| Message ID | 20230217161038.3130053-1-angelo@amarulasolutions.com |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | [v3,1/3] misc: servo-pwm: driver for controlling servo motors via PWM | expand |
Hi Angelo,
I love your patch! Perhaps something to improve:
[auto build test WARNING on char-misc/char-misc-linus]
[also build test WARNING on linus/master v6.2-rc8]
[cannot apply to char-misc/char-misc-testing char-misc/char-misc-next next-20230217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Angelo-Compagnucci/misc-servo-pwm-Add-sysfs-entries-to-control-motor-angle/20230218-001254
patch link: https://lore.kernel.org/r/20230217161038.3130053-1-angelo%40amarulasolutions.com
patch subject: [PATCH v3 1/3] misc: servo-pwm: driver for controlling servo motors via PWM
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20230218/202302180429.NvI1mwuf-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/0ae16e16da0aa94de0d3ae63166f50a4a6fdef8a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Angelo-Compagnucci/misc-servo-pwm-Add-sysfs-entries-to-control-motor-angle/20230218-001254
git checkout 0ae16e16da0aa94de0d3ae63166f50a4a6fdef8a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash drivers/misc/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202302180429.NvI1mwuf-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from include/linux/mm_types_task.h:16,
from include/linux/mm_types.h:5,
from include/linux/buildid.h:5,
from include/linux/module.h:14,
from drivers/misc/servo-pwm.c:7:
drivers/misc/servo-pwm.c: In function 'angle_show':
>> arch/loongarch/include/asm/page.h:23:25: warning: passing argument 2 of 'sysfs_emit' makes pointer from integer without a cast [-Wint-conversion]
23 | #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| long unsigned int
drivers/misc/servo-pwm.c:54:32: note: in expansion of macro 'PAGE_SIZE'
54 | return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->angle);
| ^~~~~~~~~
In file included from include/linux/kobject.h:20,
from include/linux/module.h:21:
include/linux/sysfs.h:357:39: note: expected 'const char *' but argument is of type 'long unsigned int'
357 | int sysfs_emit(char *buf, const char *fmt, ...);
| ~~~~~~~~~~~~^~~
drivers/misc/servo-pwm.c: In function 'degrees_show':
>> arch/loongarch/include/asm/page.h:23:25: warning: passing argument 2 of 'sysfs_emit' makes pointer from integer without a cast [-Wint-conversion]
23 | #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| long unsigned int
drivers/misc/servo-pwm.c:84:32: note: in expansion of macro 'PAGE_SIZE'
84 | return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->degrees);
| ^~~~~~~~~
include/linux/sysfs.h:357:39: note: expected 'const char *' but argument is of type 'long unsigned int'
357 | int sysfs_emit(char *buf, const char *fmt, ...);
| ~~~~~~~~~~~~^~~
vim +/sysfs_emit +23 arch/loongarch/include/asm/page.h
09cfefb7fa70c3 Huacai Chen 2022-05-31 10
09cfefb7fa70c3 Huacai Chen 2022-05-31 11 /*
09cfefb7fa70c3 Huacai Chen 2022-05-31 12 * PAGE_SHIFT determines the page size
09cfefb7fa70c3 Huacai Chen 2022-05-31 13 */
09cfefb7fa70c3 Huacai Chen 2022-05-31 14 #ifdef CONFIG_PAGE_SIZE_4KB
09cfefb7fa70c3 Huacai Chen 2022-05-31 15 #define PAGE_SHIFT 12
09cfefb7fa70c3 Huacai Chen 2022-05-31 16 #endif
09cfefb7fa70c3 Huacai Chen 2022-05-31 17 #ifdef CONFIG_PAGE_SIZE_16KB
09cfefb7fa70c3 Huacai Chen 2022-05-31 18 #define PAGE_SHIFT 14
09cfefb7fa70c3 Huacai Chen 2022-05-31 19 #endif
09cfefb7fa70c3 Huacai Chen 2022-05-31 20 #ifdef CONFIG_PAGE_SIZE_64KB
09cfefb7fa70c3 Huacai Chen 2022-05-31 21 #define PAGE_SHIFT 16
09cfefb7fa70c3 Huacai Chen 2022-05-31 22 #endif
09cfefb7fa70c3 Huacai Chen 2022-05-31 @23 #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT)
