SPI add devices/GPIO CS/shared MISO MOSI

Mark Nagaev

Hello, I'm trying to add some devices on spi. Here i found the way to do it.
This my spi section in device tree:

pinctrl-names = "default";
pinctrl-0 = <&spi_pins>, <&spi_cs1_pins>;
cs-gpios = <0>, <0>, <&gpio1 17 0>;

m25p80@0 {
	#address-cells = <1>;
	#size-cells = <1>;
	compatible = "jedec,spi-nor";
	reg = <0>;
	spi-max-frequency = <40000000>;
	m25p,chunked-io = <31>;

	partition@0 {
		label = "u-boot";
		reg = <0x0 0x30000>;
		read-only;
	};

	partition@30000 {
		label = "u-boot-env";
		reg = <0x30000 0x10000>;
		read-only;
	};

	factory: partition@40000 {
		label = "factory";
		reg = <0x40000 0x10000>;
		read-only;
	};

	firmware: partition@50000 {
		label = "firmware";
	};
};

spidev@1 {
	compatible = "linux,spidev";
	reg = <1>;
	spi-max-frequency = <40000000>;
};

spidev@2 {
	compatible = "linux,spidev";
	reg = <2>;
	spi-max-frequency = <40000000>;
};

current driver : https://github.com/wdu/mt7688

my code, using python :

import onionSpi, onionGpio, time

busNumber = 2
deviceId = 32766

rst  = onionGpio.OnionGpio(15)

rst.setOutputDirection(0)

codec = onionSpi.OnionSpi(busNumber, deviceId)

codec.sck =  7
codec.mosi = 8
codec.miso = 9
codec.cs = 17
codec.mode = 3
codec.speed = 3125000

# check the device
if codec.checkDevice() is 0:
        mapped = "the device adapter is already mapped."
else:
        mapped = "the device adapter is NOT mapped."
print("Registered: {}".format(mapped))

# register the device
if codec.registerDevice() is 0:
        success = "Device with the specified bus number and device ID is already registered OR         successfully registered SPI device adapter."
else:
        success = "Unable to register device."
print("Registering.. : {}".format(success))

# initialize the device parameters
if codec.setupDevice() is 0:
        success = "Setup successful."
else:
        success = "Setup failed."

print("Setting up spi device: {}".format(success))

# check the device again
if codec.checkDevice() is 0:
        mapped = "the device adapter is already mapped."
else:
        mapped = "the device adapter is NOT mapped."
print("Registered: {}".format(mapped))


rst.setOutputDirection(1)

time.sleep(0.0001)

rst.setOutputDirection(0)
ret     = codec.writeBytes(0x04, [0x1A])
print(ret)

it's returned:

Registered: the device adapter is already mapped.
SPI device already available
Registering.. : Device with the specified bus number and device ID is already registered OR successfully registered SPI device adapter.
Initializing SPI parameters...
Set SPI mode: 0x500
Set bits per word: 0
Set max speed: 3125000 Hz (3125 KHz)
ERROR: Cannot set SPI mode 0x500
Setting up spi device: Setup failed.
Registered: the device adapter is already mapped.
ERROR: SPI transfer failed
Traceback (most recent call last):
File "/root/kek.py", line 56, in <module>
ret = codec.writeBytes(0x04, [0x1A])
IOError: SPI transaction failed.

spidev is returned :

[ 2084.178830] spidev spi32766.2: setup: ignoring unsupported mode bits 500
[ 2084.185747] spidev spi32766.2: failed to request gpio cs 49

WHY GPIO 49??

GPIO 17 always HIGH. Any Ideas?

Mark Nagaev

Ok, i understand why it was 49, i was using wrong gpio bank, but anyway now it's look like that

root@Omega-6D86:/# cat /sys/kernel/debug/gpio
GPIOs 0-31, platform/10000600.gpio, 10000600.gpio:
 gpio-17  (                    |spi-mt7621          ) out hi

GPIOs 32-63, platform/10000600.gpio, 10000600.gpio:
 gpio-38  (                    |reset               ) in  lo

GPIOs 64-95, platform/10000600.gpio, 10000600.gpio:

gpio 17 really registred like cs, but when i'm tryin to make a transaction:

root@Omega-6D86:~# python writebytes2.py
Traceback (most recent call last):
 File "writebytes2.py", line 16, in <module>
  time.sleep(0.0004)
IOError: [Errno 16] Resource busy

and what i have, when tryin to export this pin:

     root@Omega-6D86:/sys/class/gpio# echo 17 > export
     -ash: write error: Resource busy

Any ideas?

Mark Nagaev

Okay, I solved this, now i have workin SPI with cs lines on gpio.
This final spi driver spi-mt7621

In Device tree(Omega2.dtsi) in node spi u need to add cs-gpios like this:

&spi0 {
status = "okay";

pinctrl-names = "default";
pinctrl-0 = <&spi_pins>, <&spi_cs1_pins>;
cs-gpios = <0>, <0>, <&gpio0 17 1>;

m25p80@0 {
	#address-cells = <1>;
	#size-cells = <1>;
	compatible = "jedec,spi-nor";

and u need to add spi-device node like this :

spidev@1 {
	#address-cells = <1>;
	#size-cells = <1>;
	compatible = "linux,spidev";
	spi-max-frequency = <3125000>;
	reg = <1>;
	};

ad193x: ad193x@2 {
	#address-cells = <1>;
	#size-cells = <1>;
	compatible = "adi,ad193x";
	spi-max-frequency = <3125000>;
	reg = <2>;
	#sound-dai-cells = <0>;
	};

It must be work fine.

Rogier Lodewijks

As you're also linking in the source of the driver, the following question arises:

Is this purely a device tree addition/enhancement, or is also a patch to the spidev kernel module needed?

Btw: great work!

Mark Nagaev

@Rogier-Lodewijks no, u don't need patch spidev, only spi-mt7621.c source file and it's in kernel yea. After this u can add cs-gpios in device tree, and spi device in node. Spi device can be spidev if u developing spi driver and u need its API. Thank you)