linux-kernel - [PATCH 6/8] usb: gadget: f_acm: add an ioctl to get the current line coding

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Message-Id: <1497288375-3559-7-git-send-email-tal.shorer@gmail.com>
Date:   Mon, 12 Jun 2017 20:26:13 +0300
From:   Tal Shorer <tal.shorer@...il.com>
To:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, gregkh@...uxfoundation.org,
        balbi@...nel.org, corbet@....net
Cc:     Tal Shorer <tal.shorer@...il.com>
Subject: [PATCH 6/8] usb: gadget: f_acm: add an ioctl to get the current line coding

The user can issue USB_F_GET_LINE_CODING to get the current line coding
as set by the host (or the default if unset yet).

Signed-off-by: Tal Shorer <tal.shorer@...il.com>
---
 Documentation/ioctl/ioctl-number.txt |  1 +
 drivers/usb/gadget/function/f_acm.c  | 27 +++++++++++++++++++++++----
 include/uapi/linux/usb/f_acm.h       | 12 ++++++++++++
 3 files changed, 36 insertions(+), 4 deletions(-)
 create mode 100644 include/uapi/linux/usb/f_acm.h

diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index 1e9fcb4..3d70680 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -329,6 +329,7 @@ Code  Seq#(hex)	Include File		Comments
 0xCA	80-8F	uapi/scsi/cxlflash_ioctl.h
 0xCB	00-1F	CBM serial IEC bus	in development:
 					<mailto:michael.klein@...fin.lb.shuttle.de>
+0xCD	10-1F	linux/usb/f_acm.h
 0xCD	01	linux/reiserfs_fs.h
 0xCF	02	fs/cifs/ioctl.c
 0xDB	00-0F	drivers/char/mwave/mwavepub.h
diff --git a/drivers/usb/gadget/function/f_acm.c b/drivers/usb/gadget/function/f_acm.c
index b7a1466..5feea7c 100644
--- a/drivers/usb/gadget/function/f_acm.c
+++ b/drivers/usb/gadget/function/f_acm.c
@@ -19,6 +19,7 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <uapi/linux/usb/f_acm.h>
 
 #include "u_serial.h"
 
@@ -611,6 +612,23 @@ static int acm_send_break(struct gserial *port, int duration)
 	return acm_notify_serial_state(acm);
 }
 
+static int acm_ioctl(struct gserial *port, unsigned int cmd, unsigned long arg)
+{
+	struct f_acm	*acm = port_to_acm(port);
+	int 		ret = -ENOIOCTLCMD;
+
+	switch (cmd) {
+	case USB_F_ACM_GET_LINE_CODING:
+		if (copy_to_user((__user void *)arg, &acm->port_line_coding,
+				sizeof(acm->port_line_coding)))
+			ret = -EFAULT;
+		else
+			ret = 0;
+		break;
+	}
+	return ret;
+}
+
 /*-------------------------------------------------------------------------*/
 
 /* ACM function driver setup/binding */
@@ -749,6 +767,7 @@ static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
 	acm->port.connect = acm_connect;
 	acm->port.disconnect = acm_disconnect;
 	acm->port.send_break = acm_send_break;
+	acm->port.ioctl = acm_ioctl;
 
 	acm->port.func.name = "acm";
 	acm->port.func.strings = acm_strings;
@@ -764,10 +783,10 @@ static struct usb_function *acm_alloc_func(struct usb_function_instance *fi)
 	acm->port.func.free_func = acm_free_func;
 
 	/* initialize port_line_coding with something that makes sense */
-	coding.dwDTERate = cpu_to_le32(9600);
-	coding.bCharFormat = USB_CDC_1_STOP_BITS;
-	coding.bParityType = USB_CDC_NO_PARITY;
-	coding.bDataBits = 8;
+	acm->port_line_coding.dwDTERate = cpu_to_le32(9600);
+	acm->port_line_coding.bCharFormat = USB_CDC_1_STOP_BITS;
+	acm->port_line_coding.bParityType = USB_CDC_NO_PARITY;
+	acm->port_line_coding.bDataBits = 8;
 
 	return &acm->port.func;
 }
diff --git a/include/uapi/linux/usb/f_acm.h b/include/uapi/linux/usb/f_acm.h
new file mode 100644
index 0000000..51f96f0
--- /dev/null
+++ b/include/uapi/linux/usb/f_acm.h
@@ -0,0 +1,12 @@
+/* f_acm.h -- Header file for USB CDC-ACM gadget function */
+
+#ifndef __UAPI_LINUX_USB_F_ACM_H
+#define __UAPI_LINUX_USB_F_ACM_H
+
+#include <linux/usb/cdc.h>
+#include <linux/ioctl.h>
+
+/* The 0xCD code is also used by reiserfs. we use 0x10-0x1F range */
+#define USB_F_ACM_GET_LINE_CODING _IOR(0xCD, 0x10, struct usb_cdc_line_coding)
+
+#endif /* __UAPI_LINUX_USB_F_ACM_H */
-- 
2.7.4