09cfefb7fa70c3 Huacai Chen 2022-05-31 24 #define PAGE_MASK (~(PAGE_SIZE - 1))
09cfefb7fa70c3 Huacai Chen 2022-05-31 25
Hi Angelo,
I love your patch! Perhaps something to improve:
[auto build test WARNING on char-misc/char-misc-linus]
[also build test WARNING on linus/master v6.2-rc8]
[cannot apply to char-misc/char-misc-testing char-misc/char-misc-next next-20230217]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Angelo-Compagnucci/misc-servo-pwm-Add-sysfs-entries-to-control-motor-angle/20230218-001254
patch link: https://lore.kernel.org/r/20230217161038.3130053-1-angelo%40amarulasolutions.com
patch subject: [PATCH v3 1/3] misc: servo-pwm: driver for controlling servo motors via PWM
config: sparc-allyesconfig (https://download.01.org/0day-ci/archive/20230218/202302180513.AlOeQWNt-lkp@intel.com/config)
compiler: sparc64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/0ae16e16da0aa94de0d3ae63166f50a4a6fdef8a
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Angelo-Compagnucci/misc-servo-pwm-Add-sysfs-entries-to-control-motor-angle/20230218-001254
git checkout 0ae16e16da0aa94de0d3ae63166f50a4a6fdef8a
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sparc olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sparc SHELL=/bin/bash drivers/misc/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202302180513.AlOeQWNt-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from arch/sparc/include/asm/page.h:8,
from arch/sparc/include/asm/sparsemem.h:7,
from include/linux/numa.h:25,
from include/linux/cpumask.h:16,
from include/linux/mm_types_task.h:14,
from include/linux/mm_types.h:5,
from include/linux/buildid.h:5,
from include/linux/module.h:14,
from drivers/misc/servo-pwm.c:7:
drivers/misc/servo-pwm.c: In function 'angle_show':
>> arch/sparc/include/asm/page_64.h:9:22: warning: passing argument 2 of 'sysfs_emit' makes pointer from integer without a cast [-Wint-conversion]
9 | #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
| ^~~~~~~~~~~~~~~~~~~~~~~~~
| |
| long unsigned int
drivers/misc/servo-pwm.c:54:32: note: in expansion of macro 'PAGE_SIZE'
54 | return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->angle);
| ^~~~~~~~~
In file included from include/linux/kobject.h:20,
from include/linux/module.h:21:
include/linux/sysfs.h:357:39: note: expected 'const char *' but argument is of type 'long unsigned int'
357 | int sysfs_emit(char *buf, const char *fmt, ...);
| ~~~~~~~~~~~~^~~
drivers/misc/servo-pwm.c: In function 'degrees_show':
>> arch/sparc/include/asm/page_64.h:9:22: warning: passing argument 2 of 'sysfs_emit' makes pointer from integer without a cast [-Wint-conversion]
9 | #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
| ^~~~~~~~~~~~~~~~~~~~~~~~~
| |
| long unsigned int
drivers/misc/servo-pwm.c:84:32: note: in expansion of macro 'PAGE_SIZE'
84 | return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->degrees);
| ^~~~~~~~~
include/linux/sysfs.h:357:39: note: expected 'const char *' but argument is of type 'long unsigned int'
357 | int sysfs_emit(char *buf, const char *fmt, ...);
| ~~~~~~~~~~~~^~~
vim +/sysfs_emit +9 arch/sparc/include/asm/page_64.h
f5e706ad886b6a include/asm-sparc/page_64.h Sam Ravnborg 2008-07-17 8
f5e706ad886b6a include/asm-sparc/page_64.h Sam Ravnborg 2008-07-17 @9 #define PAGE_SIZE (_AC(1,UL) << PAGE_SHIFT)
f5e706ad886b6a include/asm-sparc/page_64.h Sam Ravnborg 2008-07-17 10 #define PAGE_MASK (~(PAGE_SIZE-1))
f5e706ad886b6a include/asm-sparc/page_64.h Sam Ravnborg 2008-07-17 11
