| Message ID | 20210118123244.13669-12-nsaenzjulienne@suse.de |
|---|---|
| State | New |
| Headers | show |
| Series | Raspberry Pi PoE HAT fan support | expand |
On Mon, 2021-01-18 at 13:32 +0100, Nicolas Saenz Julienne wrote: > Adds support to control the PWM bus available in official Raspberry Pi > PoE HAT. Only RPi's co-processor has access to it, so commands have to > be sent through RPi's firmware mailbox interface. > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > > --- ping :) Regards, Nicolas
On Mon, 2021-01-18 at 13:32 +0100, Nicolas Saenz Julienne wrote: > Adds support to control the PWM bus available in official Raspberry Pi > PoE HAT. Only RPi's co-processor has access to it, so commands have to > be sent through RPi's firmware mailbox interface. > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > > --- ping :) > Changes since v6: > - Use %pe > - Round divisions properly > - Use dev_err_probe() > - Pass check_patch > > Changes since v3: > - Rename compatible string to be more explicit WRT to bus's limitations > > Changes since v2: > - Use devm_rpi_firmware_get() > - Rename driver > - Small cleanups > > Changes since v1: > - Use default pwm bindings and get rid of xlate() function > - Correct spelling errors > - Correct apply() function > - Round values > - Fix divisions in arm32 mode > - Small cleanups > > drivers/pwm/Kconfig | 9 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-raspberrypi-poe.c | 220 ++++++++++++++++++++++++++++++ > 3 files changed, 230 insertions(+) > create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 0937e1c047ac..75e2344703b3 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -423,6 +423,15 @@ config PWM_PXA > To compile this driver as a module, choose M here: the module > will be called pwm-pxa. > > > +config PWM_RASPBERRYPI_POE > + tristate "Raspberry Pi Firwmware PoE Hat PWM support" > + # Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only > + # happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE. > + depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE) > + help > + Enable Raspberry Pi firmware controller PWM bus used to control the > + official RPI PoE hat > + > config PWM_RCAR > tristate "Renesas R-Car PWM support" > depends on ARCH_RENESAS || COMPILE_TEST > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 18b89d7fd092..ed28d7bd4c64 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -38,6 +38,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o > obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o > obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o > obj-$(CONFIG_PWM_PXA) += pwm-pxa.o > +obj-$(CONFIG_PWM_RASPBERRYPI_POE) += pwm-raspberrypi-poe.o > obj-$(CONFIG_PWM_RCAR) += pwm-rcar.o > obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o > obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o > diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c > new file mode 100644 > index 000000000000..ca845e8fabe6 > --- /dev/null > +++ b/drivers/pwm/pwm-raspberrypi-poe.c > @@ -0,0 +1,220 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > + * For more information on Raspberry Pi's PoE hat see: > + * https://www.raspberrypi.org/products/poe-hat/ > + * > + * Limitations: > + * - No disable bit, so a disabled PWM is simulated by duty_cycle 0 > + * - Only normal polarity > + * - Fixed 12.5 kHz period > + * > + * The current period is completed when HW is reconfigured. > + */ > + > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/pwm.h> > + > +#include <soc/bcm2835/raspberrypi-firmware.h> > +#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h> > + > +#define RPI_PWM_MAX_DUTY 255 > +#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */ > + > +#define RPI_PWM_CUR_DUTY_REG 0x0 > +#define RPI_PWM_DEF_DUTY_REG 0x1 > + > +struct raspberrypi_pwm { > + struct rpi_firmware *firmware; > + struct pwm_chip chip; > + unsigned int duty_cycle; > +}; > + > +struct raspberrypi_pwm_prop { > + __le32 reg; > + __le32 val; > + __le32 ret; > +} __packed; > + > +static inline > +struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip) > +{ > + return container_of(chip, struct raspberrypi_pwm, chip); > +} > + > +static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware, > + u32 reg, u32 val) > +{ > + struct raspberrypi_pwm_prop msg = { > + .reg = cpu_to_le32(reg), > + .val = cpu_to_le32(val), > + }; > + int ret; > + > + ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL, > + &msg, sizeof(msg)); > + if (ret) > + return ret; > + if (msg.ret) > + return -EIO; > + > + return 0; > +} > + > +static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware, > + u32 reg, u32 *val) > +{ > + struct raspberrypi_pwm_prop msg = { > + .reg = reg > + }; > + int ret; > + > + ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL, > + &msg, sizeof(msg)); > + if (ret) > + return ret; > + if (msg.ret) > + return -EIO; > + > + *val = le32_to_cpu(msg.val); > + > + return 0; > +} > + > +static void raspberrypi_pwm_get_state(struct pwm_chip *chip, > + struct pwm_device *pwm, > + struct pwm_state *state) > +{ > + struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); > + > + state->period = RPI_PWM_PERIOD_NS; > + state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS, > + RPI_PWM_MAX_DUTY); > + state->enabled = !!(rpipwm->duty_cycle); > + state->polarity = PWM_POLARITY_NORMAL; > +} > + > +static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); > + unsigned int duty_cycle; > + int ret; > + > + if (state->period < RPI_PWM_PERIOD_NS || > + state->polarity != PWM_POLARITY_NORMAL) > + return -EINVAL; > + > + if (!state->enabled) > + duty_cycle = 0; > + else if (state->duty_cycle < RPI_PWM_PERIOD_NS) > + duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY, > + RPI_PWM_PERIOD_NS); > + else > + duty_cycle = RPI_PWM_MAX_DUTY; > + > + if (duty_cycle == rpipwm->duty_cycle) > + return 0; > + > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG, > + duty_cycle); > + if (ret) { > + dev_err(chip->dev, "Failed to set duty cycle: %pe\n", > + ERR_PTR(ret)); > + return ret; > + } > + > + /* > + * This sets the default duty cycle after resetting the board, we > + * updated it every time to mimic Raspberry Pi's downstream's driver > + * behaviour. > + */ > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, > + duty_cycle); > + if (ret) { > + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", > + ERR_PTR(ret)); > + return ret; > + } > + > + rpipwm->duty_cycle = duty_cycle; > + > + return 0; > +} > + > +static const struct pwm_ops raspberrypi_pwm_ops = { > + .get_state = raspberrypi_pwm_get_state, > + .apply = raspberrypi_pwm_apply, > + .owner = THIS_MODULE, > +}; > + > +static int raspberrypi_pwm_probe(struct platform_device *pdev) > +{ > + struct device_node *firmware_node; > + struct device *dev = &pdev->dev; > + struct rpi_firmware *firmware; > + struct raspberrypi_pwm *rpipwm; > + int ret; > + > + firmware_node = of_get_parent(dev->of_node); > + if (!firmware_node) { > + dev_err(dev, "Missing firmware node\n"); > + return -ENOENT; > + } > + > + firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node); > + of_node_put(firmware_node); > + if (!firmware) > + return dev_err_probe(dev, -EPROBE_DEFER, > + "Failed to get firmware handle\n"); > + > + rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL); > + if (!rpipwm) > + return -ENOMEM; > + > + rpipwm->firmware = firmware; > + rpipwm->chip.dev = dev; > + rpipwm->chip.ops = &raspberrypi_pwm_ops; > + rpipwm->chip.base = -1; > + rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM; > + > + platform_set_drvdata(pdev, rpipwm); > + > + ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG, > + &rpipwm->duty_cycle); > + if (ret) { > + dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret)); > + return ret; > + } > + > + return pwmchip_add(&rpipwm->chip); > +} > + > +static int raspberrypi_pwm_remove(struct platform_device *pdev) > +{ > + struct raspberrypi_pwm *rpipwm = platform_get_drvdata(pdev); > + > + return pwmchip_remove(&rpipwm->chip); > +} > + > +static const struct of_device_id raspberrypi_pwm_of_match[] = { > + { .compatible = "raspberrypi,firmware-poe-pwm", }, > + { } > +}; > +MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match); > + > +static struct platform_driver raspberrypi_pwm_driver = { > + .driver = { > + .name = "raspberrypi-poe-pwm", > + .of_match_table = raspberrypi_pwm_of_match, > + }, > + .probe = raspberrypi_pwm_probe, > + .remove = raspberrypi_pwm_remove, > +}; > +module_platform_driver(raspberrypi_pwm_driver); > + > +MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>"); > +MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver"); > +MODULE_LICENSE("GPL v2");
