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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * drivers/pwm/pwm-tegra.c
4 *
5 * Tegra pulse-width-modulation controller driver
6 *
7 * Copyright (c) 2010-2020, NVIDIA Corporation.
8 * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
9 *
10 * Overview of Tegra Pulse Width Modulator Register:
11 * 1. 13-bit: Frequency division (SCALE)
12 * 2. 8-bit : Pulse division (DUTY)
13 * 3. 1-bit : Enable bit
14 *
15 * The PWM clock frequency is divided by 256 before subdividing it based
16 * on the programmable frequency division value to generate the required
17 * frequency for PWM output. The maximum output frequency that can be
18 * achieved is (max rate of source clock) / 256.
19 * e.g. if source clock rate is 408 MHz, maximum output frequency can be:
20 * 408 MHz/256 = 1.6 MHz.
21 * This 1.6 MHz frequency can further be divided using SCALE value in PWM.
22 *
23 * PWM pulse width: 8 bits are usable [23:16] for varying pulse width.
24 * To achieve 100% duty cycle, program Bit [24] of this register to
25 * 1’b1. In which case the other bits [23:16] are set to don't care.
26 *
27 * Limitations:
28 * - When PWM is disabled, the output is driven to inactive.
29 * - It does not allow the current PWM period to complete and
30 * stops abruptly.
31 *
32 * - If the register is reconfigured while PWM is running,
33 * it does not complete the currently running period.
34 *
35 * - If the user input duty is beyond acceptible limits,
36 * -EINVAL is returned.
37 */
38
39#include <linux/clk.h>
40#include <linux/err.h>
41#include <linux/io.h>
42#include <linux/module.h>
43#include <linux/of.h>
44#include <linux/of_device.h>
45#include <linux/pm_opp.h>
46#include <linux/pwm.h>
47#include <linux/platform_device.h>
48#include <linux/pinctrl/consumer.h>
49#include <linux/pm_runtime.h>
50#include <linux/slab.h>
51#include <linux/reset.h>
52
53#include <soc/tegra/common.h>
54
55#define PWM_ENABLE (1 << 31)
56#define PWM_DUTY_WIDTH 8
57#define PWM_DUTY_SHIFT 16
58#define PWM_SCALE_WIDTH 13
59#define PWM_SCALE_SHIFT 0
60
61struct tegra_pwm_soc {
62 unsigned int num_channels;
63
64 /* Maximum IP frequency for given SoCs */
65 unsigned long max_frequency;
66};
67
68struct tegra_pwm_chip {
69 struct pwm_chip chip;
70 struct device *dev;
71
72 struct clk *clk;
73 struct reset_control*rst;
74
75 unsigned long clk_rate;
76 unsigned long min_period_ns;
77
78 void __iomem *regs;
79
80 const struct tegra_pwm_soc *soc;
81};
82
83static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
84{
85 return container_of(chip, struct tegra_pwm_chip, chip);
86}
87
88static inline u32 pwm_readl(struct tegra_pwm_chip *pc, unsigned int offset)
89{
90 return readl(pc->regs + (offset << 4));
91}
92
93static inline void pwm_writel(struct tegra_pwm_chip *pc, unsigned int offset, u32 value)
94{
95 writel(value, pc->regs + (offset << 4));
96}
97
98static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
99 int duty_ns, int period_ns)
100{
101 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
102 unsigned long long c = duty_ns;
103 unsigned long rate, required_clk_rate;
104 u32 val = 0;
105 int err;
106
107 /*
108 * Convert from duty_ns / period_ns to a fixed number of duty ticks
109 * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
110 * nearest integer during division.
111 */
112 c *= (1 << PWM_DUTY_WIDTH);
113 c = DIV_ROUND_CLOSEST_ULL(c, period_ns);
114
115 val = (u32)c << PWM_DUTY_SHIFT;
116
117 /*
118 * min period = max clock limit >> PWM_DUTY_WIDTH
119 */
120 if (period_ns < pc->min_period_ns)
121 return -EINVAL;
122
123 /*
124 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
125 * cycles at the PWM clock rate will take period_ns nanoseconds.
126 *
127 * num_channels: If single instance of PWM controller has multiple
128 * channels (e.g. Tegra210 or older) then it is not possible to
129 * configure separate clock rates to each of the channels, in such
130 * case the value stored during probe will be referred.
