RP1 Audio Out

arch/arm/boot/dts/overlays/Makefile

@@ -33,6 +33,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	audioinjector-wm8731-audio.dtbo \
 	audiosense-pi.dtbo \
 	audremap.dtbo \
+	audremap-pi5.dtbo \
 	balena-fin.dtbo \
 	bcm2712d0.dtbo \
 	camera-mux-2port.dtbo \

arch/arm/boot/dts/overlays/README

@@ -871,6 +871,17 @@ Params: swap_lr                 Reverse the channel allocation, which will also
                                 pins are on different controllers)
 
 
+Name:   audremap-pi5
+Info:   On Raspberry Pi 5 / 500 /CM5, enable digital audio output
+        and route it to GPIOs 12 & 13 on the 40-pin header
+Load:   dtoverlay=audremap-pi5,<param>=<val>
+Params: swap_lr                 Reverse the channel allocation (default off)
+        pins_12_13              Select GPIOs 12 & 13 (default)
+        pins_18_19              Not available; this will not enable audio out
+        pins_40_41              Not available; this will not enable audio out
+        pins_40_45              Not available; this will not enable audio out
+
+
 Name:   balena-fin
 Info:   Overlay that enables WLAN, Bluetooth and the GPIO expander on the
         balenaFin carrier board for the Raspberry Pi Compute Module 3/3+ Lite.

arch/arm/boot/dts/overlays/audremap-pi5-overlay.dts

@@ -0,0 +1,65 @@
+/dts-v1/;
+/plugin/;
+
+/*
+ * Raspberry Pi 5 has a different Audio Out hardware from earlier Raspberry Pis.
+ * It can output only to GPIOs 12 and 13. We therefore enable it *only* when
+ * that particular GPIO mapping is requested here. To make it work with ASOC
+ * we must also define a "dummy" codec and a generic audio card.
+ */
+
+/ {
+	compatible = "brcm,bcm2712";
+
+	fragment@0 {
+		target = <&rp1_audio_out>;
+		frag0: __overlay__ {
+			pinctrl-0 = <&rp1_audio_out_12_13>;
+			pinctrl-names = "default";
+			status = "ok";
+		};
+	};
+
+	fragment@1 {
+		 target-path = "/";
+		 __overlay__ {
+
+			 rp1_audio_out_codec: rp1_audio_out_codec@0 {
+			     compatible = "linux,spdif-dit";
+			     #sound-dai-cells = <0>;
+			     status = "ok";
+			 };
+
+			 rp1_audio_out_simple_card@0 {
+			     compatible = "simple-audio-card";
+			     simple-audio-card,name = "RP1-Audio-Out";
+			     #address-cells = <1>;
+			     #size-cells = <0>;
+			     status = "ok";
+
+			     simple-audio-card,dai-link@0 {
+				 reg = <0>;
+				 format = "left_j";
+				 bitclock-master = <&sndcpu0>;
+				 frame-master = <&sndcpu0>;
+
+				sndcpu0: cpu {
+					sound-dai = <&rp1_audio_out>;
+				};
+
+				codec {
+				    sound-dai = <&rp1_audio_out_codec>;
+				};
+			    };
+			};
+		};
+	};
+
+	__overrides__ {
+		swap_lr = <&frag0>, "swap_lr?";
+		pins_12_13 = <0>, "+0+1"; /* this is the default */
+		pins_18_19 = <0>, "-0-1"; /* sorry not supported */
+		pins_40_41 = <0>, "-0-1"; /* sorry not supported */
+		pins_40_45 = <0>, "-0-1"; /* sorry not supported */
+	};
+};

arch/arm/boot/dts/overlays/overlay_map.dts

@@ -4,6 +4,11 @@
 	audremap {
 		bcm2835;
 		bcm2711;
+		bcm2712 = "audremap-pi5";
+	};
+
+	audremap-pi5 {
+		bcm2712;
 	};
 
 	balena-fin {

arch/arm64/boot/dts/broadcom/rp1.dtsi

@@ -49,7 +49,7 @@
 					       <125000000>,  // RP1_PLL_SYS_SEC
 					       <125000000>,  // RP1_CLK_ETH
 					       <61440000>,   // RP1_PLL_AUDIO
-					       <192000000>,  // RP1_PLL_AUDIO_SEC
+					       <153600000>,  // RP1_PLL_AUDIO_SEC
 					       <200000000>,  // RP1_CLK_SYS
 					       <100000000>,  // RP1_PLL_SYS_PRI_PH
 					       // Must match the XOSC frequency
@@ -380,6 +380,20 @@
 			status = "disabled";
 		};
 
