drivers/pwm/pwm-brcmstb.c

   1 /*
   2  * Broadcom BCM7038 PWM driver
   3  * Author: Florian Fainelli
   4  *
   5  * Copyright (C) 2015 Broadcom Corporation
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  19
  20 #include <linux/clk.h>
  21 #include <linux/export.h>
  22 #include <linux/init.h>
  23 #include <linux/io.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/of.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/pwm.h>
  29 #include <linux/spinlock.h>
  30
  31 #define PWM_CTRL                0x00
  32 #define  CTRL_START             BIT(0)
  33 #define  CTRL_OEB               BIT(1)
  34 #define  CTRL_FORCE_HIGH        BIT(2)
  35 #define  CTRL_OPENDRAIN         BIT(3)
  36 #define  CTRL_CHAN_OFFS         4
  37
  38 #define PWM_CTRL2               0x04
  39 #define  CTRL2_OUT_SELECT       BIT(0)
  40
  41 #define PWM_CH_SIZE             0x8
  42
  43 #define PWM_CWORD_MSB(ch)       (0x08 + ((ch) * PWM_CH_SIZE))
  44 #define PWM_CWORD_LSB(ch)       (0x0c + ((ch) * PWM_CH_SIZE))
  45
  46 /* Number of bits for the CWORD value */
  47 #define CWORD_BIT_SIZE          16
  48
  49 /*
  50  * Maximum control word value allowed when variable-frequency PWM is used as a
  51  * clock for the constant-frequency PMW.
  52  */
  53 #define CONST_VAR_F_MAX         32768
  54 #define CONST_VAR_F_MIN         1
  55
  56 #define PWM_ON(ch)              (0x18 + ((ch) * PWM_CH_SIZE))
  57 #define  PWM_ON_MIN             1
  58 #define PWM_PERIOD(ch)          (0x1c + ((ch) * PWM_CH_SIZE))
  59 #define  PWM_PERIOD_MIN         0
  60
  61 #define PWM_ON_PERIOD_MAX       0xff
  62
  63 struct brcmstb_pwm {
  64         void __iomem *base;
  65         spinlock_t lock;
  66         struct clk *clk;
  67         struct pwm_chip chip;
  68 };
  69
  70 static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
  71                                     unsigned int offset)
  72 {
  73         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  74                 return __raw_readl(p->base + offset);
  75         else
  76                 return readl_relaxed(p->base + offset);
  77 }
  78
  79 static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
  80                                       unsigned int offset)
  81 {
  82         if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
  83                 __raw_writel(value, p->base + offset);
  84         else
  85                 writel_relaxed(value, p->base + offset);
  86 }
  87
  88 static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
  89 {
  90         return container_of(chip, struct brcmstb_pwm, chip);
  91 }
  92
  93 /*
  94  * Fv is derived from the variable frequency output. The variable frequency
  95  * output is configured using this formula:
  96  *
  97  * W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
  98  *
  99  * Fv = W x 2 ^ -16 x 27Mhz (reference clock)
 100  *
 101  * The period is: (period + 1) / Fv and "on" time is on / (period + 1)
 102  *
 103  * The PWM core framework specifies that the "duty_ns" parameter is in fact the
 104  * "on" time, so this translates directly into our HW programming here.
 105  */
 106 static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 107                               int duty_ns, int period_ns)
 108 {
 109         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 110         unsigned long pc, dc, cword = CONST_VAR_F_MAX;
 111         unsigned int channel = pwm->hwpwm;
 112         u32 value;
 113
 114         /*
 115          * If asking for a duty_ns equal to period_ns, we need to substract
 116          * the period value by 1 to make it shorter than the "on" time and
 117          * produce a flat 100% duty cycle signal, and max out the "on" time
 118          */
 119         if (duty_ns == period_ns) {
 120                 dc = PWM_ON_PERIOD_MAX;
 121                 pc = PWM_ON_PERIOD_MAX - 1;
 122                 goto done;
 123         }
 124
 125         while (1) {
 126                 u64 rate, tmp;
 127
 128                 /*
 129                  * Calculate the base rate from base frequency and current
 130                  * cword
 131                  */
 132                 rate = (u64)clk_get_rate(p->clk) * (u64)cword;
 133                 do_div(rate, 1 << CWORD_BIT_SIZE);
 134
 135                 tmp = period_ns * rate;
 136                 do_div(tmp, NSEC_PER_SEC);
 137                 pc = tmp;
 138
 139                 tmp = (duty_ns + 1) * rate;
 140                 do_div(tmp, NSEC_PER_SEC);
 141                 dc = tmp;
 142
 143                 /*
 144                  * We can be called with separate duty and period updates,
 145                  * so do not reject dc == 0 right away
 146                  */
 147                 if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
 148                         return -EINVAL;
 149
 150                 /* We converged on a calculation */
 151                 if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
 152                         break;
 153
 154                 /*
 155                  * The cword needs to be a power of 2 for the variable
 156                  * frequency generator to output a 50% duty cycle variable
 157                  * frequency which is used as input clock to the fixed
 158                  * frequency generator.
