| Message ID | 1331740593-10807-4-git-send-email-thierry.reding@avionic-design.de |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Wed, Mar 14, 2012 at 04:56:26PM +0100, Thierry Reding wrote: > This patch adds helpers to support device tree bindings for the generic > PWM API. Device tree binding documentation for PWM controllers is also > provided. > > Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de> > --- > Changes in v4: > - add OF-specific code removed from patch 2 > - make of_node_to_pwmchip() and of_pwm_simple_xlate() static > - rename of_get_named_pwm() to of_pwm_request(), return a struct > pwm_device, get rid of the now unused spec parameter and use the > device_node.name field as the PWM's name > - return a requested struct pwm_device from pwm_chip.of_xlate and > drop the now unused spec parameter > - move OF support code into drivers/pwm/core.c > - used deferred probing if a PWM chip is not available yet > > Changes in v2: > - add device tree binding documentation > - add of_xlate to parse controller-specific PWM-specifier > > Documentation/devicetree/bindings/pwm/pwm.txt | 48 ++++++++++ > drivers/of/Kconfig | 6 ++ > drivers/pwm/core.c | 127 +++++++++++++++++++++++++ > include/linux/of_pwm.h | 36 +++++++ > include/linux/pwm.h | 8 ++ > 5 files changed, 225 insertions(+) > create mode 100644 Documentation/devicetree/bindings/pwm/pwm.txt > create mode 100644 include/linux/of_pwm.h > > diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt > new file mode 100644 > index 0000000..9421fe7 > --- /dev/null > +++ b/Documentation/devicetree/bindings/pwm/pwm.txt > @@ -0,0 +1,48 @@ > +Specifying PWM information for devices > +====================================== > + > +1) PWM user nodes > +----------------- > + > +PWM users should specify a list of PWM devices that they want to use > +with a property containing a 'pwm-list': > + > + pwm-list ::= <single-pwm> [pwm-list] > + single-pwm ::= <pwm-phandle> <pwm-specifier> > + pwm-phandle : phandle to PWM controller node > + pwm-specifier : array of #pwm-cells specifying the given PWM > + (controller specific) > + > +PWM properties should be named "[<name>-]pwms". Exact meaning of each > +pwms property must be documented in the device tree binding for each > +device. > + > +The following example could be used to describe a PWM-based backlight > +device: > + > + pwm: pwm { > + #pwm-cells = <2>; > + }; > + > + [...] > + > + bl: backlight { > + pwms = <&pwm 0 5000000>; > + }; > + > +pwm-specifier typically encodes the chip-relative PWM number and the PWM > +period in nanoseconds. > + > +2) PWM controller nodes > +----------------------- > + > +PWM controller nodes must specify the number of cells used for the > +specifier using the '#pwm-cells' property. > + > +An example PWM controller might look like this: > + > + pwm: pwm@7000a000 { > + compatible = "nvidia,tegra20-pwm"; > + reg = <0x7000a000 0x100>; > + #pwm-cells = <2>; > + }; > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig > index 6ea51dc..d47b8ee 100644 > --- a/drivers/of/Kconfig > +++ b/drivers/of/Kconfig > @@ -57,6 +57,12 @@ config OF_GPIO > help > OpenFirmware GPIO accessors > > +config OF_PWM > + def_bool y > + depends on PWM > + help > + OpenFirmware PWM accessors > + > config OF_I2C > def_tristate I2C > depends on I2C && !SPARC > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index 74dd295..c600606 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -20,6 +20,7 @@ > */ > > #include <linux/module.h> > +#include <linux/of_pwm.h> > #include <linux/pwm.h> > #include <linux/radix-tree.h> > #include <linux/list.h> > @@ -121,6 +122,75 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) > return 0; > } > > +#ifdef CONFIG_OF_PWM > +static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > +{ > + struct pwm_chip *chip; > + > + mutex_lock(&pwm_lock); > + > + list_for_each_entry(chip, &pwm_chips, list) > + if (chip->dev && chip->dev->of_node == np) { > + mutex_unlock(&pwm_lock); > + return chip; > + } > + > + mutex_unlock(&pwm_lock); > + > + return ERR_PTR(-EPROBE_DEFER); > +} > + > +static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc, > + const struct of_phandle_args *args) > +{ > + struct pwm_device *pwm; > + > + if (pc->of_pwm_n_cells < 2) > + return ERR_PTR(-EINVAL); > + > + if (args->args_count < pc->of_pwm_n_cells) > + return ERR_PTR(-EINVAL); > + > + if (args->args[0] >= pc->npwm) > + return ERR_PTR(-EINVAL); > + > + pwm = pwm_request_from_device(pc->dev, args->args[0], NULL); > + if (IS_ERR(pwm)) > + return ERR_PTR(-ENODEV); > + > + pwm_set_period(pwm, args->args[1]); > + > + return pwm; > +} > + > +void of_pwmchip_add(struct pwm_chip *chip) > +{ > + if (!chip->dev || !chip->dev->of_node) > + return; > + > + if (!chip->of_xlate) { > + chip->of_xlate = of_pwm_simple_xlate; > + chip->of_pwm_n_cells = 2; > + } > + > + of_node_get(chip->dev->of_node); > +} > + > +void of_pwmchip_remove(struct pwm_chip *chip) > +{ > + if (chip->dev && chip->dev->of_node) > + of_node_put(chip->dev->of_node); > +} > +#else > +static inline void of_pwmchip_add(struct pwm_chip *pc) > +{ > +} > + > +static inline void of_pwmchip_remove(struct pwm_chip *pc) > +{ > +} > +#endif /* CONFIG_OF_PWM */ > + > /** > * pwm_set_chip_data - set private chip data for a PWM > * @pwm: PWM device > @@ -184,6 +254,7 @@ int pwmchip_add(struct pwm_chip *chip) > > INIT_LIST_HEAD(&chip->list); > list_add(&chip->list, &pwm_chips); > + of_pwmchip_add(chip); > > out: > mutex_unlock(&pwm_lock); > @@ -215,6 +286,7 @@ int pwmchip_remove(struct pwm_chip *chip) > } > > list_del_init(&chip->list); > + of_pwmchip_remove(chip); > free_pwms(chip); > > out: > @@ -364,6 +436,61 @@ void pwm_disable(struct pwm_device *pwm) > } > EXPORT_SYMBOL_GPL(pwm_disable); > > +#ifdef CONFIG_OF > +/** > + * of_pwm_request() - request a PWM via the PWM framework > + * @np: device node to get the PWM from > + * @propname: property name containing PWM specifier(s) > + * @index: index of the PWM > + * > + * Returns the PWM device parsed from the phandle specified in the given > + * property of a device tree node or NULL on failure. Values parsed from > + * the device tree are stored in the returned PWM device object. > + */ > +struct pwm_device *of_pwm_request(struct device_node *np, > + const char *propname, int index) > +{ > + struct pwm_device *pwm = NULL; > + struct of_phandle_args args; > + struct pwm_chip *pc; > + int err; > + > + err = of_parse_phandle_with_args(np, propname, "#pwm-cells", index, > + &args); > + if (err) { > + pr_debug("%s(): can't parse property \"%s\"\n", __func__, > + propname); > + return ERR_PTR(err); > + } > + > + pc = of_node_to_pwmchip(args.np); > + if (IS_ERR(pc)) { > + pr_debug("%s(): PWM chip not found\n", __func__); > + pwm = ERR_CAST(pc); > + goto put; > + } > + > + if (args.args_count != pc->of_pwm_n_cells) { > + pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name, > + args.np->full_name); > + pwm = ERR_PTR(-EINVAL); > + goto put; > + } > + > + pwm = pc->of_xlate(pc, &args); > + if (IS_ERR(pwm)) > + goto put; > + > + pwm->label = np->name; > + > +put: > + of_node_put(args.np); > + > + return pwm; > +} > +EXPORT_SYMBOL(of_pwm_request); > +#endif > + > #ifdef CONFIG_DEBUG_FS > static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) > { > diff --git a/include/linux/of_pwm.h b/include/linux/of_pwm.h > new file mode 100644 > index 0000000..a3a3da7 > --- /dev/null > +++ b/include/linux/of_pwm.h > @@ -0,0 +1,36 @@ > +/* > + * OF helpers for the PWM API > + * > + * Copyright (c) 2011-2012 Avionic Design GmbH > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + */ > + > +#ifndef __LINUX_OF_PWM_H > +#define __LINUX_OF_PWM_H > + > +#include <linux/err.h> > +#include <linux/pwm.h> > + > +struct device_node; > + > +#ifdef CONFIG_OF_PWM > + > +struct pwm_device *of_pwm_request(struct device_node *np, > + const char *propname, int index); > + > +#else > + > +static inline struct pwm_device *of_pwm_request(struct device_node *np, > + const char *propname, > + int index); ^^^ No semicolon here please. Sascha
* Sascha Hauer wrote: > On Wed, Mar 14, 2012 at 04:56:26PM +0100, Thierry Reding wrote: > > +static inline struct pwm_device *of_pwm_request(struct device_node *np, > > + const char *propname, > > + int index); > ^^^ > > No semicolon here please. Ugh. I've been doing extra compile tests to make sure the series stays bisectible, but I guess I need to add further tests with !PWM and !OF configurations. Thanks, Thierry
On Wednesday 14 March 2012, Thierry Reding wrote: > This patch adds helpers to support device tree bindings for the generic > PWM API. Device tree binding documentation for PWM controllers is also > provided. > > Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de> > --- > Changes in v4: > - add OF-specific code removed from patch 2 > - make of_node_to_pwmchip() and of_pwm_simple_xlate() static > - rename of_get_named_pwm() to of_pwm_request(), return a struct > pwm_device, get rid of the now unused spec parameter and use the > device_node.name field as the PWM's name > - return a requested struct pwm_device from pwm_chip.of_xlate and > drop the now unused spec parameter > - move OF support code into drivers/pwm/core.c > - used deferred probing if a PWM chip is not available yet > > Changes in v2: > - add device tree binding documentation > - add of_xlate to parse controller-specific PWM-specifier Looks very cool now, and much simpler! > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig > index 6ea51dc..d47b8ee 100644 > --- a/drivers/of/Kconfig > +++ b/drivers/of/Kconfig > @@ -57,6 +57,12 @@ config OF_GPIO > help > OpenFirmware GPIO accessors > > +config OF_PWM > + def_bool y > + depends on PWM > + help > + OpenFirmware PWM accessors > + > config OF_I2C > def_tristate I2C > depends on I2C && !SPARC You might want to remove this one now and just use CONFIG_OF in the driver, unless there is a reason to keep it here. > +#ifdef CONFIG_OF_PWM > +static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > +{ > + struct pwm_chip *chip; > + > + mutex_lock(&pwm_lock); > + > + list_for_each_entry(chip, &pwm_chips, list) > + if (chip->dev && chip->dev->of_node == np) { > + mutex_unlock(&pwm_lock); > + return chip; > + } > + > + mutex_unlock(&pwm_lock); > + > + return ERR_PTR(-EPROBE_DEFER); > +} EPROBE_DEFER doesn't exist yet in my kernel, and I wonder if it's actually safe to be used this way, because it can result in arbitrary drivers using this to be put on the defered probe list. It certainly sounds like the right thing to do in the long run though. > +#else > +static inline void of_pwmchip_add(struct pwm_chip *pc) > +{ > +} > + > +static inline void of_pwmchip_remove(struct pwm_chip *pc) > +{ > +} > +#endif /* CONFIG_OF_PWM */ > + > /** > * pwm_set_chip_data - set private chip data for a PWM > * @pwm: