1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * simple driver for PWM (Pulse Width Modulator) controller
4 *
5 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
6 *
7 * Limitations:
8 * - When disabled the output is driven to 0 independent of the configured
9 * polarity.
10 */
11
12 #include <linux/bitfield.h>
13 #include <linux/bitops.h>
14 #include <linux/clk.h>
15 #include <linux/delay.h>
16 #include <linux/err.h>
17 #include <linux/io.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/of.h>
21 #include <linux/of_device.h>
22 #include <linux/platform_device.h>
23 #include <linux/pwm.h>
24 #include <linux/slab.h>
25
26 #define MX3_PWMCR 0x00 /* PWM Control Register */
27 #define MX3_PWMSR 0x04 /* PWM Status Register */
28 #define MX3_PWMSAR 0x0C /* PWM Sample Register */
29 #define MX3_PWMPR 0x10 /* PWM Period Register */
30
31 #define MX3_PWMCR_FWM GENMASK(27, 26)
32 #define MX3_PWMCR_STOPEN BIT(25)
33 #define MX3_PWMCR_DOZEN BIT(24)
34 #define MX3_PWMCR_WAITEN BIT(23)
35 #define MX3_PWMCR_DBGEN BIT(22)
36 #define MX3_PWMCR_BCTR BIT(21)
37 #define MX3_PWMCR_HCTR BIT(20)
38
39 #define MX3_PWMCR_POUTC GENMASK(19, 18)
40 #define MX3_PWMCR_POUTC_NORMAL 0
41 #define MX3_PWMCR_POUTC_INVERTED 1
42 #define MX3_PWMCR_POUTC_OFF 2
43
44 #define MX3_PWMCR_CLKSRC GENMASK(17, 16)
45 #define MX3_PWMCR_CLKSRC_OFF 0
46 #define MX3_PWMCR_CLKSRC_IPG 1
47 #define MX3_PWMCR_CLKSRC_IPG_HIGH 2
48 #define MX3_PWMCR_CLKSRC_IPG_32K 3
49
50 #define MX3_PWMCR_PRESCALER GENMASK(15, 4)
51
52 #define MX3_PWMCR_SWR BIT(3)
53
54 #define MX3_PWMCR_REPEAT GENMASK(2, 1)
55 #define MX3_PWMCR_REPEAT_1X 0
56 #define MX3_PWMCR_REPEAT_2X 1
57 #define MX3_PWMCR_REPEAT_4X 2
58 #define MX3_PWMCR_REPEAT_8X 3
59
60 #define MX3_PWMCR_EN BIT(0)
61
62 #define MX3_PWMSR_FWE BIT(6)
63 #define MX3_PWMSR_CMP BIT(5)
64 #define MX3_PWMSR_ROV BIT(4)
65 #define MX3_PWMSR_FE BIT(3)
66
67 #define MX3_PWMSR_FIFOAV GENMASK(2, 0)
68 #define MX3_PWMSR_FIFOAV_EMPTY 0
69 #define MX3_PWMSR_FIFOAV_1WORD 1
70 #define MX3_PWMSR_FIFOAV_2WORDS 2
71 #define MX3_PWMSR_FIFOAV_3WORDS 3
72 #define MX3_PWMSR_FIFOAV_4WORDS 4
73
74 #define MX3_PWMCR_PRESCALER_SET(x) FIELD_PREP(MX3_PWMCR_PRESCALER, (x) - 1)
75 #define MX3_PWMCR_PRESCALER_GET(x) (FIELD_GET(MX3_PWMCR_PRESCALER, \
76 (x)) + 1)
77
78 #define MX3_PWM_SWR_LOOP 5
79
80 /* PWMPR register value of 0xffff has the same effect as 0xfffe */
81 #define MX3_PWMPR_MAX 0xfffe
82
83 struct pwm_imx27_chip {
84 struct clk *clk_ipg;
85 struct clk *clk_per;
86 void __iomem *mmio_base;
87 struct pwm_chip chip;
88 };
89
90 #define to_pwm_imx27_chip(chip) container_of(chip, struct pwm_imx27_chip, chip)
91
pwm_imx27_clk_prepare_enable(struct pwm_chip * chip)92 static int pwm_imx27_clk_prepare_enable(struct pwm_chip *chip)
93 {
94 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
95 int ret;
96
97 ret = clk_prepare_enable(imx->clk_ipg);
98 if (ret)
99 return ret;
100
101 ret = clk_prepare_enable(imx->clk_per);
102 if (ret) {
103 clk_disable_unprepare(imx->clk_ipg);
104 return ret;
105 }
106
107 return 0;
108 }
109
pwm_imx27_clk_disable_unprepare(struct pwm_chip * chip)110 static void pwm_imx27_clk_disable_unprepare(struct pwm_chip *chip)
111 {
112 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
113
114 clk_disable_unprepare(imx->clk_per);
115 clk_disable_unprepare(imx->clk_ipg);
116 }
117
pwm_imx27_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)118 static void pwm_imx27_get_state(struct pwm_chip *chip,
119 struct pwm_device *pwm, struct pwm_state *state)
120 {
121 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
