1 // SPDX-License-Identifier: GPL-2.0
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/
8 * - No disable bit, so a disabled PWM is simulated by duty_cycle 0
9 * - Only normal polarity
10 * - Fixed 12.5 kHz period
12 * The current period is completed when HW is reconfigured.
15 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/pwm.h>
20 #include <soc/bcm2835/raspberrypi-firmware.h>
21 #include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h>
23 #define RPI_PWM_MAX_DUTY 255
24 #define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */
26 #define RPI_PWM_CUR_DUTY_REG 0x0
28 struct raspberrypi_pwm
{
29 struct rpi_firmware
*firmware
;
31 unsigned int duty_cycle
;
34 struct raspberrypi_pwm_prop
{
41 struct raspberrypi_pwm
*raspberrypi_pwm_from_chip(struct pwm_chip
*chip
)
43 return container_of(chip
, struct raspberrypi_pwm
, chip
);
46 static int raspberrypi_pwm_set_property(struct rpi_firmware
*firmware
,
49 struct raspberrypi_pwm_prop msg
= {
50 .reg
= cpu_to_le32(reg
),
51 .val
= cpu_to_le32(val
),
55 ret
= rpi_firmware_property(firmware
, RPI_FIRMWARE_SET_POE_HAT_VAL
,
65 static int raspberrypi_pwm_get_property(struct rpi_firmware
*firmware
,
68 struct raspberrypi_pwm_prop msg
= {
73 ret
= rpi_firmware_property(firmware
, RPI_FIRMWARE_GET_POE_HAT_VAL
,
80 *val
= le32_to_cpu(msg
.val
);
85 static void raspberrypi_pwm_get_state(struct pwm_chip
*chip
,
86 struct pwm_device
*pwm
,
87 struct pwm_state
*state
)
89 struct raspberrypi_pwm
*rpipwm
= raspberrypi_pwm_from_chip(chip
);
91 state
->period
= RPI_PWM_PERIOD_NS
;
92 state
->duty_cycle
= DIV_ROUND_UP(rpipwm
->duty_cycle
* RPI_PWM_PERIOD_NS
,
94 state
->enabled
= !!(rpipwm
->duty_cycle
);
95 state
->polarity
= PWM_POLARITY_NORMAL
;
98 static int raspberrypi_pwm_apply(struct pwm_chip
*chip
, struct pwm_device
*pwm
,
99 const struct pwm_state
*state
)
101 struct raspberrypi_pwm
*rpipwm
= raspberrypi_pwm_from_chip(chip
);
102 unsigned int duty_cycle
;
105 if (state
->period
< RPI_PWM_PERIOD_NS
||
106 state
->polarity
!= PWM_POLARITY_NORMAL
)
111 else if (state
->duty_cycle
< RPI_PWM_PERIOD_NS
)
112 duty_cycle
= DIV_ROUND_DOWN_ULL(state
->duty_cycle
* RPI_PWM_MAX_DUTY
,
115 duty_cycle
= RPI_PWM_MAX_DUTY
;
117 if (duty_cycle
== rpipwm
->duty_cycle
)
120 ret
= raspberrypi_pwm_set_property(rpipwm
->firmware
, RPI_PWM_CUR_DUTY_REG
,
123 dev_err(chip
->dev
, "Failed to set duty cycle: %pe\n",
128 rpipwm
->duty_cycle
= duty_cycle
;
133 static const struct pwm_ops raspberrypi_pwm_ops
= {
134 .get_state
= raspberrypi_pwm_get_state
,
135 .apply
= raspberrypi_pwm_apply
,
136 .owner
= THIS_MODULE
,
139 static int raspberrypi_pwm_probe(struct platform_device
*pdev
)
141 struct device_node
*firmware_node
;
142 struct device
*dev
= &pdev
->dev
;
143 struct rpi_firmware
*firmware
;
144 struct raspberrypi_pwm
*rpipwm
;
147 firmware_node
= of_get_parent(dev
->of_node
);
148 if (!firmware_node
) {
149 dev_err(dev
, "Missing firmware node\n");
153 firmware
= devm_rpi_firmware_get(&pdev
->dev
, firmware_node
);
154 of_node_put(firmware_node
);
156 return dev_err_probe(dev
, -EPROBE_DEFER
,
157 "Failed to get firmware handle\n");
159 rpipwm
= devm_kzalloc(&pdev
->dev
, sizeof(*rpipwm
), GFP_KERNEL
);
163 rpipwm
->firmware
= firmware
;
164 rpipwm
->chip
.dev
= dev
;
165 rpipwm
->chip
.ops
= &raspberrypi_pwm_ops
;
166 rpipwm
->chip
.base
= -1;
167 rpipwm
->chip
.npwm
= RASPBERRYPI_FIRMWARE_PWM_NUM
;
169 ret
= raspberrypi_pwm_get_property(rpipwm
->firmware
, RPI_PWM_CUR_DUTY_REG
,
170 &rpipwm
->duty_cycle
);
172 dev_err(dev
, "Failed to get duty cycle: %pe\n", ERR_PTR(ret
));
176 return devm_pwmchip_add(dev
, &rpipwm
->chip
);
179 static const struct of_device_id raspberrypi_pwm_of_match
[] = {
180 { .compatible
= "raspberrypi,firmware-poe-pwm", },
183 MODULE_DEVICE_TABLE(of
, raspberrypi_pwm_of_match
);
185 static struct platform_driver raspberrypi_pwm_driver
= {
187 .name
= "raspberrypi-poe-pwm",
188 .of_match_table
= raspberrypi_pwm_of_match
,
190 .probe
= raspberrypi_pwm_probe
,
192 module_platform_driver(raspberrypi_pwm_driver
);
194 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
195 MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");
196 MODULE_LICENSE("GPL v2");