linux-kernel - [PATCH 3.19 115/175] tty/serial: at91: enable peripheral clock before accessing I/O registers

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20150304061044.978626776@linuxfoundation.org>
Date:	Tue,  3 Mar 2015 22:14:53 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Cyrille Pitchen <cyrille.pitchen@...el.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: [PATCH 3.19 115/175] tty/serial: at91: enable peripheral clock before accessing I/O registers

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Cyrille Pitchen <cyrille.pitchen@...el.com>

commit d4f641876a68d1961e30c202709cc2d484f69f6f upstream.

atmel_serial_probe() calls atmel_init_port(). In turn, atmel_init_port() calls
clk_disable_unprepare() to disable the peripheral clock before returning.

Later atmel_serial_probe() accesses some I/O registers such as the Mode and
Control registers for RS485 support then the Name and Version registers, through a call to
atmel_get_ip_name(), but at that moment the peripheral clock was still
disabled.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...el.com>
Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/serial/atmel_serial.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2596,6 +2596,12 @@ static int atmel_serial_probe(struct pla
 	device_init_wakeup(&pdev->dev, 1);
 	platform_set_drvdata(pdev, port);
 
+	/*
+	 * The peripheral clock has been disabled by atmel_init_port():
+	 * enable it before accessing I/O registers
+	 */
+	clk_prepare_enable(port->clk);
+
 	if (rs485_enabled) {
 		UART_PUT_MR(&port->uart, ATMEL_US_USMODE_NORMAL);
 		UART_PUT_CR(&port->uart, ATMEL_US_RTSEN);
@@ -2606,6 +2612,12 @@ static int atmel_serial_probe(struct pla
 	 */
 	atmel_get_ip_name(&port->uart);
 
+	/*
+	 * The peripheral clock can now safely be disabled till the port
+	 * is used
+	 */
+	clk_disable_unprepare(port->clk);
+
 	return 0;
 
 err_add_port:


--
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/