[PATCH v6] serial: rewrite pxa2xx-uart to use 8250_core

Sergei Ianovich
2015-12-24T15:15:49Z

pxa2xx-uart was a separate uart platform driver. It was declaring
the same device names and numbers as 8250 driver. As a result,
it was impossible to use 8250 driver on PXA SoCs.

Upon closer examination pxa2xx-uart turned out to be a clone of
8250_core driver.

Workaround for Erratum #19 according to Marvel(R) PXA270M Processor
Specification Update (April 19, 2010) is dropped. 8250_core reads
from FIFO immediately after checking DR bit in LSR.

The patch leaves the original SERIAL_PXA driver around. The original
driver is just marked DEPRECATED in Kconfig and C source. When
the original driver is considered safe to remove, no changes
to SERIAL_8250 will be necessary.

Compiling SERIAL_8250_CONSOLE and SERIAL_PXA_CONSOLE even without
SERIAL_8250_PXA breaks console for SERIAL_PXA. For this reasons, the new
and the original drivers are made mutually exclusive.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Heikki Krogerus <heikki.krogerus@linux.intel.com>
CC: James Cameron <quozl@laptop.org>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Robert Jarzmik <robert.jarzmik@free.fr>
CC: Russell King <linux@arm.linux.org.uk>

---
The patch was reviewed/acked at version 3. Changes in version 4
are simple unbitrotting. Changes in version 5 require re-review
according to Robert Jarzmik comment.

changes v5..v6 suggest by kbuild test robot
* narrow SERIAL_8250 to SERIAL_8250=y in Kconfig dependencies

changes v4..v5 as suggested by Robert Jarzmik
* keep pxa.c until it is considered safe to remove
* keep SERIAL_PXA and SERIAL_PXA_CONSOLE Kconfig options,
but deprecate them
* allow selection of either the new or the original driver
by Kconfig
* ensure SERIAL_PXA_CONSOLE is respected with either driver

changes v3..v4
* remove owner field from platform_driver structure
* make of_device_id structure constant
* use CONFIG_SERIAL_8250_PXA instead of CONFIG_SERIAL_PXA

changes v2..v3
* remove devm_free/put as suggested by Heikki Krogerus
* use SET_SYSTEM_SLEEP_PM_OPS macro to set pm ops as suggested
by Heikki Krogerus

changes v1..v2
* actually implement workaround for E74 in dl_write as spooted
by James Cameron
* added comment about E19 in commit message

drivers/tty/serial/8250/8250_pxa.c | 177 +++++++++++++++++++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 8 ++
drivers/tty/serial/8250/Makefile | 1 +
drivers/tty/serial/Kconfig | 17 +++-
drivers/tty/serial/Makefile | 2 +-
drivers/tty/serial/pxa.c | 4 +-
6 files changed, 205 insertions(+), 4 deletions(-)
create mode 100644 drivers/tty/serial/8250/8250_pxa.c

