linux-kernel - [PATCH] ARM: PL011: add support for extended FIFO-size of PL011-r1p5

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Date:	Fri, 12 Apr 2013 18:18:47 +0900
From:	"Jongsung Kim" <neidhard.kim@....com>
To:	"Russell King" <linux@....linux.org.uk>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, <jslaby@...e.cz>
Cc:	<linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] ARM: PL011: add support for extended FIFO-size of PL011-r1p5

The latest r1p5-revision of the ARM PL011 UART has 32-byte FIFOs, while all
earlier ones have 16-byte FIFOs. This patch suggests a way to set the
FIFO-size correctly & flexibly by using a
function(vendor_data::get_fifosize) rather than using the
vendor_data::fifosize variable. The function takes the UARTPeriphID, and
returns the correct size.

Signed-off-by: Jongsung Kim <neidhard.kim@....com>

 drivers/tty/serial/amba-pl011.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/amba-pl011.c
b/drivers/tty/serial/amba-pl011.c
index 3ea5408..22af0c8 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -72,32 +72,44 @@
 /* There is by now at least one vendor with differing details, so handle it
*/
 struct vendor_data {
 	unsigned int		ifls;
-	unsigned int		fifosize;
 	unsigned int		lcrh_tx;
 	unsigned int		lcrh_rx;
 	bool			oversampling;
 	bool			dma_threshold;
 	bool			cts_event_workaround;
+
+	unsigned int (*get_fifosize)(unsigned int periphid);
 };
 
+static unsigned int get_fifosize_arm(unsigned int periphid)
+{
+	unsigned int rev = (periphid >> 20) & 0xf;
+	return rev < 3 ? 16 : 32;
+}
+
 static struct vendor_data vendor_arm = {
 	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
-	.fifosize		= 16,
 	.lcrh_tx		= UART011_LCRH,
 	.lcrh_rx		= UART011_LCRH,
 	.oversampling		= false,
 	.dma_threshold		= false,
 	.cts_event_workaround	= false,
+	.get_fifosize		= get_fifosize_arm,
 };
 
+static unsigned int get_fifosize_st(unsigned int periphid)
+{
+	return 64;
+}
+
 static struct vendor_data vendor_st = {
 	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
-	.fifosize		= 64,
 	.lcrh_tx		= ST_UART011_LCRH_TX,
 	.lcrh_rx		= ST_UART011_LCRH_RX,
 	.oversampling		= true,
 	.dma_threshold		= true,
 	.cts_event_workaround	= true,
+	.get_fifosize		= get_fifosize_st,
 };
 
 static struct uart_amba_port *amba_ports[UART_NR];
@@ -2010,7 +2022,7 @@ static int pl011_probe(struct amba_device *dev, const
struct amba_id *id)
 	uap->lcrh_rx = vendor->lcrh_rx;
 	uap->lcrh_tx = vendor->lcrh_tx;
 	uap->old_cr = 0;
-	uap->fifosize = vendor->fifosize;
+	uap->fifosize = vendor->get_fifosize(dev->periphid);
 	uap->port.dev = &dev->dev;
 	uap->port.mapbase = dev->res.start;
 	uap->port.membase = base;

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