f051c466cf
Many PWM controllers provide access to more than a single PWM output and may even share some resource among them. Allowing a PWM chip to provide multiple PWM devices enables better sharing of those resources. As a side-effect this change allows easy integration with the device tree where a given PWM can be looked up based on the PWM chip's phandle and a corresponding index. This commit modifies the PWM core to support multiple PWMs per struct pwm_chip. It achieves this in a similar way to how gpiolib works, by allowing PWM ranges to be requested dynamically (pwm_chip.base == -1) or starting at a given offset (pwm_chip.base >= 0). A chip specifies how many PWMs it controls using the npwm member. Each of the functions in the pwm_ops structure gets an additional argument that specified the PWM number (it can be converted to a per-chip index by subtracting the chip's base). The total maximum number of PWM devices is currently fixed to 1024 while the data is actually stored in a radix tree, thus saving resources if not all of them are used. Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> [eric@eukrea.com: fix error handling in pwmchip_add] Signed-off-by: Eric Bénard <eric@eukrea.com> Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
#ifndef __LINUX_PWM_H
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#define __LINUX_PWM_H
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struct pwm_device;
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/*
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* pwm_request - request a PWM device
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*/
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struct pwm_device *pwm_request(int pwm_id, const char *label);
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/*
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* pwm_free - free a PWM device
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*/
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void pwm_free(struct pwm_device *pwm);
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/*
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* pwm_config - change a PWM device configuration
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*/
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int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns);
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/*
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* pwm_enable - start a PWM output toggling
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*/
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int pwm_enable(struct pwm_device *pwm);
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/*
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* pwm_disable - stop a PWM output toggling
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*/
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void pwm_disable(struct pwm_device *pwm);
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#ifdef CONFIG_PWM
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struct pwm_chip;
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enum {
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PWMF_REQUESTED = 1 << 0,
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PWMF_ENABLED = 1 << 1,
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};
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struct pwm_device {
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const char *label;
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unsigned long flags;
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unsigned int hwpwm;
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unsigned int pwm;
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struct pwm_chip *chip;
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void *chip_data;
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unsigned int period; /* in nanoseconds */
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};
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static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
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{
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if (pwm)
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pwm->period = period;
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}
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static inline unsigned int pwm_get_period(struct pwm_device *pwm)
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{
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return pwm ? pwm->period : 0;
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}
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/**
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* struct pwm_ops - PWM controller operations
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* @request: optional hook for requesting a PWM
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* @free: optional hook for freeing a PWM
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* @config: configure duty cycles and period length for this PWM
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* @enable: enable PWM output toggling
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* @disable: disable PWM output toggling
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* @owner: helps prevent removal of modules exporting active PWMs
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*/
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struct pwm_ops {
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int (*request)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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void (*free)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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int (*config)(struct pwm_chip *chip,
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struct pwm_device *pwm,
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int duty_ns, int period_ns);
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int (*enable)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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void (*disable)(struct pwm_chip *chip,
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struct pwm_device *pwm);
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struct module *owner;
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};
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/**
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* struct pwm_chip - abstract a PWM controller
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* @dev: device providing the PWMs
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* @list: list node for internal use
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* @ops: callbacks for this PWM controller
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* @base: number of first PWM controlled by this chip
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* @npwm: number of PWMs controlled by this chip
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* @pwms: array of PWM devices allocated by the framework
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*/
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struct pwm_chip {
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struct device *dev;
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struct list_head list;
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const struct pwm_ops *ops;
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int base;
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unsigned int npwm;
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struct pwm_device *pwms;
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};
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int pwm_set_chip_data(struct pwm_device *pwm, void *data);
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void *pwm_get_chip_data(struct pwm_device *pwm);
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int pwmchip_add(struct pwm_chip *chip);
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int pwmchip_remove(struct pwm_chip *chip);
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struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
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unsigned int index,
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const char *label);
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#endif
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#endif /* __LINUX_PWM_H */
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