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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 | ||
48 | #define PWM_CONTROL_OFFSET (0x00000000) | |
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 | ||
54 | #define PRESCALE_OFFSET (0x00000004) | |
55 | #define PRESCALE_SHIFT(chan) ((chan) << 2) | |
56 | #define PRESCALE_MASK(chan) (0x7 << PRESCALE_SHIFT(chan)) | |
57 | #define PRESCALE_MIN (0x00000000) | |
58 | #define PRESCALE_MAX (0x00000007) | |
59 | ||
60 | #define PERIOD_COUNT_OFFSET(chan) (0x00000008 + ((chan) << 3)) | |
61 | #define PERIOD_COUNT_MIN (0x00000002) | |
62 | #define PERIOD_COUNT_MAX (0x00ffffff) | |
63 | ||
64 | #define DUTY_CYCLE_HIGH_OFFSET(chan) (0x0000000c + ((chan) << 3)) | |
65 | #define DUTY_CYCLE_HIGH_MIN (0x00000000) | |
66 | #define DUTY_CYCLE_HIGH_MAX (0x00ffffff) | |
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 | ||
79 | static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan) | |
80 | { | |
81 | unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); | |
82 | ||
83 | /* Clear trigger bit but set smooth bit to maintain old output */ | |
84 | value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan); | |
85 | value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); | |
86 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
87 | ||
88 | /* Set trigger bit and clear smooth bit to apply new settings */ | |
89 | value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); | |
90 | value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan); | |
91 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
92 | } | |
93 | ||
94 | static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm, | |
95 | int duty_ns, int period_ns) | |
96 | { | |
97 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
98 | u64 val, div, rate; | |
99 | unsigned long prescale = PRESCALE_MIN, pc, dc; | |
100 | unsigned int value, chan = pwm->hwpwm; | |
101 | ||
102 | /* | |
103 | * Find period count, duty count and prescale to suit duty_ns and | |
104 | * period_ns. This is done according to formulas described below: | |
105 | * | |
106 | * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE | |
107 | * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE | |
108 | * | |
109 | * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1)) | |
110 | * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1)) | |
111 | */ | |
112 | ||
113 | rate = clk_get_rate(kp->clk); | |
114 | ||
115 | while (1) { | |
116 | div = 1000000000; | |
117 | div *= 1 + prescale; | |
118 | val = rate * period_ns; | |
119 | pc = div64_u64(val, div); | |
120 | val = rate * duty_ns; | |
121 | dc = div64_u64(val, div); | |
122 | ||
123 | /* If duty_ns or period_ns are not achievable then return */ | |
124 | if (pc < PERIOD_COUNT_MIN || dc < DUTY_CYCLE_HIGH_MIN) | |
125 | return -EINVAL; | |
126 | ||
127 | /* If pc and dc are in bounds, the calculation is done */ | |
128 | if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX) | |
129 | break; | |
130 | ||
131 | /* Otherwise, increase prescale and recalculate pc and dc */ | |
132 | if (++prescale > PRESCALE_MAX) | |
133 | return -EINVAL; | |
134 | } | |
135 | ||
136 | /* If the PWM channel is enabled, write the settings to the HW */ | |
137 | if (test_bit(PWMF_ENABLED, &pwm->flags)) { | |
138 | value = readl(kp->base + PRESCALE_OFFSET); | |
139 | value &= ~PRESCALE_MASK(chan); | |
140 | value |= prescale << PRESCALE_SHIFT(chan); | |
141 | writel(value, kp->base + PRESCALE_OFFSET); | |
142 | ||
143 | writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan)); | |
144 | ||
145 | writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); | |
146 | ||
147 | kona_pwmc_apply_settings(kp, chan); | |
148 | } | |
149 | ||
150 | return 0; | |
151 | } | |
152 | ||
153 | static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, | |
154 | enum pwm_polarity polarity) | |
155 | { | |
156 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
157 | unsigned int chan = pwm->hwpwm; | |
158 | unsigned int value; | |
159 | int ret; | |
160 | ||
161 | ret = clk_prepare_enable(kp->clk); | |
162 | if (ret < 0) { | |
163 | dev_err(chip->dev, "failed to enable clock: %d\n", ret); | |
164 | return ret; | |
165 | } | |
166 | ||
167 | value = readl(kp->base + PWM_CONTROL_OFFSET); | |
168 | ||
169 | if (polarity == PWM_POLARITY_NORMAL) | |
170 | value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan); | |
171 | else | |
172 | value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan)); | |
173 | ||
174 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
175 | ||
176 | kona_pwmc_apply_settings(kp, chan); | |
177 | ||