131 *
132 * If every PWM controller instance has one channel respectively, i.e.
133 * nums_channels == 1 then only the clock rate can be modified
134 * dynamically (e.g. Tegra186 or Tegra194).
135 */
136 if (pc->soc->num_channels == 1) {
137 /*
138 * Rate is multiplied with 2^PWM_DUTY_WIDTH so that it matches
139 * with the maximum possible rate that the controller can
140 * provide. Any further lower value can be derived by setting
141 * PFM bits[0:12].
142 *
143 * required_clk_rate is a reference rate for source clock and
144 * it is derived based on user requested period. By setting the
145 * source clock rate as required_clk_rate, PWM controller will
146 * be able to configure the requested period.
147 */
148 required_clk_rate = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC << PWM_DUTY_WIDTH,
149 period_ns);
150
151 if (required_clk_rate > clk_round_rate(pc->clk, required_clk_rate))
152 /*
153 * required_clk_rate is a lower bound for the input
154 * rate; for lower rates there is no value for PWM_SCALE
155 * that yields a period less than or equal to the
156 * requested period. Hence, for lower rates, double the
157 * required_clk_rate to get a clock rate that can meet
158 * the requested period.
159 */
160 required_clk_rate *= 2;
161
162 err = dev_pm_opp_set_rate(pc->dev, required_clk_rate);
163 if (err < 0)
164 return -EINVAL;
165
166 /* Store the new rate for further references */
167 pc->clk_rate = clk_get_rate(pc->clk);
168 }
169
170 /* Consider precision in PWM_SCALE_WIDTH rate calculation */
171 rate = mul_u64_u64_div_u64(pc->clk_rate, period_ns,
172 (u64)NSEC_PER_SEC << PWM_DUTY_WIDTH);
173
174 /*
175 * Since the actual PWM divider is the register's frequency divider
176 * field plus 1, we need to decrement to get the correct value to
177 * write to the register.
178 */
179 if (rate > 0)
180 rate--;
181 else
182 return -EINVAL;
183
184 /*
185 * Make sure that the rate will fit in the register's frequency
186 * divider field.
187 */
188 if (rate >> PWM_SCALE_WIDTH)
189 return -EINVAL;
190
191 val |= rate << PWM_SCALE_SHIFT;
192
193 /*
194 * If the PWM channel is disabled, make sure to turn on the clock
195 * before writing the register. Otherwise, keep it enabled.
196 */
197 if (!pwm_is_enabled(pwm)) {
198 err = pm_runtime_resume_and_get(pc->dev);
199 if (err)
200 return err;
201 } else
202 val |= PWM_ENABLE;
203
204 pwm_writel(pc, pwm->hwpwm, val);
205
206 /*
207 * If the PWM is not enabled, turn the clock off again to save power.
208 */
209 if (!pwm_is_enabled(pwm))
210 pm_runtime_put(pc->dev);
211
212 return 0;
213}
214
215static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
216{
217 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
218 int rc = 0;
219 u32 val;
220
221 rc = pm_runtime_resume_and_get(pc->dev);
222 if (rc)
223 return rc;
224
225 val = pwm_readl(pc, pwm->hwpwm);
226 val |= PWM_ENABLE;
227 pwm_writel(pc, pwm->hwpwm, val);
228
229 return 0;
230}
231
232static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
233{
234 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
235 u32 val;
236
237 val = pwm_readl(pc, pwm->hwpwm);
238 val &= ~PWM_ENABLE;
239 pwm_writel(pc, pwm->hwpwm, val);
240
241 pm_runtime_put_sync(pc->dev);
242}
243
244static int tegra_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
245 const struct pwm_state *state)
246{
247 int err;
248 bool enabled = pwm->state.enabled;
249
250 if (state->polarity != PWM_POLARITY_NORMAL)
251 return -EINVAL;
252
253 if (!state->enabled) {
254 if (enabled)
255 tegra_pwm_disable(chip, pwm);
256
257 return 0;
258 }
259
260 err = tegra_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
261 if (err)
262 return err;
263
264 if (!enabled)
265 err = tegra_pwm_enable(chip, pwm);
266
267 return err;
268}
269
270static const struct pwm_ops tegra_pwm_ops = {
271 .apply = tegra_pwm_apply,
272 .owner = THIS_MODULE,
273};
274
275static int tegra_pwm_probe(struct platform_device *pdev)
276{
277 struct tegra_pwm_chip *pc;
278 int ret;
279
280 pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
281 if (!pc)
282 return -ENOMEM;
283
284 pc->soc = of_device_get_match_data(&pdev->dev);
285 pc->dev = &pdev->dev;
286
287 pc->regs = devm_platform_ioremap_resource(pdev, 0);
288 if (IS_ERR(pc->regs))
