drivers/pwm/pwm-brcmstb.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Broadcom BCM7038 PWM driver
   4  * Author: Florian Fainelli
   5  *
   6  * Copyright (C) 2015 Broadcom Corporation
   7  */
   8
   9 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/clk.h>
  12 #include <linux/export.h>
  13 #include <linux/init.h>
  14 #include <linux/io.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pwm.h>
  20 #include <linux/spinlock.h>
  21
  22 #define PWM_CTRL                0x00
  23 #define  CTRL_START             BIT(0)
  24 #define  CTRL_OEB               BIT(1)
  25 #define  CTRL_FORCE_HIGH        BIT(2)
  26 #define  CTRL_OPENDRAIN         BIT(3)
  27 #define  CTRL_CHAN_OFFS         4
  28
  29 #define PWM_CTRL2               0x04
  30 #define  CTRL2_OUT_SELECT       BIT(0)
  31
  32 #define PWM_CH_SIZE             0x8
  33
  34 #define PWM_CWORD_MSB(ch)       (0x08 + ((ch) * PWM_CH_SIZE))
  35 #define PWM_CWORD_LSB(ch)       (0x0c + ((ch) * PWM_CH_SIZE))
  36
  37 /* Number of bits for the CWORD value */
  38 #define CWORD_BIT_SIZE          16
  39
  40 /*
  41  * Maximum control word value allowed when variable-frequency PWM is used as a
  42  * clock for the constant-frequency PMW.
  43  */
  44 #define CONST_VAR_F_MAX         32768
  45 #define CONST_VAR_F_MIN         1
  46
  47 #define PWM_ON(ch)              (0x18 + ((ch) * PWM_CH_SIZE))
  48 #define  PWM_ON_MIN             1
  49 #define PWM_PERIOD(ch)          (0x1c + ((ch) * PWM_CH_SIZE))
  50 #define  PWM_PERIOD_MIN         0
  51
  52 #define PWM_ON_PERIOD_MAX       0xff
  53
  54 struct brcmstb_pwm {
  55         void __iomem *base;
  56         spinlock_t lock;
  57         struct clk *clk;
  58         struct pwm_chip chip;
  59 };
  60
  61 static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
  62                                     unsigned int offset)
  63 {
  64         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  65                 return __raw_readl(p->base + offset);
  66         else
  67                 return readl_relaxed(p->base + offset);
  68 }
  69
  70 static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
  71                                       unsigned int offset)
  72 {
  73         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  74                 __raw_writel(value, p->base + offset);
  75         else
  76                 writel_relaxed(value, p->base + offset);
  77 }
  78
  79 static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
  80 {
  81         return container_of(chip, struct brcmstb_pwm, chip);
  82 }
  83
  84 /*
  85  * Fv is derived from the variable frequency output. The variable frequency
  86  * output is configured using this formula:
  87  *
  88  * W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
  89  *
  90  * Fv = W x 2 ^ -16 x 27Mhz (reference clock)
  91  *
  92  * The period is: (period + 1) / Fv and "on" time is on / (period + 1)
  93  *
  94  * The PWM core framework specifies that the "duty_ns" parameter is in fact the
  95  * "on" time, so this translates directly into our HW programming here.
  96  */
  97 static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  98                               int duty_ns, int period_ns)
  99 {
 100         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 101         unsigned long pc, dc, cword = CONST_VAR_F_MAX;
 102         unsigned int channel = pwm->hwpwm;
 103         u32 value;
 104
 105         /*
 106          * If asking for a duty_ns equal to period_ns, we need to substract
 107          * the period value by 1 to make it shorter than the "on" time and
 108          * produce a flat 100% duty cycle signal, and max out the "on" time
 109          */
 110         if (duty_ns == period_ns) {
 111                 dc = PWM_ON_PERIOD_MAX;
 112                 pc = PWM_ON_PERIOD_MAX - 1;
 113                 goto done;
 114         }
 115
 116         while (1) {
 117                 u64 rate, tmp;
 118
 119                 /*
 120                  * Calculate the base rate from base frequency and current
 121                  * cword
 122                  */
 123                 rate = (u64)clk_get_rate(p->clk) * (u64)cword;
 124                 do_div(rate, 1 << CWORD_BIT_SIZE);
 125
 126                 tmp = period_ns * rate;
 127                 do_div(tmp, NSEC_PER_SEC);
 128                 pc = tmp;
 129
 130                 tmp = (duty_ns + 1) * rate;
 131                 do_div(tmp, NSEC_PER_SEC);
 132                 dc = tmp;
 133
 134                 /*
 135                  * We can be called with separate duty and period updates,
 136                  * so do not reject dc == 0 right away
 137                  */
 138                 if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
 139                         return -EINVAL;
 140
 141                 /* We converged on a calculation */
 142                 if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
 143                         break;
 144
 145                 /*
 146                  * The cword needs to be a power of 2 for the variable
 147                  * frequency generator to output a 50% duty cycle variable
 148                  * frequency which is used as input clock to the fixed
 149                  * frequency generator.
