1/*
  2 * PWM framework driver for Cirrus Logic EP93xx
  3 *
  4 * Copyright (c) 2009        Matthieu Crapet <mcrapet@gmail.com>
  5 * Copyright (c) 2009, 2013  H Hartley Sweeten <hsweeten@visionengravers.com>
  6 *
  7 * EP9301/02 have only one channel:
  8 *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
  9 *
 10 * EP9307 has only one channel:
 11 *   platform device ep93xx-pwm.0 - PWMOUT
 12 *
 13 * EP9312/15 have two channels:
 14 *   platform device ep93xx-pwm.0 - PWMOUT
 15 *   platform device ep93xx-pwm.1 - PWMOUT1 (EGPIO14)
 16 *
 17 * This program is free software; you can redistribute it and/or
 18 * modify it under the terms of the GNU General Public License
 19 * as published by the Free Software Foundation; either version
 20 * 2 of the License, or (at your option) any later version.
 21 *
 22 * This program is distributed in the hope that it will be useful,
 23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 25 * GNU General Public License for more details.
 26 */
 27
 28#include <linux/module.h>
 29#include <linux/platform_device.h>
 30#include <linux/slab.h>
 31#include <linux/clk.h>
 32#include <linux/err.h>
 33#include <linux/io.h>
 34#include <linux/pwm.h>
 35
 36#include <asm/div64.h>
 37
 38#include <mach/platform.h>	/* for ep93xx_pwm_{acquire,release}_gpio() */
 39
 40#define EP93XX_PWMx_TERM_COUNT	0x00
 41#define EP93XX_PWMx_DUTY_CYCLE	0x04
 42#define EP93XX_PWMx_ENABLE	0x08
 43#define EP93XX_PWMx_INVERT	0x0c
 44
 45struct ep93xx_pwm {
 46	void __iomem *base;
 47	struct clk *clk;
 48	struct pwm_chip chip;
 49};
 50
 51static inline struct ep93xx_pwm *to_ep93xx_pwm(struct pwm_chip *chip)
 52{
 53	return container_of(chip, struct ep93xx_pwm, chip);
 54}
 55
 56static int ep93xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 57{
 58	struct platform_device *pdev = to_platform_device(chip->dev);
 59
 60	return ep93xx_pwm_acquire_gpio(pdev);
 61}
 62
 63static void ep93xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 64{
 65	struct platform_device *pdev = to_platform_device(chip->dev);
 66
 67	ep93xx_pwm_release_gpio(pdev);
 68}
 69
 70static int ep93xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 71			     int duty_ns, int period_ns)
 72{
 73	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
 74	void __iomem *base = ep93xx_pwm->base;
 75	unsigned long long c;
 76	unsigned long period_cycles;
 77	unsigned long duty_cycles;
 78	unsigned long term;
 79	int ret = 0;
 80
 81	/*
 82	 * The clock needs to be enabled to access the PWM registers.
 83	 * Configuration can be changed at any time.
 84	 */
 85	if (!pwm_is_enabled(pwm)) {
 86		ret = clk_enable(ep93xx_pwm->clk);
 87		if (ret)
 88			return ret;
 89	}
 90
 91	c = clk_get_rate(ep93xx_pwm->clk);
 92	c *= period_ns;
 93	do_div(c, 1000000000);
 94	period_cycles = c;
 95
 96	c = period_cycles;
 97	c *= duty_ns;
 98	do_div(c, period_ns);
 99	duty_cycles = c;
100
101	if (period_cycles < 0x10000 && duty_cycles < 0x10000) {
102		term = readw(base + EP93XX_PWMx_TERM_COUNT);
103
104		/* Order is important if PWM is running */
105		if (period_cycles > term) {
106			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
107			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
108		} else {
109			writew(duty_cycles, base + EP93XX_PWMx_DUTY_CYCLE);
110			writew(period_cycles, base + EP93XX_PWMx_TERM_COUNT);
111		}
112	} else {
113		ret = -EINVAL;
114	}
115
116	if (!pwm_is_enabled(pwm))
117		clk_disable(ep93xx_pwm->clk);
118
119	return ret;
120}
121
122static int ep93xx_pwm_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
123			       enum pwm_polarity polarity)
124{
125	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
126	int ret;
127
128	/*
129	 * The clock needs to be enabled to access the PWM registers.
