1/*
2 * Copyright 2012 Freescale Semiconductor, Inc.
3 *
4 * The code contained herein is licensed under the GNU General Public
5 * License. You may obtain a copy of the GNU General Public License
6 * Version 2 or later at the following locations:
7 *
8 * http://www.opensource.org/licenses/gpl-license.html
9 * http://www.gnu.org/copyleft/gpl.html
10 */
11
12#include <linux/clk.h>
13#include <linux/err.h>
14#include <linux/io.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/of.h>
18#include <linux/of_address.h>
19#include <linux/platform_device.h>
20#include <linux/pwm.h>
21#include <linux/slab.h>
22#include <linux/stmp_device.h>
23
24#define SET	0x4
25#define CLR	0x8
26#define TOG	0xc
27
28#define PWM_CTRL		0x0
29#define PWM_ACTIVE0		0x10
30#define PWM_PERIOD0		0x20
31#define  PERIOD_PERIOD(p)	((p) & 0xffff)
32#define  PERIOD_PERIOD_MAX	0x10000
33#define  PERIOD_ACTIVE_HIGH	(3 << 16)
34#define  PERIOD_INACTIVE_LOW	(2 << 18)
35#define  PERIOD_CDIV(div)	(((div) & 0x7) << 20)
36#define  PERIOD_CDIV_MAX	8
37
38static const unsigned int cdiv[PERIOD_CDIV_MAX] = {
39	1, 2, 4, 8, 16, 64, 256, 1024
40};
41
42struct mxs_pwm_chip {
43	struct pwm_chip chip;
44	struct clk *clk;
45	void __iomem *base;
46};
47
48#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
49
50static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
51			  int duty_ns, int period_ns)
52{
53	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
54	int ret, div = 0;
55	unsigned int period_cycles, duty_cycles;
56	unsigned long rate;
57	unsigned long long c;
58
59	rate = clk_get_rate(mxs->clk);
60	while (1) {
61		c = rate / cdiv[div];
62		c = c * period_ns;
63		do_div(c, 1000000000);
64		if (c < PERIOD_PERIOD_MAX)
65			break;
66		div++;
67		if (div >= PERIOD_CDIV_MAX)
68			return -EINVAL;
69	}
70
71	period_cycles = c;
72	c *= duty_ns;
73	do_div(c, period_ns);
74	duty_cycles = c;
75
76	/*
77	 * If the PWM channel is disabled, make sure to turn on the clock
78	 * before writing the register. Otherwise, keep it enabled.
79	 */
80	if (!pwm_is_enabled(pwm)) {
81		ret = clk_prepare_enable(mxs->clk);
82		if (ret)
83			return ret;
84	}
85
86	writel(duty_cycles << 16,
87			mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
88	writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
89	       PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
90			mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
91
92	/*
93	 * If the PWM is not enabled, turn the clock off again to save power.
94	 */
95	if (!pwm_is_enabled(pwm))
96		clk_disable_unprepare(mxs->clk);
97
98	return 0;
99}
100
101static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
102{
103	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
104	int ret;
105
106	ret = clk_prepare_enable(mxs->clk);
107	if (ret)
108		return ret;
109
110	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
111
112	return 0;
113}
114
115static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
116{
117	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
118
119	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
120
121	clk_disable_unprepare(mxs->clk);
122}
123
124static const struct pwm_ops mxs_pwm_ops = {
125	.config = mxs_pwm_config,
126	.enable = mxs_pwm_enable,
127	.disable = mxs_pwm_disable,
128	.owner = THIS_MODULE,
129};
130
131static int mxs_pwm_probe(struct platform_device *pdev)
132{
133	struct device_node *np = pdev->dev.of_node;
134	struct mxs_pwm_chip *mxs;
135	struct resource *res;
136	int ret;
137
138	mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
139	if (!mxs)
140		return -ENOMEM;
141
142	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
143	mxs->base = devm_ioremap_resource(&pdev->dev, res);
144	if (IS_ERR(mxs->base))
145		return PTR_ERR(mxs->base);
146
147	mxs->clk = devm_clk_get(&pdev->dev, NULL);
148	if (IS_ERR(mxs->clk))
149		return PTR_ERR(mxs->clk);
150
151	mxs->chip.dev = &pdev->dev;
152	mxs->chip.ops = &mxs_pwm_ops;
153	mxs->chip.base = -1;
154	mxs->chip.can_sleep = true;
155	ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
156	if (ret < 0) {
157		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
158		return ret;
159	}
160
161	ret = pwmchip_add(&mxs->chip);
162	if (ret < 0) {
163		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
164		return ret;
165	}
166
167	platform_set_drvdata(pdev, mxs);
168
169	ret = stmp_reset_block(mxs->base);
170	if (ret)
171		goto pwm_remove;
172
173	return 0;
174
175pwm_remove:
176	pwmchip_remove(&mxs->chip);
177	return ret;
178}
179
180static int mxs_pwm_remove(struct platform_device *pdev)
181{
182	struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
183
184	return pwmchip_remove(&mxs->chip);
185}
186
187static const struct of_device_id mxs_pwm_dt_ids[] = {
188	{ .compatible = "fsl,imx23-pwm", },
189	{ /* sentinel */ }
190};
191MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
192
193static struct platform_driver mxs_pwm_driver = {
194	.driver = {
195		.name = "mxs-pwm",
196		.of_match_table = mxs_pwm_dt_ids,
197	},
198	.probe = mxs_pwm_probe,
199	.remove = mxs_pwm_remove,
200};
201module_platform_driver(mxs_pwm_driver);
202
203MODULE_ALIAS("platform:mxs-pwm");
204MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
205MODULE_DESCRIPTION("Freescale MXS PWM Driver");
206MODULE_LICENSE("GPL v2");
207