PWM device > @@ -184,6 +254,7 @@ int pwmchip_add(struct pwm_chip *chip) > > INIT_LIST_HEAD(&chip->list); > list_add(&chip->list, &pwm_chips); > + of_pwmchip_add(chip); > > out: > mutex_unlock(&pwm_lock); You could express the same thing using if (IS_ENABLED(CONFIG_OF_PWM)) of_pwmchip_add(chip); The advantage of this is that you always get compile coverage for the entire file, but the function is automatically discarded by the compiler when the condition is false at compile time. That obviously doesn't work for exported functions. > +#ifdef CONFIG_OF > +/** > + * of_pwm_request() - request a PWM via the PWM framework > + * @np: device node to get the PWM from > + * @propname: property name containing PWM specifier(s) > + * @index: index of the PWM > + * > + * Returns the PWM device parsed from the phandle specified in the given > + * property of a device tree node or NULL on failure. Values parsed from > + * the device tree are stored in the returned PWM device object. > + */ > +struct pwm_device *of_pwm_request(struct device_node *np, > + const char *propname, int index) > +{ > + struct pwm_device *pwm = NULL; > + struct of_phandle_args args; > + struct pwm_chip *pc; > + int err; > + > + err = of_parse_phandle_with_args(np, propname, "#pwm-cells", index, > + &args); Wow, I just looked up what of_parse_phandle_with_args() does and that is extremely helpful indeed. > /* > @@ -102,6 +104,12 @@ struct pwm_chip { > unsigned int npwm; > > struct pwm_device *pwms; > + > +#ifdef CONFIG_OF_PWM > + struct pwm_device * (*of_xlate)(struct pwm_chip *pc, > + const struct of_phandle_args *args); > + unsigned int of_pwm_n_cells; > +#endif > }; > > int pwm_set_chip_data(struct pwm_device *pwm, void *data); If you use IS_ENABLED() as I suggested above, this #ifdef will have to go away, too, which is a very small size overhead. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Mar 15, 2012 at 08:40:42AM +0000, Arnd Bergmann wrote: > On Wednesday 14 March 2012, Thierry Reding wrote: > > +static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) > > +{ > > + return ERR_PTR(-EPROBE_DEFER); > > +} > EPROBE_DEFER doesn't exist yet in my kernel, and I wonder if it's actually > safe to be used this way, because it can result in arbitrary drivers using > this to be put on the defered probe list. It certainly sounds like the > right thing to do in the long run though. Similar code is going in for regulators in 3.4 along with the core -EPROBE_DEFER change (though not OF specific) and I sent a similar patch for GPIOs too, hopefully Grant will ack it in time for it to make it in. My theory is that since you need to explicitly know that the thing you're requesting is there in order to request it (eg, have a PWM number or DT link) the overwhemlingly common case for a failure to request will be that the provider didn't register yet which is exactly the case where deferral is desired. It therefore seems sensible to have the framework default the drivers to retrying rather than have almost every individual driver look at the failure, figure out if it was a missing provider, and then retry. Drivers that have a good reason to fail can always check for -EPROBE_DEFER and override it. The result should be that we can take advantage of probe deferral over large areas of the kernel without having to go and explicitly modify so many drivers - if the frameworks like GPIO, clk and regulator can do this that ought to cover 90% of the cases where probe deferral will be needed without having to do anything more than have good error handling paths on probe which is a good idea anyway.