On Fri, Feb 17, 2023 at 05:10:35PM +0100, Angelo Compagnucci wrote: > This patch adds a simple driver to control servo motor position via > PWM signal. > The driver allows to set the angle from userspace, while min/max > positions duty cycle and the motor degrees aperture are defined in > the dts. > > Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com> > --- > v2: > * Driver mostly rewritten for kernel 6.2 > v3: > * Fixed sysfs_emit (greg k-h) > > MAINTAINERS | 6 ++ > drivers/misc/Kconfig | 11 +++ > drivers/misc/Makefile | 1 + > drivers/misc/servo-pwm.c | 149 +++++++++++++++++++++++++++++++++++++++ > 4 files changed, 167 insertions(+) > create mode 100644 drivers/misc/servo-pwm.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 39ff1a717625..8f4af64deb1b 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -8737,6 +8737,12 @@ F: Documentation/devicetree/bindings/power/power?domain* > F: drivers/base/power/domain*.c > F: include/linux/pm_domain.h > > +GENERIC PWM SERVO DRIVER > +M: "Angelo Compagnucci" <angelo@amarulasolutions.com> > +L: linux-pwm@vger.kernel.org > +S: Maintained > +F: drivers/misc/servo-pwm.c > + > GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER > M: Eugen Hristev <eugen.hristev@microchip.com> > L: linux-input@vger.kernel.org > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > index 9947b7892bd5..8a74087149ac 100644 > --- a/drivers/misc/Kconfig > +++ b/drivers/misc/Kconfig > @@ -518,6 +518,17 @@ config VCPU_STALL_DETECTOR > > If you do not intend to run this kernel as a guest, say N. > > +config SERVO_PWM > + tristate "Servo motor positioning" > + depends on PWM > + help > + Driver to control generic servo motor positioning. > + Writing to the "angle" device attribute, the motor will move to > + the angle position. > + > + To compile this driver as a module, choose M here: the module > + will be called servo-pwm. > + > source "drivers/misc/c2port/Kconfig" > source "drivers/misc/eeprom/Kconfig" > source "drivers/misc/cb710/Kconfig" > diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile > index 87b54a4a4422..936629b648a9 100644 > --- a/drivers/misc/Makefile > +++ b/drivers/misc/Makefile > @@ -64,3 +64,4 @@ obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o > obj-$(CONFIG_OPEN_DICE) += open-dice.o > obj-$(CONFIG_GP_PCI1XXXX) += mchp_pci1xxxx/ > obj-$(CONFIG_VCPU_STALL_DETECTOR) += vcpu_stall_detector.o > +obj-$(CONFIG_SERVO_PWM) += servo-pwm.o > diff --git a/drivers/misc/servo-pwm.c b/drivers/misc/servo-pwm.c > new file mode 100644 > index 000000000000..1303ddda8d07 > --- /dev/null > +++ b/drivers/misc/servo-pwm.c > @@ -0,0 +1,149 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Copyright (c) 2023 Angelo Compagnucci <angelo@amarulasolutions.com> > + * servo-pwm.c - driver for controlling servo motors via pwm. > + */ > + > +#include <linux/module.h> > +#include <linux/kernel.h> > +#include <linux/platform_device.h> > +#include <linux/err.h> > +#include <linux/pwm.h> > + > +#define DEFAULT_DUTY_MIN 500000 > +#define DEFAULT_DUTY_MAX 2500000 > +#define DEFAULT_DEGREES 175 > +#define DEFAULT_ANGLE 0 > + > +struct servo_pwm_data { > + u32 duty_min; > + u32 duty_max; > + u32 degrees; > + u32 angle; > + > + struct mutex lock; > + struct pwm_device *pwm; > + struct pwm_state pwmstate; > +}; > + > +static int servo_pwm_set(struct servo_pwm_data *data, int val) > +{ > + u64 new_duty = (((data->duty_max - data->duty_min) / > + data->degrees) * val) + data->duty_min; This one formula is basically the only thing that this driver adds. The remaining 150+ lines are essentially boilerplate to expose the "angle" property via sysfs. We can already do everything that this driver does via the PWM sysfs, so I wonder if we really need this. Also, how are other aspects of the motor (such as velocity) controlled? Wouldn't you want to expose these other controls as well? Thierry