+		rp1_audio_out: audio_out@94000 {
+			compatible = "raspberrypi,rp1-audio-out";
+			reg = <0xc0 0x40094000 0x0 0x4000>;
+			clocks = <&rp1_clocks RP1_CLK_AUDIO_OUT>;
+			assigned-clocks = <&rp1_clocks RP1_CLK_AUDIO_OUT>;
+			assigned-clock-rates = <153600000>;
+			assigned-clock-parents = <&rp1_clocks RP1_PLL_AUDIO_SEC>;
+			dmas = <&rp1_dma RP1_DMA_AUDIO_OUT>;
+			dma-maxburst = <4>;
+			dma-names = "tx";
+			#sound-dai-cells = <0>;
+			status = "disabled";
+		};
+
 		rp1_pwm0: pwm@98000 {
 			compatible = "raspberrypi,rp1-pwm";
 			reg = <0xc0 0x40098000  0x0 0x100>;
@@ -974,6 +988,12 @@
 				pins = "gpio52", "gpio53";
 				bias-pull-up;
 			};
+
+			rp1_audio_out_12_13: rp1_audio_out_12_13 {
+				function = "aaud";
+				pins = "gpio12", "gpio13";
+				bias-disable;
+			};
 		};
 
 		rp1_eth: ethernet@100000 {

arch/arm64/configs/bcm2712_defconfig

@@ -1151,6 +1151,7 @@ CONFIG_SND_PISOUND=m
 CONFIG_SND_DACBERRY400=m
 CONFIG_SND_DESIGNWARE_I2S=m
 CONFIG_SND_DESIGNWARE_PCM=y
+CONFIG_SND_RP1_AUDIO_OUT=m
 CONFIG_SND_SOC_AD193X_SPI=m
 CONFIG_SND_SOC_AD193X_I2C=m
 CONFIG_SND_SOC_ADAU1701=m

drivers/clk/clk-rp1.c

@@ -1326,9 +1326,11 @@ static void rp1_clock_choose_div_and_prate(struct clk_hw *hw,
 	/*
 	 * Prevent overclocks - if all parent choices result in
 	 * a downstream clock in excess of the maximum, then the
-	 * call to set the clock will fail.
+	 * call to set the clock will fail. But due to round-to-
+	 * nearest in the PLL core (which has 24 fractional bits),
+	 * it's expedient to tolerate a tiny error (1Hz/33MHz).
 	 */
-	if (tmp > clock->data->max_freq)
+	if (tmp > clock->data->max_freq + (clock->data->max_freq >> 25))
 		*calc_rate = 0;
 	else
 		*calc_rate = tmp;
@@ -2006,7 +2008,7 @@ static const struct rp1_clk_desc clk_desc_array[] = {
 	[RP1_CLK_AUDIO_OUT] = REGISTER_CLK(
 				.name = "clk_audio_out",
 				.parents = {"", //"pll_audio",
-					    "", //"pll_audio_sec",
+					    "pll_audio_sec",
 					    "pll_video_sec",
 					    "xosc",
 					    "clksrc_gp0",

sound/soc/Kconfig

@@ -106,6 +106,7 @@ source "sound/soc/meson/Kconfig"
 source "sound/soc/mxs/Kconfig"
 source "sound/soc/pxa/Kconfig"
 source "sound/soc/qcom/Kconfig"
+source "sound/soc/raspberrypi/Kconfig"
 source "sound/soc/rockchip/Kconfig"
 source "sound/soc/samsung/Kconfig"
 source "sound/soc/sh/Kconfig"

sound/soc/Makefile

@@ -59,6 +59,7 @@ obj-$(CONFIG_SND_SOC)	+= mxs/
 obj-$(CONFIG_SND_SOC)	+= kirkwood/
 obj-$(CONFIG_SND_SOC)	+= pxa/
 obj-$(CONFIG_SND_SOC)	+= qcom/
+obj-$(CONFIG_SND_SOC)	+= raspberrypi/
 obj-$(CONFIG_SND_SOC)	+= rockchip/
 obj-$(CONFIG_SND_SOC)	+= samsung/
 obj-$(CONFIG_SND_SOC)	+= sh/

sound/soc/raspberrypi/Kconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config SND_RP1_AUDIO_OUT
+	tristate "PWM Audio Out from RP1"
+	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select SND_SOC_SPDIF
+	help
+	 Say Y or M if you want to add support for PWM digital
+	 audio output from a Raspberry Pi 5, 500 or CM5.
+
+	 Output is from RP1 GPIOs pins 12 and 13 only, and additional
+	 components will be needed. It may be useful when HDMI, I2S
+	 or USB audio devices are unavailable, or for compatibility.

sound/soc/raspberrypi/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_SND_RP1_AUDIO_OUT) += rp1_aout.o