[PATCH v10] serial: support for 16550A serial ports on LP-8x4x

Sergei Ianovich
2016-03-01T21:25:57Z

The patch adds support for 3 additional LP-8x4x built-in serial
ports.

The device can also host up to 8 extension cards with 4 serial ports
on each card for a total of 35 ports. However, I don't have
the hardware to test extension cards, so they are not supported, yet.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
CC: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
CC: Arnd Bergmann <arnd@arndb.de>

v9..v10
fix review comments by Andy Shevchenko
* fix code styling

v8..v9
fix review comments by Alan Cox
* further simplify speed check

v7..v8
* call serial8250_do_set_termios() after speed check, not before.
This way clock divisor is properly inited for the new baud rate,
if any
fix review comments by Andy Shevchenko
* change board variable name and type
* use ternary operators
* use #defines instead of magic numbers
* simplify speed check and use uart_get_baud_rate()
* zero-init uart structure
* re-organized probing calls

v6..v7
fix review comments by Andy Shevchenko
not applying Acked-by as the 1st change is big
* handle unsupported tty modes correctly
* remove extra check of platform_get_resource() result
* propagate error code from devm_ioremap_resource()
* drop uart.port.iobase for UPIO_MEM device

v5..v6
fix review comments by Arnd Bergmann
* remove wildcards from compatible
* update doc file
* drop interrupt parent from doc file
* replace uart w/ serial in device names in doc file

fix review comments by Andy Shevchenko
* exchange labels in switch block
* replace iowrite8() with writeb()
* compact comment to one line

v4..v5
* constify struct of_device_id
* drop .owner from struct platform_driver
* rewrite set_termios() baud rate hadnling as suggested by Alan Cox

v3..v4
* move DTS bindings to a different patch (8/21) as suggested by
Heikki Krogerus

v2..v3
* no changes (except number 10/16 -> 12/21)

v0..v2
* register platform driver instead of platform device
* use device tree
* use devm helpers where possible

.../bindings/serial/icpdas-lp8841-uart.txt | 41 ++++++
drivers/tty/serial/8250/8250_lp8841.c | 156 +++++++++++++++++++++
drivers/tty/serial/8250/Kconfig | 14 ++
drivers/tty/serial/8250/Makefile | 2 +
4 files changed, 213 insertions(+)
create mode 100644 Documentation/devicetree/bindings/serial/icpdas-lp8841-uart.txt
create mode 100644 drivers/tty/serial/8250/8250_lp8841.c

