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6a4e4bff TK |
1 | /* |
2 | * Copyright (C) 2014 Broadcom Corporation | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License as | |
6 | * published by the Free Software Foundation version 2. | |
7 | * | |
8 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any | |
9 | * kind, whether express or implied; without even the implied warranty | |
10 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | */ | |
13 | ||
14 | #include <linux/clk.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/io.h> | |
18 | #include <linux/ioport.h> | |
19 | #include <linux/math64.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/of.h> | |
22 | #include <linux/platform_device.h> | |
23 | #include <linux/pwm.h> | |
24 | #include <linux/slab.h> | |
25 | #include <linux/types.h> | |
26 | ||
27 | /* | |
28 | * The Kona PWM has some unusual characteristics. Here are the main points. | |
29 | * | |
30 | * 1) There is no disable bit and the hardware docs advise programming a zero | |
31 | * duty to achieve output equivalent to that of a normal disable operation. | |
32 | * | |
33 | * 2) Changes to prescale, duty, period, and polarity do not take effect until | |
34 | * a subsequent rising edge of the trigger bit. | |
35 | * | |
36 | * 3) If the smooth bit and trigger bit are both low, the output is a constant | |
37 | * high signal. Otherwise, the earlier waveform continues to be output. | |
38 | * | |
39 | * 4) If the smooth bit is set on the rising edge of the trigger bit, output | |
40 | * will transition to the new settings on a period boundary (which could be | |
41 | * seconds away). If the smooth bit is clear, new settings will be applied | |
42 | * as soon as possible (the hardware always has a 400ns delay). | |
43 | * | |
44 | * 5) When the external clock that feeds the PWM is disabled, output is pegged | |
45 | * high or low depending on its state at that exact instant. | |
46 | */ | |
47 | ||
6571d13e | 48 | #define PWM_CONTROL_OFFSET 0x00000000 |
6a4e4bff TK |
49 | #define PWM_CONTROL_SMOOTH_SHIFT(chan) (24 + (chan)) |
50 | #define PWM_CONTROL_TYPE_SHIFT(chan) (16 + (chan)) | |
51 | #define PWM_CONTROL_POLARITY_SHIFT(chan) (8 + (chan)) | |
52 | #define PWM_CONTROL_TRIGGER_SHIFT(chan) (chan) | |
53 | ||
6571d13e | 54 | #define PRESCALE_OFFSET 0x00000004 |
6a4e4bff TK |
55 | #define PRESCALE_SHIFT(chan) ((chan) << 2) |
56 | #define PRESCALE_MASK(chan) (0x7 << PRESCALE_SHIFT(chan)) | |
6571d13e ST |
57 | #define PRESCALE_MIN 0x00000000 |
58 | #define PRESCALE_MAX 0x00000007 | |
6a4e4bff TK |
59 | |
60 | #define PERIOD_COUNT_OFFSET(chan) (0x00000008 + ((chan) << 3)) | |
6571d13e ST |
61 | #define PERIOD_COUNT_MIN 0x00000002 |
62 | #define PERIOD_COUNT_MAX 0x00ffffff | |
6a4e4bff TK |
63 | |
64 | #define DUTY_CYCLE_HIGH_OFFSET(chan) (0x0000000c + ((chan) << 3)) | |
6571d13e ST |
65 | #define DUTY_CYCLE_HIGH_MIN 0x00000000 |
66 | #define DUTY_CYCLE_HIGH_MAX 0x00ffffff | |
6a4e4bff TK |
67 | |
68 | struct kona_pwmc { | |
69 | struct pwm_chip chip; | |
70 | void __iomem *base; | |
71 | struct clk *clk; | |
72 | }; | |
73 | ||
74 | static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *_chip) | |
75 | { | |
76 | return container_of(_chip, struct kona_pwmc, chip); | |
77 | } | |
78 | ||
fe0aea79 JR |
79 | /* |
80 | * Clear trigger bit but set smooth bit to maintain old output. | |
81 | */ | |
82 | static void kona_pwmc_prepare_for_settings(struct kona_pwmc *kp, | |
83 | unsigned int chan) | |
6a4e4bff TK |
84 | { |
85 | unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); | |
86 | ||
6a4e4bff TK |
87 | value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan); |
88 | value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); | |
89 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
90 | ||
fe0aea79 JR |
91 | /* |
92 | * There must be a min 400ns delay between clearing trigger and setting | |
93 | * it. Failing to do this may result in no PWM signal. | |
94 | */ | |
95 | ndelay(400); | |
96 | } | |
97 | ||
98 | static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan) | |
99 | { | |
100 | unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); | |
101 | ||
6a4e4bff TK |