122 u32 period, prescaler, pwm_clk, val;
123 u64 tmp;
124 int ret;
125
126 ret = pwm_imx27_clk_prepare_enable(chip);
127 if (ret < 0)
128 return;
129
130 val = readl(imx->mmio_base + MX3_PWMCR);
131
132 if (val & MX3_PWMCR_EN)
133 state->enabled = true;
134 else
135 state->enabled = false;
136
137 switch (FIELD_GET(MX3_PWMCR_POUTC, val)) {
138 case MX3_PWMCR_POUTC_NORMAL:
139 state->polarity = PWM_POLARITY_NORMAL;
140 break;
141 case MX3_PWMCR_POUTC_INVERTED:
142 state->polarity = PWM_POLARITY_INVERSED;
143 break;
144 default:
145 dev_warn(chip->dev, "can't set polarity, output disconnected");
146 }
147
148 prescaler = MX3_PWMCR_PRESCALER_GET(val);
149 pwm_clk = clk_get_rate(imx->clk_per);
150 pwm_clk = DIV_ROUND_CLOSEST_ULL(pwm_clk, prescaler);
151 val = readl(imx->mmio_base + MX3_PWMPR);
152 period = val >= MX3_PWMPR_MAX ? MX3_PWMPR_MAX : val;
153
154 /* PWMOUT (Hz) = PWMCLK / (PWMPR + 2) */
155 tmp = NSEC_PER_SEC * (u64)(period + 2);
156 state->period = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
157
158 /* PWMSAR can be read only if PWM is enabled */
159 if (state->enabled) {
160 val = readl(imx->mmio_base + MX3_PWMSAR);
161 tmp = NSEC_PER_SEC * (u64)(val);
162 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk);
163 } else {
164 state->duty_cycle = 0;
165 }
166
167 if (!state->enabled)
168 pwm_imx27_clk_disable_unprepare(chip);
169 }
170
pwm_imx27_sw_reset(struct pwm_chip * chip)171 static void pwm_imx27_sw_reset(struct pwm_chip *chip)
172 {
173 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
174 struct device *dev = chip->dev;
175 int wait_count = 0;
176 u32 cr;
177
178 writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
179 do {
180 usleep_range(200, 1000);
181 cr = readl(imx->mmio_base + MX3_PWMCR);
182 } while ((cr & MX3_PWMCR_SWR) &&
183 (wait_count++ < MX3_PWM_SWR_LOOP));
184
185 if (cr & MX3_PWMCR_SWR)
186 dev_warn(dev, "software reset timeout\n");
187 }
188
pwm_imx27_wait_fifo_slot(struct pwm_chip * chip,struct pwm_device * pwm)189 static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip,
190 struct pwm_device *pwm)
191 {
192 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
193 struct device *dev = chip->dev;
194 unsigned int period_ms;
195 int fifoav;
196 u32 sr;
197
198 sr = readl(imx->mmio_base + MX3_PWMSR);
199 fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
200 if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
201 period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
202 NSEC_PER_MSEC);
203 msleep(period_ms);
204
205 sr = readl(imx->mmio_base + MX3_PWMSR);
206 if (fifoav == FIELD_GET(MX3_PWMSR_FIFOAV, sr))
207 dev_warn(dev, "there is no free FIFO slot\n");
208 }
209 }
210
pwm_imx27_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)211 static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
212 const struct pwm_state *state)
213 {
214 unsigned long period_cycles, duty_cycles, prescale;
215 struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
216 struct pwm_state cstate;
217 unsigned long long c;
218 int ret;
219 u32 cr;
220
221 pwm_get_state(pwm, &cstate);
222
223 if (state->enabled) {
224 c = clk_get_rate(imx->clk_per);
225 c *= state->period;
226
227 do_div(c, 1000000000);
228 period_cycles = c;
229
230 prescale = period_cycles / 0x10000 + 1;
231
232 period_cycles /= prescale;
233 c = (unsigned long long)period_cycles * state->duty_cycle;
234 do_div(c, state->period);
235 duty_cycles = c;
236
237 /*
238 * according to imx pwm RM, the real period value should be
239 * PERIOD value in PWMPR plus 2.
