linux-kernel - [PATCH v4 10/12] usb: xhci: dbc: add handshake between debug target and host

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1447742338-8381-11-git-send-email-baolu.lu@linux.intel.com>
Date:	Tue, 17 Nov 2015 14:38:56 +0800
From:	Lu Baolu <baolu.lu@...ux.intel.com>
To:	Mathias Nyman <mathias.nyman@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-usb@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v4 10/12] usb: xhci: dbc: add handshake between debug target and host

After DbC setup, debug target needs to wait until tty driver and
application (e.g. mincom) on debug taget start.  Otherwise, out
messages might be ignored.

This patch adds a ping/pong mechanism between debug target and
host. Debug target will be waiting there until user presses 'Y'
or 'y' in the tty application.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/usb/early/xhci-dbc.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c
index 68a7139..b75c523 100644
--- a/drivers/usb/early/xhci-dbc.c
+++ b/drivers/usb/early/xhci-dbc.c
@@ -32,6 +32,9 @@
 static struct xdbc_state xdbc_stat;
 static struct xdbc_state *xdbcp = &xdbc_stat;
 
+static int early_xdbc_read(struct console *con, char *str, unsigned n);
+static void early_xdbc_write(struct console *con, const char *str, u32 n);
+
 #ifdef DBC_DEBUG
 #define	XDBC_DEBUG_BUF_SIZE	(PAGE_SIZE * 32)
 #define	MSG_MAX_LINE		128
@@ -873,8 +876,12 @@ int __init early_xdbc_init(char *s)
 {
 	u32 bus = 0, dev = 0, func = 0;
 	unsigned long dbgp_num = 0;
+	char *ping = "Press Y to continue...\n";
+	char pong[64];
+	size_t size;
 	u32 offset;
 	int ret;
+	int retry = 20;
 
 	if (!early_pci_allowed())
 		return -EPERM;
@@ -917,6 +924,21 @@ int __init early_xdbc_init(char *s)
 		return ret;
 	}
 
+	while (retry > 0) {
+		early_xdbc_write(NULL, ping, strlen(ping));
+		size = early_xdbc_read(NULL, pong, 64);
+		if (size > 0) {
+			xdbc_trace("%s: pong message: %s\n", __func__, pong);
+			if (pong[0] == 'Y' || pong[0] == 'y')
+				break;
+		} else {
+			xdbc_trace("%s: pong message error %d\n",
+				__func__, size);
+		}
+
+		retry--;
+	}
+
 	return 0;
 }
 
@@ -1338,6 +1360,11 @@ int xdbc_bulk_write(const char *bytes, int size)
  * Start a bulk-in or bulk-out transfer, wait until transfer completion
  * or error. Return the count of actually transferred bytes or error.
  */
+static int early_xdbc_read(struct console *con, char *str, unsigned n)
+{
+	return xdbc_bulk_read(str, n, 0);
+}
+
 static void early_xdbc_write(struct console *con, const char *str, u32 n)
 {
 	int chunk, ret;
-- 
2.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/