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  * @chip: the abstract pwm_chip structure.
  30  * @regmap: the regmap from the parent device.
  31  */
  32 struct crystalcove_pwm {
  33         struct pwm_chip chip;
  34         struct regmap *regmap;
  35 };
  36
  37 static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *chip)
  38 {
  39         return container_of(chip, struct crystalcove_pwm, chip);
  40 }
  41
  42 static int crc_pwm_calc_clk_div(int period_ns)
  43 {
  44         int clk_div;
  45
  46         clk_div = PWM_BASE_CLK_MHZ * period_ns / (256 * NSEC_PER_USEC);
  47         /* clk_div 1 - 128, maps to register values 0-127 */
  48         if (clk_div > 0)
  49                 clk_div--;
  50
  51         return clk_div;
  52 }
  53
  54 static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  55                          const struct pwm_state *state)
  56 {
  57         struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
  58         struct device *dev = crc_pwm->chip.dev;
  59         int err;
  60
  61         if (state->period > PWM_MAX_PERIOD_NS) {
  62                 dev_err(dev, "un-supported period_ns\n");
  63                 return -EINVAL;
  64         }
  65
  66         if (state->polarity != PWM_POLARITY_NORMAL)
  67                 return -EINVAL;
  68
  69         if (pwm_is_enabled(pwm) && !state->enabled) {
  70                 err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
  71                 if (err) {
  72                         dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
  73                         return err;
  74                 }
  75         }
  76
  77         if (pwm_get_duty_cycle(pwm) != state->duty_cycle ||
  78             pwm_get_period(pwm) != state->period) {
  79                 u64 level = state->duty_cycle * PWM_MAX_LEVEL;
  80
  81                 do_div(level, state->period);
  82
  83                 err = regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
  84                 if (err) {
  85                         dev_err(dev, "Error writing PWM0_DUTY_CYCLE %d\n", err);
  86                         return err;
  87                 }
  88         }
  89
  90         if (pwm_is_enabled(pwm) && state->enabled &&
  91             pwm_get_period(pwm) != state->period) {
  92                 /* changing the clk divisor, clear PWM_OUTPUT_ENABLE first */
  93                 err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, 0);
  94                 if (err) {
  95                         dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
  96                         return err;
  97                 }
  98         }
  99
 100         if (pwm_get_period(pwm) != state->period ||
 101             pwm_is_enabled(pwm) != state->enabled) {
 102                 int clk_div = crc_pwm_calc_clk_div(state->period);
 103                 int pwm_output_enable = state->enabled ? PWM_OUTPUT_ENABLE : 0;
 104
 105                 err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
 106                                    clk_div | pwm_output_enable);
 107                 if (err) {
 108                         dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
 109                         return err;
 110                 }
 111         }
 112
 113         if (!pwm_is_enabled(pwm) && state->enabled) {
 114                 err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
 115                 if (err) {
 116                         dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
 117                         return err;
 118                 }
 119         }
 120
 121         return 0;
 122 }
 123
 124 static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 125                              struct pwm_state *state)
 126 {
 127         struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
 128         struct device *dev = crc_pwm->chip.dev;
 129         unsigned int clk_div, clk_div_reg, duty_cycle_reg;
 130         int error;
 131
 132         error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
 133         if (error) {
 134                 dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
 135                 return error;
 136         }
 137
 138         error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
 139         if (error) {
 140                 dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
 141                 return error;
 142         }
 143
 144         clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1;
 145
 146         state->period =
 147                 DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ);
 148         state->duty_cycle =
 149                 DIV_ROUND_UP_ULL(duty_cycle_reg * state->period, PWM_MAX_LEVEL);
 150         state->polarity = PWM_POLARITY_NORMAL;
 151         state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE);
 152
 153         return 0;
 154 }
 155
 156 static const struct pwm_ops crc_pwm_ops = {
 157         .apply = crc_pwm_apply,
 158         .get_state = crc_pwm_get_state,
 159 };
 160
 161 static int crystalcove_pwm_probe(struct platform_device *pdev)
 162 {
 163         struct crystalcove_pwm *pwm;
 164         struct device *dev = pdev->dev.parent;
 165         struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
 166
 167         pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
 168         if (!pwm)
 169                 return -ENOMEM;
 170
 171         pwm->chip.dev = &pdev->dev;
 172         pwm->chip.ops = &crc_pwm_ops;
 173         pwm->chip.npwm = 1;
 174
 175         /* get the PMIC regmap */
 176         pwm->regmap = pmic->regmap;
 177
 178         return devm_pwmchip_add(&pdev->dev, &pwm->chip);
 179 }
 180
 181 static struct platform_driver crystalcove_pwm_driver = {
 182         .probe = crystalcove_pwm_probe,
 183         .driver = {
 184                 .name = "crystal_cove_pwm",
 185         },
 186 };
 187
 188 builtin_platform_driver(crystalcove_pwm_driver);