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 #include <linux/pinctrl/consumer.h>
  30
  31 #include "pwm-tipwmss.h"
  32
  33 /* ECAP registers and bits definitions */
  34 #define CAP1                    0x08
  35 #define CAP2                    0x0C
  36 #define CAP3                    0x10
  37 #define CAP4                    0x14
  38 #define ECCTL2                  0x2A
  39 #define ECCTL2_APWM_POL_LOW     BIT(10)
  40 #define ECCTL2_APWM_MODE        BIT(9)
  41 #define ECCTL2_SYNC_SEL_DISA    (BIT(7) | BIT(6))
  42 #define ECCTL2_TSCTR_FREERUN    BIT(4)
  43
  44 struct ecap_pwm_chip {
  45         struct pwm_chip chip;
  46         unsigned int    clk_rate;
  47         void __iomem    *mmio_base;
  48 };
  49
  50 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
  51 {
  52         return container_of(chip, struct ecap_pwm_chip, chip);
  53 }
  54
  55 /*
  56  * period_ns = 10^9 * period_cycles / PWM_CLK_RATE
  57  * duty_ns   = 10^9 * duty_cycles / PWM_CLK_RATE
  58  */
  59 static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  60                 int duty_ns, int period_ns)
  61 {
  62         struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
  63         unsigned long long c;
  64         unsigned long period_cycles, duty_cycles;
  65         unsigned int reg_val;
  66
  67         if (period_ns > NSEC_PER_SEC)
  68                 return -ERANGE;
  69
  70         c = pc->clk_rate;
  71         c = c * period_ns;
  72         do_div(c, NSEC_PER_SEC);
  73         period_cycles = (unsigned long)c;
  74
  75         if (period_cycles < 1) {
  76                 period_cycles = 1;
  77                 duty_cycles = 1;
  78         } else {
  79                 c = pc->clk_rate;
  80                 c = c * duty_ns;
  81                 do_div(c, NSEC_PER_SEC);
  82                 duty_cycles = (unsigned long)c;
  83         }
  84
  85         pm_runtime_get_sync(pc->chip.dev);
  86
  87         reg_val = readw(pc->mmio_base + ECCTL2);
  88
  89         /* Configure APWM mode & disable sync option */
  90         reg_val |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA;
  91
  92         writew(reg_val, pc->mmio_base + ECCTL2);
  93
  94         if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
  95                 /* Update active registers if not running */
  96                 writel(duty_cycles, pc->mmio_base + CAP2);
  97                 writel(period_cycles, pc->mmio_base + CAP1);
  98         } else {
  99                 /*
 100                  * Update shadow registers to configure period and
 101                  * compare values. This helps current PWM period to
 102                  * complete on reconfiguring
 103                  */
 104                 writel(duty_cycles, pc->mmio_base + CAP4);
 105                 writel(period_cycles, pc->mmio_base + CAP3);
 106         }
 107
 108         if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
 109                 reg_val = readw(pc->mmio_base + ECCTL2);
 110                 /* Disable APWM mode to put APWM output Low */
 111                 reg_val &= ~ECCTL2_APWM_MODE;
 112                 writew(reg_val, pc->mmio_base + ECCTL2);
 113         }
 114
 115         pm_runtime_put_sync(pc->chip.dev);
 116         return 0;
 117 }
 118
 119 static int ecap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 120                 enum pwm_polarity polarity)
 121 {
 122         struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
 123         unsigned short reg_val;
 124
 125         pm_runtime_get_sync(pc->chip.dev);
 126         reg_val = readw(pc->mmio_base + ECCTL2);
 127         if (polarity == PWM_POLARITY_INVERSED)
 128                 /* Duty cycle defines LOW period of PWM */
 129                 reg_val |= ECCTL2_APWM_POL_LOW;
 130         else
 131                 /* Duty cycle defines HIGH period of PWM */
 132                 reg_val &= ~ECCTL2_APWM_POL_LOW;
 133
 134         writew(reg_val, pc->mmio_base + ECCTL2);
 135         pm_runtime_put_sync(pc->chip.dev);
 136         return 0;
 137 }
 138
 139 static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 140 {
 141         struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
 142         unsigned int reg_val;
 143
 144         /* Leave clock enabled on enabling PWM */
 145         pm_runtime_get_sync(pc->chip.dev);
 146
 147         /*
 148          * Enable 'Free run Time stamp counter mode' to start counter
 149          * and  'APWM mode' to enable APWM output
 150          */
 151         reg_val = readw(pc->mmio_base + ECCTL2);
 152         reg_val |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE;
 153         writew(reg_val, pc->mmio_base + ECCTL2);
 154         return 0;
 155 }
 156
 157 static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 158 {
 159         struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
 160         unsigned int reg_val;
 161
 162         /*
 163          * Disable 'Free run Time stamp counter mode' to stop counter
