updated drvier for kernels 4.9+ where usb_control_msg cannot be fed with...

CP210X_NAME="cp210x.c"

CP210X_ADDRESS="https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/plain/drivers/usb/serial/cp210x.c?id=refs/tags/v"

PATCH_NAME="cp210x.patch"

LINUX_KERNEL_VERSION=$(uname -r | cut -f1 -d"-")

LKV_P1=$(echo $LINUX_KERNEL_VERSION | cut -f1 -d".")

LKV_P2=$(echo $LINUX_KERNEL_VERSION | cut -f2 -d".")

  CP210X_VERSION=$(echo "$LKV_P1.$LKV_P2.$LKV_P3")

fi

if [ $LKV_P1 -le 4 ] && [ $LKV_P2 -lt 9 ]; then

  echo "Selecting patch for kernel <4.9.0!"

  PATCH_NAME="cp210x.patch"

else

  echo "Selecting patch for kernel 4.9+!"

  PATCH_NAME="cp210x_kernel_4.9.x+.patch"

fi

#uncomment if patch doesn't work 

#CP210X_VERSION="3.8.0"

--- a/cp210x.c	2019-07-18 13:10:09.000000000 -0600

+++ b/cp210x.c	2019-07-18 13:06:25.000000000 -0600

@@ -31,6 +31,8 @@

  */

 static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *);

 static void cp210x_close(struct usb_serial_port *);

+static int cp210x_ioctl(struct tty_struct *tty,

+	unsigned int cmd, unsigned long arg);

 static void cp210x_get_termios(struct tty_struct *, struct usb_serial_port *);

 static void cp210x_get_termios_port(struct usb_serial_port *port,

 	tcflag_t *cflagp, unsigned int *baudp);

@@ -245,6 +247,7 @@

 	.bulk_out_size		= 256,

 	.open			= cp210x_open,

 	.close			= cp210x_close,

+        .ioctl			= cp210x_ioctl,

 	.break_ctl		= cp210x_break_ctl,

 	.set_termios		= cp210x_set_termios,

 	.tx_empty		= cp210x_tx_empty,

@@ -262,6 +265,10 @@

 	&cp210x_device, NULL

 };

+/* IOCTLs */

+#define IOCTL_GPIOGET	 0x8000

+#define IOCTL_GPIOSET	 0x8001

+

 /* Config request types */

 #define REQTYPE_HOST_TO_INTERFACE	0x41

 #define REQTYPE_INTERFACE_TO_HOST	0xc1

@@ -867,6 +874,66 @@

 	return !count;

 }

+// Elphel

+static int cp210x_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)

+{

+	struct usb_serial_port *port = tty->driver_data;

+	struct usb_serial *serial = port->serial;

+

+	int result = 0;

+	unsigned int latch_setting = 0;

+        int bufsize = 1;

+

+	// usb_control_msg used to be able to read to statically allocated buffer

+	// now it does not, have to create this buffer

+	// https://stackoverflow.com/questions/52685669/usb-control-msg-returns-eagain

+	void *dmabuf;

+

+	dmabuf = kmalloc(bufsize, GFP_KERNEL);

+	if (!dmabuf)

+            return -ENOMEM;

+

+	switch (cmd) {

+	    case IOCTL_GPIOGET:

+		result = usb_control_msg(

+			      serial->dev,

+			      usb_rcvctrlpipe(serial->dev, 0),

+			      CP210X_VENDOR_SPECIFIC,

+			      REQTYPE_DEVICE_TO_HOST,

+			      CP210X_READ_LATCH,

+			      cp210x_interface_num(serial),

+			      dmabuf, bufsize,

+			      USB_CTRL_GET_TIMEOUT);

+		if (result != bufsize)

+		    return -EPROTO;

+                memcpy(&latch_setting, dmabuf, bufsize);

+		*(unsigned long *)arg = (unsigned long)latch_setting;

+		return 0;

+	    break;

+	    case IOCTL_GPIOSET:

+		latch_setting = *(unsigned int *)arg & 0x000000FF;

+		//why [23:16] bits are taken for value is unknown

+		latch_setting |= (*(unsigned int *)arg & 0x00FF0000) >> 8;

+

+		result = usb_control_msg(

+			      serial->dev,

+			      usb_sndctrlpipe(serial->dev, 0),

+			      CP210X_VENDOR_SPECIFIC,

+			      REQTYPE_HOST_TO_DEVICE,

+			      CP210X_WRITE_LATCH,

+			      latch_setting,

+			      NULL, 0,

+			      USB_CTRL_SET_TIMEOUT);

+		if (result != 0)

+		    return -EPROTO;

+		return 0;

+	    break;

+	    default:

+	    break;

+	}

+	return -ENOIOCTLCMD;

+}

+

 /*

  * cp210x_get_termios

  * Reads the baud rate, data bits, parity, stop bits and flow control mode