240 */
241 if (period_cycles > 2)
242 period_cycles -= 2;
243 else
244 period_cycles = 0;
245
246 /*
247 * Wait for a free FIFO slot if the PWM is already enabled, and
248 * flush the FIFO if the PWM was disabled and is about to be
249 * enabled.
250 */
251 if (cstate.enabled) {
252 pwm_imx27_wait_fifo_slot(chip, pwm);
253 } else {
254 ret = pwm_imx27_clk_prepare_enable(chip);
255 if (ret)
256 return ret;
257
258 pwm_imx27_sw_reset(chip);
259 }
260
261 writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
262 writel(period_cycles, imx->mmio_base + MX3_PWMPR);
263
264 cr = MX3_PWMCR_PRESCALER_SET(prescale) |
265 MX3_PWMCR_STOPEN | MX3_PWMCR_DOZEN | MX3_PWMCR_WAITEN |
266 FIELD_PREP(MX3_PWMCR_CLKSRC, MX3_PWMCR_CLKSRC_IPG_HIGH) |
267 MX3_PWMCR_DBGEN | MX3_PWMCR_EN;
268
269 if (state->polarity == PWM_POLARITY_INVERSED)
270 cr |= FIELD_PREP(MX3_PWMCR_POUTC,
271 MX3_PWMCR_POUTC_INVERTED);
272
273 writel(cr, imx->mmio_base + MX3_PWMCR);
274 } else if (cstate.enabled) {
275 writel(0, imx->mmio_base + MX3_PWMCR);
276
277 pwm_imx27_clk_disable_unprepare(chip);
278 }
279
280 return 0;
281 }
282
283 static const struct pwm_ops pwm_imx27_ops = {
284 .apply = pwm_imx27_apply,
285 .get_state = pwm_imx27_get_state,
286 .owner = THIS_MODULE,
287 };
288
289 static const struct of_device_id pwm_imx27_dt_ids[] = {
290 { .compatible = "fsl,imx27-pwm", },
291 { /* sentinel */ }
292 };
293 MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids);
294
pwm_imx27_probe(struct platform_device * pdev)295 static int pwm_imx27_probe(struct platform_device *pdev)
296 {
297 struct pwm_imx27_chip *imx;
298
299 imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
300 if (imx == NULL)
301 return -ENOMEM;
302
303 platform_set_drvdata(pdev, imx);
304
305 imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
306 if (IS_ERR(imx->clk_ipg)) {
307 dev_err(&pdev->dev, "getting ipg clock failed with %ld\n",
308 PTR_ERR(imx->clk_ipg));
309 return PTR_ERR(imx->clk_ipg);
310 }
311
312 imx->clk_per = devm_clk_get(&pdev->dev, "per");
313 if (IS_ERR(imx->clk_per)) {
314 int ret = PTR_ERR(imx->clk_per);
315
316 if (ret != -EPROBE_DEFER)
317 dev_err(&pdev->dev,
318 "failed to get peripheral clock: %d\n",
319 ret);
320
321 return ret;
322 }
323
324 imx->chip.ops = &pwm_imx27_ops;
325 imx->chip.dev = &pdev->dev;
326 imx->chip.base = -1;
327 imx->chip.npwm = 1;
328
329 imx->chip.of_xlate = of_pwm_xlate_with_flags;
330 imx->chip.of_pwm_n_cells = 3;
331
332 imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
333 if (IS_ERR(imx->mmio_base))
334 return PTR_ERR(imx->mmio_base);
335
336 return pwmchip_add(&imx->chip);
337 }
338
pwm_imx27_remove(struct platform_device * pdev)339 static int pwm_imx27_remove(struct platform_device *pdev)
340 {
341 struct pwm_imx27_chip *imx;
342
343 imx = platform_get_drvdata(pdev);
344
345 pwm_imx27_clk_disable_unprepare(&imx->chip);
346
347 return pwmchip_remove(&imx->chip);
348 }
349
350 static struct platform_driver imx_pwm_driver = {
351 .driver = {
352 .name = "pwm-imx27",
353 .of_match_table = pwm_imx27_dt_ids,
354 },
355 .probe = pwm_imx27_probe,
356 .remove = pwm_imx27_remove,
357 };
358 module_platform_driver(imx_pwm_driver);
359
360 MODULE_LICENSE("GPL v2");
361 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
362