On Thursday 15 March 2012, Mark Brown wrote: > Similar code is going in for regulators in 3.4 along with the core > -EPROBE_DEFER change (though not OF specific) and I sent a similar patch > for GPIOs too, hopefully Grant will ack it in time for it to make it in. > > My theory is that since you need to explicitly know that the thing > you're requesting is there in order to request it (eg, have a PWM number > or DT link) the overwhemlingly common case for a failure to request will > be that the provider didn't register yet which is exactly the case where > deferral is desired. It therefore seems sensible to have the framework > default the drivers to retrying rather than have almost every individual > driver look at the failure, figure out if it was a missing provider, and > then retry. Drivers that have a good reason to fail can always check > for -EPROBE_DEFER and override it. > > The result should be that we can take advantage of probe deferral over > large areas of the kernel without having to go and explicitly modify so > many drivers - if the frameworks like GPIO, clk and regulator can do > this that ought to cover 90% of the cases where probe deferral will be > needed without having to do anything more than have good error handling > paths on probe which is a good idea anyway. Ok, makes sense. Thanks, Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/14/2012 09:56 AM, Thierry Reding wrote: > This patch adds helpers to support device tree bindings for the generic > PWM API. Device tree binding documentation for PWM controllers is also > provided. ... > +static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc, > + const struct of_phandle_args *args) ... > + if (args->args_count < pc->of_pwm_n_cells) > + return ERR_PTR(-EINVAL); I think you can drop that error-check given the code quoted below? (and if not, shouldn't it be != not >= ?) > +struct pwm_device *of_pwm_request(struct device_node *np, > + const char *propname, int index) ... > + if (args.args_count != pc->of_pwm_n_cells) { > + pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name, > + args.np->full_name); > + pwm = ERR_PTR(-EINVAL); > + goto put; > + } > + > + pwm = pc->of_xlate(pc, &args); -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
* Stephen Warren wrote: > On 03/14/2012 09:56 AM, Thierry Reding wrote: > > This patch adds helpers to support device tree bindings for the generic > > PWM API. Device tree binding documentation for PWM controllers is also > > provided. > ... > > +static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc, > > + const struct of_phandle_args *args) > ... > > + if (args->args_count < pc->of_pwm_n_cells) > > + return ERR_PTR(-EINVAL); > > I think you can drop that error-check given the code quoted below? > > (and if not, shouldn't it be != not >= ?) > > > +struct pwm_device *of_pwm_request(struct device_node *np, > > + const char *propname, int index) > ... > > + if (args.args_count != pc->of_pwm_n_cells) { > > + pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name, > > + args.np->full_name); > > + pwm = ERR_PTR(-EINVAL); > > + goto put; > > + } > > + > > + pwm = pc->of_xlate(pc, &args); Yes, you're right. It is completely redundant. Thierry