289 return PTR_ERR(pc->regs);
290
291 platform_set_drvdata(pdev, pc);
292
293 pc->clk = devm_clk_get(&pdev->dev, NULL);
294 if (IS_ERR(pc->clk))
295 return PTR_ERR(pc->clk);
296
297 ret = devm_tegra_core_dev_init_opp_table_common(&pdev->dev);
298 if (ret)
299 return ret;
300
301 pm_runtime_enable(&pdev->dev);
302 ret = pm_runtime_resume_and_get(&pdev->dev);
303 if (ret)
304 return ret;
305
306 /* Set maximum frequency of the IP */
307 ret = dev_pm_opp_set_rate(pc->dev, pc->soc->max_frequency);
308 if (ret < 0) {
309 dev_err(&pdev->dev, "Failed to set max frequency: %d\n", ret);
310 goto put_pm;
311 }
312
313 /*
314 * The requested and configured frequency may differ due to
315 * clock register resolutions. Get the configured frequency
316 * so that PWM period can be calculated more accurately.
317 */
318 pc->clk_rate = clk_get_rate(pc->clk);
319
320 /* Set minimum limit of PWM period for the IP */
321 pc->min_period_ns =
322 (NSEC_PER_SEC / (pc->soc->max_frequency >> PWM_DUTY_WIDTH)) + 1;
323
324 pc->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
325 if (IS_ERR(pc->rst)) {
326 ret = PTR_ERR(pc->rst);
327 dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
328 goto put_pm;
329 }
330
331 reset_control_deassert(pc->rst);
332
333 pc->chip.dev = &pdev->dev;
334 pc->chip.ops = &tegra_pwm_ops;
335 pc->chip.npwm = pc->soc->num_channels;
336
337 ret = pwmchip_add(&pc->chip);
338 if (ret < 0) {
339 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
340 reset_control_assert(pc->rst);
341 goto put_pm;
342 }
343
344 pm_runtime_put(&pdev->dev);
345
346 return 0;
347put_pm:
348 pm_runtime_put_sync_suspend(&pdev->dev);
349 pm_runtime_force_suspend(&pdev->dev);
350 return ret;
351}
352
353static int tegra_pwm_remove(struct platform_device *pdev)
354{
355 struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
356
357 pwmchip_remove(&pc->chip);
358
359 reset_control_assert(pc->rst);
360
361 pm_runtime_force_suspend(&pdev->dev);
362
363 return 0;
364}
365
366static int __maybe_unused tegra_pwm_runtime_suspend(struct device *dev)
367{
368 struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
369 int err;
370
371 clk_disable_unprepare(pc->clk);
372
373 err = pinctrl_pm_select_sleep_state(dev);
374 if (err) {
375 clk_prepare_enable(pc->clk);
376 return err;
377 }
378
379 return 0;
380}
381
382static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
383{
384 struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
385 int err;
386
387 err = pinctrl_pm_select_default_state(dev);
388 if (err)
389 return err;
390
391 err = clk_prepare_enable(pc->clk);
392 if (err) {
393 pinctrl_pm_select_sleep_state(dev);
394 return err;
395 }
396
397 return 0;
398}
399
400static const struct tegra_pwm_soc tegra20_pwm_soc = {
401 .num_channels = 4,
402 .max_frequency = 48000000UL,
403};
404
405static const struct tegra_pwm_soc tegra186_pwm_soc = {
406 .num_channels = 1,
407 .max_frequency = 102000000UL,
408};
409
410static const struct tegra_pwm_soc tegra194_pwm_soc = {
411 .num_channels = 1,
412 .max_frequency = 408000000UL,
413};
414
415static const struct of_device_id tegra_pwm_of_match[] = {
416 { .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
417 { .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
418 { .compatible = "nvidia,tegra194-pwm", .data = &tegra194_pwm_soc },
419 { }
420};
421MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
422
423static const struct dev_pm_ops tegra_pwm_pm_ops = {
424 SET_RUNTIME_PM_OPS(tegra_pwm_runtime_suspend, tegra_pwm_runtime_resume,
425 NULL)
426 SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
427 pm_runtime_force_resume)
428};
429
430static struct platform_driver tegra_pwm_driver = {
431 .driver = {
432 .name = "tegra-pwm",
433 .of_match_table = tegra_pwm_of_match,
434 .pm = &tegra_pwm_pm_ops,
435 },
436 .probe = tegra_pwm_probe,
437 .remove = tegra_pwm_remove,
438};
439
440module_platform_driver(tegra_pwm_driver);
441
442MODULE_LICENSE("GPL");
443MODULE_AUTHOR("Sandipan Patra <spatra@nvidia.com>");
444MODULE_DESCRIPTION("Tegra PWM controller driver");
445MODULE_ALIAS("platform:tegra-pwm");
1/*
2 * drivers/pwm/pwm-tegra.c
3 *
4 * Tegra pulse-width-modulation controller driver
5 *
6 * Copyright (c) 2010, NVIDIA Corporation.
