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overlays: Add overlay pwm1

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pwm1 enables the second PWM interface found on BCM2711. It can only
be mapped to GPIOs 40 & 41.

See: https://forums.raspberrypi.com/viewtopic.php?t=342458

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
This commit is contained in:
Phil Elwell
2022-11-16 14:54:08 +00:00
committed by Dom Cobley
parent 1752d9f7ae
commit d200f7b7bb
4 changed files with 83 additions and 0 deletions
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1
arch/arm/boot/dts/overlays/Makefile
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@@ -183,6 +183,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
pwm.dtbo \
pwm-2chan.dtbo \
pwm-ir-tx.dtbo \
pwm1.dtbo \
qca7000.dtbo \
qca7000-uart0.dtbo \
ramoops.dtbo \

18
arch/arm/boot/dts/overlays/README
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@@ -3216,6 +3216,24 @@ Params: gpio_pin Output GPIO (default 18)
func Pin function (default 2 = Alt5)
Name: pwm1
Info: Configures one or two PWM channel on PWM1 (BCM2711 only)
N.B.:
1) The onboard analogue audio output uses both PWM channels.
2) So be careful mixing audio and PWM.
Note that even when only one pin is enabled, both channels are available
from the PWM driver, so be careful to use the correct one.
Load: dtoverlay=pwm1,<param>=<val>
Params: clock PWM clock frequency (informational)
pins_40 Enable channel 0 (PWM1_0) on GPIO 40
pins_41 Enable channel 1 (PWM1_1) on GPIO 41
pins_40_41 Enable channels 0 (PWM1_0) and 1 (PW1_1) on
GPIOs 40 and 41 (default)
pull_up Enable pull-ups on the PWM pins (default)
pull_down Enable pull-downs on the PWM pins
pull_off Disable pulls on the PWM pins
Name: qca7000
Info: in-tech's Evaluation Board for PLC Stamp micro
This uses spi0 and a separate GPIO interrupt to connect the QCA7000.

4
arch/arm/boot/dts/overlays/overlay_map.dts
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@@ -77,6 +77,10 @@
renamed = "miniuart-bt";
};
pwm1 {
bcm2711;
};
ramoops {
bcm2835;
bcm2711 = "ramoops-pi4";

60
arch/arm/boot/dts/overlays/pwm1-overlay.dts Normal file
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@@ -0,0 +1,60 @@
/dts-v1/;
/plugin/;
#include <dt-bindings/pinctrl/bcm2835.h>
/ {
compatible = "brcm,bcm2711";
fragment@0 {
target = <&pins>;
__overlay__ {
brcm,pins = <40 41>;
};
};
fragment@1 {
target = <&pins>;
__dormant__ {
brcm,pins = <40>;
};
};
fragment@2 {
target = <&pins>;
__dormant__ {
brcm,pins = <41>;
};
};
fragment@3 {
target = <&gpio>;
__overlay__ {
pins: pwm1_overlay_pins {
brcm,pins = <40 41>;
brcm,function = <BCM2835_FSEL_ALT0>;
brcm,pull = <BCM2835_PUD_UP>;
};
};
};
fragment@4 {
target = <&pwm1>;
pwm: __overlay__ {
status = "okay";
assigned-clock-rates = <100000000>;
pinctrl-names = "default";
pinctrl-0 = <&pins>;
};
};
__overrides__ {
clock = <&pwm>, "assigned-clock-rates:0";
pins_40_41 = <0>,"+0-1-2";
pins_40 = <0>,"-0+1-2";
pins_41 = <0>,"-0-1+2";
pull_up = <&pins>, "brcm,pull:0=", <BCM2835_PUD_UP>;
pull_down = <&pins>, "brcm,pull:0=", <BCM2835_PUD_DOWN>;
pull_off = <&pins>, "brcm,pull:0=", <BCM2835_PUD_OFF>;
};
};