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Linux/drivers/pwm/pwm-tiecap.c

  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 
 43 struct ecap_context {
 44         u32     cap3;
 45         u32     cap4;
 46         u16     ecctl2;
 47 };
 48 
 49 struct 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 
 56 static 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  */
 65 static 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 (!test_bit(PWMF_ENABLED, &pwm->flags)) {
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 (!test_bit(PWMF_ENABLED, &pwm->flags)) {
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 
125 static 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 
145 static 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 
163 static 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 
180 static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
181 {
182         if (test_bit(PWMF_ENABLED, &pwm->flags)) {
183                 dev_warn(chip->dev, "Removing PWM device without disabling\n");
184                 pm_runtime_put_sync(chip->dev);
185         }
186 }
187 
188 static 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 
197 static const struct of_device_id ecap_of_match[] = {
198         { .compatible   = "ti,am33xx-ecap" },
199         {},
200 };
201 MODULE_DEVICE_TABLE(of, ecap_of_match);
202 
203 static 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 
261 pwmss_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 
268 static 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
285 static 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 
294 static 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 
301 static 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 (test_bit(PWMF_ENABLED, &pwm->flags))
310                 pm_runtime_put_sync(dev);
311 
312         return 0;
313 }
314 
315 static 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 (test_bit(PWMF_ENABLED, &pwm->flags))
322                 pm_runtime_get_sync(dev);
323 
324         ecap_pwm_restore_context(pc);
325         return 0;
326 }
327 #endif
328 
329 static SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume);
330 
331 static struct platform_driver ecap_pwm_driver = {
332         .driver = {
333                 .name   = "ecap",
334                 .owner  = THIS_MODULE,
335                 .of_match_table = ecap_of_match,
336                 .pm     = &ecap_pwm_pm_ops,
337         },
338         .probe = ecap_pwm_probe,
339         .remove = ecap_pwm_remove,
340 };
341 
342 module_platform_driver(ecap_pwm_driver);
343 
344 MODULE_DESCRIPTION("ECAP PWM driver");
345 MODULE_AUTHOR("Texas Instruments");
346 MODULE_LICENSE("GPL");
347 

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