From: Antony Pavlov <antonynpavlov@gmail.com>
To: barebox@lists.infradead.org
Subject: [PATCH v4 4/4] ns16550: fix ier selection
Date: Wed, 18 Jan 2012 10:31:56 +0400 [thread overview]
Message-ID: <1326868316-29385-5-git-send-email-antonynpavlov@gmail.com> (raw)
In-Reply-To: <1326868316-29385-1-git-send-email-antonynpavlov@gmail.com>
The document "PC16550D Universal Asynchronous
Receiver Transmitter with FIFOs" (vers. June 1995,
http://www.national.com/ds/PC/PC16550D.pdf) states
that IER (Interrupt Enable Register) is accessible
if the bit DLAB = 0 (DLAB is bit 7 in LCR; in barebox
DLAB known as LCR_BKSE).
So before IER access we need set DLAB to 0.
Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
---
drivers/serial/serial_ns16550.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
index 802331d..88ba836 100644
--- a/drivers/serial/serial_ns16550.c
+++ b/drivers/serial/serial_ns16550.c
@@ -140,7 +140,9 @@ static inline unsigned int ns16550_calc_divisor(struct console_device *cdev,
static void ns16550_serial_init_port(struct console_device *cdev)
{
/* initializing the device for the first time */
+ ns16550_write(cdev, 0x00, lcr); /* select ier reg */
ns16550_write(cdev, 0x00, ier);
+
#ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
ns16550_write(cdev, 0x07, mdr1); /* Disable */
#endif
--
1.7.8.3
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prev parent reply other threads:[~2012-01-18 6:32 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-18 6:31 [PATCH v4 0/2] ns16550-related patches Antony Pavlov
2012-01-18 6:31 ` [PATCH v4 1/4] ns16550: support for UART with broken FIFO Antony Pavlov
2012-01-18 6:31 ` [PATCH v4 2/4] ns16550: make ns16550_serial_init_port() shorter Antony Pavlov
2012-01-18 6:31 ` [PATCH v4 3/4] ns16550: write zero to ier only once Antony Pavlov
2012-01-18 6:31 ` Antony Pavlov [this message]
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