178 | /* Wait for waveform to settle before gating off the clock */ | |
179 | ndelay(400); | |
180 | ||
181 | clk_disable_unprepare(kp->clk); | |
182 | ||
183 | return 0; | |
184 | } | |
185 | ||
186 | static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm) | |
187 | { | |
188 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
189 | int ret; | |
190 | ||
191 | ret = clk_prepare_enable(kp->clk); | |
192 | if (ret < 0) { | |
193 | dev_err(chip->dev, "failed to enable clock: %d\n", ret); | |
194 | return ret; | |
195 | } | |
196 | ||
197 | ret = kona_pwmc_config(chip, pwm, pwm->duty_cycle, pwm->period); | |
198 | if (ret < 0) { | |
199 | clk_disable_unprepare(kp->clk); | |
200 | return ret; | |
201 | } | |
202 | ||
203 | return 0; | |
204 | } | |
205 | ||
206 | static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) | |
207 | { | |
208 | struct kona_pwmc *kp = to_kona_pwmc(chip); | |
209 | unsigned int chan = pwm->hwpwm; | |
210 | ||
211 | /* Simulate a disable by configuring for zero duty */ | |
212 | writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); | |
213 | kona_pwmc_apply_settings(kp, chan); | |
214 | ||
215 | /* Wait for waveform to settle before gating off the clock */ | |
216 | ndelay(400); | |
217 | ||
218 | clk_disable_unprepare(kp->clk); | |
219 | } | |
220 | ||
221 | static const struct pwm_ops kona_pwm_ops = { | |
222 | .config = kona_pwmc_config, | |
223 | .set_polarity = kona_pwmc_set_polarity, | |
224 | .enable = kona_pwmc_enable, | |
225 | .disable = kona_pwmc_disable, | |
226 | .owner = THIS_MODULE, | |
227 | }; | |
228 | ||
229 | static int kona_pwmc_probe(struct platform_device *pdev) | |
230 | { | |
231 | struct kona_pwmc *kp; | |
232 | struct resource *res; | |
233 | unsigned int chan; | |
234 | unsigned int value = 0; | |
235 | int ret = 0; | |
236 | ||
237 | kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL); | |
238 | if (kp == NULL) | |
239 | return -ENOMEM; | |
240 | ||
241 | platform_set_drvdata(pdev, kp); | |
242 | ||
243 | kp->chip.dev = &pdev->dev; | |
244 | kp->chip.ops = &kona_pwm_ops; | |
245 | kp->chip.base = -1; | |
246 | kp->chip.npwm = 6; | |
247 | kp->chip.of_xlate = of_pwm_xlate_with_flags; | |
248 | kp->chip.of_pwm_n_cells = 3; | |
249 | kp->chip.can_sleep = true; | |
250 | ||
251 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
252 | kp->base = devm_ioremap_resource(&pdev->dev, res); | |
253 | if (IS_ERR(kp->base)) | |
254 | return PTR_ERR(kp->base); | |
255 | ||
256 | kp->clk = devm_clk_get(&pdev->dev, NULL); | |
257 | if (IS_ERR(kp->clk)) { | |
258 | dev_err(&pdev->dev, "failed to get clock: %ld\n", | |
259 | PTR_ERR(kp->clk)); | |
260 | return PTR_ERR(kp->clk); | |
261 | } | |
262 | ||
263 | ret = clk_prepare_enable(kp->clk); | |
264 | if (ret < 0) { | |
265 | dev_err(&pdev->dev, "failed to enable clock: %d\n", ret); | |
266 | return ret; | |
267 | } | |
268 | ||
e23db65f AR |
269 | /* Set push/pull for all channels */ |
270 | for (chan = 0; chan < kp->chip.npwm; chan++) | |
6a4e4bff | 271 | value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan)); |
6a4e4bff TK |
272 | |
273 | writel(value, kp->base + PWM_CONTROL_OFFSET); | |
274 | ||
275 | clk_disable_unprepare(kp->clk); | |
276 | ||
e23db65f | 277 | ret = pwmchip_add_with_polarity(&kp->chip, PWM_POLARITY_INVERSED); |
6a4e4bff TK |
278 | if (ret < 0) |
279 | dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); | |
280 | ||
281 | return ret; | |
282 | } | |
283 | ||
284 | static int kona_pwmc_remove(struct platform_device *pdev) | |
285 | { | |
286 | struct kona_pwmc *kp = platform_get_drvdata(pdev); | |
287 | unsigned int chan; | |
288 | ||
289 | for (chan = 0; chan < kp->chip.npwm; chan++) | |
290 | if (test_bit(PWMF_ENABLED, &kp->chip.pwms[chan].flags)) | |
291 | clk_disable_unprepare(kp->clk); | |
292 | ||
293 | return pwmchip_remove(&kp->chip); | |
294 | } | |
295 | ||
296 | static const struct of_device_id bcm_kona_pwmc_dt[] = { | |
297 | { .compatible = "brcm,kona-pwm" }, | |
298 | { }, | |
299 | }; | |
300 | MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt); | |
301 | ||
302 | static struct platform_driver kona_pwmc_driver = { | |
303 | .driver = { | |
304 | .name = "bcm-kona-pwm", | |
305 | .of_match_table = bcm_kona_pwmc_dt, | |
306 | }, | |
307 | .probe = kona_pwmc_probe, | |
308 | .remove = kona_pwmc_remove, | |
309 | }; | |
310 | module_platform_driver(kona_pwmc_driver); | |
311 | ||
312 | MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@broadcom.com>"); | |
313 | MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>"); | |
314 | MODULE_DESCRIPTION("Broadcom Kona PWM driver"); | |
315 | MODULE_LICENSE("GPL v2"); |