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
platform driver that uses these accessors.
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Jamie Iles <jamie@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
.../bindings/tty/serial/snps-dw-apb-uart.txt | 25 +++
drivers/tty/serial/8250_dw.c | 194 ++++++++++++++++++++
drivers/tty/serial/Kconfig | 7 +
drivers/tty/serial/Makefile | 1 +
4 files changed, 227 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt
create mode 100644 drivers/tty/serial/8250_dw.c
diff --git a/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt b/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt
new file mode 100644
index 0000000..f13f1c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt
@@ -0,0 +1,25 @@
+* Synopsys DesignWare ABP UART
+
+Required properties:
+- compatible : "snps,dw-apb-uart"
+- reg : offset and length of the register set for the device.
+- interrupts : should contain uart interrupt.
+- clock-frequency : the input clock frequency for the UART.
+
+Optional properties:
+- reg-shift : quantity to shift the register offsets by. If this property is
+ not present then the register offsets are not shifted.
+- reg-io-width : the size (in bytes) of the IO accesses that should be
+ performed on the device. If this property is not present then single byte
+ accesses are used.
+
+Example:
+
+ uart@80230000 {
+ compatible = "snps,dw-apb-uart";
+ reg = <0x80230000 0x100>;
+ clock-frequency = <3686400>;
+ interrupts = <10>;
+ reg-shift = <2>;
+ reg-io-width = <4>;
+ };
diff --git a/drivers/tty/serial/8250_dw.c b/drivers/tty/serial/8250_dw.c
new file mode 100644
index 0000000..bf1fba6
--- /dev/null
+++ b/drivers/tty/serial/8250_dw.c
@@ -0,0 +1,194 @@
+/*
+ * Synopsys DesignWare 8250 driver.
+ *
+ * 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/device.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct dw8250_data {
+ int last_lcr;
+ int line;
+};
+
+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;
+}
+
+static int __devinit dw8250_probe(struct platform_device *pdev)
+{
+ struct uart_port port = {};
+ struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+ struct device_node *np = pdev->dev.of_node;
+ u32 val;
+ struct dw8250_data *data;
+
+ if (!regs || !irq) {
+ dev_err(&pdev->dev, "no registers/irq defined\n");
+ return -EINVAL;
+ }
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ port.private_data = data;
+
+ spin_lock_init(&port.lock);
+ port.mapbase = regs->start;
+ port.irq = irq->start;
+ port.handle_irq = dw8250_handle_irq;
+ port.type = PORT_8250;
+ port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP |
+ UPF_FIXED_PORT | UPF_FIXED_TYPE;
+ port.dev = &pdev->dev;
+
+ port.iotype = UPIO_MEM;
+ port.serial_in = dw8250_serial_in;
+ port.serial_out = dw8250_serial_out;
+ if (!of_property_read_u32(np, "reg-io-width", &val)) {
+ switch (val) {
+ case 1:
+ break;
+ case 4:
+ port.iotype = UPIO_MEM32;
+ port.serial_in = dw8250_serial_in32;
+ port.serial_out = dw8250_serial_out32;
+ break;
+ default:
+ dev_err(&pdev->dev, "unsupported reg-io-width (%u)\n",
+ val);
+ return -EINVAL;
+ }
+ }
+
+ if (!of_property_read_u32(np, "reg-shift", &val))
+ port.regshift = val;
+
+ if (of_property_read_u32(np, "clock-frequency", &val)) {
+ dev_err(&pdev->dev, "no clock-frequency property set\n");
+ return -EINVAL;
+ }
+ port.uartclk = val;
+
+ data->line = serial8250_register_port(&port);
+ if (data->line < 0)
+ return data->line;
+
+ platform_set_drvdata(pdev, data);
+
+ return 0;
+}
+
+static int __devexit dw8250_remove(struct platform_device *pdev)
+{
+ struct dw8250_data *data = platform_get_drvdata(pdev);
+
+ serial8250_unregister_port(data->line);
+
+ return 0;
+}
+
+static const struct of_device_id dw8250_match[] = {
+ { .compatible = "snps,dw-apb-uart" },
+ { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, dw8250_match);
+
+static struct platform_driver dw8250_platform_driver = {
+ .driver = {
+ .name = "dw-apb-uart",
+ .owner = THIS_MODULE,
+ .of_match_table = dw8250_match,
+ },
+ .probe = dw8250_probe,
+ .remove = __devexit_p(dw8250_remove),
+};
+
+static int __init dw8250_init(void)
+{
+ return platform_driver_register(&dw8250_platform_driver);
+}
+module_init(dw8250_init);
+
+static void __exit dw8250_exit(void)
+{
+ platform_driver_unregister(&dw8250_platform_driver);
+}
+module_exit(dw8250_exit);
+
+MODULE_AUTHOR("Jamie Iles");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Synopsys DesignWare 8250 serial port driver");
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 10babe2..8ee3a66 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
+ tristate "Support for Synopsys DesignWare 8250 quirks"
+ depends on SERIAL_8250 && OF
+ 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
--
1.7.7
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