1 files changed, 99 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250_dw.c b/drivers/tty/serial/8250_dw.c
new file mode 100644
index 00000000000..e25782aeec7
--- /dev/null
+++ b/drivers/tty/serial/8250_dw.c
@@ -0,0 +1,99 @@
+/*
+ * Synopsys DesignWare specific 8250 operations.
+ *
+ * Copyright 2011 Picochip, Jamie Iles.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * The Synopsys DesignWare 8250 has an extra feature whereby it detects if the
+ * LCR is written whilst busy.  If it is, then a busy detect interrupt is
+ * raised, the LCR needs to be rewritten and the uart status register read.
+ */
+#include <linux/io.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/slab.h>
+
+struct dw8250_data {
+	int	last_lcr;
+};
+
+static void dw8250_serial_out(struct uart_port *p, int offset, int value)
+{
+	struct dw8250_data *d = p->private_data;
+
+	if (offset == UART_LCR)
+		d->last_lcr = value;
+
+	offset <<= p->regshift;
+	writeb(value, p->membase + offset);
+}
+
+static unsigned int dw8250_serial_in(struct uart_port *p, int offset)
+{
+	offset <<= p->regshift;
+
+	return readb(p->membase + offset);
+}
+
+static void dw8250_serial_out32(struct uart_port *p, int offset,
+				int value)
+{
+	struct dw8250_data *d = p->private_data;
+
+	if (offset == UART_LCR)
+		d->last_lcr = value;
+
+	offset <<= p->regshift;
+	writel(value, p->membase + offset);
+}
+
+static unsigned int dw8250_serial_in32(struct uart_port *p, int offset)
+{
+	offset <<= p->regshift;
+
+	return readl(p->membase + offset);
+}
+
+/* Offset for the DesignWare's UART Status Register. */
+#define UART_USR	0x1f
+
+static int dw8250_handle_irq(struct uart_port *p)
+{
+	struct dw8250_data *d = p->private_data;
+	unsigned int iir = p->serial_in(p, UART_IIR);
+
+	if (serial8250_handle_irq(p, iir)) {
+		return 1;
+	} else if ((iir & UART_IIR_BUSY) == UART_IIR_BUSY) {
+		/* Clear the USR and write the LCR again. */
+		(void)p->serial_in(p, UART_USR);
+		p->serial_out(p, d->last_lcr, UART_LCR);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+int serial8250_use_designware_io(struct uart_port *up)
+{
+	up->private_data = kzalloc(sizeof(struct dw8250_data), GFP_KERNEL);
+	if (!up->private_data)
+		return -ENOMEM;
+
+	if (up->iotype == UPIO_MEM32) {
+		up->serial_out = dw8250_serial_out32;
+		up->serial_in = dw8250_serial_in32;
+	} else {
+		up->serial_out = dw8250_serial_out;
+		up->serial_in = dw8250_serial_in;
+	}
+	up->handle_irq = dw8250_handle_irq;
+
+	return 0;
+}