diff --git a/drivers/tty/serial/8250/8250_pxa.c b/drivers/tty/serial/8250/8250_pxa.c
new file mode 100644
index 0000000..6a14df0
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_pxa.c
@@ -0,0 +1,177 @@
+/*
+ * drivers/tty/serial/8250/8250_pxa.c -- driver for PXA on-board UARTS
+ * Copyright: (C) 2013 Sergei Ianovich <ynvich@gmail.com>
+ *
+ * replaces drivers/serial/pxa.c by Nicolas Pitre
+ * Created: Feb 20, 2003
+ * Copyright: (C) 2003 Monta Vista Software, Inc.
+ *
+ * Based on drivers/serial/8250.c by Russell King.
+ *
+ * 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.
+ *
+ */
+
+#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>
+#include <linux/clk.h>
+#include <linux/pm_runtime.h>
+
+#include "8250.h"
+
+struct pxa8250_data {
+ int line;
+ struct clk *clk;
+};
+
+#ifdef CONFIG_PM
+static int serial_pxa_suspend(struct device *dev)
+{
+ struct pxa8250_data *data = dev_get_drvdata(dev);
+
+ serial8250_suspend_port(data->line);
+
+ return 0;
+}
+
+static int serial_pxa_resume(struct device *dev)
+{
+ struct pxa8250_data *data = dev_get_drvdata(dev);
+
+ serial8250_resume_port(data->line);
+
+ return 0;
+}
+#endif
+
+static const struct dev_pm_ops serial_pxa_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(serial_pxa_suspend, serial_pxa_resume)
+};
+
+static const struct of_device_id serial_pxa_dt_ids[] = {
+ { .compatible = "mrvl,pxa-uart", },
+ { .compatible = "mrvl,mmp-uart", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, serial_pxa_dt_ids);
+
+/* Uart divisor latch write */
+static void serial_pxa_dl_write(struct uart_8250_port *up, int value)
+{
+ unsigned int dll;
+
+ serial_out(up, UART_DLL, value & 0xff);
+ /*
+ * work around Erratum #74 according to Marvel(R) PXA270M Processor
+ * Specification Update (April 19, 2010)
+ */
+ dll = serial_in(up, UART_DLL);
+ WARN_ON(dll != (value & 0xff));
+
+ serial_out(up, UART_DLM, value >> 8 & 0xff);
+}
+
+
+static void serial_pxa_pm(struct uart_port *port, unsigned int state,
+ unsigned int oldstate)
+{
+ struct pxa8250_data *data = port->private_data;
+
+ if (!state)
+ clk_prepare_enable(data->clk);
+ else
+ clk_disable_unprepare(data->clk);
+}
+
+static int serial_pxa_probe(struct platform_device *pdev)
+{
+ struct uart_8250_port uart = {};
+ struct pxa8250_data *data;
+ struct resource *mmres, *irqres;
+ int ret;
+
+ mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ irqres = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+ if (!mmres || !irqres)
+ return -ENODEV;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(data->clk))
+ return PTR_ERR(data->clk);
+
+ ret = clk_prepare(data->clk);
+ if (ret)
+ return ret;
+
+ uart.port.type = PORT_XSCALE;
+ uart.port.iotype = UPIO_MEM32;
+ uart.port.mapbase = mmres->start;
+ uart.port.regshift = 2;
+ uart.port.irq = irqres->start;
+ uart.port.fifosize = 64;
+ uart.port.flags = UPF_IOREMAP | UPF_SKIP_TEST;
+ uart.port.dev = &pdev->dev;
+ uart.port.uartclk = clk_get_rate(data->clk);
+ uart.port.pm = serial_pxa_pm;
+ uart.port.private_data = data;
+ uart.dl_write = serial_pxa_dl_write;
+
+ ret = serial8250_register_8250_port(&uart);
+ if (ret < 0)
+ goto err_clk;
+
+ data->line = ret;
+
+ platform_set_drvdata(pdev, data);
+
+ return 0;
+
+ err_clk:
+ clk_unprepare(data->clk);
+ return ret;
+}
+
+static int serial_pxa_remove(struct platform_device *pdev)
+{
+ struct pxa8250_data *data = platform_get_drvdata(pdev);
+
+ serial8250_unregister_port(data->line);
+
+ clk_unprepare(data->clk);
+
+ return 0;
+}
+
+static struct platform_driver serial_pxa_driver = {
+ .probe = serial_pxa_probe,
+ .remove = serial_pxa_remove,
+
+ .driver = {
+ .name = "pxa2xx-uart",
+ .pm = &serial_pxa_pm_ops,
+ .of_match_table = serial_pxa_dt_ids,
+ },
+};
+
+module_platform_driver(serial_pxa_driver);
+
+MODULE_AUTHOR("Sergei Ianovich");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pxa2xx-uart");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 6412f14..4dc45ff 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -378,3 +378,11 @@ config SERIAL_8250_MID
Selecting this option will enable handling of the extra features
present on the UART found on Intel Medfield SOC and various other
Intel platforms.
+
+config SERIAL_8250_PXA
+ tristate "PXA serial port support"
+ depends on SERIAL_8250
+ depends on ARCH_PXA || ARCH_MMP
+ help
+ If you have a machine based on an Intel XScale PXA2xx CPU you
+ can enable its onboard serial ports by enabling this option.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index e177f86..7e54413 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -28,5 +28,6 @@ obj-$(CONFIG_SERIAL_8250_MT6577) += 8250_mtk.o
obj-$(CONFIG_SERIAL_8250_UNIPHIER) += 8250_uniphier.o
obj-$(CONFIG_SERIAL_8250_INGENIC) += 8250_ingenic.o
obj-$(CONFIG_SERIAL_8250_MID) += 8250_mid.o
+obj-$(CONFIG_SERIAL_8250_PXA) += 8250_pxa.o

CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index f38beb2..161f33f 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -436,17 +436,27 @@ config SERIAL_MPSC_CONSOLE
Say Y here if you want to support a serial console on a Marvell MPSC.

config SERIAL_PXA
- bool "PXA serial port support"
+ bool "PXA serial port support (DEPRECATED)"
depends on ARCH_PXA || ARCH_MMP
select SERIAL_CORE
+ select SERIAL_8250_PXA if SERIAL_8250=y
+ select SERIAL_PXA_NON8250 if !SERIAL_8250=y
help
If you have a machine based on an Intel XScale PXA2xx CPU you
can enable its onboard serial ports by enabling this option.

+ Unless you have a specific need, you should use SERIAL_8250_PXA
+ instead of this.
+
+config SERIAL_PXA_NON8250
+ bool
+ depends on !SERIAL_8250
+
config SERIAL_PXA_CONSOLE
- bool "Console on PXA serial port"
+ bool "Console on PXA serial port (DEPRECATED)"
depends on SERIAL_PXA
select SERIAL_CORE_CONSOLE
+ select SERIAL_8250_CONSOLE if SERIAL_8250=y
help
If you have enabled the serial port on the Intel XScale PXA
CPU you can make it the console by answering Y to this option.
@@ -458,6 +468,9 @@ config SERIAL_PXA_CONSOLE
your boot loader (lilo or loadlin) about how to pass options to the
kernel at boot time.)

+ Unless you have a specific need, you should use SERIAL_8250_PXA
+ and SERIAL_8250_CONSOLE instead of this.
+
config SERIAL_SA1100
bool "SA1100 serial port support"
depends on ARCH_SA1100
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 5ab4111..96741d5 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -23,7 +23,7 @@ obj-$(CONFIG_SERIAL_8250) += 8250/
obj-$(CONFIG_SERIAL_AMBA_PL010) += amba-pl010.o
obj-$(CONFIG_SERIAL_AMBA_PL011) += amba-pl011.o
obj-$(CONFIG_SERIAL_CLPS711X) += clps711x.o
-obj-$(CONFIG_SERIAL_PXA) += pxa.o
+obj-$(CONFIG_SERIAL_PXA_NON8250) += pxa.o
obj-$(CONFIG_SERIAL_PNX8XXX) += pnx8xxx_uart.o
obj-$(CONFIG_SERIAL_SA1100) += sa1100.o
obj-$(CONFIG_SERIAL_BCM63XX) += bcm63xx_uart.o
diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c
index 9becba6..74aac45 100644
--- a/drivers/tty/serial/pxa.c
+++ b/drivers/tty/serial/pxa.c
@@ -940,7 +940,9 @@ static struct platform_driver serial_pxa_driver = {
},
};

-static int __init serial_pxa_init(void)
+
+/* 8250 driver for PXA serial ports should be used */
+static int __deprecated __init serial_pxa_init(void)
{
int ret;

--
2.6.3