Hello Nicolas, On Mon, Jan 18, 2021 at 01:32:44PM +0100, Nicolas Saenz Julienne wrote: > diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c > new file mode 100644 > index 000000000000..ca845e8fabe6 > --- /dev/null > +++ b/drivers/pwm/pwm-raspberrypi-poe.c > @@ -0,0 +1,220 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> > + * For more information on Raspberry Pi's PoE hat see: > + * https://www.raspberrypi.org/products/poe-hat/ > + * > + * Limitations: > + * - No disable bit, so a disabled PWM is simulated by duty_cycle 0 > + * - Only normal polarity > + * - Fixed 12.5 kHz period > + * > + * The current period is completed when HW is reconfigured. nice. > + */ > + > [...] > +static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); > + unsigned int duty_cycle; > + int ret; > + > + if (state->period < RPI_PWM_PERIOD_NS || > + state->polarity != PWM_POLARITY_NORMAL) > + return -EINVAL; > + > + if (!state->enabled) > + duty_cycle = 0; > + else if (state->duty_cycle < RPI_PWM_PERIOD_NS) > + duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY, > + RPI_PWM_PERIOD_NS); > + else > + duty_cycle = RPI_PWM_MAX_DUTY; > + > + if (duty_cycle == rpipwm->duty_cycle) > + return 0; > + > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG, > + duty_cycle); > + if (ret) { > + dev_err(chip->dev, "Failed to set duty cycle: %pe\n", > + ERR_PTR(ret)); > + return ret; > + } > + > + /* > + * This sets the default duty cycle after resetting the board, we > + * updated it every time to mimic Raspberry Pi's downstream's driver > + * behaviour. > + */ > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, > + duty_cycle); > + if (ret) { > + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", > + ERR_PTR(ret)); > + return ret; This only has an effect for the next reboot, right? If so I wonder if it is a good idea in general. (Think: The current PWM setting enables a motor that makes a self-driving car move at 100 km/h. Consider the rpi crashes, do I want to car to pick up driving 100 km/h at power up even before Linux is up again?) And if we agree it's a good idea: Should raspberrypi_pwm_apply return 0 if setting the duty cycle succeeded and only setting the default didn't? Other than that the patch looks fine. Best regards Uwe
Hi Uwe, thanks for taking the time to look into this. :) On Wed, 2021-03-10 at 12:50 +0100, Uwe Kleine-König wrote: > Hello Nicolas, > > On Mon, Jan 18, 2021 at 01:32:44PM +0100, Nicolas Saenz Julienne wrote: [...] > > + /* > > + * This sets the default duty cycle after resetting the board, we > > + * updated it every time to mimic Raspberry Pi's downstream's driver > > + * behaviour. > > + */ > > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, > > + duty_cycle); > > + if (ret) { > > + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", > > + ERR_PTR(ret)); > > + return ret; > > This only has an effect for the next reboot, right? It effects all reboots until it's further changed. > If so I wonder if it is a good idea in general. (Think: The current PWM > setting enables a motor that makes a self-driving car move at 100 km/h. > Consider the rpi crashes, do I want to car to pick up driving 100 km/h at > power up even before Linux is up again?) I get your point. But this isn't used as a general purpose PWM. For now the interface is solely there to drive a PWM fan that's arguably harmless. This doesn't mean that the RPi foundation will not reuse the firmware