drivers/pwm/pwm-berlin.c

   1 /*
   2  * Marvell Berlin PWM driver
   3  *
   4  * Copyright (C) 2015 Marvell Technology Group Ltd.
   5  *
   6  * Author: Antoine Tenart <antoine.tenart@free-electrons.com>
   7  *
   8  * This file is licensed under the terms of the GNU General Public
   9  * License version 2. This program is licensed "as is" without any
  10  * warranty of any kind, whether express or implied.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/io.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pwm.h>
  19 #include <linux/slab.h>
  20
  21 #define BERLIN_PWM_EN                   0x0
  22 #define  BERLIN_PWM_ENABLE              BIT(0)
  23 #define BERLIN_PWM_CONTROL              0x4
  24 /*
  25  * The prescaler claims to support 8 different moduli, configured using the
  26  * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64,
  27  * 256, 1024, and 4096.)  However, the moduli from 4 to 1024 appear to be
  28  * implemented by internally shifting TCNT left without adding additional
  29  * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff;
  30  * for 8, 0x1fff; and so on. This means that those moduli are entirely
  31  * useless, as we could just do the shift ourselves. The 4096 modulus is
  32  * implemented with a real prescaler, so we do use that, but we treat it
  33  * as a flag instead of pretending the modulus is actually configurable.
  34  */
  35 #define  BERLIN_PWM_PRESCALE_4096       0x7
  36 #define  BERLIN_PWM_INVERT_POLARITY     BIT(3)
  37 #define BERLIN_PWM_DUTY                 0x8
  38 #define BERLIN_PWM_TCNT                 0xc
  39 #define  BERLIN_PWM_MAX_TCNT            65535
  40
  41 struct berlin_pwm_channel {
  42         u32 enable;
  43         u32 ctrl;
  44         u32 duty;
  45         u32 tcnt;
  46 };
  47
  48 struct berlin_pwm_chip {
  49         struct pwm_chip chip;
  50         struct clk *clk;
  51         void __iomem *base;
  52 };
  53
  54 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
  55 {
  56         return container_of(chip, struct berlin_pwm_chip, chip);
  57 }
  58
  59 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc,
  60                                    unsigned int channel, unsigned long offset)
  61 {
  62         return readl_relaxed(bpc->base + channel * 0x10 + offset);
  63 }
  64
  65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc,
  66                                      unsigned int channel, u32 value,
  67                                      unsigned long offset)
  68 {
  69         writel_relaxed(value, bpc->base + channel * 0x10 + offset);
  70 }
  71
  72 static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  73 {
  74         struct berlin_pwm_channel *channel;
  75
  76         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
  77         if (!channel)
  78                 return -ENOMEM;
  79
  80         return pwm_set_chip_data(pwm, channel);
  81 }
  82
  83 static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  84 {
  85         struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm);
  86
  87         kfree(channel);
  88 }
  89
  90 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  91                              u64 duty_ns, u64 period_ns)
  92 {
  93         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
  94         bool prescale_4096 = false;
  95         u32 value, duty, period;
  96         u64 cycles;
  97
  98         cycles = clk_get_rate(bpc->clk);
  99         cycles *= period_ns;
 100         do_div(cycles, NSEC_PER_SEC);
 101
 102         if (cycles > BERLIN_PWM_MAX_TCNT) {
 103                 prescale_4096 = true;
 104                 cycles >>= 12; // Prescaled by 4096
 105
 106                 if (cycles > BERLIN_PWM_MAX_TCNT)
 107                         return -ERANGE;
 108         }
 109
 110         period = cycles;
 111         cycles *= duty_ns;
 112         do_div(cycles, period_ns);
 113         duty = cycles;
 114
 115         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
 116         if (prescale_4096)
 117                 value |= BERLIN_PWM_PRESCALE_4096;
 118         else
 119                 value &= ~BERLIN_PWM_PRESCALE_4096;
 120         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
 121
 122         berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY);
 123         berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT);
 124
 125         return 0;
 126 }
 127
 128 static int berlin_pwm_set_polarity(struct pwm_chip *chip,
 129                                    struct pwm_device *pwm,
 130                                    enum pwm_polarity polarity)
 131 {
 132         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 133         u32 value;
 134
 135         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
 136
 137         if (polarity == PWM_POLARITY_NORMAL)
 138                 value &= ~BERLIN_PWM_INVERT_POLARITY;
 139         else
 140                 value |= BERLIN_PWM_INVERT_POLARITY;
 141
 142         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
 143
 144         return 0;
 145 }
 146
 147 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 148 {
 149         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 150         u32 value;
 151
 152         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
 153         value |= BERLIN_PWM_ENABLE;
 154         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
 155
 156         return 0;
 157 }
 158
 159 static void berlin_pwm_disable(struct pwm_chip *chip,
 160                                struct pwm_device *pwm)
 161 {
 162         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 163         u32 value;
 164
