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