 159                  */
 160                 cword >>= 1;
 161
 162                 /*
 163                  * Desired periods are too large, we do not have a divider
 164                  * for them
 165                  */
 166                 if (cword < CONST_VAR_F_MIN)
 167                         return -EINVAL;
 168         }
 169
 170 done:
 171         /*
 172          * Configure the defined "cword" value to have the variable frequency
 173          * generator output a base frequency for the constant frequency
 174          * generator to derive from.
 175          */
 176         spin_lock(&p->lock);
 177         brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
 178         brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
 179
 180         /* Select constant frequency signal output */
 181         value = brcmstb_pwm_readl(p, PWM_CTRL2);
 182         value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
 183         brcmstb_pwm_writel(p, value, PWM_CTRL2);
 184
 185         /* Configure on and period value */
 186         brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
 187         brcmstb_pwm_writel(p, dc, PWM_ON(channel));
 188         spin_unlock(&p->lock);
 189
 190         return 0;
 191 }
 192
 193 static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
 194                                           unsigned int channel, bool enable)
 195 {
 196         unsigned int shift = channel * CTRL_CHAN_OFFS;
 197         u32 value;
 198
 199         spin_lock(&p->lock);
 200         value = brcmstb_pwm_readl(p, PWM_CTRL);
 201
 202         if (enable) {
 203                 value &= ~(CTRL_OEB << shift);
 204                 value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
 205         } else {
 206                 value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
 207                 value |= CTRL_OEB << shift;
 208         }
 209
 210         brcmstb_pwm_writel(p, value, PWM_CTRL);
 211         spin_unlock(&p->lock);
 212 }
 213
 214 static int brcmstb_pwm_enable(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, true);
 219
 220         return 0;
 221 }
 222
 223 static void brcmstb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 224 {
 225         struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
 226
 227         brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
 228 }
 229
 230 static const struct pwm_ops brcmstb_pwm_ops = {
 231         .config = brcmstb_pwm_config,
 232         .enable = brcmstb_pwm_enable,
 233         .disable = brcmstb_pwm_disable,
 234         .owner = THIS_MODULE,
 235 };
 236
 237 static const struct of_device_id brcmstb_pwm_of_match[] = {
 238         { .compatible = "brcm,bcm7038-pwm", },
 239         { /* sentinel */ }
 240 };
 241 MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
 242
 243 static int brcmstb_pwm_probe(struct platform_device *pdev)
 244 {
 245         struct brcmstb_pwm *p;
 246         struct resource *res;
 247         int ret;
 248
 249         p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
 250         if (!p)
 251                 return -ENOMEM;
 252
 253         spin_lock_init(&p->lock);
 254
 255         p->clk = devm_clk_get(&pdev->dev, NULL);
 256         if (IS_ERR(p->clk)) {
 257                 dev_err(&pdev->dev, "failed to obtain clock\n");
 258                 return PTR_ERR(p->clk);
 259         }
 260
 261         ret = clk_prepare_enable(p->clk);
 262         if (ret < 0) {
 263                 dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
 264                 return ret;
 265         }
 266
 267         platform_set_drvdata(pdev, p);
 268
 269         p->chip.dev = &pdev->dev;
 270         p->chip.ops = &brcmstb_pwm_ops;
 271         p->chip.base = -1;
 272         p->chip.npwm = 2;
 273
 274         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 275         p->base = devm_ioremap_resource(&pdev->dev, res);
 276         if (IS_ERR(p->base)) {
 277                 ret = PTR_ERR(p->base);
 278                 goto out_clk;
 279         }
 280
 281         ret = pwmchip_add(&p->chip);
 282         if (ret) {
 283                 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
 284                 goto out_clk;
 285         }
 286
 287         return 0;
 288
 289 out_clk:
 290         clk_disable_unprepare(p->clk);
 291         return ret;
 292 }
 293
 294 static int brcmstb_pwm_remove(struct platform_device *pdev)
 295 {
 296         struct brcmstb_pwm *p = platform_get_drvdata(pdev);
 297         int ret;
 298
 299         ret = pwmchip_remove(&p->chip);
 300         clk_disable_unprepare(p->clk);
 301
 302         return ret;
 303 }
 304
 305 #ifdef CONFIG_PM_SLEEP
 306 static int brcmstb_pwm_suspend(struct device *dev)
 307 {
 308         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 309
 310         clk_disable(p->clk);
 311
 312         return 0;
 313 }
 314
 315 static int brcmstb_pwm_resume(struct device *dev)
 316 {
 317         struct brcmstb_pwm *p = dev_get_drvdata(dev);
 318
 319         clk_enable(p->clk);
 320
 321         return 0;
 322 }
 323 #endif
 324
 325 static SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
 326                          brcmstb_pwm_resume);
 327
 328 static struct platform_driver brcmstb_pwm_driver = {
 329         .probe = brcmstb_pwm_probe,
 330         .remove = brcmstb_pwm_remove,
 331         .driver = {
 332                 .name = "pwm-brcmstb",
 333                 .of_match_table = brcmstb_pwm_of_match,
 334                 .pm = &brcmstb_pwm_pm_ops,
 335         },
 336 };
 337 module_platform_driver(brcmstb_pwm_driver);
 338
 339 MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
 340 MODULE_DESCRIPTION("Broadcom STB PWM driver");
 341 MODULE_ALIAS("platform:pwm-brcmstb");
 342 MODULE_LICENSE("GPL");