interface for other means in the future. In such case we can always use a new DT compatible and bypass this feature (the current DT string is 'raspberrypi,firmware-poe-pwm', which is specific to this use-case). My aim here is to be on par feature wise with RPi's downstream implementation. So as for them to be able to use it as is and avoid duplication. Now, if this is blocking the driver from being merged, I'd rather remove it. It'll be a patch for the downstream kernel to maintain, but better than nothing. > And if we agree it's a good idea: Should raspberrypi_pwm_apply return 0 if > setting the duty cycle succeeded and only setting the default didn't? Good point. I don't think so. We'd be also missing on the following by returning early: rpipwm->duty_cycle = duty_cycle; I propose to change it to a 'best effort' approach, if it fails, log it and continue successfully. Regards, Nicolas
Hello Nicolas, On Thu, Mar 11, 2021 at 02:01:00PM +0100, Nicolas Saenz Julienne wrote: > On Wed, 2021-03-10 at 12:50 +0100, Uwe Kleine-König wrote: > > On Mon, Jan 18, 2021 at 01:32:44PM +0100, Nicolas Saenz Julienne wrote: > > [...] > > > > + /* > > > + * This sets the default duty cycle after resetting the board, we > > > + * updated it every time to mimic Raspberry Pi's downstream's driver > > > + * behaviour. > > > + */ > > > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, > > > + duty_cycle); > > > + if (ret) { > > > + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", > > > + ERR_PTR(ret)); > > > + return ret; > > > > This only has an effect for the next reboot, right? > > It effects all reboots until it's further changed. > > > If so I wonder if it is a good idea in general. (Think: The current PWM > > setting enables a motor that makes a self-driving car move at 100 km/h. > > Consider the rpi crashes, do I want to car to pick up driving 100 km/h at > > power up even before Linux is up again?) > > I get your point. But this isn't used as a general purpose PWM. For now the > interface is solely there to drive a PWM fan that's arguably harmless. This > doesn't mean that the RPi foundation will not reuse the firmware interface for > other means in the future. In such case we can always use a new DT compatible > and bypass this feature (the current DT string is > 'raspberrypi,firmware-poe-pwm', which is specific to this use-case). > > My aim here is to be on par feature wise with RPi's downstream implementation. Just because the downstream kernel does it should not be the (single) reason to do that. My gut feeling is: For a motor restoring the PWM config on reboot is bad and for a fan it doesn't really hurt if it doesn't restart automatically. So I'd prefer to to drop this feature. Best regards Uwe
On Thu, 2021-03-11 at 14:18 +0100, Uwe Kleine-König wrote: > Hello Nicolas, > > On Thu, Mar 11, 2021 at 02:01:00PM +0100, Nicolas Saenz Julienne wrote: > > On Wed, 2021-03-10 at 12:50 +0100, Uwe Kleine-König wrote: > > > On Mon, Jan 18, 2021 at 01:32:44PM +0100, Nicolas Saenz Julienne wrote: > > > > [...] > > > > > > + /* > > > > + * This sets the default duty cycle after resetting the board, we > > > > + * updated it every time to mimic Raspberry Pi's downstream's driver > > > > + * behaviour. > > > > + */ > > > > + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, > > > > + duty_cycle); > > > > + if (ret) { > > > > + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", > > > > + ERR_PTR(ret)); > > > > + return ret; > > > > > > This only has an effect for the next reboot, right? > > > > It effects all reboots until it's further changed. > > > > > If so I wonder if it is a good idea in general. (Think: The current PWM > > > setting enables a motor that makes a self-driving car move at 100 km/h. > > > Consider the rpi crashes, do I want to car to pick up driving 100 km/h at > > > power up even before Linux is up again?) > > > > I get your point. But this isn't used as a general purpose PWM. For now the > > interface is solely there to drive a PWM fan that's arguably harmless. This > > doesn't mean that the RPi foundation will not reuse the firmware interface for > > other means in the future. In such case we can always use a new DT compatible > > and bypass this feature (the current DT string is > > 'raspberrypi,firmware-poe-pwm', which is specific to this use-case). > > > > My aim here is to be on par feature wise with RPi's downstream implementation. > > Just because the downstream kernel does it should not be the (single) > reason to do that. My gut feeling is: For a motor restoring the PWM > config on reboot is bad and for a fan it doesn't really hurt if it > doesn't restart automatically. So I'd prefer to to drop this feature. Fair enough, I'll remove it then. Regards, Nicolas
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 0937e1c047ac..75e2344703b3 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -423,6 +423,15 @@ config PWM_PXA To compile this driver as a module, choose M here: the module will be called pwm-pxa. +config PWM_RASPBERRYPI_POE + tristate "Raspberry Pi Firwmware PoE Hat PWM support" + # Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only + # happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE. + depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE) + help + Enable Raspberry Pi firmware controller PWM bus used to control the + official RPI PoE hat + config PWM_RCAR tristate "Renesas R-Car PWM support" depends on ARCH_RENESAS || COMPILE_TEST diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile index 18b89d7fd092..ed28d7bd4c64 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -38,6 +38,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o obj-$(CONFIG_PWM_PXA) += pwm-pxa.o +obj-$(CONFIG_PWM_RASPBERRYPI_POE) += pwm-raspberrypi-poe.o obj-$(CONFIG_PWM_RCAR) += pwm-rcar.o obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c new file mode 100644 index 000000000000..ca845e8fabe6 --- /dev/null +++ b/drivers/pwm/pwm-raspberrypi-poe.c @@ -0,0 +1,220 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> + * For more information on Raspberry Pi's PoE hat see: + * https://www.raspberrypi.org/products/poe-hat/ + * + * Limitations: + * - No disable bit, so a disabled PWM is simulated by duty_cycle 0 + * - Only normal polarity + * - Fixed 12.5 kHz period + * + * The current period is completed when HW is reconfigured. + */ + +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> + +#include <soc/bcm2835/raspberrypi-firmware.h> +#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h> + +#define RPI_PWM_MAX_DUTY 255 +#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */ + +#define RPI_PWM_CUR_DUTY_REG 0x0 +#define RPI_PWM_DEF_DUTY_REG 0x1 + +struct raspberrypi_pwm { + struct rpi_firmware *firmware; + struct pwm_chip chip; + unsigned int duty_cycle; +}; + +struct raspberrypi_pwm_prop { + __le32 reg; + __le32 val; + __le32 ret; +} __packed; + +static inline +struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct raspberrypi_pwm, chip); +} + +static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware, + u32 reg, u32 val) +{ + struct raspberrypi_pwm_prop msg = { + .reg = cpu_to_le32(reg), + .val = cpu_to_le32(val), + }; + int ret; + + ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL, + &msg, sizeof(msg)); + if (ret) + return ret; + if (msg.ret) + return -EIO; + + return 0; +} + +static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware, + u32 reg, u32 *val) +{ + struct raspberrypi_pwm_prop msg = { + .reg = reg + }; + int ret; + + ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL, + &msg, sizeof(msg)); + if (ret) + return ret; + if (msg.ret) + return -EIO; + + *val = le32_to_cpu(msg.val); + + return 0; +} + +static void raspberrypi_pwm_get_state(struct pwm_chip *chip, + struct pwm_device *pwm, + struct pwm_state *state) +{ + struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); + + state->period = RPI_PWM_PERIOD_NS; + state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS, + RPI_PWM_MAX_DUTY); + state->enabled = !!