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211 lines
5.2 KiB
211 lines
5.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright 2021 Nicolas Saenz Julienne <[email protected]> |
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* For more information on Raspberry Pi's PoE hat see: |
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* https://www.raspberrypi.org/products/poe-hat/ |
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* |
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* Limitations: |
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* - No disable bit, so a disabled PWM is simulated by duty_cycle 0 |
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* - Only normal polarity |
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* - Fixed 12.5 kHz period |
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* |
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* The current period is completed when HW is reconfigured. |
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*/ |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/platform_device.h> |
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#include <linux/pwm.h> |
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#include <linux/regmap.h> |
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#include <soc/bcm2835/raspberrypi-firmware.h> |
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#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h> |
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#define RPI_PWM_MAX_DUTY 255 |
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#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */ |
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#define RPI_PWM_CUR_DUTY_REG 0x0 |
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struct raspberrypi_pwm { |
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struct rpi_firmware *firmware; |
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struct regmap *regmap; |
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u32 offset; |
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struct pwm_chip chip; |
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unsigned int duty_cycle; |
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}; |
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struct raspberrypi_pwm_prop { |
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__le32 reg; |
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__le32 val; |
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__le32 ret; |
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} __packed; |
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static inline |
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struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip) |
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{ |
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return container_of(chip, struct raspberrypi_pwm, chip); |
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} |
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static int raspberrypi_pwm_set_property(struct raspberrypi_pwm *pwm, |
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u32 reg, u32 val) |
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{ |
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struct raspberrypi_pwm_prop msg = { |
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.reg = cpu_to_le32(reg), |
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.val = cpu_to_le32(val), |
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}; |
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int ret; |
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if (pwm->firmware) { |
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ret = rpi_firmware_property(pwm->firmware, RPI_FIRMWARE_SET_POE_HAT_VAL, |
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&msg, sizeof(msg)); |
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if (!ret && msg.ret) |
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ret = -EIO; |
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} else { |
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ret = regmap_write(pwm->regmap, pwm->offset + reg, val); |
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} |
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return ret; |
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} |
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static int raspberrypi_pwm_get_property(struct raspberrypi_pwm *pwm, |
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u32 reg, u32 *val) |
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{ |
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struct raspberrypi_pwm_prop msg = { |
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.reg = reg |
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}; |
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int ret; |
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if (pwm->firmware) { |
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ret = rpi_firmware_property(pwm->firmware, RPI_FIRMWARE_GET_POE_HAT_VAL, |
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&msg, sizeof(msg)); |
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if (!ret && msg.ret) |
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ret = -EIO; |
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*val = le32_to_cpu(msg.val); |
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} else { |
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ret = regmap_read(pwm->regmap, pwm->offset + reg, val); |
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} |
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return ret; |
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} |
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static void raspberrypi_pwm_get_state(struct pwm_chip *chip, |
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struct pwm_device *pwm, |
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struct pwm_state *state) |
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{ |
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struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); |
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state->period = RPI_PWM_PERIOD_NS; |
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state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS, |
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RPI_PWM_MAX_DUTY); |
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state->enabled = !!(rpipwm->duty_cycle); |
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state->polarity = PWM_POLARITY_NORMAL; |
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} |
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static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, |
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const struct pwm_state *state) |
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{ |
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struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip); |
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unsigned int duty_cycle; |
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int ret; |
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if (state->period < RPI_PWM_PERIOD_NS || |
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state->polarity != PWM_POLARITY_NORMAL) |
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return -EINVAL; |
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if (!state->enabled) |
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duty_cycle = 0; |
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else if (state->duty_cycle < RPI_PWM_PERIOD_NS) |
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duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY, |
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RPI_PWM_PERIOD_NS); |
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else |
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duty_cycle = RPI_PWM_MAX_DUTY; |
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if (duty_cycle == rpipwm->duty_cycle) |
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return 0; |
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ret = raspberrypi_pwm_set_property(rpipwm, RPI_PWM_CUR_DUTY_REG, |
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duty_cycle); |
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if (ret) { |
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dev_err(chip->dev, "Failed to set duty cycle: %pe\n", |
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ERR_PTR(ret)); |
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return ret; |
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} |
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rpipwm->duty_cycle = duty_cycle; |
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return 0; |
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} |
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static const struct pwm_ops raspberrypi_pwm_ops = { |
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.get_state = raspberrypi_pwm_get_state, |
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.apply = raspberrypi_pwm_apply, |
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.owner = THIS_MODULE, |
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}; |
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static int raspberrypi_pwm_probe(struct platform_device *pdev) |
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{ |
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struct device_node *firmware_node; |
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struct device *dev = &pdev->dev; |
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struct rpi_firmware *firmware; |
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struct raspberrypi_pwm *rpipwm; |
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int ret; |
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rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL); |
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if (!rpipwm) |
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return -ENOMEM; |
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if (pdev->dev.parent) |
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rpipwm->regmap = dev_get_regmap(pdev->dev.parent, NULL); |
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if (rpipwm->regmap) { |
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ret = device_property_read_u32(&pdev->dev, "reg", &rpipwm->offset); |
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if (ret) |
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return -EINVAL; |
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} else { |
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firmware_node = of_get_parent(dev->of_node); |
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firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node); |
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of_node_put(firmware_node); |
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if (!firmware) |
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return dev_err_probe(dev, -EPROBE_DEFER, |
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"Failed to get firmware handle\n"); |
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rpipwm->firmware = firmware; |
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} |
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rpipwm->chip.dev = dev; |
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rpipwm->chip.ops = &raspberrypi_pwm_ops; |
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rpipwm->chip.base = -1; |
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rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM; |
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ret = raspberrypi_pwm_get_property(rpipwm, RPI_PWM_CUR_DUTY_REG, |
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&rpipwm->duty_cycle); |
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if (ret) { |
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dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret)); |
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return ret; |
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} |
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return devm_pwmchip_add(dev, &rpipwm->chip); |
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} |
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static const struct of_device_id raspberrypi_pwm_of_match[] = { |
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{ .compatible = "raspberrypi,firmware-poe-pwm", }, |
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{ .compatible = "raspberrypi,poe-pwm", }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match); |
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static struct platform_driver raspberrypi_pwm_driver = { |
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.driver = { |
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.name = "raspberrypi-poe-pwm", |
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.of_match_table = raspberrypi_pwm_of_match, |
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}, |
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.probe = raspberrypi_pwm_probe, |
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}; |
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module_platform_driver(raspberrypi_pwm_driver); |
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MODULE_AUTHOR("Nicolas Saenz Julienne <[email protected]>"); |
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MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver"); |
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MODULE_LICENSE("GPL v2");
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