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> --- 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 - Add comment explaining weird Kconfig construct drivers/pwm/Kconfig | 9 ++ drivers/pwm/Makefile | 1 + drivers/pwm/pwm-raspberrypi.c | 221 ++++++++++++++++++++++++++++++++++ 3 files changed, 231 insertions(+) create mode 100644 drivers/pwm/pwm-raspberrypi.c diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig index 63be5362fd3a..b0ffb1e690c0 100644 --- a/drivers/pwm/Kconfig +++ b/drivers/pwm/Kconfig @@ -379,6 +379,15 @@ config PWM_PXA To compile this driver as a module, choose M here: the module will be called pwm-pxa. +config PWM_RASPBERRYPI + tristate "Raspberry Pi Firwmware 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 cbdcd55d69ee..b557b549d9f3 100644 --- a/drivers/pwm/Makefile +++ b/drivers/pwm/Makefile @@ -35,6 +35,7 @@ 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-$(CONFIG_PWM_RASPBERRYPI) += pwm-raspberrypi.o obj-$(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.c b/drivers/pwm/pwm-raspberrypi.c new file mode 100644 index 000000000000..72dc0fc5a206 --- /dev/null +++ b/drivers/pwm/pwm-raspberrypi.c @@ -0,0 +1,221 @@ +// 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-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) +{ + 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; + else 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; + else 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); + 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); + 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; + + 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 = rpi_firmware_get(firmware_node); + of_node_put(firmware_node); + if (!firmware) + return -EPROBE_DEFER; + + 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); + return ret; + } + + return pwmchip_add(&rpipwm->chip); +} + +static int raspberrypi_pwm_remove(struct platform_device *pdev) +{ + struct raspberrypi_pwm *rpipwm = platform_get_drvdata(pdev); + int ret; + + ret = pwmchip_remove(&rpipwm->chip); + if (!ret) + rpi_firmware_put(rpipwm->firmware); + + return ret; +} + +static const struct of_device_id raspberrypi_pwm_of_match[] = { + { .compatible = "raspberrypi,firmware-pwm", }, + { } +}; +MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match); + +static struct platform_driver raspberrypi_pwm_driver = { + .driver = { + .name = "raspberrypi-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 Firwmare Based PWM Bus Driver"); +MODULE_LICENSE("GPL v2"); -- 2.28.0
