| Message ID | 20200907213802.26745-1-michael@walle.cc |
|---|---|
| Headers | show |
| Series | Add support for Kontron sl28cpld | expand |
Hello, just a bit of nitpicking left. If Lee is going to apply, I can care for a followup patch if need be. On Mon, Sep 07, 2020 at 11:37:55PM +0200, Michael Walle wrote: > [..] > +config PWM_SL28CPLD > + tristate "Kontron sl28cpld PWM support" > + depends on MFD_SL28CPLD || COMPILE_TEST s/ / / (@Lee, maybe fixup during application?) > + help > + Generic PWM framework driver for board management controller > + found on the Kontron sl28 CPLD. > [...] > +#define SL28CPLD_PWM_CLK 32000 /* 32 kHz */ > +#define SL28CPLD_PWM_MAX_DUTY_CYCLE(prescaler) (1 << (7 - (prescaler))) > +#define SL28CPLD_PWM_PERIOD(prescaler) \ > + (NSEC_PER_SEC / SL28CPLD_PWM_CLK * SL28CPLD_PWM_MAX_DUTY_CYCLE(prescaler)) > + > +/* > + * We calculate the duty cycle like this: > + * duty_cycle_ns = pwm_cycle_reg * max_period_ns / max_duty_cycle > + * > + * With > + * max_period_ns = 1 << (7 - prescaler) / pwm_clk * NSEC_PER_SEC > + * max_duty_cycle = 1 << (7 - prescaler) > + * this then simplifies to: > + * duty_cycle_ns = pwm_cycle_reg / pwm_clk * NSEC_PER_SEC > + * > + * NSEC_PER_SEC is a multiple of SL28CPLD_PWM_CLK, therefore we're not losing > + * precision by doing the divison first. The division you're talking about is NSEC_PER_SEC / pwm_clk which isn't obvious in the formula in the line above. Maybe: ... this then simplifies to: duty_cycle_ns = NSEC_PER_SEC / SL28CPLD_PWM_CLK * pwm_cycle_reg NSEC_PER_SEC is a multiple of SL28CPLD_PWM_CLK, therefor ... to make it easier to understand the comment. > + */ > +#define SL28CPLD_PWM_TO_DUTY_CYCLE(reg) \ > + (NSEC_PER_SEC / SL28CPLD_PWM_CLK * (reg)) > +#define SL28CPLD_PWM_FROM_DUTY_CYCLE(duty_cycle) \ > + (DIV_ROUND_DOWN_ULL((duty_cycle), NSEC_PER_SEC / SL28CPLD_PWM_CLK)) > [...] > + /* > + * To avoid glitches when we switch the prescaler, we have to make sure > + * we have a valid duty cycle for the new mode. > + * > + * Take the current prescaler (or the current period length) into > + * account to decide whether we have to write the duty cycle or the new > + * prescaler first. If the period length is decreasing we have to > + * write the duty cycle first. > + */ > + write_duty_cycle_first = pwm->state.period > state->period; > + > + if (write_duty_cycle_first) { > + ret = sl28cpld_pwm_write(priv, SL28CPLD_PWM_CYCLE, cycle); > + if (ret) > + return ret; > + } > + > + ret = sl28cpld_pwm_write(priv, SL28CPLD_PWM_CTRL, ctrl); > + if (ret) > + return ret; > + > + if (!write_duty_cycle_first) { > + ret = sl28cpld_pwm_write(priv, SL28CPLD_PWM_CYCLE, cycle); > + if (ret) > + return ret; > + } Nice! I didn't spend the necessary brain cycles to confirm this algorithm, but it seems you did :-) > + > + return 0; > +} > [...] Best regards Uwe
The Kontron sl28cpld is a board management chip providing gpio, pwm, fan monitoring and an interrupt controller. For now this controller is used on the Kontron SMARC-sAL28 board. But because of its flexible nature, it might also be used on other boards in the future. The individual blocks (like gpio, pwm, etc) are kept intentionally small. The MFD core driver then instantiates different (or multiple of the same) blocks. It also provides the register layout so it might be updated in the future without a device tree change; and support other boards with a different layout or functionalities. See also [1] for more information. This is my first take of a MFD driver. I don't know whether the subsystem maintainers should only be CCed on the patches which affect the subsystem or on all patches for this series. I've chosen the latter so you can get a more complete picture. [1] https://lore.kernel.org/linux-devicetree/0e3e8204ab992d75aa07fc36af7e4ab2@walle.cc/ Changes for v4 and above are tracked in the patches, suggested by Lee. Changes since v3: - use of_platform_populate() to populate internal devices using the internal register offsets as unit-addresses - because we don't use mfd_cells anymore, we cannot use IORESOURCE_REG, but instead parse the reg property in each individual driver - dropped the following patches because they were already merged: gpiolib: Introduce gpiochip_irqchip_add_domain() gpio: add a reusable generic gpio_chip using regmap - dropped the following patches because they are no longer needed: include/linux/ioport.h: add helper to define REG resource constructs mfd: mfd-core: Don't overwrite the dma_mask of the child device mfd: mfd-core: match device tree node against reg property - rephrase commit messages, as suggested by Thomas Gleixner Changes since v2: As suggested by Guenter Roeck: - added sl28cpld.rst to index.rst - removed sl28cpld_wdt_status() - reverse christmas tree local variable ordering - assign device_property_read_bool() retval directly - introduce WDT_DEFAULT_TIMEOUT and use it if the hardware reports 0 as timeout. - set WDOG_HW_RUNNING if applicable - remove platform_set_drvdata() leftover