 164          * and 'APWM mode' to put APWM output to low
 165          */
 166         reg_val = readw(pc->mmio_base + ECCTL2);
 167         reg_val &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE);
 168         writew(reg_val, pc->mmio_base + ECCTL2);
 169
 170         /* Disable clock on PWM disable */
 171         pm_runtime_put_sync(pc->chip.dev);
 172 }
 173
 174 static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 175 {
 176         if (test_bit(PWMF_ENABLED, &pwm->flags)) {
 177                 dev_warn(chip->dev, "Removing PWM device without disabling\n");
 178                 pm_runtime_put_sync(chip->dev);
 179         }
 180 }
 181
 182 static const struct pwm_ops ecap_pwm_ops = {
 183         .free           = ecap_pwm_free,
 184         .config         = ecap_pwm_config,
 185         .set_polarity   = ecap_pwm_set_polarity,
 186         .enable         = ecap_pwm_enable,
 187         .disable        = ecap_pwm_disable,
 188         .owner          = THIS_MODULE,
 189 };
 190
 191 static const struct of_device_id ecap_of_match[] = {
 192         { .compatible   = "ti,am33xx-ecap" },
 193         {},
 194 };
 195 MODULE_DEVICE_TABLE(of, ecap_of_match);
 196
 197 static int __devinit ecap_pwm_probe(struct platform_device *pdev)
 198 {
 199         int ret;
 200         struct resource *r;
 201         struct clk *clk;
 202         struct ecap_pwm_chip *pc;
 203         u16 status;
 204         struct pinctrl *pinctrl;
 205
 206         pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
 207         if (IS_ERR(pinctrl))
 208                 dev_warn(&pdev->dev, "unable to select pin group\n");
 209
 210         pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
 211         if (!pc) {
 212                 dev_err(&pdev->dev, "failed to allocate memory\n");
 213                 return -ENOMEM;
 214         }
 215
 216         clk = devm_clk_get(&pdev->dev, "fck");
 217         if (IS_ERR(clk)) {
 218                 dev_err(&pdev->dev, "failed to get clock\n");
 219                 return PTR_ERR(clk);
 220         }
 221
 222         pc->clk_rate = clk_get_rate(clk);
 223         if (!pc->clk_rate) {
 224                 dev_err(&pdev->dev, "failed to get clock rate\n");
 225                 return -EINVAL;
 226         }
 227
 228         pc->chip.dev = &pdev->dev;
 229         pc->chip.ops = &ecap_pwm_ops;
 230         pc->chip.of_xlate = of_pwm_xlate_with_flags;
 231         pc->chip.of_pwm_n_cells = 3;
 232         pc->chip.base = -1;
 233         pc->chip.npwm = 1;
 234
 235         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 236         if (!r) {
 237                 dev_err(&pdev->dev, "no memory resource defined\n");
 238                 return -ENODEV;
 239         }
 240
 241         pc->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
 242         if (!pc->mmio_base)
 243                 return -EADDRNOTAVAIL;
 244
 245         ret = pwmchip_add(&pc->chip);
 246         if (ret < 0) {
 247                 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
 248                 return ret;
 249         }
 250
 251         pm_runtime_enable(&pdev->dev);
 252         pm_runtime_get_sync(&pdev->dev);
 253
 254         status = pwmss_submodule_state_change(pdev->dev.parent,
 255                         PWMSS_ECAPCLK_EN);
 256         if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
 257                 dev_err(&pdev->dev, "PWMSS config space clock enable failed\n");
 258                 ret = -EINVAL;
 259                 goto pwmss_clk_failure;
 260         }
 261
 262         pm_runtime_put_sync(&pdev->dev);
 263
 264         platform_set_drvdata(pdev, pc);
 265         return 0;
 266
 267 pwmss_clk_failure:
 268         pm_runtime_put_sync(&pdev->dev);
 269         pm_runtime_disable(&pdev->dev);
 270         pwmchip_remove(&pc->chip);
 271         return ret;
 272 }
 273
 274 static int __devexit ecap_pwm_remove(struct platform_device *pdev)
 275 {
 276         struct ecap_pwm_chip *pc = platform_get_drvdata(pdev);
 277
 278         pm_runtime_get_sync(&pdev->dev);
 279         /*
 280          * Due to hardware misbehaviour, acknowledge of the stop_req
 281          * is missing. Hence checking of the status bit skipped.
 282          */
 283         pwmss_submodule_state_change(pdev->dev.parent, PWMSS_ECAPCLK_STOP_REQ);
 284         pm_runtime_put_sync(&pdev->dev);
 285
 286         pm_runtime_put_sync(&pdev->dev);
 287         pm_runtime_disable(&pdev->dev);
 288         return pwmchip_remove(&pc->chip);
 289 }
 290
 291 static struct platform_driver ecap_pwm_driver = {
 292         .driver = {
 293                 .name   = "ecap",
 294                 .owner  = THIS_MODULE,
 295                 .of_match_table = ecap_of_match,
 296         },
 297         .probe = ecap_pwm_probe,
 298         .remove = __devexit_p(ecap_pwm_remove),
 299 };
 300
 301 module_platform_driver(ecap_pwm_driver);
 302
 303 MODULE_DESCRIPTION("ECAP PWM driver");
 304 MODULE_AUTHOR("Texas Instruments");
 305 MODULE_LICENSE("GPL");