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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 | // SPDX-License-Identifier: GPL-2.0 /* * Copyright 2021 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> * 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 struct raspberrypi_pwm { struct rpi_firmware *firmware; 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 pwmchip_get_drvdata(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 = cpu_to_le32(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 int 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; return 0; } 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(pwmchip_parent(chip), "Failed to set 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, }; static int raspberrypi_pwm_probe(struct platform_device *pdev) { struct device_node *firmware_node; struct device *dev = &pdev->dev; struct rpi_firmware *firmware; struct pwm_chip *chip; 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"); chip = devm_pwmchip_alloc(&pdev->dev, RASPBERRYPI_FIRMWARE_PWM_NUM, sizeof(*rpipwm)); if (IS_ERR(chip)) return PTR_ERR(chip); rpipwm = raspberrypi_pwm_from_chip(chip); rpipwm->firmware = firmware; chip->ops = &raspberrypi_pwm_ops; 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 devm_pwmchip_add(dev, 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, }; module_platform_driver(raspberrypi_pwm_driver); MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>"); MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver"); MODULE_LICENSE("GPL v2"); |