 165         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
 166         value &= ~BERLIN_PWM_ENABLE;
 167         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
 168 }
 169
 170 static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 171                             const struct pwm_state *state)
 172 {
 173         int err;
 174         bool enabled = pwm->state.enabled;
 175
 176         if (state->polarity != pwm->state.polarity) {
 177                 if (enabled) {
 178                         berlin_pwm_disable(chip, pwm);
 179                         enabled = false;
 180                 }
 181
 182                 err = berlin_pwm_set_polarity(chip, pwm, state->polarity);
 183                 if (err)
 184                         return err;
 185         }
 186
 187         if (!state->enabled) {
 188                 if (enabled)
 189                         berlin_pwm_disable(chip, pwm);
 190                 return 0;
 191         }
 192
 193         if (state->period != pwm->state.period ||
 194             state->duty_cycle != pwm->state.duty_cycle) {
 195                 err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period);
 196                 if (err)
 197                         return err;
 198         }
 199
 200         if (!enabled)
 201                 return berlin_pwm_enable(chip, pwm);
 202
 203         return 0;
 204 }
 205
 206 static const struct pwm_ops berlin_pwm_ops = {
 207         .request = berlin_pwm_request,
 208         .free = berlin_pwm_free,
 209         .apply = berlin_pwm_apply,
 210         .owner = THIS_MODULE,
 211 };
 212
 213 static const struct of_device_id berlin_pwm_match[] = {
 214         { .compatible = "marvell,berlin-pwm" },
 215         { },
 216 };
 217 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
 218
 219 static int berlin_pwm_probe(struct platform_device *pdev)
 220 {
 221         struct berlin_pwm_chip *bpc;
 222         int ret;
 223
 224         bpc = devm_kzalloc(&pdev->dev, sizeof(*bpc), GFP_KERNEL);
 225         if (!bpc)
 226                 return -ENOMEM;
 227
 228         bpc->base = devm_platform_ioremap_resource(pdev, 0);
 229         if (IS_ERR(bpc->base))
 230                 return PTR_ERR(bpc->base);
 231
 232         bpc->clk = devm_clk_get(&pdev->dev, NULL);
 233         if (IS_ERR(bpc->clk))
 234                 return PTR_ERR(bpc->clk);
 235
 236         ret = clk_prepare_enable(bpc->clk);
 237         if (ret)
 238                 return ret;
 239
 240         bpc->chip.dev = &pdev->dev;
 241         bpc->chip.ops = &berlin_pwm_ops;
 242         bpc->chip.npwm = 4;
 243
 244         ret = pwmchip_add(&bpc->chip);
 245         if (ret < 0) {
 246                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 247                 clk_disable_unprepare(bpc->clk);
 248                 return ret;
 249         }
 250
 251         platform_set_drvdata(pdev, bpc);
 252
 253         return 0;
 254 }
 255
 256 static int berlin_pwm_remove(struct platform_device *pdev)
 257 {
 258         struct berlin_pwm_chip *bpc = platform_get_drvdata(pdev);
 259
 260         pwmchip_remove(&bpc->chip);
 261
 262         clk_disable_unprepare(bpc->clk);
 263
 264         return 0;
 265 }
 266
 267 #ifdef CONFIG_PM_SLEEP
 268 static int berlin_pwm_suspend(struct device *dev)
 269 {
 270         struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
 271         unsigned int i;
 272
 273         for (i = 0; i < bpc->chip.npwm; i++) {
 274                 struct berlin_pwm_channel *channel;
 275
 276                 channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
 277                 if (!channel)
 278                         continue;
 279
 280                 channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
 281                 channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL);
 282                 channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY);
 283                 channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT);
 284         }
 285
 286         clk_disable_unprepare(bpc->clk);
 287
 288         return 0;
 289 }
 290
 291 static int berlin_pwm_resume(struct device *dev)
 292 {
 293         struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
 294         unsigned int i;
 295         int ret;
 296
 297         ret = clk_prepare_enable(bpc->clk);
 298         if (ret)
 299                 return ret;
 300
 301         for (i = 0; i < bpc->chip.npwm; i++) {
 302                 struct berlin_pwm_channel *channel;
 303
 304                 channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
 305                 if (!channel)
 306                         continue;
 307
 308                 berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL);
 309                 berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY);
 310                 berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT);
 311                 berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE);
 312         }
 313
 314         return 0;
 315 }
 316 #endif
 317
 318 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
 319                          berlin_pwm_resume);
 320
 321 static struct platform_driver berlin_pwm_driver = {
 322         .probe = berlin_pwm_probe,
 323         .remove = berlin_pwm_remove,
 324         .driver = {
 325                 .name = "berlin-pwm",
 326                 .of_match_table = berlin_pwm_match,
 327                 .pm = &berlin_pwm_pm_ops,
 328         },
 329 };
 330 module_platform_driver(berlin_pwm_driver);
 331
 332 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
 333 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
 334 MODULE_LICENSE("GPL v2");