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         pwm_set_chip_data(pwm, NULL);
  88         kfree(channel);
  89 }
  90
  91 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
  92                              int duty_ns, int period_ns)
  93 {
  94         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
  95         bool prescale_4096 = false;
  96         u32 value, duty, period;
  97         u64 cycles;
  98
  99         cycles = clk_get_rate(pwm->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(pwm, pwm_dev->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(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
 122
 123         berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
 124         berlin_pwm_writel(pwm, pwm_dev->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_dev,
 131                                    enum pwm_polarity polarity)
 132 {
 133         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 134         u32 value;
 135
 136         value = berlin_pwm_readl(pwm, pwm_dev->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(pwm, pwm_dev->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_dev)
 149 {
 150         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 151         u32 value;
 152
 153         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 154         value |= BERLIN_PWM_ENABLE;
 155         berlin_pwm_writel(pwm, pwm_dev->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_dev)
 162 {
 163         struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 164         u32 value;
 165
 166         value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
 167         value &= ~BERLIN_PWM_ENABLE;
 168         berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
 169 }
 170
 171 static const struct pwm_ops berlin_pwm_ops = {
 172         .request = berlin_pwm_request,
 173         .free = berlin_pwm_free,
 174         .config = berlin_pwm_config,
 175         .set_polarity = berlin_pwm_set_polarity,
 176         .enable = berlin_pwm_enable,
 177         .disable = berlin_pwm_disable,
 178         .owner = THIS_MODULE,
 179 };
 180
 181 static const struct of_device_id berlin_pwm_match[] = {
 182         { .compatible = "marvell,berlin-pwm" },
 183         { },
 184 };
 185 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
 186
 187 static int berlin_pwm_probe(struct platform_device *pdev)
 188 {
 189         struct berlin_pwm_chip *pwm;
 190         struct resource *res;
 191         int ret;
 192
 193         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 194         if (!pwm)
 195                 return -ENOMEM;
 196
 197         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 198         pwm->base = devm_ioremap_resource(&pdev->dev, res);
 199         if (IS_ERR(pwm->base))
 200                 return PTR_ERR(pwm->base);
 201
 202         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 203         if (IS_ERR(pwm->clk))
 204                 return PTR_ERR(pwm->clk);
 205
 206         ret = clk_prepare_enable(pwm->clk);
 207         if (ret)
 208                 return ret;
 209
 210         pwm->chip.dev = &pdev->dev;
 211         pwm->chip.ops = &berlin_pwm_ops;
 212         pwm->chip.base = -1;
 213         pwm->chip.npwm = 4;
 214         pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 215         pwm->chip.of_pwm_n_cells = 3;
 216
 217         ret = pwmchip_add(&pwm->chip);
 218         if (ret < 0) {
 219                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 220                 clk_disable_unprepare(pwm->clk);
 221                 return ret;
 222         }
 223
 224         platform_set_drvdata(pdev, pwm);
 225
 226         return 0;
 227 }
 228
 229 static int berlin_pwm_remove(struct platform_device *pdev)
 230 {
 231         struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
 232         int ret;
 233
 234         ret = pwmchip_remove(&pwm->chip);
 235         clk_disable_unprepare(pwm->clk);
 236
 237         return ret;
 238 }
 239
 240 #ifdef CONFIG_PM_SLEEP
 241 static int berlin_pwm_suspend(struct device *dev)
 242 {
 243         struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
 244         unsigned int i;
 245
 246         for (i = 0; i < pwm->chip.npwm; i++) {
 247                 struct berlin_pwm_channel *channel;
 248
 249                 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
 250                 if (!channel)
 251                         continue;
 252
 253                 channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE);
 254                 channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL);
 255                 channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY);
 256                 channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT);
 257         }
 258
 259         clk_disable_unprepare(pwm->clk);
 260
 261         return 0;
 262 }
 263
 264 static int berlin_pwm_resume(struct device *dev)
 265 {
 266         struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
 267         unsigned int i;
 268         int ret;
 269
 270         ret = clk_prepare_enable(pwm->clk);
 271         if (ret)
 272                 return ret;
 273
 274         for (i = 0; i < pwm->chip.npwm; i++) {
 275                 struct berlin_pwm_channel *channel;
 276
 277                 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
 278                 if (!channel)
 279                         continue;
 280
 281                 berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL);
 282                 berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY);
 283                 berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT);
 284                 berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE);
 285         }
 286
 287         return 0;
 288 }
 289 #endif
 290
 291 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
 292                          berlin_pwm_resume);
 293
 294 static struct platform_driver berlin_pwm_driver = {
 295         .probe = berlin_pwm_probe,
 296         .remove = berlin_pwm_remove,
 297         .driver = {
 298                 .name = "berlin-pwm",
 299                 .of_match_table = berlin_pwm_match,
 300                 .pm = &berlin_pwm_pm_ops,
 301         },
 302 };
 303 module_platform_driver(berlin_pwm_driver);
 304
 305 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
 306 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
 307 MODULE_LICENSE("GPL v2");