drivers/pwm/pwm-crc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2015 Intel Corporation. All rights reserved.
   4  *
   5  * Author: Shobhit Kumar <shobhit.kumar@intel.com>
   6  */
   7
   8 #include <linux/platform_device.h>
   9 #include <linux/regmap.h>
  10 #include <linux/mfd/intel_soc_pmic.h>
  11 #include <linux/pwm.h>
  12
  13 #define PWM0_CLK_DIV            0x4B
  14 #define  PWM_OUTPUT_ENABLE      BIT(7)
  15 #define  PWM_DIV_CLK_0          0x00 /* DIVIDECLK = BASECLK */
  16 #define  PWM_DIV_CLK_100        0x63 /* DIVIDECLK = BASECLK/100 */
  17 #define  PWM_DIV_CLK_128        0x7F /* DIVIDECLK = BASECLK/128 */
  18
  19 #define PWM0_DUTY_CYCLE         0x4E
  20 #define BACKLIGHT_EN            0x51
  21
  22 #define PWM_MAX_LEVEL           0xFF
  23
  24 #define PWM_BASE_CLK_MHZ        6       /* 6 MHz */
  25 #define PWM_MAX_PERIOD_NS       5461334 /* 183 Hz */
  26
  27 /**
  28  * struct crystalcove_pwm - Crystal Cove PWM controller
  29  * @regmap: the regmap from the parent device.
  30  */
  31 struct crystalcove_pwm {
  32         struct regmap *regmap;
  33 };
  34
  35 static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *chip)
  36 {
  37         return pwmchip_get_drvdata(chip);
  38 }
  39
  40 static int crc_pwm_calc_clk_div(int period_ns)
  41 {
  42         int clk_div;
  43
  44         clk_div = PWM_BASE_CLK_MHZ * period_ns / (256 * NSEC_PER_USEC);
  45         /* clk_div 1 - 128, maps to register values 0-127 */
  46         if (clk_div > 0)
  47                 clk_div--;
  48
  49         return clk_div;
  50 }
  51
  52 static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  53                          const struct pwm_state *state)
  54 {
  55         struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
  56         struct device *dev = pwmchip_parent(chip);
  57         int err;
  58
  59         if (state->period > PWM_MAX_PERIOD_NS) {
  60                 dev_err(dev, "un-supported period_ns\n");
  61                 return -EINVAL;
  62         }
  63
  64         if (state->polarity != PWM_POLARITY_NORMAL)
  65                 return -EINVAL;
  66
  67         if (pwm_is_enabled(pwm) && !state->enabled) {
  68                 err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
  69                 if (err) {
  70                         dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
  71                         return err;
  72                 }
  73         }
  74
  75         if (pwm_get_duty_cycle(pwm) != state->duty_cycle ||
  76             pwm_get_period(pwm) != state->period) {
  77                 u64 level = state->duty_cycle * PWM_MAX_LEVEL;
  78
  79                 do_div(level, state->period);
  80
  81                 err = regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
  82                 if (err) {
  83                         dev_err(dev, "Error writing PWM0_DUTY_CYCLE %d\n", err);
  84                         return err;
  85                 }
  86         }
  87
  88         if (pwm_is_enabled(pwm) && state->enabled &&
  89             pwm_get_period(pwm) != state->period) {
  90                 /* changing the clk divisor, clear PWM_OUTPUT_ENABLE first */
  91                 err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, 0);
  92                 if (err) {
  93                         dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
  94                         return err;
  95                 }
  96         }
  97
  98         if (pwm_get_period(pwm) != state->period ||
  99             pwm_is_enabled(pwm) != state->enabled) {
 100                 int clk_div = crc_pwm_calc_clk_div(state->period);
 101                 int pwm_output_enable = state->enabled ? PWM_OUTPUT_ENABLE : 0;
 102
 103                 err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
 104                                    clk_div | pwm_output_enable);
 105                 if (err) {
 106                         dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
 107                         return err;
 108                 }
 109         }
 110
 111         if (!pwm_is_enabled(pwm) && state->enabled) {
 112                 err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
 113                 if (err) {
 114                         dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
 115                         return err;
 116                 }
 117         }
 118
 119         return 0;
 120 }
 121
 122 static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 123                              struct pwm_state *state)
 124 {
 125         struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
 126         struct device *dev = pwmchip_parent(chip);
 127         unsigned int clk_div, clk_div_reg, duty_cycle_reg;
 128         int error;
 129
 130         error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
 131         if (error) {
 132                 dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
 133                 return error;
 134         }
 135
 136         error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
 137         if (error) {
 138                 dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
 139                 return error;
 140         }
 141
 142         clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1;
 143
 144         state->period =
 145                 DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ);
 146         state->duty_cycle =
 147                 DIV_ROUND_UP_ULL(duty_cycle_reg * state->period, PWM_MAX_LEVEL);
 148         state->polarity = PWM_POLARITY_NORMAL;
 149         state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE);
 150
 151         return 0;
 152 }
 153
 154 static const struct pwm_ops crc_pwm_ops = {
 155         .apply = crc_pwm_apply,
 156         .get_state = crc_pwm_get_state,
 157 };
 158
 159 static int crystalcove_pwm_probe(struct platform_device *pdev)
 160 {
 161         struct pwm_chip *chip;
 162         struct crystalcove_pwm *crc_pwm;
 163         struct device *dev = pdev->dev.parent;
 164         struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
 165
 166         chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*crc_pwm));
 167         if (IS_ERR(chip))
 168                 return PTR_ERR(chip);
 169         crc_pwm = to_crc_pwm(chip);
 170
 171         chip->ops = &crc_pwm_ops;
 172
 173         /* get the PMIC regmap */
 174         crc_pwm->regmap = pmic->regmap;
 175
 176         return devm_pwmchip_add(&pdev->dev, chip);
 177 }
 178
 179 static struct platform_driver crystalcove_pwm_driver = {
 180         .probe = crystalcove_pwm_probe,
 181         .driver = {
 182                 .name = "crystal_cove_pwm",
 183         },
 184 };
 185 module_platform_driver(crystalcove_pwm_driver);
 186
 187 MODULE_ALIAS("platform:crystal_cove_pwm");
 188 MODULE_DESCRIPTION("Intel Crystalcove (CRC) PWM support");
 189 MODULE_LICENSE("GPL");