diff --git a/Documentation/devicetree/bindings/serial/icpdas-lp8841-uart.txt b/Documentation/devicetree/bindings/serial/icpdas-lp8841-uart.txt
new file mode 100644
index 0000000..d6acd22
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/icpdas-lp8841-uart.txt
@@ -0,0 +1,41 @@
+* UART ports on ICP DAS LP-8841
+
+LP-8441, LP-8141 and LP-8041 are fully compatible.
+
+ICP DAS LP-8841 contains three additional serial ports interfaced via
+Analog Devices ADM213EA chips in addition to 3 serial ports on PXA CPU.
+
+The chips themselves are standard, they would work with 8250_core if
+properly connected. However, they are not connected normally. Al least
+some of their config pins are wired to a different address region. So
+the driver is board-specific.
+
+Required properties:
+- compatible : should be "icpdas,uart-lp8841"
+
+- reg : should provide 16 byte man IO memory region and 1 byte region for
+ termios
+
+- interrupts : should provide interrupt
+
+Optional property:
+- interrupt-parent : should provide a link to interrupt controller either
+ explicitly or implicitly from a parent node
+
+Examples (from pxa27x-lp8x4x.dts):
+
+ serial@9050 {
+ compatible = "icpdas,uart-lp8841";
+ reg = <0x9050 0x10
+ 0x9030 0x02>;
+ interrupts = <13>;
+ status = "okay";
+ };
+
+ serial@9060 {
+ compatible = "icpdas,uart-lp8841";
+ reg = <0x9060 0x10
+ 0x9032 0x02>;
+ interrupts = <14>;
+ status = "okay";
+ };
diff --git a/drivers/tty/serial/8250/8250_lp8841.c b/drivers/tty/serial/8250/8250_lp8841.c
new file mode 100644
index 0000000..d3a72da
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_lp8841.c
@@ -0,0 +1,156 @@
+/* linux/drivers/tty/serial/8250/8250_lp8841.c
+ *
+ * Support for 16550A serial ports on ICP DAS LP-8841
+ *
+ * Copyright (C) 2013 Sergei Ianovich <ynvich@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/serial_8250.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct lp8841_serial_data {
+ int line;
+ void __iomem *ios_mem;
+};
+
+#define LP8841_DATA_LEN_MASK 0x3
+#define LP8841_DATA_LEN_SHIFT 3
+
+static void lp8841_serial_set_termios(struct uart_port *port,
+ struct ktermios *termios, struct ktermios *old)
+{
+ struct lp8841_serial_data *data = port->private_data;
+ unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
+ unsigned int baud;
+ u8 value;
+
+ /* We only support CS7 and CS8 */
+ while ((termios->c_cflag & CSIZE) != CS7 &&
+ (termios->c_cflag & CSIZE) != CS8) {
+ termios->c_cflag &= ~CSIZE;
+ termios->c_cflag |= old_csize;
+ old_csize = CS8;
+ }
+
+ value = (termios->c_cflag & CSIZE) == CS7 ? 0 : 1;
+ value += (termios->c_cflag & CSTOPB) ? 1 : 0;
+ value += (termios->c_cflag & PARENB) ? 1 : 0;
+ value += (termios->c_cflag & PARODD) ? 0 : 1;
+#ifdef CMSPAR
+ value += (termios->c_cflag & CMSPAR) ? 1 : 0;
+#endif
+
+ value &= LP8841_DATA_LEN_MASK;
+ value <<= LP8841_DATA_LEN_SHIFT;
+
+ baud = tty_termios_baud_rate(termios);
+
+ switch (baud) {
+ case 115200:
+ value |= 7;
+ break;
+ case 57600:
+ value |= 6;
+ break;
+ case 38400:
+ value |= 5;
+ break;
+ case 19200:
+ value |= 4;
+ break;
+ case 9600:
+ value |= 3;
+ break;
+ case 4800:
+ value |= 2;
+ break;
+ default:
+ tty_termios_encode_baud_rate(termios, 2400, 2400);
+ case 2400:
+ value |= 1;
+ break;
+ };
+ writeb(value, data->ios_mem);
+
+ serial8250_do_set_termios(port, termios, old);
+}
+
+static const struct of_device_id lp8841_serial_dt_ids[] = {
+ { .compatible = "icpdas,lp8841-uart", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, lp8841_serial_dt_ids);
+
+static int lp8841_serial_probe(struct platform_device *pdev)
+{
+ struct uart_8250_port uart;
+ struct lp8841_serial_data *data;
+ struct resource *mmres, *mires;
+ int ret;
+
+ mmres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!mmres)
+ return -ENODEV;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ mires = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+ data->ios_mem = devm_ioremap_resource(&pdev->dev, mires);
+ if (IS_ERR(data->ios_mem))
+ return PTR_ERR(data->ios_mem);
+
+ memset(&uart, 0, sizeof(uart));
+ uart.port.iotype = UPIO_MEM;
+ uart.port.mapbase = mmres->start;
+ uart.port.regshift = 1;
+ uart.port.irq = platform_get_irq(pdev, 0);
+ uart.port.flags = UPF_IOREMAP;
+ uart.port.dev = &pdev->dev;
+ uart.port.uartclk = 14745600;
+ uart.port.set_termios = lp8841_serial_set_termios;
+ uart.port.private_data = data;
+
+ ret = serial8250_register_8250_port(&uart);
+ if (ret < 0)
+ return ret;
+
+ data->line = ret;
+
+ platform_set_drvdata(pdev, data);
+
+ return 0;
+}
+
+static int lp8841_serial_remove(struct platform_device *pdev)
+{
+ struct lp8841_serial_data *data = platform_get_drvdata(pdev);
+
+ serial8250_unregister_port(data->line);
+
+ return 0;
+}
+
+static struct platform_driver lp8841_serial_driver = {
+ .probe = lp8841_serial_probe,
+ .remove = lp8841_serial_remove,
+ .driver = {
+ .name = "uart-lp8841",
+ .of_match_table = lp8841_serial_dt_ids,
+ },
+};
+
+module_platform_driver(lp8841_serial_driver);
+
+MODULE_AUTHOR("Sergei Ianovich");
+MODULE_DESCRIPTION("8250 serial port module for LP-8841");
+MODULE_LICENSE("GPL");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 3b5cf9c..68640c1 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -394,3 +394,17 @@ config SERIAL_8250_PXA
help
If you have a machine based on an Intel XScale PXA2xx CPU you
can enable its onboard serial ports by enabling this option.
+
+ If you choose M here, the module name will be 8250_pxa.
+
+config SERIAL_8250_LP8841
+ tristate "Support 16550A ports on ICP DAS LP-8841"
+ depends on SERIAL_8250 && MACH_PXA27X_DT
+ select LP8841_IRQ
+ help
+ In addition to serial ports on PXA270 SoC, LP-8841 has 1 dual
+ RS232/RS485 port, 1 RS485 port and 1 RS232 port.
+
+ Say N here, unless you plan to run this kernel on a LP-8841 system.
+
+ If you choose M here, the module name will be 8250_lp8841.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index d1e2f2d..10b4bf0 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_SERIAL_8250_ACCENT) += 8250_accent.o
obj-$(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-$(CONFIG_SERIAL_8250_LP8X4X) += 8250_lp8x4x.o
obj-$(CONFIG_SERIAL_8250_FSL) += 8250_fsl.o
obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o
obj-$(CONFIG_SERIAL_8250_EM) += 8250_em.o
@@ -30,5 +31,6 @@ obj-$(CONFIG_SERIAL_8250_INGENIC) += 8250_ingenic.o
obj-$(CONFIG_SERIAL_8250_MID) += 8250_mid.o
obj-$(CONFIG_SERIAL_OF_PLATFORM) += 8250_of.o
obj-$(CONFIG_SERIAL_8250_PXA) += 8250_pxa.o
+obj-$(CONFIG_SERIAL_8250_LP8841) += 8250_lp8841.o

CFLAGS_8250_ingenic.o += -I$(srctree)/scripts/dtc/libfdt
--
2.7.0