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 #define BERLIN_PWM_NUMPWMS              4
  43
  44 struct berlin_pwm_channel {
  45         u32 enable;
  46         u32 ctrl;
  47         u32 duty;
  48         u32 tcnt;
  49 };
  50
  51 struct berlin_pwm_chip {
  52         struct clk *clk;
  53         void __iomem *base;
  54         struct berlin_pwm_channel channel[BERLIN_PWM_NUMPWMS];
  55 };
  56
  57 static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
  58 {
  59         return pwmchip_get_drvdata(chip);
  60 }
  61
  62 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc,
  63                                    unsigned int channel, unsigned long offset)
  64 {
  65         return readl_relaxed(bpc->base + channel * 0x10 + offset);
  66 }
  67
  68 static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc,
  69                                      unsigned int channel, u32 value,
  70                                      unsigned long offset)
  71 {
  72         writel_relaxed(value, bpc->base + channel * 0x10 + offset);
  73 }
  74
  75 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  76                              u64 duty_ns, u64 period_ns)
  77 {
  78         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
  79         bool prescale_4096 = false;
  80         u32 value, duty, period;
  81         u64 cycles;
  82
  83         cycles = clk_get_rate(bpc->clk);
  84         cycles *= period_ns;
  85         do_div(cycles, NSEC_PER_SEC);
  86
  87         if (cycles > BERLIN_PWM_MAX_TCNT) {
  88                 prescale_4096 = true;
  89                 cycles >>= 12; // Prescaled by 4096
  90
  91                 if (cycles > BERLIN_PWM_MAX_TCNT)
  92                         return -ERANGE;
  93         }
  94
  95         period = cycles;
  96         cycles *= duty_ns;
  97         do_div(cycles, period_ns);
  98         duty = cycles;
  99
 100         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
 101         if (prescale_4096)
 102                 value |= BERLIN_PWM_PRESCALE_4096;
 103         else
 104                 value &= ~BERLIN_PWM_PRESCALE_4096;
 105         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
 106
 107         berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY);
 108         berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT);
 109
 110         return 0;
 111 }
 112
 113 static int berlin_pwm_set_polarity(struct pwm_chip *chip,
 114                                    struct pwm_device *pwm,
 115                                    enum pwm_polarity polarity)
 116 {
 117         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 118         u32 value;
 119
 120         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_CONTROL);
 121
 122         if (polarity == PWM_POLARITY_NORMAL)
 123                 value &= ~BERLIN_PWM_INVERT_POLARITY;
 124         else
 125                 value |= BERLIN_PWM_INVERT_POLARITY;
 126
 127         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
 128
 129         return 0;
 130 }
 131
 132 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 133 {
 134         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 135         u32 value;
 136
 137         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
 138         value |= BERLIN_PWM_ENABLE;
 139         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
 140
 141         return 0;
 142 }
 143
 144 static void berlin_pwm_disable(struct pwm_chip *chip,
 145                                struct pwm_device *pwm)
 146 {
 147         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 148         u32 value;
 149
 150         value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
 151         value &= ~BERLIN_PWM_ENABLE;
 152         berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
 153 }
 154
 155 static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 156                             const struct pwm_state *state)
 157 {
 158         int err;
 159         bool enabled = pwm->state.enabled;
 160
 161         if (state->polarity != pwm->state.polarity) {
 162                 if (enabled) {
 163                         berlin_pwm_disable(chip, pwm);
 164                         enabled = false;
 165                 }
 166
 167                 err = berlin_pwm_set_polarity(chip, pwm, state->polarity);
 168                 if (err)
 169                         return err;
 170         }
 171
 172         if (!state->enabled) {
 173                 if (enabled)
 174                         berlin_pwm_disable(chip, pwm);
 175                 return 0;
 176         }
 177
 178         err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period);
 179         if (err)
 180                 return err;
 181
 182         if (!enabled)
 183                 return berlin_pwm_enable(chip, pwm);
 184
 185         return 0;
 186 }
 187
 188 static const struct pwm_ops berlin_pwm_ops = {
 189         .apply = berlin_pwm_apply,
 190 };
 191
 192 static const struct of_device_id berlin_pwm_match[] = {
 193         { .compatible = "marvell,berlin-pwm" },
 194         { },
 195 };
 196 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
 197
 198 static int berlin_pwm_probe(struct platform_device *pdev)
 199 {
 200         struct pwm_chip *chip;
 201         struct berlin_pwm_chip *bpc;
 202         int ret;
 203
 204         chip = devm_pwmchip_alloc(&pdev->dev, BERLIN_PWM_NUMPWMS, sizeof(*bpc));
 205         if (IS_ERR(chip))
 206                 return PTR_ERR(chip);
 207         bpc = to_berlin_pwm_chip(chip);
 208
 209         bpc->base = devm_platform_ioremap_resource(pdev, 0);
 210         if (IS_ERR(bpc->base))
 211                 return PTR_ERR(bpc->base);
 212
 213         bpc->clk = devm_clk_get_enabled(&pdev->dev, NULL);
 214         if (IS_ERR(bpc->clk))
 215                 return PTR_ERR(bpc->clk);
 216
 217         chip->ops = &berlin_pwm_ops;
 218
 219         ret = devm_pwmchip_add(&pdev->dev, chip);
 220         if (ret < 0)
 221                 return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");
 222
 223         platform_set_drvdata(pdev, chip);
 224
 225         return 0;
 226 }
 227
 228 static int berlin_pwm_suspend(struct device *dev)
 229 {
 230         struct pwm_chip *chip = dev_get_drvdata(dev);
 231         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 232         unsigned int i;
 233
 234         for (i = 0; i < chip->npwm; i++) {
 235                 struct berlin_pwm_channel *channel = &bpc->channel[i];
 236
 237                 channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
 238                 channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL);
 239                 channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY);
 240                 channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT);
 241         }
 242
 243         clk_disable_unprepare(bpc->clk);
 244
 245         return 0;
 246 }
 247
 248 static int berlin_pwm_resume(struct device *dev)
 249 {
 250         struct pwm_chip *chip = dev_get_drvdata(dev);
 251         struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
 252         unsigned int i;
 253         int ret;
 254
 255         ret = clk_prepare_enable(bpc->clk);
 256         if (ret)
 257                 return ret;
 258
 259         for (i = 0; i < chip->npwm; i++) {
 260                 struct berlin_pwm_channel *channel = &bpc->channel[i];
 261
 262                 berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL);
 263                 berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY);
 264                 berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT);
 265                 berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE);
 266         }
 267
 268         return 0;
 269 }
 270
 271 static DEFINE_SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
 272                                 berlin_pwm_resume);
 273
 274 static struct platform_driver berlin_pwm_driver = {
 275         .probe = berlin_pwm_probe,
 276         .driver = {
 277                 .name = "berlin-pwm",
 278                 .of_match_table = berlin_pwm_match,
 279                 .pm = pm_ptr(&berlin_pwm_pm_ops),
 280         },
 281 };
 282 module_platform_driver(berlin_pwm_driver);
 283
 284 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
 285 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
 286 MODULE_LICENSE("GPL v2");