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UART to BLSP12 not detected - DragonBoard 820c - 96Boards Forum

UART to BLSP12 not detected

Products Support DragonBoard 820c
#1

Hi,
I connected a Sigfox module by UART to the blsp_uart12 GPIOs (85 & 86). My kernel version is linaro-qcomlt-4.14.

The blsp_uart12 isn’t initialized in the device tree, so I added these lines (patch):

diff --git a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
index 5020191d9edf..c85ee440053a 100644
--- a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
+++ b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
@@ -25,6 +25,7 @@
 		serial0 = &blsp2_uart1;
 		serial1 = &blsp2_uart2;
 		serial2 = &blsp1_uart1;
+		serial3 = &blsp2_uart5;
 		i2c0	= &blsp1_i2c2;
 		i2c1	= &blsp2_i2c1;
 		i2c2	= &blsp2_i2c0;
@@ -87,6 +88,15 @@
 			pinctrl-1 = <&blsp2_uart1_2pins_sleep>;
 		};
 
+		serial@75b4000 {
+                        label = "LS-UART0";
+                        status = "okay";
+                        pinctrl-names = "default", "sleep";
+                        pinctrl-0 = <&blsp2_uart5_2pins_default>;
+                        pinctrl-1 = <&blsp2_uart5_2pins_sleep>;
+                };
+
+
//		serial@75b1000 {
//			label = "LS-UART0";
//			status = "okay";
diff --git a/arch/arm64/boot/dts/qcom/msm8996-pins.dtsi b/arch/arm64/boot/dts/qcom/msm8996-pins.dtsi
index ff862c8c828f..6e69c518c8e5 100644
--- a/arch/arm64/boot/dts/qcom/msm8996-pins.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8996-pins.dtsi
@@ -215,6 +215,31 @@
 		};
 	};
 
+	//add uart
+	blsp2_uart5_2pins_default: blsp2_uart5_2pins {
+		pinmux {
+			function = "blsp_uart12";
+			pins = "gpio85", "gpio86";
+		};
+		pinconf {
+			pins = "gpio85", "gpio86";
+			drive-strength = <16>;
+			bias-disable;
+		};
+	};
+
+	blsp2_uart5_2pins_sleep: blsp2_uart5_2pins_sleep {
+		pinmux {
+			function = "gpio";
+			pins = "gpio85", "gpio86";
+		};
+		pinconf {
+			pins = "gpio85", "gpio86";
+			drive-strength = <2>;
+			bias-disable;
+		};
+	};
+
 	blsp2_i2c1_default: blsp2_i2c1 {
 		pinmux {
 			function = "blsp_i2c8";
diff --git a/arch/arm64/boot/dts/qcom/msm8996.dtsi b/arch/arm64/boot/dts/qcom/msm8996.dtsi
index 39f69190eaa5..69564a389420 100644
--- a/arch/arm64/boot/dts/qcom/msm8996.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8996.dtsi
@@ -700,6 +700,15 @@
 			clock-names = "core", "iface";
 			status = "disabled";>
 		};
+		 blsp2_uart5: serial@75b4000 {
+                        compatible = "qcom,msm-uartdm-v1.4", "qcom,msm-uartdm";
+                        reg = <0x075b4000 0x1000>;
+                        interrupts = <GIC_SPI 118 IRQ_TYPE_LEVEL_HIGH>;
+                        clocks = <&gcc gcc_BLSP2_UART6_APPS_CLK>,
+                                 <&gcc gcc_BLSP2_AHB_CLK>;
+                        clock-names = "core", "iface";
+                        status = "okay";
+                };

 		blsp1_spi0: spi@07575000 {
 			compatible = "qcom,spi-qup-v2.2.1";
-- 
2.20.1

The device is booting, and in /sys/devices/platform/soc the UART seems to be well created. But the device is not detected by the driver…

sh-5.0# cat 75b4000.serial/uevent
OF_NAME=serial
OF_FULLNAME=/soc/serial@75b4000
OF_COMPATIBLE_0=qcom,msm-uartdm-v1.4
OF_COMPATIBLE_1=qcom,msm-uartdm
OF_COMPATIBLE_N=2
OF_ALIAS_0=serial3
MODALIAS=of:NserialT<NULL>Cqcom,msm-uartdm-v1.4Cqcom,msm-uartdm

Any ideas on this ? (Hardware connections are good).
Thanks :slight_smile:

#2

any related message in dmesg output? dmesg | grep -e uart -e serial

#3

No, nothing…

There is something suspicious, in the device tree from linaro, the blsp2_uart2 is commented. There is maybe some issues with it…

(I didn’t find any proof that the blsp2_uart5 is working :thinking: )

#4

I forgot to do add lines to the msm-serial driver :sweat_smile:

Kernel/drivers/tty/serial/msm_serial.c :

static struct msm_port msm_uart_ports[] = {
+	{
		.uart = {
+ 			.iotype = UPIO_MEM,
+ 			.ops = &msm_uart_pops,
+ 			.flags = UPF_BOOT_AUTOCONF,
+ 			.fifosize = 64,
+ 			.line = 3,
+		},
+
+	},
};

So ttyMSM3 is well initialized but the boot crash like in this post :
Is BLSP12(blsp2_uart5) tested for UART transfers?
#5

Yeah, AFAIR its because this UART is reserved for ‘secure world’ and not accessible from regular OS. You either have to use an other UART instance or to get a modified firmware.

#6

Yeah, thank you…
Is there a list with all usable UARTs ?

#7

AFAIK all others are usable, as long as properly routed to usable pins