1/*
2 * ECAP PWM driver
3 *
4 * Copyright (C) 2012 Texas Instruments, Inc. - http://www.ti.com/
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 */
20
21#include <linux/module.h>
22#include <linux/platform_device.h>
23#include <linux/io.h>
24#include <linux/err.h>
25#include <linux/clk.h>
26#include <linux/pm_runtime.h>
27#include <linux/pwm.h>
28#include <linux/of_device.h>
29
30#include "pwm-tipwmss.h"
31
32/* ECAP registers and bits definitions */
33#define CAP1			0x08
34#define CAP2			0x0C
35#define CAP3			0x10
36#define CAP4			0x14
37#define ECCTL2			0x2A
38#define ECCTL2_APWM_POL_LOW	BIT(10)
39#define ECCTL2_APWM_MODE	BIT(9)
40#define ECCTL2_SYNC_SEL_DISA	(BIT(7) | BIT(6))
41#define ECCTL2_TSCTR_FREERUN	BIT(4)
42
43struct ecap_context {
44	u32	cap3;
45	u32	cap4;
46	u16	ecctl2;
47};
48
49struct ecap_pwm_chip {
50	struct pwm_chip	chip;
51	unsigned int	clk_rate;
52	void __iomem	*mmio_base;
53	struct ecap_context ctx;
54};
55
56static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
57{
58	return container_of(chip, struct ecap_pwm_chip, chip);
59}
60
61/*
62 * period_ns = 10^9 * period_cycles / PWM_CLK_RATE
63 * duty_ns   = 10^9 * duty_cycles / PWM_CLK_RATE
64 */
65static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
66		int duty_ns, int period_ns)
67{
68	struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
69	unsigned long long c;
70	unsigned long period_cycles, duty_cycles;
71	unsigned int reg_val;
72
73	if (period_ns > NSEC_PER_SEC)
74		return -ERANGE;
75
76	c = pc->clk_rate;
77	c = c * period_ns;
78	do_div(c, NSEC_PER_SEC);
79	period_cycles = (unsigned long)c;
80
81	if (period_cycles < 1) {
82		period_cycles = 1;
83		duty_cycles = 1;
84	} else {
85		c = pc->clk_rate;
86		c = c * duty_ns;
87		do_div(c, NSEC_PER_SEC);
88		duty_cycles = (unsigned long)c;
89	}
90
91	pm_runtime_get_sync(pc->chip.dev);
92
93	reg_val = readw(pc->mmio_base + ECCTL2);
94
95	/* Configure APWM mode & disable sync option */
96	reg_val |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA;
97
98	writew(reg_val, pc->mmio_base + ECCTL2);
99
100	if (!pwm_is_enabled(pwm)) {
101		/* Update active registers if not running */
102		writel(duty_cycles, pc->mmio_base + CAP2);
103		writel(period_cycles, pc->mmio_base + CAP1);
104	} else {
105		/*
106		 * Update shadow registers to configure period and
107		 * compare values. This helps current PWM period to
108		 * complete on reconfiguring
109		 */
110		writel(duty_cycles, pc->mmio_base + CAP4);
111		writel(period_cycles, pc->mmio_base + CAP3);
112	}
113
114	if (!pwm_is_enabled(pwm)) {
115		reg_val = readw(pc->mmio_base + ECCTL2);
116		/* Disable APWM mode to put APWM output Low */
117		reg_val &= ~ECCTL2_APWM_MODE;
118		writew(reg_val, pc->mmio_base + ECCTL2);
119	}
120
121	pm_runtime_put_sync(pc->chip.dev);
122	return 0;
123}
124
125static int ecap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
126		enum pwm_polarity polarity)
127{
128	struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
129	unsigned short reg_val;
130
131	pm_runtime_get_sync(pc->chip.dev);
132	reg_val = readw(pc->mmio_base + ECCTL2);
133	if (polarity == PWM_POLARITY_INVERSED)
134		/* Duty cycle defines LOW period of PWM */
135		reg_val |= ECCTL2_APWM_POL_LOW;
136	else
137		/* Duty cycle defines HIGH period of PWM */
138		reg_val &= ~ECCTL2_APWM_POL_LOW;
139
140	writew(reg_val, pc->mmio_base + ECCTL2);
141	pm_runtime_put_sync(pc->chip.dev);
142	return 0;
143}
144
145static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
146{
147	struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
148	unsigned int reg_val;
149
150	/* Leave clock enabled on enabling PWM */
151	pm_runtime_get_sync(pc->chip.dev);
152
153	/*
154	 * Enable 'Free run Time stamp counter mode' to start counter
155	 * and  'APWM mode' to enable APWM output
156	 */
157	reg_val = readw(pc->mmio_base + ECCTL2);
158	reg_val |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE;
159	writew(reg_val, pc->mmio_base + ECCTL2);
160	return 0;
161}
162
163static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
164{
165	struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
166	unsigned int reg_val;
167
168	/*
169	 * Disable 'Free run Time stamp counter mode' to stop counter
170	 * and 'APWM mode' to put APWM output to low
171	 */
172	reg_val = readw(pc->mmio_base + ECCTL2);
173	reg_val &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE);
174	writew(reg_val, pc->mmio_base + ECCTL2);
175
176	/* Disable clock on PWM disable */
177	pm_runtime_put_sync(pc->chip.dev);