102 | /* Set trigger bit and clear smooth bit to apply new settings */ |
103 | value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); | |
104 | value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan); | |
105 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
fe0aea79 JR |
106 | |
107 | /* Trigger bit must be held high for at least 400 ns. */ | |
108 | ndelay(400); | |
6a4e4bff TK |
109 | } |
110 | ||
111 | static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm, | |
112 | int duty_ns, int period_ns) | |
113 | { | |
114 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
115 | u64 val, div, rate; | |
116 | unsigned long prescale = PRESCALE_MIN, pc, dc; | |
117 | unsigned int value, chan = pwm->hwpwm; | |
118 | ||
119 | /* | |
120 | * Find period count, duty count and prescale to suit duty_ns and | |
121 | * period_ns. This is done according to formulas described below: | |
122 | * | |
123 | * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE | |
124 | * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE | |
125 | * | |
126 | * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1)) | |
127 | * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1)) | |
128 | */ | |
129 | ||
130 | rate = clk_get_rate(kp->clk); | |
131 | ||
132 | while (1) { | |
133 | div = 1000000000; | |
134 | div *= 1 + prescale; | |
135 | val = rate * period_ns; | |
136 | pc = div64_u64(val, div); | |
137 | val = rate * duty_ns; | |
138 | dc = div64_u64(val, div); | |
139 | ||
140 | /* If duty_ns or period_ns are not achievable then return */ | |
75de7259 | 141 | if (pc < PERIOD_COUNT_MIN) |
6a4e4bff TK |
142 | return -EINVAL; |
143 | ||
144 | /* If pc and dc are in bounds, the calculation is done */ | |
145 | if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX) | |
146 | break; | |
147 | ||
148 | /* Otherwise, increase prescale and recalculate pc and dc */ | |
149 | if (++prescale > PRESCALE_MAX) | |
150 | return -EINVAL; | |
151 | } | |
152 | ||
fe0aea79 JR |
153 | /* |
154 | * Don't apply settings if disabled. The period and duty cycle are | |
155 | * always calculated above to ensure the new values are | |
156 | * validated immediately instead of on enable. | |
157 | */ | |
5c31252c | 158 | if (pwm_is_enabled(pwm)) { |
fe0aea79 JR |
159 | kona_pwmc_prepare_for_settings(kp, chan); |
160 | ||
6a4e4bff TK |
161 | value = readl(kp->base + PRESCALE_OFFSET); |
162 | value &= ~PRESCALE_MASK(chan); | |
163 | value |= prescale << PRESCALE_SHIFT(chan); | |
164 | writel(value, kp->base + PRESCALE_OFFSET); | |
165 | ||
166 | writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan)); | |
167 | ||
168 | writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); | |
169 | ||
170 | kona_pwmc_apply_settings(kp, chan); | |
171 | } | |
172 | ||
173 | return 0; | |
174 | } | |
175 | ||
176 | static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, | |
177 | enum pwm_polarity polarity) | |
178 | { | |
179 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
180 | unsigned int chan = pwm->hwpwm; | |
181 | unsigned int value; | |
182 | int ret; | |
183 | ||
184 | ret = clk_prepare_enable(kp->clk); | |
185 | if (ret < 0) { | |
186 | dev_err(chip->dev, "failed to enable clock: %d\n", ret); | |
187 | return ret; | |
188 | } | |
189 | ||
fe0aea79 JR |
190 | kona_pwmc_prepare_for_settings(kp, chan); |
191 | ||
6a4e4bff TK |
192 | value = readl(kp->base + PWM_CONTROL_OFFSET); |
193 | ||
194 | if (polarity == PWM_POLARITY_NORMAL) | |
195 | value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan); | |
196 | else | |
197 | value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan)); | |
198 | ||
199 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
200 | ||
201 | kona_pwmc_apply_settings(kp, chan); | |
202 | ||
6a4e4bff TK |
203 | clk_disable_unprepare(kp->clk); |
204 | ||
205 | return 0; | |
206 | } | |
207 | ||
208 | static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm) | |
209 | { | |
210 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
211 | int ret; | |
212 | ||
213 | ret = clk_prepare_enable(kp->clk); | |
214 | if (ret < 0) { | |
215 | dev_err(chip->dev, "failed to enable clock: %d\n", ret); | |
216 | return ret; | |
