kernel/drivers/pwm/pwm-sun4i.c

   1 /*
   2  * Driver for Allwinner sun4i Pulse Width Modulation Controller
   3  *
   4  * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
   5  *
   6  * Licensed under GPLv2.
   7  */
   8
   9 #include <linux/bitops.h>
  10 #include <linux/clk.h>
  11 #include <linux/err.h>
  12 #include <linux/io.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/of_device.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/pwm.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/time.h>
  21
  22 #define PWM_CTRL_REG            0x0
  23
  24 #define PWM_CH_PRD_BASE         0x4
  25 #define PWM_CH_PRD_OFFSET       0x4
  26 #define PWM_CH_PRD(ch)          (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))
  27
  28 #define PWMCH_OFFSET            15
  29 #define PWM_PRESCAL_MASK        GENMASK(3, 0)
  30 #define PWM_PRESCAL_OFF         0
  31 #define PWM_EN                  BIT(4)
  32 #define PWM_ACT_STATE           BIT(5)
  33 #define PWM_CLK_GATING          BIT(6)
  34 #define PWM_MODE                BIT(7)
  35 #define PWM_PULSE               BIT(8)
  36 #define PWM_BYPASS              BIT(9)
  37
  38 #define PWM_RDY_BASE            28
  39 #define PWM_RDY_OFFSET          1
  40 #define PWM_RDY(ch)             BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))
  41
  42 #define PWM_PRD(prd)            (((prd) - 1) << 16)
  43 #define PWM_PRD_MASK            GENMASK(15, 0)
  44
  45 #define PWM_DTY_MASK            GENMASK(15, 0)
  46
  47 #define BIT_CH(bit, chan)       ((bit) << ((chan) * PWMCH_OFFSET))
  48
  49 static const u32 prescaler_table[] = {
  50         120,
  51         180,
  52         240,
  53         360,
  54         480,
  55         0,
  56         0,
  57         0,
  58         12000,
  59         24000,
  60         36000,
  61         48000,
  62         72000,
  63         0,
  64         0,
  65         0, /* Actually 1 but tested separately */
  66 };
  67
  68 struct sun4i_pwm_data {
  69         bool has_prescaler_bypass;
  70         bool has_rdy;
  71 };
  72
  73 struct sun4i_pwm_chip {
  74         struct pwm_chip chip;
  75         struct clk *clk;
  76         void __iomem *base;
  77         spinlock_t ctrl_lock;
  78         const struct sun4i_pwm_data *data;
  79 };
  80
  81 static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
  82 {
  83         return container_of(chip, struct sun4i_pwm_chip, chip);
  84 }
  85
  86 static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
  87                                   unsigned long offset)
  88 {
  89         return readl(chip->base + offset);
  90 }
  91
  92 static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
  93                                     u32 val, unsigned long offset)
  94 {
  95         writel(val, chip->base + offset);
  96 }
  97
  98 static int sun4i_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  99                             int duty_ns, int period_ns)
 100 {
 101         struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 102         u32 prd, dty, val, clk_gate;
 103         u64 clk_rate, div = 0;
 104         unsigned int prescaler = 0;
 105         int err;
 106
 107         clk_rate = clk_get_rate(sun4i_pwm->clk);
 108
 109         if (sun4i_pwm->data->has_prescaler_bypass) {
 110                 /* First, test without any prescaler when available */
 111                 prescaler = PWM_PRESCAL_MASK;
 112                 /*
 113                  * When not using any prescaler, the clock period in nanoseconds
 114                  * is not an integer so round it half up instead of
 115                  * truncating to get less surprising values.
