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         struct clk *clk;
  57         struct pwm_chip chip;
  58 };
  59
  60 static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
  61                                     unsigned int offset)
  62 {
  63         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  64                 return __raw_readl(p->base + offset);
  65         else
  66                 return readl_relaxed(p->base + offset);
  67 }
  68
  69 static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
  70                                       unsigned int offset)
  71 {
  72         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  73                 __raw_writel(value, p->base + offset);
  74         else
  75                 writel_relaxed(value, p->base + offset);
  76 }
  77
  78 static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
  79 {
  80         return container_of(chip, struct brcmstb_pwm, chip);
  81 }
  82
  83 /*
  84  * Fv is derived from the variable frequency output. The variable frequency
  85  * output is configured using this formula:
  86  *
  87  * W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
  88  *
  89  * Fv = W x 2 ^ -16 x 27Mhz (reference clock)
  90  *
  91  * The period is: (period + 1) / Fv and "on" time is on / (period + 1)
  92  *
  93  * The PWM core framework specifies that the "duty_ns" parameter is in fact the
  94  * "on" time, so this translates directly into our HW programming here.
  95  */
  96 static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
  97                               u64 duty_ns, u64 period_ns)
  98 {
  99         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 100         unsigned long pc, dc, cword = CONST_VAR_F_MAX;
 101         unsigned int channel = pwm->hwpwm;
 102         u32 value;
 103
 104         /*
 105          * If asking for a duty_ns equal to period_ns, we need to substract
 106          * the period value by 1 to make it shorter than the "on" time and
 107          * produce a flat 100% duty cycle signal, and max out the "on" time
 108          */
 109         if (duty_ns == period_ns) {
 110                 dc = PWM_ON_PERIOD_MAX;
 111                 pc = PWM_ON_PERIOD_MAX - 1;
 112                 goto done;
 113         }
 114
 115         while (1) {
 116                 u64 rate;
 117
 118                 /*
 119                  * Calculate the base rate from base frequency and current
 120                  * cword
 121                  */
 122                 rate = (u64)clk_get_rate(p->clk) * (u64)cword;
 123                 rate >>= CWORD_BIT_SIZE;
 124
 125                 pc = mul_u64_u64_div_u64(period_ns, rate, NSEC_PER_SEC);
 126                 dc = mul_u64_u64_div_u64(duty_ns + 1, rate, NSEC_PER_SEC);
 127
 128                 /*
 129                  * We can be called with separate duty and period updates,
 130                  * so do not reject dc == 0 right away
 131                  */
 132                 if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
 133                         return -EINVAL;
 134
 135                 /* We converged on a calculation */
 136                 if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
 137                         break;
 138
 139                 /*
 140                  * The cword needs to be a power of 2 for the variable
 141                  * frequency generator to output a 50% duty cycle variable
 142                  * frequency which is used as input clock to the fixed
 143                  * frequency generator.
 144                  */
 145                 cword >>= 1;
 146
 147                 /*
 148                  * Desired periods are too large, we do not have a divider
 149                  * for them
 150                  */
 151                 if (cword < CONST_VAR_F_MIN)
 152                         return -EINVAL;
 153         }
 154
 155 done:
 156         /*
 157          * Configure the defined "cword" value to have the variable frequency
 158          * generator output a base frequency for the constant frequency
 159          * generator to derive from.
