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
 38struct mxs_pwm_chip {
 39	struct pwm_chip chip;
 40	struct clk *clk;
 41	void __iomem *base;
 42};
 43
 44#define to_mxs_pwm_chip(_chip) container_of(_chip, struct mxs_pwm_chip, chip)
 45
 46static int mxs_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 47			  int duty_ns, int period_ns)
 48{
 49	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
 50	int ret, div = 0;
 51	unsigned int period_cycles, duty_cycles;
 52	unsigned long rate;
 53	unsigned long long c;
 54
 55	rate = clk_get_rate(mxs->clk);
 56	while (1) {
 57		c = rate / (1 << div);
 58		c = c * period_ns;
 59		do_div(c, 1000000000);
 60		if (c < PERIOD_PERIOD_MAX)
 61			break;
 62		div++;
 63		if (div > PERIOD_CDIV_MAX)
 64			return -EINVAL;
 65	}
 66
 67	period_cycles = c;
 68	c *= duty_ns;
 69	do_div(c, period_ns);
 70	duty_cycles = c;
 71
 72	/*
 73	 * If the PWM channel is disabled, make sure to turn on the clock
 74	 * before writing the register. Otherwise, keep it enabled.
 75	 */
 76	if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
 77		ret = clk_prepare_enable(mxs->clk);
 78		if (ret)
 79			return ret;
 80	}
 81
 82	writel(duty_cycles << 16,
 83			mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
 84	writel(PERIOD_PERIOD(period_cycles) | PERIOD_ACTIVE_HIGH |
 85	       PERIOD_INACTIVE_LOW | PERIOD_CDIV(div),
 86			mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
 87
 88	/*
 89	 * If the PWM is not enabled, turn the clock off again to save power.
 90	 */
 91	if (!test_bit(PWMF_ENABLED, &pwm->flags))
 92		clk_disable_unprepare(mxs->clk);
 93
 94	return 0;
 95}
 96
 97static int mxs_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 98{
 99	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
100	int ret;
101
102	ret = clk_prepare_enable(mxs->clk);
103	if (ret)
104		return ret;
105
106	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + SET);
107
108	return 0;
109}
110
111static void mxs_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
112{
113	struct mxs_pwm_chip *mxs = to_mxs_pwm_chip(chip);
114
115	writel(1 << pwm->hwpwm, mxs->base + PWM_CTRL + CLR);
116
117	clk_disable_unprepare(mxs->clk);
118}
119
120static const struct pwm_ops mxs_pwm_ops = {
121	.config = mxs_pwm_config,
122	.enable = mxs_pwm_enable,
123	.disable = mxs_pwm_disable,
124	.owner = THIS_MODULE,
125};
126
127static int mxs_pwm_probe(struct platform_device *pdev)
128{
129	struct device_node *np = pdev->dev.of_node;
130	struct mxs_pwm_chip *mxs;
131	struct resource *res;
132	int ret;
133
134	mxs = devm_kzalloc(&pdev->dev, sizeof(*mxs), GFP_KERNEL);
135	if (!mxs)
136		return -ENOMEM;
137
138	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
139	mxs->base = devm_ioremap_resource(&pdev->dev, res);
140	if (IS_ERR(mxs->base))
141		return PTR_ERR(mxs->base);
142
143	mxs->clk = devm_clk_get(&pdev->dev, NULL);
144	if (IS_ERR(mxs->clk))
145		return PTR_ERR(mxs->clk);
146
147	mxs->chip.dev = &pdev->dev;
148	mxs->chip.ops = &mxs_pwm_ops;
149	mxs->chip.base = -1;
150	ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);
151	if (ret < 0) {
152		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
153		return ret;
154	}
155
156	ret = pwmchip_add(&mxs->chip);
157	if (ret < 0) {
158		dev_err(&pdev->dev, "failed to add pwm chip %d\n", ret);
159		return ret;
160	}
161
162	platform_set_drvdata(pdev, mxs);
163
164	ret = stmp_reset_block(mxs->base);
165	if (ret)
166		goto pwm_remove;
167
168	return 0;
169
170pwm_remove:
171	pwmchip_remove(&mxs->chip);
172	return ret;
173}
174
175static int mxs_pwm_remove(struct platform_device *pdev)
176{
177	struct mxs_pwm_chip *mxs = platform_get_drvdata(pdev);
178
179	return pwmchip_remove(&mxs->chip);
180}
181
182static const struct of_device_id mxs_pwm_dt_ids[] = {
183	{ .compatible = "fsl,imx23-pwm", },
184	{ /* sentinel */ }
185};
186MODULE_DEVICE_TABLE(of, mxs_pwm_dt_ids);
187
188static struct platform_driver mxs_pwm_driver = {
189	.driver = {
190		.name = "mxs-pwm",
191		.owner = THIS_MODULE,
192		.of_match_table = mxs_pwm_dt_ids,
193	},
194	.probe = mxs_pwm_probe,
195	.remove = mxs_pwm_remove,
196};
197module_platform_driver(mxs_pwm_driver);
198
199MODULE_ALIAS("platform:mxs-pwm");
200MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
201MODULE_DESCRIPTION("Freescale MXS PWM Driver");
202MODULE_LICENSE("GPL v2");