7 * Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful, but WITHOUT
15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
17 * more details.
18 *
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22 */
23
24#include <linux/clk.h>
25#include <linux/err.h>
26#include <linux/io.h>
27#include <linux/module.h>
28#include <linux/of.h>
29#include <linux/of_device.h>
30#include <linux/pwm.h>
31#include <linux/platform_device.h>
32#include <linux/slab.h>
33#include <linux/reset.h>
34
35#define PWM_ENABLE (1 << 31)
36#define PWM_DUTY_WIDTH 8
37#define PWM_DUTY_SHIFT 16
38#define PWM_SCALE_WIDTH 13
39#define PWM_SCALE_SHIFT 0
40
41struct tegra_pwm_soc {
42 unsigned int num_channels;
43};
44
45struct tegra_pwm_chip {
46 struct pwm_chip chip;
47 struct device *dev;
48
49 struct clk *clk;
50 struct reset_control*rst;
51
52 void __iomem *regs;
53
54 const struct tegra_pwm_soc *soc;
55};
56
57static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
58{
59 return container_of(chip, struct tegra_pwm_chip, chip);
60}
61
62static inline u32 pwm_readl(struct tegra_pwm_chip *chip, unsigned int num)
63{
64 return readl(chip->regs + (num << 4));
65}
66
67static inline void pwm_writel(struct tegra_pwm_chip *chip, unsigned int num,
68 unsigned long val)
69{
70 writel(val, chip->regs + (num << 4));
71}
72
73static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
74 int duty_ns, int period_ns)
75{
76 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
77 unsigned long long c = duty_ns;
78 unsigned long rate, hz;
79 u32 val = 0;
80 int err;
81
82 /*
83 * Convert from duty_ns / period_ns to a fixed number of duty ticks
84 * per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
85 * nearest integer during division.
86 */
87 c *= (1 << PWM_DUTY_WIDTH);
88 c += period_ns / 2;
89 do_div(c, period_ns);
90
91 val = (u32)c << PWM_DUTY_SHIFT;
92
93 /*
94 * Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
95 * cycles at the PWM clock rate will take period_ns nanoseconds.
96 */
97 rate = clk_get_rate(pc->clk) >> PWM_DUTY_WIDTH;
98 hz = NSEC_PER_SEC / period_ns;
99
100 rate = (rate + (hz / 2)) / hz;
101
102 /*
103 * Since the actual PWM divider is the register's frequency divider
104 * field minus 1, we need to decrement to get the correct value to
105 * write to the register.
106 */
107 if (rate > 0)
108 rate--;
109
110 /*
111 * Make sure that the rate will fit in the register's frequency
112 * divider field.
113 */
114 if (rate >> PWM_SCALE_WIDTH)
115 return -EINVAL;
116
117 val |= rate << PWM_SCALE_SHIFT;
118
119 /*
120 * If the PWM channel is disabled, make sure to turn on the clock
121 * before writing the register. Otherwise, keep it enabled.
122 */
123 if (!pwm_is_enabled(pwm)) {
124 err = clk_prepare_enable(pc->clk);
125 if (err < 0)
126 return err;
127 } else
128 val |= PWM_ENABLE;
129
130 pwm_writel(pc, pwm->hwpwm, val);
131
132 /*
133 * If the PWM is not enabled, turn the clock off again to save power.
