[PATCH 2/2] tty: pl011: use "qdf2400_e44" as the earlycon name for QDF2400 E44

[manoj.iyer at canonical.com]

From: Timur Tabi <timur at codeaurora.org>

Define a new early console name for Qualcomm Datacenter Technologies
QDF2400 SOCs affected by erratum 44, instead of piggy-backing on "pl011".
Previously, to enable traditional (non-SPCR) earlycon, the documentation
said to specify "earlycon=pl011,<address>,qdf2400_e44", but the code was
broken and this didn't actually work.

So instead, the method for specifying the E44 work-around with traditional
earlycon is "earlycon=qdf2400_e44,<address>".  Both methods of earlycon
are now enabled with the same function.

BugLink: http://bugs.launchpad.net/bugs/1689818

Fixes: e53e597fd4c4 ("tty: pl011: fix earlycon work-around for QDF2400 erratum 44")
Signed-off-by: Timur Tabi <timur at codeaurora.org>
Cc: stable <stable at vger.kernel.org> # 4.11
Tested-by: Shanker Donthineni <shankerd at codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 5a0722b898f851b9ef108ea7babc529e4efc773d)
Signed-off-by: Manoj Iyer <manoj.iyer at canonical.com>
---
 drivers/tty/serial/amba-pl011.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 27835393ffe2..0875f7d01fa5 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2470,19 +2470,34 @@ static int __init pl011_early_console_setup(struct earlycon_device *device,
 	if (!device->port.membase)
 		return -ENODEV;
 
-	/* On QDF2400 SOCs affected by Erratum 44, the "qdf2400_e44" must
-	 * also be specified, e.g. "earlycon=pl011,<address>,qdf2400_e44".
-	 */
-	if (!strcmp(device->options, "qdf2400_e44"))
-		device->con->write = qdf2400_e44_early_write;
-	else
-		device->con->write = pl011_early_write;
+	device->con->write = pl011_early_write;
 
 	return 0;
 }
 OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);
 OF_EARLYCON_DECLARE(pl011, "arm,sbsa-uart", pl011_early_console_setup);
-EARLYCON_DECLARE(qdf2400_e44, pl011_early_console_setup);
+
+/*
+ * On Qualcomm Datacenter Technologies QDF2400 SOCs affected by
+ * Erratum 44, traditional earlycon can be enabled by specifying
+ * "earlycon=qdf2400_e44,<address>".  Any options are ignored.
+ *
+ * Alternatively, you can just specify "earlycon", and the early console
+ * will be enabled with the information from the SPCR table.  In this
+ * case, the SPCR code will detect the need for the E44 work-around,
+ * and set the console name to "qdf2400_e44".
+ */
+static int __init
+qdf2400_e44_early_console_setup(struct earlycon_device *device,
+				const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = qdf2400_e44_early_write;
+	return 0;
+}
+EARLYCON_DECLARE(qdf2400_e44, qdf2400_e44_early_console_setup);
 
 #else
 #define AMBA_CONSOLE	NULL
-- 
2.11.0