217 | } | |
218 | ||
15da7b50 BB |
219 | ret = kona_pwmc_config(chip, pwm, pwm_get_duty_cycle(pwm), |
220 | pwm_get_period(pwm)); | |
6a4e4bff TK |
221 | if (ret < 0) { |
222 | clk_disable_unprepare(kp->clk); | |
223 | return ret; | |
224 | } | |
225 | ||
226 | return 0; | |
227 | } | |
228 | ||
229 | static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) | |
230 | { | |
231 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
232 | unsigned int chan = pwm->hwpwm; | |
fe0aea79 JR |
233 | unsigned int value; |
234 | ||
235 | kona_pwmc_prepare_for_settings(kp, chan); | |
6a4e4bff TK |
236 | |
237 | /* Simulate a disable by configuring for zero duty */ | |
238 | writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); | |
fe0aea79 | 239 | writel(0, kp->base + PERIOD_COUNT_OFFSET(chan)); |
6a4e4bff | 240 | |
fe0aea79 JR |
241 | /* Set prescale to 0 for this channel */ |
242 | value = readl(kp->base + PRESCALE_OFFSET); | |
243 | value &= ~PRESCALE_MASK(chan); | |
244 | writel(value, kp->base + PRESCALE_OFFSET); | |
245 | ||
246 | kona_pwmc_apply_settings(kp, chan); | |
6a4e4bff TK |
247 | |
248 | clk_disable_unprepare(kp->clk); | |
249 | } | |
250 | ||
251 | static const struct pwm_ops kona_pwm_ops = { | |
252 | .config = kona_pwmc_config, | |
253 | .set_polarity = kona_pwmc_set_polarity, | |
254 | .enable = kona_pwmc_enable, | |
255 | .disable = kona_pwmc_disable, | |
256 | .owner = THIS_MODULE, | |
257 | }; | |
258 | ||
259 | static int kona_pwmc_probe(struct platform_device *pdev) | |
260 | { | |
261 | struct kona_pwmc *kp; | |
6a4e4bff TK |
262 | unsigned int chan; |
263 | unsigned int value = 0; | |
264 | int ret = 0; | |
265 | ||
266 | kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL); | |
267 | if (kp == NULL) | |
268 | return -ENOMEM; | |
269 | ||
270 | platform_set_drvdata(pdev, kp); | |
271 | ||
272 | kp->chip.dev = &pdev->dev; | |
273 | kp->chip.ops = &kona_pwm_ops; | |
6a4e4bff TK |
274 | kp->chip.npwm = 6; |
275 | kp->chip.of_xlate = of_pwm_xlate_with_flags; | |
276 | kp->chip.of_pwm_n_cells = 3; | |
6a4e4bff | 277 | |
537fe687 | 278 | kp->base = devm_platform_ioremap_resource(pdev, 0); |
6a4e4bff TK |
279 | if (IS_ERR(kp->base)) |
280 | return PTR_ERR(kp->base); | |
281 | ||
282 | kp->clk = devm_clk_get(&pdev->dev, NULL); | |
283 | if (IS_ERR(kp->clk)) { | |
284 | dev_err(&pdev->dev, "failed to get clock: %ld\n", | |
285 | PTR_ERR(kp->clk)); | |
286 | return PTR_ERR(kp->clk); | |
287 | } | |
288 | ||
289 | ret = clk_prepare_enable(kp->clk); | |
290 | if (ret < 0) { | |
291 | dev_err(&pdev->dev, "failed to enable clock: %d\n", ret); | |
292 | return ret; | |
293 | } | |
294 | ||
e23db65f AR |
295 | /* Set push/pull for all channels */ |
296 | for (chan = 0; chan < kp->chip.npwm; chan++) | |
6a4e4bff | 297 | value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan)); |
6a4e4bff TK |
298 | |
299 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
300 | ||
301 | clk_disable_unprepare(kp->clk); | |
302 | ||
fc423f29 | 303 | ret = pwmchip_add(&kp->chip); |
6a4e4bff TK |
304 | if (ret < 0) |
305 | dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); | |
306 | ||
307 | return ret; | |
308 | } | |
309 | ||
310 | static int kona_pwmc_remove(struct platform_device *pdev) | |
311 | { | |
312 | struct kona_pwmc *kp = platform_get_drvdata(pdev); | |
6a4e4bff TK |
313 | |
314 | return pwmchip_remove(&kp->chip); | |
315 | } | |
316 | ||
317 | static const struct of_device_id bcm_kona_pwmc_dt[] = { | |
318 | { .compatible = "brcm,kona-pwm" }, | |
319 | { }, | |
320 | }; | |
321 | MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt); | |
322 | ||
323 | static struct platform_driver kona_pwmc_driver = { | |
324 | .driver = { | |
325 | .name = "bcm-kona-pwm", | |
326 | .of_match_table = bcm_kona_pwmc_dt, | |
327 | }, | |
328 | .probe = kona_pwmc_probe, | |
329 | .remove = kona_pwmc_remove, | |
330 | }; | |
331 | module_platform_driver(kona_pwmc_driver); | |
332 | ||
333 | MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@broadcom.com>"); | |
334 | MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>"); | |
335 | MODULE_DESCRIPTION("Broadcom Kona PWM driver"); | |
336 | MODULE_LICENSE("GPL v2"); |