134 */
135 if (!pwm_is_enabled(pwm))
136 clk_disable_unprepare(pc->clk);
137
138 return 0;
139}
140
141static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
142{
143 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
144 int rc = 0;
145 u32 val;
146
147 rc = clk_prepare_enable(pc->clk);
148 if (rc < 0)
149 return rc;
150
151 val = pwm_readl(pc, pwm->hwpwm);
152 val |= PWM_ENABLE;
153 pwm_writel(pc, pwm->hwpwm, val);
154
155 return 0;
156}
157
158static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
159{
160 struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
161 u32 val;
162
163 val = pwm_readl(pc, pwm->hwpwm);
164 val &= ~PWM_ENABLE;
165 pwm_writel(pc, pwm->hwpwm, val);
166
167 clk_disable_unprepare(pc->clk);
168}
169
170static const struct pwm_ops tegra_pwm_ops = {
171 .config = tegra_pwm_config,
172 .enable = tegra_pwm_enable,
173 .disable = tegra_pwm_disable,
174 .owner = THIS_MODULE,
175};
176
177static int tegra_pwm_probe(struct platform_device *pdev)
178{
179 struct tegra_pwm_chip *pwm;
180 struct resource *r;
181 int ret;
182
183 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
184 if (!pwm)
185 return -ENOMEM;
186
187 pwm->soc = of_device_get_match_data(&pdev->dev);
188 pwm->dev = &pdev->dev;
189
190 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
191 pwm->regs = devm_ioremap_resource(&pdev->dev, r);
192 if (IS_ERR(pwm->regs))
193 return PTR_ERR(pwm->regs);
194
195 platform_set_drvdata(pdev, pwm);
196
197 pwm->clk = devm_clk_get(&pdev->dev, NULL);
198 if (IS_ERR(pwm->clk))
199 return PTR_ERR(pwm->clk);
200
201 pwm->rst = devm_reset_control_get(&pdev->dev, "pwm");
202 if (IS_ERR(pwm->rst)) {
203 ret = PTR_ERR(pwm->rst);
204 dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
205 return ret;
206 }
207
208 reset_control_deassert(pwm->rst);
209
210 pwm->chip.dev = &pdev->dev;
211 pwm->chip.ops = &tegra_pwm_ops;
212 pwm->chip.base = -1;
213 pwm->chip.npwm = pwm->soc->num_channels;
214
215 ret = pwmchip_add(&pwm->chip);
216 if (ret < 0) {
217 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
218 reset_control_assert(pwm->rst);
219 return ret;
220 }
221
222 return 0;
223}
224
225static int tegra_pwm_remove(struct platform_device *pdev)
226{
227 struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
228 unsigned int i;
229 int err;
230
231 if (WARN_ON(!pc))
232 return -ENODEV;
233
234 err = clk_prepare_enable(pc->clk);
235 if (err < 0)
236 return err;
237
238 for (i = 0; i < pc->chip.npwm; i++) {
239 struct pwm_device *pwm = &pc->chip.pwms[i];
240
241 if (!pwm_is_enabled(pwm))
242 if (clk_prepare_enable(pc->clk) < 0)
243 continue;
244
245 pwm_writel(pc, i, 0);
246
247 clk_disable_unprepare(pc->clk);
248 }
249
250 reset_control_assert(pc->rst);
251 clk_disable_unprepare(pc->clk);
252
253 return pwmchip_remove(&pc->chip);
254}
255
256static const struct tegra_pwm_soc tegra20_pwm_soc = {
257 .num_channels = 4,
258};
259
260static const struct tegra_pwm_soc tegra186_pwm_soc = {
261 .num_channels = 1,
262};
263
264static const struct of_device_id tegra_pwm_of_match[] = {
265 { .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
266 { .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
267 { }
268};
269
270MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
271
272static struct platform_driver tegra_pwm_driver = {
273 .driver = {
274 .name = "tegra-pwm",
275 .of_match_table = tegra_pwm_of_match,
276 },
277 .probe = tegra_pwm_probe,
278 .remove = tegra_pwm_remove,
279};
280
281module_platform_driver(tegra_pwm_driver);
282
283MODULE_LICENSE("GPL");
284MODULE_AUTHOR("NVIDIA Corporation");
285MODULE_ALIAS("platform:tegra-pwm");