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 *chip,
  60                                    unsigned int channel, unsigned long offset)
  61 {
  62         return readl_relaxed(chip->base + channel * 0x10 + offset);
  63 }
  64
  65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,
  66                                      unsigned int channel, u32 value,
  67                                      unsigned long offset)
  68 {
  69         writel_relaxed(value, chip->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_dev,
  91                              int duty_ns, int period_ns)
  92 {
  93         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
  94         bool prescale_4096 = false;
  95         u32 value, duty, period;
  96         u64 cycles;
  97
  98         cycles = clk_get_rate(pwm->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(pwm, pwm_dev->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(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
 121
 122         berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
 123         berlin_pwm_writel(pwm, pwm_dev->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_dev,
 130                                    enum pwm_polarity polarity)
 131 {
 132         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 133         u32 value;
 134
 135         value = berlin_pwm_readl(pwm, pwm_dev->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(pwm, pwm_dev->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_dev)
 148 {
 149         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 150         u32 value;
 151
 152         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 153         value |= BERLIN_PWM_ENABLE;
 154         berlin_pwm_writel(pwm, pwm_dev->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_dev)
 161 {
 162         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 163         u32 value;
 164
 165         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 166         value &= ~BERLIN_PWM_ENABLE;
 167         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
 168 }
 169
 170 static const struct pwm_ops berlin_pwm_ops = {
 171         .request = berlin_pwm_request,
 172         .free = berlin_pwm_free,
 173         .config = berlin_pwm_config,
 174         .set_polarity = berlin_pwm_set_polarity,
 175         .enable = berlin_pwm_enable,
 176         .disable = berlin_pwm_disable,
 177         .owner = THIS_MODULE,
 178 };
 179
 180 static const struct of_device_id berlin_pwm_match[] = {
 181         { .compatible = "marvell,berlin-pwm" },
 182         { },
 183 };
 184 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
 185
 186 static int berlin_pwm_probe(struct platform_device *pdev)
 187 {
 188         struct berlin_pwm_chip *pwm;
 189         struct resource *res;
 190         int ret;
 191
 192         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 193         if (!pwm)
 194                 return -ENOMEM;
 195
 196         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 197         pwm->base = devm_ioremap_resource(&pdev->dev, res);
 198         if (IS_ERR(pwm->base))
 199                 return PTR_ERR(pwm->base);
 200
 201         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 202         if (IS_ERR(pwm->clk))
 203                 return PTR_ERR(pwm->clk);
 204
 205         ret = clk_prepare_enable(pwm->clk);
 206         if (ret)
 207                 return ret;
 208
 209         pwm->chip.dev = &pdev->dev;
 210         pwm->chip.ops = &berlin_pwm_ops;
 211         pwm->chip.base = -1;
 212         pwm->chip.npwm = 4;
 213         pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 214         pwm->chip.of_pwm_n_cells = 3;
 215
 216         ret = pwmchip_add(&pwm->chip);
 217         if (ret < 0) {
 218                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 219                 clk_disable_unprepare(pwm->clk);
 220                 return ret;
 221         }
 222
 223         platform_set_drvdata(pdev, pwm);
 224
 225         return 0;
 226 }
 227
 228 static int berlin_pwm_remove(struct platform_device *pdev)
 229 {
 230         struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
 231         int ret;
 232
 233         ret = pwmchip_remove(&pwm->chip);
 234         clk_disable_unprepare(pwm->clk);
 235
 236         return ret;
 237 }
 238
 239 #ifdef CONFIG_PM_SLEEP
 240 static int berlin_pwm_suspend(struct device *dev)
 241 {
 242         struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
 243         unsigned int i;
 244
 245         for (i = 0; i < pwm->chip.npwm; i++) {
 246                 struct berlin_pwm_channel *channel;
 247
 248                 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
 249                 if (!channel)
 250                         continue;
 251
 252                 channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE);
 253                 channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL);
 254                 channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY);
 255                 channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT);
 256         }
 257
 258         clk_disable_unprepare(pwm->clk);
 259
 260         return 0;
 261 }
 262
 263 static int berlin_pwm_resume(struct device *dev)
 264 {
 265         struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
 266         unsigned int i;
 267         int ret;
 268
 269         ret = clk_prepare_enable(pwm->clk);
 270         if (ret)
 271                 return ret;
 272
 273         for (i = 0; i < pwm->chip.npwm; i++) {
 274                 struct berlin_pwm_channel *channel;
 275
 276                 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
 277                 if (!channel)
 278                         continue;
 279
 280                 berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL);
 281                 berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY);
 282                 berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT);
 283                 berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE);
 284         }
 285
 286         return 0;
 287 }
 288 #endif
 289
 290 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
 291                          berlin_pwm_resume);
 292
 293 static struct platform_driver berlin_pwm_driver = {
 294         .probe = berlin_pwm_probe,
 295         .remove = berlin_pwm_remove,
 296         .driver = {
 297                 .name = "berlin-pwm",
 298                 .of_match_table = berlin_pwm_match,
 299                 .pm = &berlin_pwm_pm_ops,
 300         },
 301 };
 302 module_platform_driver(berlin_pwm_driver);
 303
 304 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
 305 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
 306 MODULE_LICENSE("GPL v2");