From 0c2498f1660878339350bea8d18550b1b87ca055 Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Fri, 28 Jan 2011 09:40:40 +0100 Subject: pwm: Add PWM framework support This patch adds framework support for PWM (pulse width modulation) devices. The is a barebone PWM API already in the kernel under include/linux/pwm.h, but it does not allow for multiple drivers as each of them implements the pwm_*() functions. There are other PWM framework patches around from Bill Gatliff. Unlike his framework this one does not change the existing API for PWMs so that this framework can act as a drop in replacement for the existing API. Why another framework? Several people argue that there should not be another framework for PWMs but they should be integrated into one of the existing frameworks like led or hwmon. Unlike these frameworks the PWM framework is agnostic to the purpose of the PWM. In fact, a PWM can drive a LED, but this makes the LED framework a user of a PWM, like already done in leds-pwm.c. The gpio framework also is not suitable for PWMs. Every gpio could be turned into a PWM using timer based toggling, but on the other hand not every PWM hardware device can be turned into a gpio due to the lack of hardware capabilities. This patch does not try to improve the PWM API yet, this could be done in subsequent patches. Signed-off-by: Sascha Hauer Acked-by: Kurt Van Dijck Reviewed-by: Arnd Bergmann Reviewed-by: Matthias Kaehlcke Reviewed-by: Mark Brown Reviewed-by: Shawn Guo [thierry.reding@avionic-design.de: fixup typos, kerneldoc comments] Signed-off-by: Thierry Reding --- include/linux/pwm.h | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 7c775751392c..1f308a13105f 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -28,4 +28,42 @@ int pwm_enable(struct pwm_device *pwm); */ void pwm_disable(struct pwm_device *pwm); +#ifdef CONFIG_PWM +struct pwm_chip; + +/** + * struct pwm_ops - PWM controller operations + * @request: optional hook for requesting a PWM + * @free: optional hook for freeing a PWM + * @config: configure duty cycles and period length for this PWM + * @enable: enable PWM output toggling + * @disable: disable PWM output toggling + * @owner: helps prevent removal of modules exporting active PWMs + */ +struct pwm_ops { + int (*request)(struct pwm_chip *chip); + void (*free)(struct pwm_chip *chip); + int (*config)(struct pwm_chip *chip, int duty_ns, + int period_ns); + int (*enable)(struct pwm_chip *chip); + void (*disable)(struct pwm_chip *chip); + struct module *owner; +}; + +/** + * struct pwm_chip - abstract a PWM + * @pwm_id: global PWM device index + * @label: PWM device label + * @ops: controller operations + */ +struct pwm_chip { + int pwm_id; + const char *label; + struct pwm_ops *ops; +}; + +int pwmchip_add(struct pwm_chip *chip); +int pwmchip_remove(struct pwm_chip *chip); +#endif + #endif /* __LINUX_PWM_H */ -- cgit v1.2.3 From f051c466cf690ac661d713d3ceb56b4efcecc853 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Wed, 14 Dec 2011 11:12:23 +0100 Subject: pwm: Allow chips to support multiple PWMs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Shawn Guo [eric@eukrea.com: fix error handling in pwmchip_add] Signed-off-by: Eric Bénard Signed-off-by: Thierry Reding --- include/linux/pwm.h | 71 +++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 58 insertions(+), 13 deletions(-) (limited to 'include/linux') diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 1f308a13105f..57103911f4c7 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -31,6 +31,33 @@ void pwm_disable(struct pwm_device *pwm); #ifdef CONFIG_PWM struct pwm_chip; +enum { + PWMF_REQUESTED = 1 << 0, + PWMF_ENABLED = 1 << 1, +}; + +struct pwm_device { + const char *label; + unsigned long flags; + unsigned int hwpwm; + unsigned int pwm; + struct pwm_chip *chip; + void *chip_data; + + unsigned int period; /* in nanoseconds */ +}; + +static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period) +{ + if (pwm) + pwm->period = period; +} + +static inline unsigned int pwm_get_period(struct pwm_device *pwm) +{ + return pwm ? pwm->period : 0; +} + /** * struct pwm_ops - PWM controller operations * @request: optional hook for requesting a PWM @@ -41,29 +68,47 @@ struct pwm_chip; * @owner: helps prevent removal of modules exporting active PWMs */ struct pwm_ops { - int (*request)(struct pwm_chip *chip); - void (*free)(struct pwm_chip *chip); - int (*config)(struct pwm_chip *chip, int duty_ns, - int period_ns); - int (*enable)(struct pwm_chip *chip); - void (*disable)(struct pwm_chip *chip); + int (*request)(struct pwm_chip *chip, + struct pwm_device *pwm); + void (*free)(struct pwm_chip *chip, + struct pwm_device *pwm); + int (*config)(struct pwm_chip *chip, + struct pwm_device *pwm, + int duty_ns, int period_ns); + int (*enable)(struct pwm_chip *chip, + struct pwm_device *pwm); + void (*disable)(struct pwm_chip *chip, + struct pwm_device *pwm); struct module *owner; }; /** - * struct pwm_chip - abstract a PWM - * @pwm_id: global PWM device index - * @label: PWM device label - * @ops: controller operations + * struct pwm_chip - abstract a PWM controller + * @dev: device providing the PWMs + * @list: list node for internal use + * @ops: callbacks for this PWM controller + * @base: number of first PWM controlled by this chip + * @npwm: number of PWMs controlled by this chip + * @pwms: array of PWM devices allocated by the framework */ struct pwm_chip { - int pwm_id; - const char *label; - struct pwm_ops *ops; + struct device *dev; + struct list_head list; + const struct pwm_ops *ops; + int base; + unsigned int npwm; + + struct pwm_device *pwms; }; +int pwm_set_chip_data(struct pwm_device *pwm, void *data); +void *pwm_get_chip_data(struct pwm_device *pwm); + int pwmchip_add(struct pwm_chip *chip); int pwmchip_remove(struct pwm_chip *chip); +struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip, + unsigned int index, + const char *label); #endif #endif /* __LINUX_PWM_H */ -- cgit v1.2.3 From 62099abf67a20cfb98d4c031fb1925e10a78ee1b Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Mon, 26 Mar 2012 09:31:48 +0200 Subject: pwm: Add debugfs interface This commit adds a debugfs interface that can be used to list the current internal state of the PWM devices registered with the PWM framework. Reviewed-by: Mark Brown Reviewed-by: Shawn Guo Signed-off-by: Thierry Reding --- include/linux/pwm.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 57103911f4c7..047cd5351a3b 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -2,6 +2,7 @@ #define __LINUX_PWM_H struct pwm_device; +struct seq_file; /* * pwm_request - request a PWM device @@ -65,6 +66,7 @@ static inline unsigned int pwm_get_period(struct pwm_device *pwm) * @config: configure duty cycles and period length for this PWM * @enable: enable PWM output toggling * @disable: disable PWM output toggling + * @dbg_show: optional routine to show contents in debugfs * @owner: helps prevent removal of modules exporting active PWMs */ struct pwm_ops { @@ -79,6 +81,10 @@ struct pwm_ops { struct pwm_device *pwm); void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm); +#ifdef CONFIG_DEBUG_FS + void (*dbg_show)(struct pwm_chip *chip, + struct seq_file *s); +#endif struct module *owner; }; -- cgit v1.2.3 From 8138d2ddbcca2a100482dac390133f83c5a60f94 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Mon, 26 Mar 2012 08:42:48 +0200 Subject: pwm: Add table-based lookup for static mappings In order to get rid of the global namespace for PWM devices, this commit provides an alternative method, similar to that of the regulator or clock frameworks, for registering a static mapping for PWM devices. This works by providing a table with a provider/consumer map in the board setup code. With the new pwm_get() and pwm_put() functions available, usage of pwm_request() and pwm_free() becomes deprecated. Reviewed-by: Shawn Guo Reviewed-by: Mark Brown Signed-off-by: Thierry Reding --- include/linux/pwm.