On Mon, Feb 20, 2023 at 12:40 PM Thierry Reding <thierry.reding@gmail.com> wrote: > > On Fri, Feb 17, 2023 at 05:10:35PM +0100, Angelo Compagnucci wrote: > > This patch adds a simple driver to control servo motor position via > > PWM signal. > > The driver allows to set the angle from userspace, while min/max > > positions duty cycle and the motor degrees aperture are defined in > > the dts. > > > > Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com> > > --- > > v2: > > * Driver mostly rewritten for kernel 6.2 > > v3: > > * Fixed sysfs_emit (greg k-h) > > > > MAINTAINERS | 6 ++ > > drivers/misc/Kconfig | 11 +++ > > drivers/misc/Makefile | 1 + > > drivers/misc/servo-pwm.c | 149 +++++++++++++++++++++++++++++++++++++++ > > 4 files changed, 167 insertions(+) > > create mode 100644 drivers/misc/servo-pwm.c > > > > diff --git a/MAINTAINERS b/MAINTAINERS > > index 39ff1a717625..8f4af64deb1b 100644 > > --- a/MAINTAINERS > > +++ b/MAINTAINERS > > @@ -8737,6 +8737,12 @@ F: Documentation/devicetree/bindings/power/power?domain* > > F: drivers/base/power/domain*.c > > F: include/linux/pm_domain.h > > > > +GENERIC PWM SERVO DRIVER > > +M: "Angelo Compagnucci" <angelo@amarulasolutions.com> > > +L: linux-pwm@vger.kernel.org > > +S: Maintained > > +F: drivers/misc/servo-pwm.c > > + > > GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER > > M: Eugen Hristev <eugen.hristev@microchip.com> > > L: linux-input@vger.kernel.org > > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > > index 9947b7892bd5..8a74087149ac 100644 > > --- a/drivers/misc/Kconfig > > +++ b/drivers/misc/Kconfig > > @@ -518,6 +518,17 @@ config VCPU_STALL_DETECTOR > > > > If you do not intend to run this kernel as a guest, say N. > > > > +config SERVO_PWM > > + tristate "Servo motor positioning" > > + depends on PWM > > + help > > + Driver to control generic servo motor positioning. > > + Writing to the "angle" device attribute, the motor will move to > > + the angle position. > > + > > + To compile this driver as a module, choose M here: the module > > + will be called servo-pwm. > > + > > source "drivers/misc/c2port/Kconfig" > > source "drivers/misc/eeprom/Kconfig" > > source "drivers/misc/cb710/Kconfig" > > diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile > > index 87b54a4a4422..936629b648a9 100644 > > --- a/drivers/misc/Makefile > > +++ b/drivers/misc/Makefile > > @@ -64,3 +64,4 @@ obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o > > obj-$(CONFIG_OPEN_DICE) += open-dice.o > > obj-$(CONFIG_GP_PCI1XXXX) += mchp_pci1xxxx/ > > obj-$(CONFIG_VCPU_STALL_DETECTOR) += vcpu_stall_detector.o > > +obj-$(CONFIG_SERVO_PWM) += servo-pwm.o > > diff --git a/drivers/misc/servo-pwm.c b/drivers/misc/servo-pwm.c > > new file mode 100644 > > index 000000000000..1303ddda8d07 > > --- /dev/null > > +++ b/drivers/misc/servo-pwm.c > > @@ -0,0 +1,149 @@ > > +// SPDX-License-Identifier: GPL-2.0-or-later > > +/* > > + * Copyright (c) 2023 Angelo Compagnucci <angelo@amarulasolutions.com> > > + * servo-pwm.c - driver for controlling servo motors via pwm. > > + */ > > + > > +#include <linux/module.h> > > +#include <linux/kernel.h> > > +#include <linux/platform_device.h> > > +#include <linux/err.h> > > +#include <linux/pwm.h> > > + > > +#define DEFAULT_DUTY_MIN 500000 > > +#define DEFAULT_DUTY_MAX 2500000 > > +#define DEFAULT_DEGREES 175 > > +#define DEFAULT_ANGLE 0 > > + > > +struct servo_pwm_data { > > + u32 duty_min; > > + u32 duty_max; > > + u32 degrees; > > + u32 angle; > > + > > + struct mutex lock; > > + struct pwm_device *pwm; > > + struct pwm_state pwmstate; > > +}; > > + > > +static int servo_pwm_set(struct servo_pwm_data *data, int val) > > +{ > > + u64 new_duty = (((data->duty_max - data->duty_min) / > > + data->degrees) * val) + data->duty_min; > > This one formula is basically the only thing that this driver adds. The > remaining 