kernel/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  */
  40 struct crystalcove_pwm {
  41         struct pwm_chip chip;
  42         struct regmap *regmap;
  43 };
  44
  45 static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc)
  46 {
  47         return container_of(pc, struct crystalcove_pwm, chip);
  48 }
  49
  50 static 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
  59 static 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
  66 static 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->period != 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
  99 static const struct pwm_ops crc_pwm_ops = {
 100         .config = crc_pwm_config,
 101         .enable = crc_pwm_enable,
 102         .disable = crc_pwm_disable,
 103 };
 104
 105 static 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
 128 static 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
 135 static 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
 143 builtin_platform_driver(crystalcove_pwm_driver);