linux-kernel - [PATCH 7/8] LinuxPPS: pps_gen_parport: Add polarity parameter for inverted signal.

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Message-Id: <1487169069-15721-8-git-send-email-immortalguardian1@gmail.com>
Date:   Wed, 15 Feb 2017 17:31:08 +0300
From:   Andrey Drobyshev <immortalguardian1@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     gq@...msu.su, giometti@...eenne.com
Subject: [PATCH 7/8] LinuxPPS: pps_gen_parport: Add polarity parameter for inverted signal.

From: Alexander GQ Gerasiov <gq@...msu.su>

On some devices it may be necessary to transmit inverted data. This commit
simply adds polarity parameter to define which state represents presence of
signal: it equals 0 if signal is on the low level (default), or 1 if signal
is on the high level (inverted signal).

Signed-off-by: Alexander GQ Gerasiov <gq@...msu.su>
---
 drivers/pps/generators/pps_gen_parport.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pps/generators/pps_gen_parport.c b/drivers/pps/generators/pps_gen_parport.c
index dcd39fb..7739301 100644
--- a/drivers/pps/generators/pps_gen_parport.c
+++ b/drivers/pps/generators/pps_gen_parport.c
@@ -36,8 +36,8 @@

 #define DRVDESC "parallel port PPS signal generator"

-#define SIGNAL		0
-#define NO_SIGNAL	PARPORT_CONTROL_STROBE
+#define SIGNAL		(polarity?PARPORT_CONTROL_STROBE:0)
+#define NO_SIGNAL	(polarity?0:PARPORT_CONTROL_STROBE)

 /* module parameters */

@@ -48,6 +48,10 @@ MODULE_PARM_DESC(delay,
 	"Delay between setting and dropping the signal (ns)");
 module_param_named(delay, send_delay, uint, 0);

+static unsigned int polarity;
+MODULE_PARM_DESC(polarity,
+	"Signal is on the low level (0 - default) or on the high level (1).");
+module_param(polarity, uint, 0);

 #define SAFETY_INTERVAL	3000	/* set the hrtimer earlier for safety (ns) */

-- 
2.1.4