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 member
function named get_fifosize, rather than using the fifosize member
variable. The function takes the UARTPeriphID, and returns the
correct FIFO size.
Signed-off-by: Jongsung Kim <neidhard.kim@lge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/amba-pl011.c

@@ -73,32 +73,44 @@
 /* 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];
@@ -2133,7 +2145,7 @@ 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;