// SPDX-License-Identifier: GPL-2.0-or-later /* * The Netronix embedded controller is a microcontroller found in some * e-book readers designed by the original design manufacturer Netronix, Inc. * It contains RTC, battery monitoring, system power management, and PWM * functionality. * * This driver implements PWM output. * * Copyright 2020 Jonathan Neuschäfer <[email protected]> * * Limitations: * - The get_state callback is not implemented, because the current state of * the PWM output can't be read back from the hardware. * - The hardware can only generate normal polarity output. * - The period and duty cycle can't be changed together in one atomic action. */ #include <linux/mfd/ntxec.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/pwm.h> #include <linux/regmap.h> #include <linux/types.h> struct ntxec_pwm { … }; static struct ntxec_pwm *ntxec_pwm_from_chip(struct pwm_chip *chip) { … } #define NTXEC_REG_AUTO_OFF_HI … #define NTXEC_REG_AUTO_OFF_LO … #define NTXEC_REG_ENABLE … #define NTXEC_REG_PERIOD_LOW … #define NTXEC_REG_PERIOD_HIGH … #define NTXEC_REG_DUTY_LOW … #define NTXEC_REG_DUTY_HIGH … /* * The time base used in the EC is 8MHz, or 125ns. Period and duty cycle are * measured in this unit. */ #define TIME_BASE_NS … /* * The maximum input value (in nanoseconds) is determined by the time base and * the range of the hardware registers that hold the converted value. * It fits into 32 bits, so we can do our calculations in 32 bits as well. */ #define MAX_PERIOD_NS … static int ntxec_pwm_set_raw_period_and_duty_cycle(struct pwm_chip *chip, int period, int duty) { … } static int ntxec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm_dev, const struct pwm_state *state) { … } static const struct pwm_ops ntxec_pwm_ops = …; static int ntxec_pwm_probe(struct platform_device *pdev) { … } static struct platform_driver ntxec_pwm_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …;
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