LXR linux/drivers/pwm/pwm-crc.c

   1/*
   2 * Copyright (C) 2015 Intel Corporation. All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public License version
   6 * 2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 * GNU General Public License for more details.
  12 *
  13 * Author: Shobhit Kumar <shobhit.kumar@intel.com>
  14 */
  15
  16#include <linux/platform_device.h>
  17#include <linux/regmap.h>
  18#include <linux/mfd/intel_soc_pmic.h>
  19#include <linux/pwm.h>
  20
  21#define PWM0_CLK_DIV            0x4B
  22#define  PWM_OUTPUT_ENABLE      BIT(7)
  23#define  PWM_DIV_CLK_0          0x00 /* DIVIDECLK = BASECLK */
  24#define  PWM_DIV_CLK_100        0x63 /* DIVIDECLK = BASECLK/100 */
  25#define  PWM_DIV_CLK_128        0x7F /* DIVIDECLK = BASECLK/128 */
  26
  27#define PWM0_DUTY_CYCLE         0x4E
  28#define BACKLIGHT_EN            0x51
  29
  30#define PWM_MAX_LEVEL           0xFF
  31
  32#define PWM_BASE_CLK            6000000  /* 6 MHz */
  33#define PWM_MAX_PERIOD_NS       21333    /* 46.875KHz */
  34
  35/**
  36 * struct crystalcove_pwm - Crystal Cove PWM controller
  37 * @chip: the abstract pwm_chip structure.
  38 * @regmap: the regmap from the parent device.
  39 */
  40struct crystalcove_pwm {
  41        struct pwm_chip chip;
  42        struct regmap *regmap;
  43};
  44
  45static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc)
  46{
  47        return container_of(pc, struct crystalcove_pwm, chip);
  48}
  49
  50static int crc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
  51{
  52        struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
  53
  54        regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
  55
  56        return 0;
  57}
  58
  59static void crc_pwm_disable(struct pwm_chip *c, struct pwm_device *pwm)
  60{
  61        struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
  62
  63        regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
  64}
  65
  66static int crc_pwm_config(struct pwm_chip *c, struct pwm_device *pwm,
  67                          int duty_ns, int period_ns)
  68{
  69        struct crystalcove_pwm *crc_pwm = to_crc_pwm(c);
  70        struct device *dev = crc_pwm->chip.dev;
  71        int level;
  72
  73        if (period_ns > PWM_MAX_PERIOD_NS) {
  74                dev_err(dev, "un-supported period_ns\n");
  75                return -EINVAL;
  76        }
  77
  78        if (pwm_get_period(pwm) != period_ns) {
  79                int clk_div;
  80
  81                /* changing the clk divisor, need to disable fisrt */
  82                crc_pwm_disable(c, pwm);
  83                clk_div = PWM_BASE_CLK * period_ns / NSEC_PER_SEC;
  84
  85                regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
  86                                        clk_div | PWM_OUTPUT_ENABLE);
  87
  88                /* enable back */
  89                crc_pwm_enable(c, pwm);
  90        }
  91
  92        /* change the pwm duty cycle */
  93        level = duty_ns * PWM_MAX_LEVEL / period_ns;
  94        regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
  95
  96        return 0;
  97}
  98
  99static const struct pwm_ops crc_pwm_ops = {
 100        .config = crc_pwm_config,
 101        .enable = crc_pwm_enable,
 102        .disable = crc_pwm_disable,
 103};
 104
 105static int crystalcove_pwm_probe(struct platform_device *pdev)
 106{
 107        struct crystalcove_pwm *pwm;
 108        struct device *dev = pdev->dev.parent;
 109        struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
 110
 111        pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 112        if (!pwm)
 113                return -ENOMEM;
 114
 115        pwm->chip.dev = &pdev->dev;
 116        pwm->chip.ops = &crc_pwm_ops;
 117        pwm->chip.base = -1;
 118        pwm->chip.npwm = 1;
 119
 120        /* get the PMIC regmap */
 121        pwm->regmap = pmic->regmap;
 122
 123        platform_set_drvdata(pdev, pwm);
 124
 125        return pwmchip_add(&pwm->chip);
 126}
 127
 128static int crystalcove_pwm_remove(struct platform_device *pdev)
 129{
 130        struct crystalcove_pwm *pwm = platform_get_drvdata(pdev);
 131
 132        return pwmchip_remove(&pwm->chip);
 133}
 134
 135static struct platform_driver crystalcove_pwm_driver = {
 136        .probe = crystalcove_pwm_probe,
 137        .remove = crystalcove_pwm_remove,
 138        .driver = {
 139                .name = "crystal_cove_pwm",
 140        },
 141};
 142
 143builtin_platform_driver(crystalcove_pwm_driver);
 144