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@xxxxxxx> > > --- 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@xxxxxxx> > + * 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@xxxxxxx>"); > +MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver"); > +MODULE_LICENSE("GPL v2");
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