(rpipwm->duty_cycle); + state->polarity = PWM_POLARITY_NORMAL; +} + +static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); + unsigned int duty_cycle; + int ret; + + if (state->period < RPI_PWM_PERIOD_NS || + state->polarity != PWM_POLARITY_NORMAL) + return -EINVAL; + + if (!state->enabled) + duty_cycle = 0; + else if (state->duty_cycle < RPI_PWM_PERIOD_NS) + duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY, + RPI_PWM_PERIOD_NS); + else + duty_cycle = RPI_PWM_MAX_DUTY; + + if (duty_cycle == rpipwm->duty_cycle) + return 0; + + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG, + duty_cycle); + if (ret) { + dev_err(chip->dev, "Failed to set duty cycle: %pe\n", + ERR_PTR(ret)); + return ret; + } + + /* + * This sets the default duty cycle after resetting the board, we + * updated it every time to mimic Raspberry Pi's downstream's driver + * behaviour. + */ + ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG, + duty_cycle); + if (ret) { + dev_err(chip->dev, "Failed to set default duty cycle: %pe\n", + ERR_PTR(ret)); + return ret; + } + + rpipwm->duty_cycle = duty_cycle; + + return 0; +} + +static const struct pwm_ops raspberrypi_pwm_ops = { + .get_state = raspberrypi_pwm_get_state, + .apply = raspberrypi_pwm_apply, + .owner = THIS_MODULE, +}; + +static int raspberrypi_pwm_probe(struct platform_device *pdev) +{ + struct device_node *firmware_node; + struct device *dev = &pdev->dev; + struct rpi_firmware *firmware; + struct raspberrypi_pwm *rpipwm; + int ret; + + firmware_node = of_get_parent(dev->of_node); + if (!firmware_node) { + dev_err(dev, "Missing firmware node\n"); + return -ENOENT; + } + + firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node); + of_node_put(firmware_node); + if (!firmware) + return dev_err_probe(dev, -EPROBE_DEFER, + "Failed to get firmware handle\n"); + + rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL); + if (!rpipwm) + return -ENOMEM; + + rpipwm->firmware = firmware; + rpipwm->chip.dev = dev; + rpipwm->chip.ops = &raspberrypi_pwm_ops; + rpipwm->chip.base = -1; + rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM; + + platform_set_drvdata(pdev, rpipwm); + + ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG, + &rpipwm->duty_cycle); + if (ret) { + dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret)); + return ret; + } + + return pwmchip_add(&rpipwm->chip); +} + +static int raspberrypi_pwm_remove(struct platform_device *pdev) +{ + struct raspberrypi_pwm *rpipwm = platform_get_drvdata(pdev); + + return pwmchip_remove(&rpipwm->chip); +} + +static const struct of_device_id raspberrypi_pwm_of_match[] = { + { .compatible = "raspberrypi,firmware-poe-pwm", }, + { } +}; +MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match); + +static struct platform_driver raspberrypi_pwm_driver = { + .driver = { + .name = "raspberrypi-poe-pwm", + .of_match_table = raspberrypi_pwm_of_match, + }, + .probe = raspberrypi_pwm_probe, + .remove = raspberrypi_pwm_remove, +}; +module_platform_driver(raspberrypi_pwm_driver); + +MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>"); +MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver"); +MODULE_LICENSE("GPL v2");
Adds support to control the PWM bus available in official Raspberry Pi PoE HAT. Only RPi's co-processor has access to it, so commands have to be sent through RPi's firmware mailbox interface. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de> --- Changes since v6: - Use %pe - Round divisions properly - Use dev_err_probe() - Pass check_patch Changes since v3: - Rename compatible string to be more explicit WRT to bus's limitations Changes since v2: - Use devm_rpi_firmware_get() - Rename driver - Small cleanups Changes since v1: - Use default pwm bindings and get rid of xlate() function - Correct spelling errors - Correct apply() function - Round values - Fix divisions in arm32 mode - Small cleanups drivers/pwm/Kconfig | 9 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-raspberrypi-poe.c | 220 ++++++++++++++++++++++++++++++ 3 files changed, 230 insertions(+) create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c