130	 * Polarity can only be changed when the PWM is disabled.
131	 */
132	ret = clk_enable(ep93xx_pwm->clk);
133	if (ret)
134		return ret;
135
136	if (polarity == PWM_POLARITY_INVERSED)
137		writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
138	else
139		writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_INVERT);
140
141	clk_disable(ep93xx_pwm->clk);
142
143	return 0;
144}
145
146static int ep93xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
147{
148	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
149	int ret;
150
151	ret = clk_enable(ep93xx_pwm->clk);
152	if (ret)
153		return ret;
154
155	writew(0x1, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
156
157	return 0;
158}
159
160static void ep93xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
161{
162	struct ep93xx_pwm *ep93xx_pwm = to_ep93xx_pwm(chip);
163
164	writew(0x0, ep93xx_pwm->base + EP93XX_PWMx_ENABLE);
165	clk_disable(ep93xx_pwm->clk);
166}
167
168static const struct pwm_ops ep93xx_pwm_ops = {
169	.request = ep93xx_pwm_request,
170	.free = ep93xx_pwm_free,
171	.config = ep93xx_pwm_config,
172	.set_polarity = ep93xx_pwm_polarity,
173	.enable = ep93xx_pwm_enable,
174	.disable = ep93xx_pwm_disable,
175	.owner = THIS_MODULE,
176};
177
178static int ep93xx_pwm_probe(struct platform_device *pdev)
179{
180	struct ep93xx_pwm *ep93xx_pwm;
181	struct resource *res;
182	int ret;
183
184	ep93xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*ep93xx_pwm), GFP_KERNEL);
185	if (!ep93xx_pwm)
186		return -ENOMEM;
187
188	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
189	ep93xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
190	if (IS_ERR(ep93xx_pwm->base))
191		return PTR_ERR(ep93xx_pwm->base);
192
193	ep93xx_pwm->clk = devm_clk_get(&pdev->dev, "pwm_clk");
194	if (IS_ERR(ep93xx_pwm->clk))
195		return PTR_ERR(ep93xx_pwm->clk);
196
197	ep93xx_pwm->chip.dev = &pdev->dev;
198	ep93xx_pwm->chip.ops = &ep93xx_pwm_ops;
199	ep93xx_pwm->chip.base = -1;
200	ep93xx_pwm->chip.npwm = 1;
201
202	ret = pwmchip_add(&ep93xx_pwm->chip);
203	if (ret < 0)
204		return ret;
205
206	platform_set_drvdata(pdev, ep93xx_pwm);
207	return 0;
208}
209
210static int ep93xx_pwm_remove(struct platform_device *pdev)
211{
212	struct ep93xx_pwm *ep93xx_pwm = platform_get_drvdata(pdev);
213
214	return pwmchip_remove(&ep93xx_pwm->chip);
215}
216
217static struct platform_driver ep93xx_pwm_driver = {
218	.driver = {
219		.name = "ep93xx-pwm",
220	},
221	.probe = ep93xx_pwm_probe,
222	.remove = ep93xx_pwm_remove,
223};
224module_platform_driver(ep93xx_pwm_driver);
225
226MODULE_DESCRIPTION("Cirrus Logic EP93xx PWM driver");
227MODULE_AUTHOR("Matthieu Crapet <mcrapet@gmail.com>");
228MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
229MODULE_ALIAS("platform:ep93xx-pwm");
230MODULE_LICENSE("GPL");