1 // SPDX-License-Identifier: GPL-2.0
4  * For more information on Raspberry Pi's PoE hat see:
5  * https://www.raspberrypi.org/products/poe-hat/
8  *  - No disable bit, so a disabled PWM is simulated by duty_cycle 0
9  *  - Only normal polarity
10  *  - Fixed 12.5 kHz period
18 #include <linux/pwm.h>
20 #include <soc/bcm2835/raspberrypi-firmware.h>
21 #include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h>
29 	struct rpi_firmware *firmware;  member
46 static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware,  in raspberrypi_pwm_set_property()  argument
55 	ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,  in raspberrypi_pwm_set_property()
60 		return -EIO;  in raspberrypi_pwm_set_property()
65 static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,  in raspberrypi_pwm_get_property()  argument
73 	ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,  in raspberrypi_pwm_get_property()
78 		return -EIO;  in raspberrypi_pwm_get_property()
86 				     struct pwm_device *pwm,  in raspberrypi_pwm_get_state()  argument
91 	state->period = RPI_PWM_PERIOD_NS;  in raspberrypi_pwm_get_state()
92 	state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS,  in raspberrypi_pwm_get_state()
94 	state->enabled = !!(rpipwm->duty_cycle);  in raspberrypi_pwm_get_state()
95 	state->polarity = PWM_POLARITY_NORMAL;  in raspberrypi_pwm_get_state()
100 static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,  in raspberrypi_pwm_apply()  argument
107 	if (state->period < RPI_PWM_PERIOD_NS ||  in raspberrypi_pwm_apply()
108 	    state->polarity != PWM_POLARITY_NORMAL)  in raspberrypi_pwm_apply()
109 		return -EINVAL;  in raspberrypi_pwm_apply()
111 	if (!state->enabled)  in raspberrypi_pwm_apply()
113 	else if (state->duty_cycle < RPI_PWM_PERIOD_NS)  in raspberrypi_pwm_apply()
114 		duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY,  in raspberrypi_pwm_apply()
119 	if (duty_cycle == rpipwm->duty_cycle)  in raspberrypi_pwm_apply()
122 	ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,  in raspberrypi_pwm_apply()
125 		dev_err(chip->dev, "Failed to set duty cycle: %pe\n",  in raspberrypi_pwm_apply()
130 	rpipwm->duty_cycle = duty_cycle;  in raspberrypi_pwm_apply()
144 	struct device *dev = &pdev->dev;  in raspberrypi_pwm_probe()
145 	struct rpi_firmware *firmware;  in raspberrypi_pwm_probe()  local
149 	firmware_node = of_get_parent(dev->of_node);  in raspberrypi_pwm_probe()
151 		dev_err(dev, "Missing firmware node\n");  in raspberrypi_pwm_probe()
152 		return -ENOENT;  in raspberrypi_pwm_probe()
155 	firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);  in raspberrypi_pwm_probe()
157 	if (!firmware)  in raspberrypi_pwm_probe()
158 		return dev_err_probe(dev, -EPROBE_DEFER,  in raspberrypi_pwm_probe()
159 				     "Failed to get firmware handle\n");  in raspberrypi_pwm_probe()
161 	rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL);  in raspberrypi_pwm_probe()
163 		return -ENOMEM;  in raspberrypi_pwm_probe()
165 	rpipwm->firmware = firmware;  in raspberrypi_pwm_probe()
166 	rpipwm->chip.dev = dev;  in raspberrypi_pwm_probe()
167 	rpipwm->chip.ops = &raspberrypi_pwm_ops;  in raspberrypi_pwm_probe()
168 	rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM;  in raspberrypi_pwm_probe()
170 	ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,  in raspberrypi_pwm_probe()
171 					   &rpipwm->duty_cycle);  in raspberrypi_pwm_probe()
177 	return devm_pwmchip_add(dev, &rpipwm->chip);  in raspberrypi_pwm_probe()
181 	{ .compatible = "raspberrypi,firmware-poe-pwm", },
188 		.name = "raspberrypi-poe-pwm",
196 MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");