diff options
Diffstat (limited to 'drivers/pwm/pwm-crc.c')
| -rw-r--r-- | drivers/pwm/pwm-crc.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c new file mode 100644 index 000000000..409985011 --- /dev/null +++ b/drivers/pwm/pwm-crc.c @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2015 Intel Corporation. All rights reserved. + * + * Author: Shobhit Kumar <shobhit.kumar@intel.com> + */ + +#include <linux/platform_device.h> +#include <linux/regmap.h> +#include <linux/mfd/intel_soc_pmic.h> +#include <linux/pwm.h> + +#define PWM0_CLK_DIV 0x4B +#define PWM_OUTPUT_ENABLE BIT(7) +#define PWM_DIV_CLK_0 0x00 /* DIVIDECLK = BASECLK */ +#define PWM_DIV_CLK_100 0x63 /* DIVIDECLK = BASECLK/100 */ +#define PWM_DIV_CLK_128 0x7F /* DIVIDECLK = BASECLK/128 */ + +#define PWM0_DUTY_CYCLE 0x4E +#define BACKLIGHT_EN 0x51 + +#define PWM_MAX_LEVEL 0xFF + +#define PWM_BASE_CLK_MHZ 6 /* 6 MHz */ +#define PWM_MAX_PERIOD_NS 5461334 /* 183 Hz */ + +/** + * struct crystalcove_pwm - Crystal Cove PWM controller + * @chip: the abstract pwm_chip structure. + * @regmap: the regmap from the parent device. + */ +struct crystalcove_pwm { + struct pwm_chip chip; + struct regmap *regmap; +}; + +static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *pc) +{ + return container_of(pc, struct crystalcove_pwm, chip); +} + +static int crc_pwm_calc_clk_div(int period_ns) +{ + int clk_div; + + clk_div = PWM_BASE_CLK_MHZ * period_ns / (256 * NSEC_PER_USEC); + /* clk_div 1 - 128, maps to register values 0-127 */ + if (clk_div > 0) + clk_div--; + + return clk_div; +} + +static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip); + struct device *dev = crc_pwm->chip.dev; + int err; + + if (state->period > PWM_MAX_PERIOD_NS) { + dev_err(dev, "un-supported period_ns\n"); + return -EINVAL; + } + + if (state->polarity != PWM_POLARITY_NORMAL) + return -EINVAL; + + if (pwm_is_enabled(pwm) && !state->enabled) { + err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0); + if (err) { + dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err); + return err; + } + } + + if (pwm_get_duty_cycle(pwm) != state->duty_cycle || + pwm_get_period(pwm) != state->period) { + u64 level = state->duty_cycle * PWM_MAX_LEVEL; + + do_div(level, state->period); + + err = regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level); + if (err) { + dev_err(dev, "Error writing PWM0_DUTY_CYCLE %d\n", err); + return err; + } + } + + if (pwm_is_enabled(pwm) && state->enabled && + pwm_get_period(pwm) != state->period) { + /* changing the clk divisor, clear PWM_OUTPUT_ENABLE first */ + err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, 0); + if (err) { + dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err); + return err; + } + } + + if (pwm_get_period(pwm) != state->period || + pwm_is_enabled(pwm) != state->enabled) { + int clk_div = crc_pwm_calc_clk_div(state->period); + int pwm_output_enable = state->enabled ? PWM_OUTPUT_ENABLE : 0; + + err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, + clk_div | pwm_output_enable); + if (err) { + dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err); + return err; + } + } + + if (!pwm_is_enabled(pwm) && state->enabled) { + err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1); + if (err) { + dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err); + return err; + } + } + + return 0; +} + +static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip); + struct device *dev = crc_pwm->chip.dev; + unsigned int clk_div, clk_div_reg, duty_cycle_reg; + int error; + + error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg); + if (error) { + dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error); + return 0; + } + + error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg); + if (error) { + dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error); + return 0; + } + + clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1; + + state->period = + DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ); + state->duty_cycle = + DIV_ROUND_UP_ULL(duty_cycle_reg * state->period, PWM_MAX_LEVEL); + state->polarity = PWM_POLARITY_NORMAL; + state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE); + + return 0; +} + +static const struct pwm_ops crc_pwm_ops = { + .apply = crc_pwm_apply, + .get_state = crc_pwm_get_state, +}; + +static int crystalcove_pwm_probe(struct platform_device *pdev) +{ + struct crystalcove_pwm *pwm; + struct device *dev = pdev->dev.parent; + struct intel_soc_pmic *pmic = dev_get_drvdata(dev); + + pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL); + if (!pwm) + return -ENOMEM; + + pwm->chip.dev = &pdev->dev; + pwm->chip.ops = &crc_pwm_ops; + pwm->chip.npwm = 1; + + /* get the PMIC regmap */ + pwm->regmap = pmic->regmap; + + return devm_pwmchip_add(&pdev->dev, &pwm->chip); +} + +static struct platform_driver crystalcove_pwm_driver = { + .probe = crystalcove_pwm_probe, + .driver = { + .name = "crystal_cove_pwm", + }, +}; + +builtin_platform_driver(crystalcove_pwm_driver); |