150+ lines are essentially boilerplate to expose the "angle" > property via sysfs. > > We can already do everything that this driver does via the PWM sysfs, so > I wonder if we really need this. That's true, but anyway it's a big improvement over writing each one of the servo parameters inside the sysfs one by one. Moreover, it makes easier to handle a product based on several servo motors. > Also, how are other aspects of the motor (such as velocity) controlled? > Wouldn't you want to expose these other controls as well? As far as I can tell, a basic servo motor only offers a way to change the angle through PWM duty cycle. The speed is controlled by the driver inside the motor: the bigger is the angle, the faster it moves. There are more complex servos out there, but they don't use plain simple PWM like those, they usually use some sort of more complex digital protocol on busses like I2C, SPI, DMX. > > Thierry
On Fri, Feb 17, 2023 at 05:10:35PM +0100, Angelo Compagnucci wrote: > This patch adds a simple driver to control servo motor position via > PWM signal. > The driver allows to set the angle from userspace, while min/max > positions duty cycle and the motor degrees aperture are defined in > the dts. > > Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com> > --- > v2: > * Driver mostly rewritten for kernel 6.2 > v3: > * Fixed sysfs_emit (greg k-h) > > MAINTAINERS | 6 ++ > drivers/misc/Kconfig | 11 +++ > drivers/misc/Makefile | 1 + > drivers/misc/servo-pwm.c | 149 +++++++++++++++++++++++++++++++++++++++ > 4 files changed, 167 insertions(+) > create mode 100644 drivers/misc/servo-pwm.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 39ff1a717625..8f4af64deb1b 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -8737,6 +8737,12 @@ F: Documentation/devicetree/bindings/power/power?domain* > F: drivers/base/power/domain*.c > F: include/linux/pm_domain.h > > +GENERIC PWM SERVO DRIVER > +M: "Angelo Compagnucci" <angelo@amarulasolutions.com> > +L: linux-pwm@vger.kernel.org > +S: Maintained > +F: drivers/misc/servo-pwm.c > + > GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER > M: Eugen Hristev <eugen.hristev@microchip.com> > L: linux-input@vger.kernel.org > diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig > index 9947b7892bd5..8a74087149ac 100644 > --- a/drivers/misc/Kconfig > +++ b/drivers/misc/Kconfig > @@ -518,6 +518,17 @@ config VCPU_STALL_DETECTOR > > If you do not intend to run this kernel as a guest, say N. > > +config SERVO_PWM > + tristate "Servo motor positioning" > + depends on PWM > + help > + Driver to control generic servo motor positioning. > + Writing to the "angle" device attribute, the motor will move to > + the angle position. > + > + To compile this driver as a module, choose M here: the module > + will be called servo-pwm. > + > source "drivers/misc/c2port/Kconfig" > source "drivers/misc/eeprom/Kconfig" > source "drivers/misc/cb710/Kconfig" > diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile > index 87b54a4a4422..936629b648a9 100644 > --- a/drivers/misc/Makefile > +++ b/drivers/misc/Makefile > @@ -64,3 +64,4 @@ obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o > obj-$(CONFIG_OPEN_DICE) += open-dice.o > obj-$(CONFIG_GP_PCI1XXXX) += mchp_pci1xxxx/ > obj-$(CONFIG_VCPU_STALL_DETECTOR) += vcpu_stall_detector.o > +obj-$(CONFIG_SERVO_PWM) += servo-pwm.o > diff --git a/drivers/misc/servo-pwm.c b/drivers/misc/servo-pwm.c > new file mode 100644 > index 000000000000..1303ddda8d07 > --- /dev/null > +++ b/drivers/misc/servo-pwm.c > @@ -0,0 +1,149 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Copyright (c) 2023 Angelo Compagnucci <angelo@amarulasolutions.com> > + * servo-pwm.c - driver for controlling servo motors via