 116                  */
 117                 div = clk_rate * period_ns + NSEC_PER_SEC/2;
 118                 do_div(div, NSEC_PER_SEC);
 119                 if (div - 1 > PWM_PRD_MASK)
 120                         prescaler = 0;
 121         }
 122
 123         if (prescaler == 0) {
 124                 /* Go up from the first divider */
 125                 for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
 126                         if (!prescaler_table[prescaler])
 127                                 continue;
 128                         div = clk_rate;
 129                         do_div(div, prescaler_table[prescaler]);
 130                         div = div * period_ns;
 131                         do_div(div, NSEC_PER_SEC);
 132                         if (div - 1 <= PWM_PRD_MASK)
 133                                 break;
 134                 }
 135
 136                 if (div - 1 > PWM_PRD_MASK) {
 137                         dev_err(chip->dev, "period exceeds the maximum value\n");
 138                         return -EINVAL;
 139                 }
 140         }
 141
 142         prd = div;
 143         div *= duty_ns;
 144         do_div(div, period_ns);
 145         dty = div;
 146
 147         err = clk_prepare_enable(sun4i_pwm->clk);
 148         if (err) {
 149                 dev_err(chip->dev, "failed to enable PWM clock\n");
 150                 return err;
 151         }
 152
 153         spin_lock(&sun4i_pwm->ctrl_lock);
 154         val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 155
 156         if (sun4i_pwm->data->has_rdy && (val & PWM_RDY(pwm->hwpwm))) {
 157                 spin_unlock(&sun4i_pwm->ctrl_lock);
 158                 clk_disable_unprepare(sun4i_pwm->clk);
 159                 return -EBUSY;
 160         }
 161
 162         clk_gate = val & BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 163         if (clk_gate) {
 164                 val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 165                 sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 166         }
 167
 168         val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 169         val &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
 170         val |= BIT_CH(prescaler, pwm->hwpwm);
 171         sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 172
 173         val = (dty & PWM_DTY_MASK) | PWM_PRD(prd);
 174         sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
 175
 176         if (clk_gate) {
 177                 val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 178                 val |= clk_gate;
 179                 sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 180         }
 181
 182         spin_unlock(&sun4i_pwm->ctrl_lock);
 183         clk_disable_unprepare(sun4i_pwm->clk);
 184
 185         return 0;
 186 }
 187
 188 static int sun4i_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
 189                                   enum pwm_polarity polarity)
 190 {
 191         struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 192         u32 val;
 193         int ret;
 194
 195         ret = clk_prepare_enable(sun4i_pwm->clk);
 196         if (ret) {
 197                 dev_err(chip->dev, "failed to enable PWM clock\n");
 198                 return ret;
 199         }
 200
 201         spin_lock(&sun4i_pwm->ctrl_lock);
 202         val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 203
 204         if (polarity != PWM_POLARITY_NORMAL)
 205                 val &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
 206         else
 207                 val |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
 208
 209         sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 210
 211         spin_unlock(&sun4i_pwm->ctrl_lock);
 212         clk_disable_unprepare(sun4i_pwm->clk);
 213
 214         return 0;
 215 }
 216
 217 static int sun4i_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 218 {
 219         struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 220         u32 val;
 221         int ret;
 222
 223         ret = clk_prepare_enable(sun4i_pwm->clk);
 224         if (ret) {
 225                 dev_err(chip->dev, "failed to enable PWM clock\n");
 226                 return ret;
 227         }
 228
 229         spin_lock(&sun4i_pwm->ctrl_lock);
 230         val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 231         val |= BIT_CH(PWM_EN, pwm->hwpwm);
 232         val |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 233         sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 234         spin_unlock(&sun4i_pwm->ctrl_lock);
