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1// SPDX-License-Identifier: GPL-2.02/*3 * Copyright 2021 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>4 * For more information on Raspberry Pi's PoE hat see:5 * https://www.raspberrypi.org/products/poe-hat/6 *7 * Limitations:8 * - No disable bit, so a disabled PWM is simulated by duty_cycle 09 * - Only normal polarity10 * - Fixed 12.5 kHz period11 *12 * The current period is completed when HW is reconfigured.13 */14 15#include <linux/module.h>16#include <linux/of.h>17#include <linux/platform_device.h>18#include <linux/pwm.h>19 20#include <soc/bcm2835/raspberrypi-firmware.h>21#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h>22 23#define RPI_PWM_MAX_DUTY 25524#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */25 26#define RPI_PWM_CUR_DUTY_REG 0x027 28struct raspberrypi_pwm {29 struct rpi_firmware *firmware;30 unsigned int duty_cycle;31};32 33struct raspberrypi_pwm_prop {34 __le32 reg;35 __le32 val;36 __le32 ret;37} __packed;38 39static inline40struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip)41{42 return pwmchip_get_drvdata(chip);43}44 45static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware,46 u32 reg, u32 val)47{48 struct raspberrypi_pwm_prop msg = {49 .reg = cpu_to_le32(reg),50 .val = cpu_to_le32(val),51 };52 int ret;53 54 ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,55 &msg, sizeof(msg));56 if (ret)57 return ret;58 if (msg.ret)59 return -EIO;60 61 return 0;62}63 64static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,65 u32 reg, u32 *val)66{67 struct raspberrypi_pwm_prop msg = {68 .reg = cpu_to_le32(reg),69 };70 int ret;71 72 ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,73 &msg, sizeof(msg));74 if (ret)75 return ret;76 if (msg.ret)77 return -EIO;78 79 *val = le32_to_cpu(msg.val);80 81 return 0;82}83 84static int raspberrypi_pwm_get_state(struct pwm_chip *chip,85 struct pwm_device *pwm,86 struct pwm_state *state)87{88 struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);89 90 state->period = RPI_PWM_PERIOD_NS;91 state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS,92 RPI_PWM_MAX_DUTY);93 state->enabled = !!(rpipwm->duty_cycle);94 state->polarity = PWM_POLARITY_NORMAL;95 96 return 0;97}98 99static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,100 const struct pwm_state *state)101{102 struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);103 unsigned int duty_cycle;104 int ret;105 106 if (state->period < RPI_PWM_PERIOD_NS ||107 state->polarity != PWM_POLARITY_NORMAL)108 return -EINVAL;109 110 if (!state->enabled)111 duty_cycle = 0;112 else if (state->duty_cycle < RPI_PWM_PERIOD_NS)113 duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY,114 RPI_PWM_PERIOD_NS);115 else116 duty_cycle = RPI_PWM_MAX_DUTY;117 118 if (duty_cycle == rpipwm->duty_cycle)119 return 0;120 121 ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,122 duty_cycle);123 if (ret) {124 dev_err(pwmchip_parent(chip), "Failed to set duty cycle: %pe\n",125 ERR_PTR(ret));126 return ret;127 }128 129 rpipwm->duty_cycle = duty_cycle;130 131 return 0;132}133 134static const struct pwm_ops raspberrypi_pwm_ops = {135 .get_state = raspberrypi_pwm_get_state,136 .apply = raspberrypi_pwm_apply,137};138 139static int raspberrypi_pwm_probe(struct platform_device *pdev)140{141 struct device_node *firmware_node;142 struct device *dev = &pdev->dev;143 struct rpi_firmware *firmware;144 struct pwm_chip *chip;145 struct raspberrypi_pwm *rpipwm;146 int ret;147 148 firmware_node = of_get_parent(dev->of_node);149 if (!firmware_node) {150 dev_err(dev, "Missing firmware node\n");151 return -ENOENT;152 }153 154 firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);155 of_node_put(firmware_node);156 if (!firmware)157 return dev_err_probe(dev, -EPROBE_DEFER,158 "Failed to get firmware handle\n");159 160 chip = devm_pwmchip_alloc(&pdev->dev, RASPBERRYPI_FIRMWARE_PWM_NUM,161 sizeof(*rpipwm));162 if (IS_ERR(chip))163 return PTR_ERR(chip);164 rpipwm = raspberrypi_pwm_from_chip(chip);165 166 rpipwm->firmware = firmware;167 chip->ops = &raspberrypi_pwm_ops;168 169 ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,170 &rpipwm->duty_cycle);171 if (ret) {172 dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret));173 return ret;174 }175 176 return devm_pwmchip_add(dev, chip);177}178 179static const struct of_device_id raspberrypi_pwm_of_match[] = {180 { .compatible = "raspberrypi,firmware-poe-pwm", },181 { }182};183MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match);184 185static struct platform_driver raspberrypi_pwm_driver = {186 .driver = {187 .name = "raspberrypi-poe-pwm",188 .of_match_table = raspberrypi_pwm_of_match,189 },190 .probe = raspberrypi_pwm_probe,191};192module_platform_driver(raspberrypi_pwm_driver);193 194MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");195MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");196MODULE_LICENSE("GPL v2");197