 160          */
 161         brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
 162         brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
 163
 164         /* Select constant frequency signal output */
 165         value = brcmstb_pwm_readl(p, PWM_CTRL2);
 166         value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
 167         brcmstb_pwm_writel(p, value, PWM_CTRL2);
 168
 169         /* Configure on and period value */
 170         brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
 171         brcmstb_pwm_writel(p, dc, PWM_ON(channel));
 172
 173         return 0;
 174 }
 175
 176 static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
 177                                           unsigned int channel, bool enable)
 178 {
 179         unsigned int shift = channel * CTRL_CHAN_OFFS;
 180         u32 value;
 181
 182         value = brcmstb_pwm_readl(p, PWM_CTRL);
 183
 184         if (enable) {
 185                 value &= ~(CTRL_OEB << shift);
 186                 value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
 187         } else {
 188                 value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
 189                 value |= CTRL_OEB << shift;
 190         }
 191
 192         brcmstb_pwm_writel(p, value, PWM_CTRL);
 193 }
 194
 195 static int brcmstb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 196                              const struct pwm_state *state)
 197 {
 198         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 199         int err;
 200
 201         if (state->polarity != PWM_POLARITY_NORMAL)
 202                 return -EINVAL;
 203
 204         if (!state->enabled) {
 205                 if (pwm->state.enabled)
 206                         brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
 207
 208                 return 0;
 209         }
 210
 211         err = brcmstb_pwm_config(chip, pwm, state->duty_cycle, state->period);
 212         if (err)
 213                 return err;
 214
 215         if (!pwm->state.enabled)
 216                 brcmstb_pwm_enable_set(p, pwm->hwpwm, true);
 217
 218         return 0;
 219 }
 220
 221 static const struct pwm_ops brcmstb_pwm_ops = {
 222         .apply = brcmstb_pwm_apply,
 223         .owner = THIS_MODULE,
 224 };
 225
 226 static const struct of_device_id brcmstb_pwm_of_match[] = {
 227         { .compatible = "brcm,bcm7038-pwm", },
 228         { /* sentinel */ }
 229 };
 230 MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
 231
 232 static int brcmstb_pwm_probe(struct platform_device *pdev)
 233 {
 234         struct brcmstb_pwm *p;
 235         int ret;
 236
 237         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 238         if (!p)
 239                 return -ENOMEM;
 240
 241         p->clk = devm_clk_get(&pdev->dev, NULL);
 242         if (IS_ERR(p->clk)) {
 243                 dev_err(&pdev->dev, "failed to obtain clock\n");
 244                 return PTR_ERR(p->clk);
 245         }
 246
 247         ret = clk_prepare_enable(p->clk);
 248         if (ret < 0) {
 249                 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
 250                 return ret;
 251         }
 252
 253         platform_set_drvdata(pdev, p);
 254
 255         p->chip.dev = &pdev->dev;
 256         p->chip.ops = &brcmstb_pwm_ops;
 257         p->chip.npwm = 2;
 258
 259         p->base = devm_platform_ioremap_resource(pdev, 0);
 260         if (IS_ERR(p->base)) {
 261                 ret = PTR_ERR(p->base);
 262                 goto out_clk;
 263         }
 264
 265         ret = pwmchip_add(&p->chip);
 266         if (ret) {
 267                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 268                 goto out_clk;
 269         }
 270
 271         return 0;
 272
 273 out_clk:
 274         clk_disable_unprepare(p->clk);
 275         return ret;
 276 }
 277
 278 static void brcmstb_pwm_remove(struct platform_device *pdev)
 279 {
 280         struct brcmstb_pwm *p = platform_get_drvdata(pdev);
 281
 282         pwmchip_remove(&p->chip);
 283         clk_disable_unprepare(p->clk);
 284 }
 285
 286 #ifdef CONFIG_PM_SLEEP
 287 static int brcmstb_pwm_suspend(struct device *dev)
 288 {
 289         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 290
 291         clk_disable(p->clk);
 292
 293         return 0;
 294 }
 295
 296 static int brcmstb_pwm_resume(struct device *dev)
 297 {
 298         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 299
 300         clk_enable(p->clk);
 301
 302         return 0;
 303 }
 304 #endif
 305
 306 static SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
 307                          brcmstb_pwm_resume);
 308
 309 static struct platform_driver brcmstb_pwm_driver = {
 310         .probe = brcmstb_pwm_probe,
 311         .remove_new = brcmstb_pwm_remove,
 312         .driver = {
 313                 .name = "pwm-brcmstb",
 314                 .of_match_table = brcmstb_pwm_of_match,
 315                 .pm = &brcmstb_pwm_pm_ops,
 316         },
 317 };
 318 module_platform_driver(brcmstb_pwm_driver);
 319
 320 MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
 321 MODULE_DESCRIPTION("Broadcom STB PWM driver");
 322 MODULE_ALIAS("platform:pwm-brcmstb");
 323 MODULE_LICENSE("GPL");