 235
 236         return 0;
 237 }
 238
 239 static void sun4i_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 240 {
 241         struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
 242         u32 val;
 243
 244         spin_lock(&sun4i_pwm->ctrl_lock);
 245         val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
 246         val &= ~BIT_CH(PWM_EN, pwm->hwpwm);
 247         val &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
 248         sun4i_pwm_writel(sun4i_pwm, val, PWM_CTRL_REG);
 249         spin_unlock(&sun4i_pwm->ctrl_lock);
 250
 251         clk_disable_unprepare(sun4i_pwm->clk);
 252 }
 253
 254 static const struct pwm_ops sun4i_pwm_ops = {
 255         .config = sun4i_pwm_config,
 256         .set_polarity = sun4i_pwm_set_polarity,
 257         .enable = sun4i_pwm_enable,
 258         .disable = sun4i_pwm_disable,
 259         .owner = THIS_MODULE,
 260 };
 261
 262 static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
 263         .has_prescaler_bypass = false,
 264         .has_rdy = false,
 265 };
 266
 267 static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
 268         .has_prescaler_bypass = true,
 269         .has_rdy = true,
 270 };
 271
 272 static const struct of_device_id sun4i_pwm_dt_ids[] = {
 273         {
 274                 .compatible = "allwinner,sun4i-a10-pwm",
 275                 .data = &sun4i_pwm_data_a10,
 276         }, {
 277                 .compatible = "allwinner,sun7i-a20-pwm",
 278                 .data = &sun4i_pwm_data_a20,
 279         }, {
 280                 /* sentinel */
 281         },
 282 };
 283 MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);
 284
 285 static int sun4i_pwm_probe(struct platform_device *pdev)
 286 {
 287         struct sun4i_pwm_chip *pwm;
 288         struct resource *res;
 289         u32 val;
 290         int i, ret;
 291         const struct of_device_id *match;
 292
 293         match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
 294
 295         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 296         if (!pwm)
 297                 return -ENOMEM;
 298
 299         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 300         pwm->base = devm_ioremap_resource(&pdev->dev, res);
 301         if (IS_ERR(pwm->base))
 302                 return PTR_ERR(pwm->base);
 303
 304         pwm->clk = devm_clk_get(&pdev->dev, NULL);
 305         if (IS_ERR(pwm->clk))
 306                 return PTR_ERR(pwm->clk);
 307
 308         pwm->chip.dev = &pdev->dev;
 309         pwm->chip.ops = &sun4i_pwm_ops;
 310         pwm->chip.base = -1;
 311         pwm->chip.npwm = 2;
 312         pwm->chip.can_sleep = true;
 313         pwm->chip.of_xlate = of_pwm_xlate_with_flags;
 314         pwm->chip.of_pwm_n_cells = 3;
 315         pwm->data = match->data;
 316
 317         spin_lock_init(&pwm->ctrl_lock);
 318
 319         ret = pwmchip_add(&pwm->chip);
 320         if (ret < 0) {
 321                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 322                 return ret;
 323         }
 324
 325         platform_set_drvdata(pdev, pwm);
 326
 327         ret = clk_prepare_enable(pwm->clk);
 328         if (ret) {
 329                 dev_err(&pdev->dev, "failed to enable PWM clock\n");
 330                 goto clk_error;
 331         }
 332
 333         val = sun4i_pwm_readl(pwm, PWM_CTRL_REG);
 334         for (i = 0; i < pwm->chip.npwm; i++)
 335                 if (!(val & BIT_CH(PWM_ACT_STATE, i)))
 336                         pwm->chip.pwms[i].polarity = PWM_POLARITY_INVERSED;
 337         clk_disable_unprepare(pwm->clk);
 338
 339         return 0;
 340
 341 clk_error:
 342         pwmchip_remove(&pwm->chip);
 343         return ret;
 344 }
 345
 346 static int sun4i_pwm_remove(struct platform_device *pdev)
 347 {
 348         struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
 349
 350         return pwmchip_remove(&pwm->chip);
 351 }
 352
 353 static struct platform_driver sun4i_pwm_driver = {
 354         .driver = {
 355                 .name = "sun4i-pwm",
 356                 .of_match_table = sun4i_pwm_dt_ids,
 357         },
 358         .probe = sun4i_pwm_probe,
 359         .remove = sun4i_pwm_remove,
 360 };
 361 module_platform_driver(sun4i_pwm_driver);
 362
 363 MODULE_ALIAS("platform:sun4i-pwm");
 364 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
 365 MODULE_DESCRIPTION("Allwinner sun4i PWM driver");
 366 MODULE_LICENSE("GPL v2");