 150                  */
 151                 cword >>= 1;
 152
 153                 /*
 154                  * Desired periods are too large, we do not have a divider
 155                  * for them
 156                  */
 157                 if (cword < CONST_VAR_F_MIN)
 158                         return -EINVAL;
 159         }
 160
 161 done:
 162         /*
 163          * Configure the defined "cword" value to have the variable frequency
 164          * generator output a base frequency for the constant frequency
 165          * generator to derive from.
 166          */
 167         spin_lock(&p->lock);
 168         brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
 169         brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
 170
 171         /* Select constant frequency signal output */
 172         value = brcmstb_pwm_readl(p, PWM_CTRL2);
 173         value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
 174         brcmstb_pwm_writel(p, value, PWM_CTRL2);
 175
 176         /* Configure on and period value */
 177         brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
 178         brcmstb_pwm_writel(p, dc, PWM_ON(channel));
 179         spin_unlock(&p->lock);
 180
 181         return 0;
 182 }
 183
 184 static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
 185                                           unsigned int channel, bool enable)
 186 {
 187         unsigned int shift = channel * CTRL_CHAN_OFFS;
 188         u32 value;
 189
 190         spin_lock(&p->lock);
 191         value = brcmstb_pwm_readl(p, PWM_CTRL);
 192
 193         if (enable) {
 194                 value &= ~(CTRL_OEB << shift);
 195                 value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
 196         } else {
 197                 value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
 198                 value |= CTRL_OEB << shift;
 199         }
 200
 201         brcmstb_pwm_writel(p, value, PWM_CTRL);
 202         spin_unlock(&p->lock);
 203 }
 204
 205 static int brcmstb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 206 {
 207         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 208
 209         brcmstb_pwm_enable_set(p, pwm->hwpwm, true);
 210
 211         return 0;
 212 }
 213
 214 static void brcmstb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 215 {
 216         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 217
 218         brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
 219 }
 220
 221 static const struct pwm_ops brcmstb_pwm_ops = {
 222         .config = brcmstb_pwm_config,
 223         .enable = brcmstb_pwm_enable,
 224         .disable = brcmstb_pwm_disable,
 225         .owner = THIS_MODULE,
 226 };
 227
 228 static const struct of_device_id brcmstb_pwm_of_match[] = {
 229         { .compatible = "brcm,bcm7038-pwm", },
 230         { /* sentinel */ }
 231 };
 232 MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
 233
 234 static int brcmstb_pwm_probe(struct platform_device *pdev)
 235 {
 236         struct brcmstb_pwm *p;
 237         int ret;
 238
 239         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 240         if (!p)
 241                 return -ENOMEM;
 242
 243         spin_lock_init(&p->lock);
 244
 245         p->clk = devm_clk_get(&pdev->dev, NULL);
 246         if (IS_ERR(p->clk)) {
 247                 dev_err(&pdev->dev, "failed to obtain clock\n");
 248                 return PTR_ERR(p->clk);
 249         }
 250
 251         ret = clk_prepare_enable(p->clk);
 252         if (ret < 0) {
 253                 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
 254                 return ret;
 255         }
 256
 257         platform_set_drvdata(pdev, p);
 258
 259         p->chip.dev = &pdev->dev;
 260         p->chip.ops = &brcmstb_pwm_ops;
 261         p->chip.npwm = 2;
 262
 263         p->base = devm_platform_ioremap_resource(pdev, 0);
 264         if (IS_ERR(p->base)) {
 265                 ret = PTR_ERR(p->base);
 266                 goto out_clk;
 267         }
 268
 269         ret = pwmchip_add(&p->chip);
 270         if (ret) {
 271                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 272                 goto out_clk;
 273         }
 274
 275         return 0;
 276
 277 out_clk:
 278         clk_disable_unprepare(p->clk);
 279         return ret;
 280 }
 281
 282 static int brcmstb_pwm_remove(struct platform_device *pdev)
 283 {
 284         struct brcmstb_pwm *p = platform_get_drvdata(pdev);
 285
 286         pwmchip_remove(&p->chip);
 287         clk_disable_unprepare(p->clk);
 288
 289         return 0;
 290 }
 291
 292 #ifdef CONFIG_PM_SLEEP
 293 static int brcmstb_pwm_suspend(struct device *dev)
 294 {
 295         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 296
 297         clk_disable(p->clk);
 298
 299         return 0;
 300 }
 301
 302 static int brcmstb_pwm_resume(struct device *dev)
 303 {
 304         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 305
 306         clk_enable(p->clk);
 307
 308         return 0;
 309 }
 310 #endif
 311
 312 static SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
 313                          brcmstb_pwm_resume);
 314
 315 static struct platform_driver brcmstb_pwm_driver = {
 316         .probe = brcmstb_pwm_probe,
 317         .remove = brcmstb_pwm_remove,
 318         .driver = {
 319                 .name = "pwm-brcmstb",
 320                 .of_match_table = brcmstb_pwm_of_match,
 321                 .pm = &brcmstb_pwm_pm_ops,
 322         },
 323 };
 324 module_platform_driver(brcmstb_pwm_driver);
 325
 326 MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
 327 MODULE_DESCRIPTION("Broadcom STB PWM driver");
 328 MODULE_ALIAS("platform:pwm-brcmstb");
 329 MODULE_LICENSE("GPL");