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 047cd5351a3b..2947a4fea6ad 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -115,6 +115,28 @@ int pwmchip_remove(struct pwm_chip *chip); struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip, unsigned int index, const char *label); + +struct pwm_device *pwm_get(struct device *dev, const char *consumer); +void pwm_put(struct pwm_device *pwm); + +struct pwm_lookup { + struct list_head list; + const char *provider; + unsigned int index; + const char *dev_id; + const char *con_id; +}; + +#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id) \ + { \ + .provider = _provider, \ + .index = _index, \ + .dev_id = _dev_id, \ + .con_id = _con_id, \ + } + +void pwm_add_table(struct pwm_lookup *table, size_t num); + #endif #endif /* __LINUX_PWM_H */ -- cgit v1.2.3 From bd3d5500f0c41a30149cb184362716096a17bc75 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Fri, 13 Apr 2012 16:18:34 +0200 Subject: dt: Add empty of_property_match_string() function This commit adds an empty of_property_match_string() function for !CONFIG_OF builds. Acked-by: Rob Herring Signed-off-by: Thierry Reding --- include/linux/of.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include/linux') diff --git a/include/linux/of.h b/include/linux/of.h index 2ec1083af7ff..597e571110a2 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -377,6 +377,13 @@ static inline int of_property_read_u64(const struct device_node *np, return -ENOSYS; } +static inline int of_property_match_string(struct device_node *np, + const char *propname, + const char *string) +{ + return -ENOSYS; +} + static inline struct device_node *of_parse_phandle(struct device_node *np, const char *phandle_name, int index) -- cgit v1.2.3 From e05e5070f0ec2557d2d2ff3655ba03f29e297151 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Fri, 13 Apr 2012 16:19:21 +0200 Subject: dt: Add empty of_parse_phandle_with_args() function This commit adds an empty of_parse_phandle_with_args() function for !CONFIG_OF builds. Acked-by: Rob Herring Signed-off-by: Thierry Reding --- include/linux/of.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux') diff --git a/include/linux/of.h b/include/linux/of.h index 597e571110a2..d5dd5c06efd3 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -391,6 +391,15 @@ static inline struct device_node *of_parse_phandle(struct device_node *np, return NULL; } +static inline int of_parse_phandle_with_args(struct device_node *np, + const char *list_name, + const char *cells_name, + int index, + struct of_phandle_args *out_args) +{ + return -ENOSYS; +} + static inline int of_alias_get_id(struct device_node *np, const char *stem) { return -ENOSYS; -- cgit v1.2.3 From 7299ab70e68e20e70cb45fe4ab4b6029fe964acd Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Wed, 14 Dec 2011 11:10:32 +0100 Subject: pwm: Add device tree support This patch adds helpers to support device tree bindings for the generic PWM API. Device tree binding documentation for PWM controllers is also provided. Acked-by: Arnd Bergmann Reviewed-by: Shawn Guo Signed-off-by: Thierry Reding --- include/linux/pwm.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 2947a4fea6ad..21d076c5089e 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -1,6 +1,8 @@ #ifndef __LINUX_PWM_H #define __LINUX_PWM_H +#include + struct pwm_device; struct seq_file; @@ -105,6 +107,10 @@ struct pwm_chip { unsigned int npwm; struct pwm_device *pwms; + + struct pwm_device * (*of_xlate)(struct pwm_chip *pc, + const struct of_phandle_args *args); + unsigned int of_pwm_n_cells; }; int pwm_set_chip_data(struct pwm_device *pwm, void *data); -- cgit v1.2.3 From 3e3ed6cdc49d758719c148a78c8b04c243ef74d0 Mon Sep 17 00:00:00 2001 From: Thierry Reding Date: Fri, 16 Dec 2011 21:25:29 +0100 Subject: pwm-backlight: Add rudimentary device tree support This commit adds very basic support for device tree probing. Currently, only a PWM and a list of distinct brightness levels can be specified. Enabling or disabling backlight power via GPIOs is not yet supported. Reviewed-by: Shawn Guo Reviewed-by: Mark Brown Signed-off-by: Thierry Reding --- include/linux/pwm_backlight.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h index 63d2df43e61a..56f4a866539a 100644 --- a/include/linux/pwm_backlight.h +++ b/include/linux/pwm_backlight.h @@ -12,6 +12,7 @@ struct platform_pwm_backlight_data { unsigned int dft_brightness; unsigned int lth_brightness; unsigned int pwm_period_ns; + unsigned int *levels; int (*init)(struct device *dev); int (*notify)(struct device *dev, int brightness); void (*notify_after)(struct device *dev, int brightness); -- cgit v1.2.3