pwm. > + */ > + > +#include <linux/module.h> > +#include <linux/kernel.h> > +#include <linux/platform_device.h> > +#include <linux/err.h> > +#include <linux/pwm.h> > + > +#define DEFAULT_DUTY_MIN 500000 > +#define DEFAULT_DUTY_MAX 2500000 > +#define DEFAULT_DEGREES 175 > +#define DEFAULT_ANGLE 0 > + > +struct servo_pwm_data { > + u32 duty_min; > + u32 duty_max; > + u32 degrees; > + u32 angle; > + > + struct mutex lock; > + struct pwm_device *pwm; > + struct pwm_state pwmstate; > +}; > + > +static int servo_pwm_set(struct servo_pwm_data *data, int val) > +{ > + u64 new_duty = (((data->duty_max - data->duty_min) / > + data->degrees) * val) + data->duty_min; You're loosing precision here. Always divide as late as possible. (If you need an example: With duty_max = 1000 duty_min = 0 degrees = 251 val = 79 the exact result for new_duty would be 314.7410358565737. Your term yields 237. If you divide after multiplying with val you get 314. All in all I think this driver is too specialized on a single motor type. IMHO what we would be more helpful is a generic framework that can abstract various different motors with the same API. A while back I already thought about a suitable driver API. The abstraction I came up with back then was: .setspeed(struct motor_device *motor, signed int speed) .disable(struct motor_device *motor) In the end this is probably too simple because it doesn't allow the consumer to specify how fast the new target speed is to be reached. (Consider the motor running at 1000 and .setspeed(mymotor, 0) is called. Should this mean "actively brake", or "stop driving and just coast down"? I don't have a good idea yet that is both simple enough and still expressive that it's both useful to consumers and sensible to implement for different motor types. Best regards Uwe
diff --git a/MAINTAINERS b/MAINTAINERS index 39ff1a717625..8f4af64deb1b 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8737,6 +8737,12 @@ F: Documentation/devicetree/bindings/power/power?domain* F: drivers/base/power/domain*.c F: include/linux/pm_domain.h +GENERIC PWM SERVO DRIVER +M: "Angelo Compagnucci" <angelo@amarulasolutions.com> +L: linux-pwm@vger.kernel.org +S: Maintained +F: drivers/misc/servo-pwm.c + GENERIC RESISTIVE TOUCHSCREEN ADC DRIVER M: Eugen Hristev <eugen.hristev@microchip.com> L: linux-input@vger.kernel.org diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 9947b7892bd5..8a74087149ac 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -518,6 +518,17 @@ config VCPU_STALL_DETECTOR If you do not intend to run this kernel as a guest, say N. +config SERVO_PWM + tristate "Servo motor positioning" + depends on PWM + help + Driver to control generic servo motor positioning. + Writing to the "angle" device attribute, the motor will move to + the angle position. + + To compile this driver as a module, choose M here: the module + will be called servo-pwm. + source "drivers/misc/c2port/Kconfig" source "drivers/misc/eeprom/Kconfig" source "drivers/misc/cb710/Kconfig" diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 87b54a4a4422..936629b648a9 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -64,3 +64,4 @@ obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o obj-$(CONFIG_OPEN_DICE) += open-dice.o obj-$(CONFIG_GP_PCI1XXXX) += mchp_pci1xxxx/ obj-$(CONFIG_VCPU_STALL_DETECTOR) += vcpu_stall_detector.o +obj-$(CONFIG_SERVO_PWM) += servo-pwm.o diff --git a/drivers/misc/servo-pwm.c b/drivers/misc/servo-pwm.c new file mode 100644 index 000000000000..1303ddda8d07 --- /dev/null +++ b/drivers/misc/servo-pwm.c @@ -0,0 +1,149 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2023 Angelo Compagnucci <angelo@amarulasolutions.com> + * servo-pwm.c - driver for controlling servo motors via pwm. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/err.h> +#include <linux/pwm.h> + +#define DEFAULT_DUTY_MIN 500000 +#define DEFAULT_DUTY_MAX 2500000 +#define DEFAULT_DEGREES 175 +#define DEFAULT_ANGLE 0 + +struct servo_pwm_data { + u32 duty_min; + u32 duty_max; + u32 degrees; + u32 angle; + + struct mutex lock; + struct pwm_device *pwm; + struct pwm_state pwmstate; +}; + +static int servo_pwm_set(struct servo_pwm_data *data, int val) +{ + u64 new_duty = (((data->duty_max - data->duty_min) / + data->degrees) * val) + data->duty_min; + int ret; + + mutex_lock(&data->lock); + + data->pwmstate.duty_cycle = new_duty; + data->pwmstate.enabled = 1; + ret = pwm_apply_state(data->pwm, &data->pwmstate); + + if (!ret) + data->angle = val; + + mutex_unlock(&data->lock); + + return ret; +} + +static ssize_t angle_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct servo_pwm_data *data = dev_get_drvdata(dev); + + return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->angle); +} + +static ssize_t angle_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct servo_pwm_data *data = dev_get_drvdata(dev); + int ret, val = 0; + + ret = kstrtoint(buf, 10, &val); + if (ret < 0) + return -EINVAL; + + if (val < 0 || val > data->degrees) + return -EINVAL; + + ret = servo_pwm_set(data, val); + if (ret) + return ret; + + return count; +} + +static DEVICE_ATTR_RW(angle); + +static ssize_t degrees_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct servo_pwm_data *data = dev_get_drvdata(dev); + + return sysfs_emit(buf, PAGE_SIZE, "%u\n", data->degrees); +} + +static DEVICE_ATTR_RO(degrees); + +static struct attribute *servo_pwm_attrs[] = { + &dev_attr_angle.attr, + &dev_attr_degrees.attr, + NULL, +}; + +ATTRIBUTE_GROUPS(servo_pwm); + +static int servo_pwm_probe(struct platform_device *pdev) +{ + struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev); + struct servo_pwm_data *data; + + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + mutex_init(&data->lock); + + if (!fwnode_property_read_u32(fwnode, "duty-min", &data->duty_min) == 0) + data->duty_min = DEFAULT_DUTY_MIN; + + if (!fwnode_property_read_u32(fwnode, "duty-max", &data->duty_max) == 0) + data->duty_max = DEFAULT_DUTY_MAX; + + if (!fwnode_property_read_u32(fwnode, "degrees", &data->degrees) == 0) + data->degrees = DEFAULT_DEGREES; + + data->pwm = devm_fwnode_pwm_get(&pdev->dev, fwnode, NULL); + if (IS_ERR(data->pwm)) { + return dev_err_probe(&pdev->dev, PTR_ERR(data->pwm), + "unable to request PWM\n"); + } + + pwm_init_state(data->pwm, &data->pwmstate); + + platform_set_drvdata(pdev, data); + + return 0; +} + +static const struct of_device_id of_servo_pwm_match[] = { + { .compatible = "servo-pwm", }, + {}, +}; +MODULE_DEVICE_TABLE(of, of_servo_pwm_match); + +static struct platform_driver servo_pwm_driver = { + .probe = servo_pwm_probe, + .driver = { + .name = "servo-pwm", + .of_match_table = of_servo_pwm_match, + .dev_groups = servo_pwm_groups, + }, +}; + +module_platform_driver(servo_pwm_driver); + +MODULE_AUTHOR("Angelo Compagnucci <angelo@amarulasolutions.com>"); +MODULE_DESCRIPTION("generic PWM servo motor driver"); +MODULE_LICENSE("GPL");
This patch adds a simple driver to control servo motor position via PWM signal. The driver allows to set the angle from userspace, while min/max positions duty cycle and the motor degrees aperture are defined in the dts. Signed-off-by: Angelo Compagnucci <angelo@amarulasolutions.com> --- v2: * Driver mostly rewritten for kernel 6.2 v3: * Fixed sysfs_emit (greg k-h) MAINTAINERS | 6 ++ drivers/misc/Kconfig | 11 +++ drivers/misc/Makefile | 1 + drivers/misc/servo-pwm.c | 149 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 167 insertions(+) create mode 100644 drivers/misc/servo-pwm.c