From: Jamie Iles <jamie@xxxxxxxxxxxxx>
The Synopsys DesignWare 8250 is an 8250 that has an extra interrupt that
gets raised when writing to the LCR when busy. To handle this we need
special serial_out, serial_in and handle_irq methods. Add a new
function serial8250_use_designware_io() that configures a uart_port with
these accessors.
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/tty/serial/8250_dw.c | 99 ++++++++++++++++++++++++++++++++++++++++++
drivers/tty/serial/Kconfig | 7 +++
drivers/tty/serial/Makefile | 1 +
include/linux/serial_8250.h | 8 +++
4 files changed, 115 insertions(+), 0 deletions(-)
create mode 100644 drivers/tty/serial/8250_dw.c
diff --git a/drivers/tty/serial/8250_dw.c b/drivers/tty/serial/8250_dw.c
new file mode 100644
index 0000000..e25782a
--- /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;
+}
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index a9b307f..d2d1cc2 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -267,6 +267,13 @@ config SERIAL_8250_RM9K
port hardware found on MIPS RM9122 and similar processors.
If unsure, say N.
+config SERIAL_8250_DW
+ bool "Support for Synopsys DesignWare 8250 quirks"
+ depends on SERIAL_8250
+ help
+ Selecting this option will enable handling of the extra features
+ present in the Synopsys DesignWare APB UART.
+
comment "Non-8250 serial port support"
config SERIAL_AMBA_PL010
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 7874813..7b59958 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_SERIAL_8250_BOCA) += 8250_boca.o
obj-$(CONFIG_SERIAL_8250_EXAR_ST16C554) += 8250_exar_st16c554.o
obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o
obj-$(CONFIG_SERIAL_8250_MCA) += 8250_mca.o
+obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o
obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 1f05bbe..09e2dbc 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -86,5 +86,13 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir);
extern void serial8250_set_isa_configurator(void (*v)
(int port, struct uart_port *up,
unsigned short *capabilities));
+#ifndef SERIAL_8250_DW
+extern int serial8250_use_designware_io(struct uart_port *up);
+#else
+static inline int serial8250_use_designware_io(struct uart_port *up)
+{
+ return -EIO;
+}
+#endif
#endif
--
1.7.7
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