diff --git a/Documentation/devicetree/bindings/pwm/pwm.txt b/Documentation/devicetree/bindings/pwm/pwm.txt new file mode 100644 index 0000000..9421fe7 --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pwm.txt @@ -0,0 +1,48 @@ +Specifying PWM information for devices +====================================== + +1) PWM user nodes +----------------- + +PWM users should specify a list of PWM devices that they want to use +with a property containing a 'pwm-list': + + pwm-list ::= <single-pwm> [pwm-list] + single-pwm ::= <pwm-phandle> <pwm-specifier> + pwm-phandle : phandle to PWM controller node + pwm-specifier : array of #pwm-cells specifying the given PWM + (controller specific) + +PWM properties should be named "[<name>-]pwms". Exact meaning of each +pwms property must be documented in the device tree binding for each +device. + +The following example could be used to describe a PWM-based backlight +device: + + pwm: pwm { + #pwm-cells = <2>; + }; + + [...] + + bl: backlight { + pwms = <&pwm 0 5000000>; + }; + +pwm-specifier typically encodes the chip-relative PWM number and the PWM +period in nanoseconds. + +2) PWM controller nodes +----------------------- + +PWM controller nodes must specify the number of cells used for the +specifier using the '#pwm-cells' property. + +An example PWM controller might look like this: + + pwm: pwm@7000a000 { + compatible = "nvidia,tegra20-pwm"; + reg = <0x7000a000 0x100>; + #pwm-cells = <2>; + }; diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 6ea51dc..d47b8ee 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -57,6 +57,12 @@ config OF_GPIO help OpenFirmware GPIO accessors +config OF_PWM + def_bool y + depends on PWM + help + OpenFirmware PWM accessors + config OF_I2C def_tristate I2C depends on I2C && !SPARC diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 74dd295..c600606 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -20,6 +20,7 @@ */ #include <linux/module.h> +#include <linux/of_pwm.h> #include <linux/pwm.h> #include <linux/radix-tree.h> #include <linux/list.h> @@ -121,6 +122,75 @@ static int pwm_device_request(struct pwm_device *pwm, const char *label) return 0; } +#ifdef CONFIG_OF_PWM +static struct pwm_chip *of_node_to_pwmchip(struct device_node *np) +{ + struct pwm_chip *chip; + + mutex_lock(&pwm_lock); + + list_for_each_entry(chip, &pwm_chips, list) + if (chip->dev && chip->dev->of_node == np) { + mutex_unlock(&pwm_lock); + return chip; + } + + mutex_unlock(&pwm_lock); + + return ERR_PTR(-EPROBE_DEFER); +} + +static struct pwm_device *of_pwm_simple_xlate(struct pwm_chip *pc, + const struct of_phandle_args *args) +{ + struct pwm_device *pwm; + + if (pc->of_pwm_n_cells < 2) + return ERR_PTR(-EINVAL); + + if (args->args_count < pc->of_pwm_n_cells) + return ERR_PTR(-EINVAL); + + if (args->args[0] >= pc->npwm) + return ERR_PTR(-EINVAL); + + pwm = pwm_request_from_device(pc->dev, args->args[0], NULL); + if (IS_ERR(pwm)) + return ERR_PTR(-ENODEV); + + pwm_set_period(pwm, args->args[1]); + + return pwm; +} + +void of_pwmchip_add(struct pwm_chip *chip) +{ + if (!chip->dev || !chip->dev->of_node) + return; + + if (!chip->of_xlate) { + chip->of_xlate = of_pwm_simple_xlate; + chip->of_pwm_n_cells = 2; + } + + of_node_get(chip->dev->of_node); +} + +void of_pwmchip_remove(struct pwm_chip *chip) +{ + if (chip->dev && chip->dev->of_node) + of_node_put(chip->dev->of_node); +} +#else +static inline void of_pwmchip_add(struct pwm_chip *pc) +{ +} + +static inline void of_pwmchip_remove(struct pwm_chip *pc) +{ +} +#endif /* CONFIG_OF_PWM */ + /** * pwm_set_chip_data - set private chip data for a PWM * @pwm: PWM device @@ -184,6 +254,7 @@ int pwmchip_add(struct pwm_chip *chip) INIT_LIST_HEAD(&chip->list); list_add(&chip->list, &pwm_chips); + of_pwmchip_add(chip); out: mutex_unlock(&pwm_lock); @@ -215,6 +286,7 @@ int pwmchip_remove(struct pwm_chip *chip) } list_del_init(&chip->list); + of_pwmchip_remove(chip); free_pwms(chip); out: @@ -364,6 +436,61 @@ void pwm_disable(struct pwm_device *pwm) } EXPORT_SYMBOL_GPL(pwm_disable); +#ifdef CONFIG_OF +/** + * of_pwm_request() - request a PWM via the PWM framework + * @np: device node to get the PWM from + * @propname: property name containing PWM