summaryrefslogtreecommitdiffstats
path: root/drivers/pwm/pwm-vt8500.c
blob: 7bfeacee05d0faed908689ec7e321c45f6a36dd6 (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
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/pwm/pwm-vt8500.c
 *
 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
 */

#include <linux/mod_devicetable.h>
#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>

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

#define REG_CTRL(pwm)		(((pwm) << 4) + 0x00)
#define REG_SCALAR(pwm)		(((pwm) << 4) + 0x04)
#define REG_PERIOD(pwm)		(((pwm) << 4) + 0x08)
#define REG_DUTY(pwm)		(((pwm) << 4) + 0x0C)
#define REG_STATUS		0x40

#define CTRL_ENABLE		BIT(0)
#define CTRL_INVERT		BIT(1)
#define CTRL_AUTOLOAD		BIT(2)
#define CTRL_STOP_IMM		BIT(3)
#define CTRL_LOAD_PRESCALE	BIT(4)
#define CTRL_LOAD_PERIOD	BIT(5)

#define STATUS_CTRL_UPDATE	BIT(0)
#define STATUS_SCALAR_UPDATE	BIT(1)
#define STATUS_PERIOD_UPDATE	BIT(2)
#define STATUS_DUTY_UPDATE	BIT(3)
#define STATUS_ALL_UPDATE	0x0F

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 vt8500_pwm_busy_wait(struct vt8500_chip *vt8500, int nr, u8 bitmask)
{
	int loops = msecs_to_loops(10);
	u32 mask = bitmask << (nr << 8);

	while ((readl(vt8500->base + REG_STATUS) & mask) && --loops)
		cpu_relax();

	if (unlikely(!loops))
		dev_warn(vt8500->chip.dev, "Waiting for status bits 0x%x to clear timed out\n",
			 mask);
}

static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
		u64 duty_ns, u64 period_ns)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	unsigned long long c;
	unsigned long period_cycles, prescale, pv, dc;
	int err;
	u32 val;

	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;

	dc = div64_u64(c, period_ns);

	writel(prescale, vt8500->base + REG_SCALAR(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_SCALAR_UPDATE);

	writel(pv, vt8500->base + REG_PERIOD(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_PERIOD_UPDATE);

	writel(dc, vt8500->base + REG_DUTY(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_DUTY_UPDATE);

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val |= CTRL_AUTOLOAD;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

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

static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	int err;
	u32 val;

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

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val |= CTRL_ENABLE;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	return 0;
}

static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	u32 val;

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
	val &= ~CTRL_ENABLE;
	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	clk_disable(vt8500->clk);
}

static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
				   struct pwm_device *pwm,
				   enum pwm_polarity polarity)
{
	struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
	u32 val;

	val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));

	if (polarity == PWM_POLARITY_INVERSED)
		val |= CTRL_INVERT;
	else
		val &= ~CTRL_INVERT;

	writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
	vt8500_pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);

	return 0;
}

static int vt8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
			    const struct pwm_state *state)
{
	int err;
	bool enabled = pwm->state.enabled;

	if (state->polarity != pwm->state.polarity) {
		/*
		 * Changing the polarity of a running PWM is only allowed when
		 * the PWM driver implements ->apply().
		 */
		if (enabled) {
			vt8500_pwm_disable(chip, pwm);

			enabled = false;
		}

		err = vt8500_pwm_set_polarity(chip, pwm, state->polarity);
		if (err)
			return err;
	}

	if (!state->enabled) {
		if (enabled)
			vt8500_pwm_disable(chip, pwm);

		return 0;
	}

	/*
	 * We cannot skip calling ->config even if state->period ==
	 * pwm->state.period && state->duty_cycle == pwm->state.duty_cycle
	 * because we might have exited early in the last call to
	 * pwm_apply_might_sleep because of !state->enabled and so the two values in
	 * pwm->state might not be configured in hardware.
	 */
	err = vt8500_pwm_config(chip, pwm, state->duty_cycle, state->period);
	if (err)
		return err;

	if (!enabled)
		err = vt8500_pwm_enable(chip, pwm);

	return err;
}

static const struct pwm_ops vt8500_pwm_ops = {
	.apply = vt8500_pwm_apply,
};

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 *vt8500;
	struct device_node *np = pdev->dev.of_node;
	int ret;

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

	vt8500 = devm_kzalloc(&pdev->dev, sizeof(*vt8500), GFP_KERNEL);
	if (vt8500 == NULL)
		return -ENOMEM;

	vt8500->chip.dev = &pdev->dev;
	vt8500->chip.ops = &vt8500_pwm_ops;
	vt8500->chip.npwm = VT8500_NR_PWMS;

	vt8500->clk = devm_clk_get_prepared(&pdev->dev, NULL);
	if (IS_ERR(vt8500->clk))
		return dev_err_probe(&pdev->dev, PTR_ERR(vt8500->clk), "clock source not specified\n");

	vt8500->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(vt8500->base))
		return PTR_ERR(vt8500->base);

	ret = devm_pwmchip_add(&pdev->dev, &vt8500->chip);
	if (ret < 0)
		return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");

	return 0;
}

static struct platform_driver vt8500_pwm_driver = {
	.probe		= vt8500_pwm_probe,
	.driver		= {
		.name	= "vt8500-pwm",
		.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");