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    Subject[PATCH v6] serial: support for 16550A serial ports on LP-8x4x
    Date
    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>
    CC: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
    CC: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
    CC: Arnd Bergmann <arnd@arndb.de>
    ---
    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 | 166 +++++++++++++++++++++
    drivers/tty/serial/8250/Kconfig | 14 ++
    drivers/tty/serial/8250/Makefile | 2 +
    4 files changed, 223 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..6fef37f
    --- /dev/null
    +++ b/drivers/tty/serial/8250/8250_lp8841.c
    @@ -0,0 +1,166 @@
    +/* 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 *ios_mem;
    +};
    +
    +static void lp8841_serial_set_termios(struct uart_port *port,
    + struct ktermios *termios, struct ktermios *old)
    +{
    + unsigned int len;
    + unsigned int baud;
    + struct lp8841_serial_data *data = port->private_data;
    +
    + serial8250_do_set_termios(port, termios, old);
    +
    + switch (termios->c_cflag & CSIZE) {
    + case CS5:
    + len = 7;
    + break;
    + case CS6:
    + len = 8;
    + break;
    + case CS7:
    + len = 9;
    + break;
    + case CS8:
    + default:
    + len = 10;
    + break;
    + }
    +
    + if (termios->c_cflag & CSTOPB)
    + len++;
    + if (termios->c_cflag & PARENB)
    + len++;
    + if (!(termios->c_cflag & PARODD))
    + len++;
    +#ifdef CMSPAR
    + if (termios->c_cflag & CMSPAR)
    + len++;
    +#endif
    +
    + len -= 9;
    + len &= 3;
    + len <<= 3;
    +
    + /* Ask the core to calculate the divisor for us. */
    + baud = tty_termios_baud_rate(termios);
    +
    + switch (baud) {
    + case 115200:
    + len |= 7;
    + break;
    + case 57600:
    + len |= 6;
    + break;
    + case 38400:
    + len |= 5;
    + break;
    + case 19200:
    + len |= 4;
    + break;
    + case 9600:
    + len |= 3;
    + break;
    + case 4800:
    + len |= 2;
    + break;
    + case 2400:
    + default:
    + len |= 1;
    + break;
    + };
    + writeb(len, data->ios_mem);
    +
    +}
    +
    +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);
    + mires = platform_get_resource(pdev, IORESOURCE_MEM, 1);
    + if (!mmres || !mires)
    + return -ENODEV;
    +
    + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
    + if (!data)
    + return -ENOMEM;
    +
    + data->ios_mem = devm_ioremap_resource(&pdev->dev, mires);
    + if (!data->ios_mem)
    + return -EFAULT;
    +
    + uart.port.iotype = UPIO_MEM;
    + uart.port.mapbase = mmres->start;
    + uart.port.iobase = 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
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