specifier(s) + * @index: index of the PWM + * + * Returns the PWM device parsed from the phandle specified in the given + * property of a device tree node or NULL on failure. Values parsed from + * the device tree are stored in the returned PWM device object. + */ +struct pwm_device *of_pwm_request(struct device_node *np, + const char *propname, int index) +{ + struct pwm_device *pwm = NULL; + struct of_phandle_args args; + struct pwm_chip *pc; + int err; + + err = of_parse_phandle_with_args(np, propname, "#pwm-cells", index, + &args); + if (err) { + pr_debug("%s(): can't parse property \"%s\"\n", __func__, + propname); + return ERR_PTR(err); + } + + pc = of_node_to_pwmchip(args.np); + if (IS_ERR(pc)) { + pr_debug("%s(): PWM chip not found\n", __func__); + pwm = ERR_CAST(pc); + goto put; + } + + if (args.args_count != pc->of_pwm_n_cells) { + pr_debug("%s: wrong #pwm-cells for %s\n", np->full_name, + args.np->full_name); + pwm = ERR_PTR(-EINVAL); + goto put; + } + + pwm = pc->of_xlate(pc, &args); + if (IS_ERR(pwm)) + goto put; + + pwm->label = np->name; + +put: + of_node_put(args.np); + + return pwm; +} +EXPORT_SYMBOL(of_pwm_request); +#endif + #ifdef CONFIG_DEBUG_FS static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s) { diff --git a/include/linux/of_pwm.h b/include/linux/of_pwm.h new file mode 100644 index 0000000..a3a3da7 --- /dev/null +++ b/include/linux/of_pwm.h @@ -0,0 +1,36 @@ +/* + * OF helpers for the PWM API + * + * Copyright (c) 2011-2012 Avionic Design GmbH + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ + +#ifndef __LINUX_OF_PWM_H +#define __LINUX_OF_PWM_H + +#include <linux/err.h> +#include <linux/pwm.h> + +struct device_node; + +#ifdef CONFIG_OF_PWM + +struct pwm_device *of_pwm_request(struct device_node *np, + const char *propname, int index); + +#else + +static inline struct pwm_device *of_pwm_request(struct device_node *np, + const char *propname, + int index); +{ + return ERR_PTR(-ENOSYS); +} + +#endif /* CONFIG_OF_PWM */ + +#endif /* __LINUX_OF_PWM_H */ diff --git a/include/linux/pwm.h b/include/linux/pwm.h index 7261911..7b42336 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -1,6 +1,8 @@ #ifndef __LINUX_PWM_H #define __LINUX_PWM_H +#include <linux/of.h> + struct pwm_device; /* @@ -102,6 +104,12 @@ struct pwm_chip { unsigned int npwm; struct pwm_device *pwms; + +#ifdef CONFIG_OF_PWM + struct pwm_device * (*of_xlate)(struct pwm_chip *pc, + const struct of_phandle_args *args); + unsigned int of_pwm_n_cells; +#endif }; int pwm_set_chip_data(struct pwm_device *pwm, void *data);
This patch adds helpers to support device tree bindings for the generic PWM API. Device tree binding documentation for PWM controllers is also provided. Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de> --- Changes in v4: - add OF-specific code removed from patch 2 - make of_node_to_pwmchip() and of_pwm_simple_xlate() static - rename of_get_named_pwm() to of_pwm_request(), return a struct pwm_device, get rid of the now unused spec parameter and use the device_node.name field as the PWM's name - return a requested struct pwm_device from pwm_chip.of_xlate and drop the now unused spec parameter - move OF support code into drivers/pwm/core.c - used deferred probing if a PWM chip is not available yet Changes in v2: - add device tree binding documentation - add of_xlate to parse controller-specific PWM-specifier Documentation/devicetree/bindings/pwm/pwm.txt | 48 ++++++++++ drivers/of/Kconfig | 6 ++ drivers/pwm/core.c | 127 +++++++++++++++++++++++++ include/linux/of_pwm.h | 36 +++++++ include/linux/pwm.h | 8 ++ 5 files changed, 225 insertions(+) create mode 100644 Documentation/devicetree/bindings/pwm/pwm.txt create mode 100644 include/linux/of_pwm.h