As suggested by Bartosz Golaszewski: - don't export gpio_regmap_simple_xlate() - combine local variable declaration of the same type - drop the "struct gpio_regmap_addr", instead use -1 to force an address offset of zero - fix typo - use "struct gpio_regmap_config" pattern, keep "struct gpio_regmap" private. this also means we need a getter/setter for the driver_data element. As suggested by Linus Walleij: - don't store irq_domain in gpio-regmap. drop to_irq() altogether for now. Instead there is now a new patch which lets us set the irqdomain of the gpiochip_irqchip and use its .to_irq() function. This way we don't have to expose the gpio_chip inside the gpio-regmap to the user. Changes since v1: - use of_match_table in all drivers, needed for automatic module loading, when using OF_MFD_CELL() - add new gpio-regmap.c which adds a generic regmap gpio_chip implementation - new patch for reqmap_irq, so we can reuse its implementation - remove almost any code from gpio-sl28cpld.c, instead use gpio-regmap and regmap-irq - change the handling of the mfd core vs device tree nodes; add a new property "of_reg" to the mfd_cell struct which, when set, is matched to the unit-address of the device tree nodes. - fix sl28cpld watchdog when it is not initialized by the bootloader. Explicitly set the operation mode. - also add support for kontron,assert-wdt-timeout-pin in sl28cpld-wdt. As suggested by Bartosz Golaszewski: - define registers as hex - make gpio enum uppercase - move parent regmap check before memory allocation - use device_property_read_bool() instead of the of_ version - mention the gpio flavors in the bindings documentation As suggested by Guenter Roeck: - cleanup #includes and sort them - use devm_watchdog_register_device() - use watchdog_stop_on_reboot() - provide a Documentation/hwmon/sl28cpld.rst - cleaned up the weird tristate->bool and I2C=y issue. Instead mention that the MFD driver is bool because of the following intc patch - removed the SL28CPLD_IRQ typo As suggested by Rob Herring: - combine all dt bindings docs into one patch - change the node name for all gpio flavors to "gpio" - removed the interrupts-extended rule - cleaned up the unit-address space, see above Michael Walle (13): mfd: add simple regmap based I2C driver dt-bindings: mfd: Add bindings for sl28cpld mfd: simple-mfd-i2c: add sl28cpld support irqchip: add sl28cpld interrupt controller support watchdog: add support for sl28cpld watchdog pwm: add support for sl28cpld PWM controller gpio: add support for the sl28cpld GPIO controller hwmon: add support for the sl28cpld hardware monitoring controller arm64: dts: freescale: sl28: enable sl28cpld arm64: dts: freescale: sl28: map GPIOs to input events arm64: dts: freescale: sl28: enable LED support arm64: dts: freescale: sl28: enable fan support arm64: defconfig: enable the sl28cpld board management controller .../bindings/gpio/kontron,sl28cpld-gpio.yaml | 54 ++++ .../hwmon/kontron,sl28cpld-hwmon.yaml | 27 ++ .../kontron,sl28cpld-intc.yaml | 54 ++++ .../bindings/mfd/kontron,sl28cpld.yaml | 153 ++++++++++ .../bindings/pwm/kontron,sl28cpld-pwm.yaml | 35 +++ .../watchdog/kontron,sl28cpld-wdt.yaml | 35 +++ Documentation/hwmon/index.rst | 1 + Documentation/hwmon/sl28cpld.rst | 36 +++ .../fsl-ls1028a-kontron-kbox-a-230-ls.dts | 18 ++ .../fsl-ls1028a-kontron-sl28-var3-ads2.dts | 9 + .../freescale/fsl-ls1028a-kontron-sl28.dts | 134 +++++++++ arch/arm64/configs/defconfig | 6 + drivers/gpio/Kconfig | 12 + drivers/gpio/Makefile | 1 + drivers/gpio/gpio-sl28cpld.c | 161 +++++++++++ drivers/hwmon/Kconfig | 10 + drivers/hwmon/Makefile | 1 + drivers/hwmon/sl28cpld-hwmon.c | 142 +++++++++ drivers/irqchip/Kconfig | 8 + drivers/irqchip/Makefile | 1 + drivers/irqchip/irq-sl28cpld.c | 96 +++++++ drivers/mfd/Kconfig | 22 ++ drivers/mfd/Makefile | 1 + drivers/mfd/simple-mfd-i2c.c | 57 ++++ drivers/pwm/Kconfig | 10 + drivers/pwm/Makefile | 1 + drivers/pwm/pwm-sl28cpld.c | 269 ++++++++++++++++++ drivers/watchdog/Kconfig | 11 + drivers/watchdog/Makefile | 1 + drivers/watchdog/sl28cpld_wdt.c | 229 +++++++++++++++ 30 files changed, 1595 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpio/kontron,sl28cpld-gpio.yaml create mode 100644 Documentation/devicetree/bindings/hwmon/kontron,sl28cpld-hwmon.yaml create mode 100644 Documentation/devicetree/bindings/interrupt-controller/kontron,sl28cpld-intc.yaml create mode 100644 Documentation/devicetree/bindings/mfd/kontron,sl28cpld.yaml create mode 100644 Documentation/devicetree/bindings/pwm/kontron,sl28cpld-pwm.yaml create mode 100644 Documentation/devicetree/bindings/watchdog/kontron,sl28cpld-wdt.yaml create mode 100644 Documentation/hwmon/sl28cpld.rst create mode 100644 drivers/gpio/gpio-sl28cpld.c create mode 100644 drivers/hwmon/sl28cpld-hwmon.c create mode 100644 drivers/irqchip/irq-sl28cpld.c create mode 100644 drivers/mfd/simple-mfd-i2c.c create mode 100644 drivers/pwm/pwm-sl28cpld.c create mode 100644 drivers/watchdog/sl28cpld_wdt.c