMF_ENABLED, &pwm->flags))
		clk_disable_unprepare(pc->clk);

	return 0;
}

static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	int rc = 0;
	u32 val;

	rc = clk_prepare_enable(pc->clk);
	if (rc < 0)
		return rc;

	val = pwm_readl(pc, pwm->hwpwm);
	val |= PWM_ENABLE;
	pwm_writel(pc, pwm->hwpwm, val);

	return 0;
}

static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
	u32 val;

	val = pwm_readl(pc, pwm->hwpwm);
	val &= ~PWM_ENABLE;
	pwm_writel(pc, pwm->hwpwm, val);

	clk_disable_unprepare(pc->clk);
}

static const struct pwm_ops tegra_pwm_ops = {
	.config = tegra_pwm_config,
	.enable = tegra_pwm_enable,
	.disable = tegra_pwm_disable,
	.owner = THIS_MODULE,
};

static int tegra_pwm_probe(struct platform_device *pdev)
{
	struct tegra_pwm_chip *pwm;
	struct resource *r;
	int ret;

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

	pwm->dev = &pdev->dev;

	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);

	platform_set_drvdata(pdev, pwm);

	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 = &tegra_pwm_ops;
	pwm->chip.base = -1;
	pwm->chip.npwm = NUM_PWM;

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

	return 0;
}

static int tegra_pwm_remove(struct platform_device *pdev)
{
	struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
	int i;

	if (WARN_ON(!pc))
		return -ENODEV;

	for (i = 0; i < NUM_PWM; i++) {
		struct pwm_device *pwm = &pc->chip.pwms[i];

		if (!test_bit(PWMF_ENABLED, &pwm->flags))
			if (clk_prepare_enable(pc->clk) < 0)
				continue;

		pwm_writel(pc, i, 0);

		clk_disable_unprepare(pc->clk);
	}

	return pwmchip_remove(&pc->chip);
}

static const struct of_device_id tegra_pwm_of_match[] = {
	{ .compatible = "nvidia,tegra20-pwm" },
	{ .compatible = "nvidia,tegra30-pwm" },
	{ }
};

MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);

static struct platform_driver tegra_pwm_driver = {
	.driver = {
		.name = "tegra-pwm",
		.of_match_table = tegra_pwm_of_match,
	},
	.probe = tegra_pwm_probe,
	.remove = tegra_pwm_remove,
};

module_platform_driver(tegra_pwm_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("NVIDIA Corporation");
MODULE_ALIAS("platform:tegra-pwm");