Hello Nicolas, On Fri, Dec 11, 2020 at 05:48:00PM +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..24b498839fcc > --- /dev/null > +++ b/drivers/pwm/pwm-raspberrypi-poe.c > @@ -0,0 +1,216 @@ > +// 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 *to_raspberrypi_pwm(struct pwm_chip *chip) I'd like to see this function use the same prefix as the other functions. I suggest "raspberrypi_pwm_from_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 = to_raspberrypi_pwm(chip); > + > + state->period = RPI_PWM_PERIOD_NS; > + state->duty_cycle = DIV_ROUND_CLOSEST(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS, > + RPI_PWM_MAX_DUTY); Please round up here ... > + 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 = to_raspberrypi_pwm(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_CLOSEST_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY, > + RPI_PWM_PERIOD_NS); ... and round down here. Just to be sure: writing RPI_PWM_MAX_DUTY (i.e. 255) yields 100% duty cycle, right? > + 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: %d\n", 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: %d\n", ret); > + return ret; > + } > + > + rpipwm->duty_cycle = duty_cycle; Please use tabs for indention. (The general hint is to use checkpatch which (I hope) tells you about problems like this.) > + > + 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 -EPROBE_DEFER; Please use dev_err_probe to benefit from recording an error message in this case. > + 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: %d\n", ret); Please use %pe for the error codes (directly or still better by using dev_err_probe here, too). > + return ret; > + } > + > + return pwmchip_add(&rpipwm->chip); > +} > [...] Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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