178}
179
180static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
181{
182	if (pwm_is_enabled(pwm)) {
183		dev_warn(chip->dev, "Removing PWM device without disabling\n");
184		pm_runtime_put_sync(chip->dev);
185	}
186}
187
188static const struct pwm_ops ecap_pwm_ops = {
189	.free		= ecap_pwm_free,
190	.config		= ecap_pwm_config,
191	.set_polarity	= ecap_pwm_set_polarity,
192	.enable		= ecap_pwm_enable,
193	.disable	= ecap_pwm_disable,
194	.owner		= THIS_MODULE,
195};
196
197static const struct of_device_id ecap_of_match[] = {
198	{ .compatible	= "ti,am33xx-ecap" },
199	{},
200};
201MODULE_DEVICE_TABLE(of, ecap_of_match);
202
203static int ecap_pwm_probe(struct platform_device *pdev)
204{
205	int ret;
206	struct resource *r;
207	struct clk *clk;
208	struct ecap_pwm_chip *pc;
209	u16 status;
210
211	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
212	if (!pc)
213		return -ENOMEM;
214
215	clk = devm_clk_get(&pdev->dev, "fck");
216	if (IS_ERR(clk)) {
217		dev_err(&pdev->dev, "failed to get clock\n");
218		return PTR_ERR(clk);
219	}
220
221	pc->clk_rate = clk_get_rate(clk);
222	if (!pc->clk_rate) {
223		dev_err(&pdev->dev, "failed to get clock rate\n");
224		return -EINVAL;
225	}
226
227	pc->chip.dev = &pdev->dev;
228	pc->chip.ops = &ecap_pwm_ops;
229	pc->chip.of_xlate = of_pwm_xlate_with_flags;
230	pc->chip.of_pwm_n_cells = 3;
231	pc->chip.base = -1;
232	pc->chip.npwm = 1;
233
234	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
235	pc->mmio_base = devm_ioremap_resource(&pdev->dev, r);
236	if (IS_ERR(pc->mmio_base))
237		return PTR_ERR(pc->mmio_base);
238
239	ret = pwmchip_add(&pc->chip);
240	if (ret < 0) {
241		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
242		return ret;
243	}
244
245	pm_runtime_enable(&pdev->dev);
246	pm_runtime_get_sync(&pdev->dev);
247
248	status = pwmss_submodule_state_change(pdev->dev.parent,
249			PWMSS_ECAPCLK_EN);
250	if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
251		dev_err(&pdev->dev, "PWMSS config space clock enable failed\n");
252		ret = -EINVAL;
253		goto pwmss_clk_failure;
254	}
255
256	pm_runtime_put_sync(&pdev->dev);
257
258	platform_set_drvdata(pdev, pc);
259	return 0;
260
261pwmss_clk_failure:
262	pm_runtime_put_sync(&pdev->dev);
263	pm_runtime_disable(&pdev->dev);
264	pwmchip_remove(&pc->chip);
265	return ret;
266}
267
268static int ecap_pwm_remove(struct platform_device *pdev)
269{
270	struct ecap_pwm_chip *pc = platform_get_drvdata(pdev);
271
272	pm_runtime_get_sync(&pdev->dev);
273	/*
274	 * Due to hardware misbehaviour, acknowledge of the stop_req
275	 * is missing. Hence checking of the status bit skipped.
276	 */
277	pwmss_submodule_state_change(pdev->dev.parent, PWMSS_ECAPCLK_STOP_REQ);
278	pm_runtime_put_sync(&pdev->dev);
279
280	pm_runtime_disable(&pdev->dev);
281	return pwmchip_remove(&pc->chip);
282}
283
284#ifdef CONFIG_PM_SLEEP
285static void ecap_pwm_save_context(struct ecap_pwm_chip *pc)
286{
287	pm_runtime_get_sync(pc->chip.dev);
288	pc->ctx.ecctl2 = readw(pc->mmio_base + ECCTL2);
289	pc->ctx.cap4 = readl(pc->mmio_base + CAP4);
290	pc->ctx.cap3 = readl(pc->mmio_base + CAP3);
291	pm_runtime_put_sync(pc->chip.dev);
292}
293
294static void ecap_pwm_restore_context(struct ecap_pwm_chip *pc)
295{
296	writel(pc->ctx.cap3, pc->mmio_base + CAP3);
297	writel(pc->ctx.cap4, pc->mmio_base + CAP4);
298	writew(pc->ctx.ecctl2, pc->mmio_base + ECCTL2);
299}
300
301static int ecap_pwm_suspend(struct device *dev)
302{
303	struct ecap_pwm_chip *pc = dev_get_drvdata(dev);
304	struct pwm_device *pwm = pc->chip.pwms;
305
306	ecap_pwm_save_context(pc);
307
308	/* Disable explicitly if PWM is running */
309	if (pwm_is_enabled(pwm))
310		pm_runtime_put_sync(dev);
311
312	return 0;
313}
314
315static int ecap_pwm_resume(struct device *dev)
316{
317	struct ecap_pwm_chip *pc = dev_get_drvdata(dev);
318	struct pwm_device *pwm = pc->chip.pwms;
319
320	/* Enable explicitly if PWM was running */
321	if (pwm_is_enabled(pwm))
322		pm_runtime_get_sync(dev);
323
324	ecap_pwm_restore_context(pc);
325	return 0;
326}
327#endif
328
329static SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume);
330
331static struct platform_driver ecap_pwm_driver = {
332	.driver = {
333		.name	= "ecap",
334		.of_match_table = ecap_of_match,
335		.pm	= &ecap_pwm_pm_ops,
336	},
337	.probe = ecap_pwm_probe,
338	.remove = ecap_pwm_remove,
339};
340
341module_platform_driver(ecap_pwm_driver);
342
343MODULE_DESCRIPTION("ECAP PWM driver");
344MODULE_AUTHOR("Texas Instruments");
345MODULE_LICENSE("GPL");
346