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