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                 .of_match_table = ecap_of_match,
 335                 .pm     = &ecap_pwm_pm_ops,
 336         },
 337         .probe = ecap_pwm_probe,
 338         .remove = ecap_pwm_remove,
 339 };
 340
 341 module_platform_driver(ecap_pwm_driver);
 342
 343 MODULE_DESCRIPTION("ECAP PWM driver");
 344 MODULE_AUTHOR("Texas Instruments");
 345 MODULE_LICENSE("GPL");