[linux-block.git] / drivers / pwm / pwm-raspberrypi-poe.c

// 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");
Commit	Line	Data
79caa362 NSJ	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	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 0
	9	* - Only normal polarity
	10	* - Fixed 12.5 kHz period
	11	*
	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 255
	24	#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */
	25
	26	#define RPI_PWM_CUR_DUTY_REG 0x0
	27
	28	struct raspberrypi_pwm {
	29	struct rpi_firmware *firmware;
79caa362 NSJ	30	unsigned int duty_cycle;
	31	};
	32
	33	struct raspberrypi_pwm_prop {
	34	__le32 reg;
	35	__le32 val;
	36	__le32 ret;
	37	} __packed;
	38
	39	static inline
	40	struct raspberrypi_pwm raspberrypi_pwm_from_chip(struct pwm_chip chip)
	41	{
05aa788c	42	return pwmchip_get_drvdata(chip);
79caa362 NSJ	43	}
	44
	45	static 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
	64	static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,
	65	u32 reg, u32 *val)
	66	{
	67	struct raspberrypi_pwm_prop msg = {
09f688f0	68	.reg = cpu_to_le32(reg),
79caa362 NSJ	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
6c452cff UKK	84	static int raspberrypi_pwm_get_state(struct pwm_chip *chip,
	85	struct pwm_device *pwm,
	86	struct pwm_state *state)
79caa362 NSJ	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;
6c452cff UKK	95
6c452cff UKK	96	return 0;
79caa362 NSJ	97	}
	98
	99	static 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	else
	116	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) {
fd20a3e1	124	dev_err(pwmchip_parent(chip), "Failed to set duty cycle: %pe\n",
79caa362 NSJ	125	ERR_PTR(ret));
	126	return ret;
	127	}
	128
	129	rpipwm->duty_cycle = duty_cycle;
	130
	131	return 0;
	132	}
	133
	134	static const struct pwm_ops raspberrypi_pwm_ops = {
	135	.get_state = raspberrypi_pwm_get_state,
	136	.apply = raspberrypi_pwm_apply,
79caa362 NSJ	137	};
	138
	139	static 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;
05aa788c	144	struct pwm_chip *chip;
79caa362 NSJ	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
05aa788c UKK	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);
79caa362 NSJ	165
79caa362 NSJ	166	rpipwm->firmware = firmware;
05aa788c	167	chip->ops = &raspberrypi_pwm_ops;
79caa362	168
79caa362 NSJ	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
05aa788c	176	return devm_pwmchip_add(dev, chip);
79caa362 NSJ	177	}
	178
	179	static const struct of_device_id raspberrypi_pwm_of_match[] = {
	180	{ .compatible = "raspberrypi,firmware-poe-pwm", },
	181	{ }
	182	};
	183	MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match);
	184
	185	static 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,
79caa362 NSJ	191	};
	192	module_platform_driver(raspberrypi_pwm_driver);
	193
	194	MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
	195	MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");
	196	MODULE_LICENSE("GPL v2");