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serial: 8250: add driver for KEBA UART
The KEBA UART is found in the system FPGA of KEBA PLC devices. It is mostly 8250 compatible with extension for some UART modes. 3 different variants exist. The simpliest variant supports only RS-232 and is used for debug interfaces. The next variant supports only RS-485 and is used mostly for communication with KEBA panel devices. The third variant is able to support RS-232, RS-485 and RS-422. For this variant not only the mode of the UART is configured, also the physics and transceivers are switched according to the mode. Signed-off-by: Gerhard Engleder <eg@keba.com> Tested-by: Daniel Gierlinger <gida@keba.com> Reviewed-by: Lukas Wunner <lukas@wunner.de> Link: https://patch.msgid.link/20251023151229.11774-3-gerhard@engleder-embedded.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gerhard Engleder
Greg Kroah-Hartman
parent
6974711cf7
commit
ab9a30d6fe
280
drivers/tty/serial/8250/8250_keba.c
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280
drivers/tty/serial/8250/8250_keba.c
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@ -0,0 +1,280 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2025 KEBA Industrial Automation GmbH
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*
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* Driver for KEBA UART FPGA IP core
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*/
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#include <linux/auxiliary_bus.h>
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#include <linux/device.h>
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#include <linux/io.h>
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#include <linux/misc/keba.h>
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#include <linux/module.h>
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#include "8250.h"
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#define KUART "kuart"
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/* flags */
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#define KUART_RS485 BIT(0)
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#define KUART_USE_CAPABILITY BIT(1)
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/* registers */
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#define KUART_VERSION 0x0000
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#define KUART_REVISION 0x0001
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#define KUART_CAPABILITY 0x0002
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#define KUART_CONTROL 0x0004
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#define KUART_BASE 0x000C
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#define KUART_REGSHIFT 2
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#define KUART_CLK 1843200
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/* mode flags */
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enum kuart_mode {
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KUART_MODE_NONE = 0,
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KUART_MODE_RS485,
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KUART_MODE_RS422,
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KUART_MODE_RS232
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};
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/* capability flags */
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#define KUART_CAPABILITY_NONE BIT(KUART_MODE_NONE)
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#define KUART_CAPABILITY_RS485 BIT(KUART_MODE_RS485)
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#define KUART_CAPABILITY_RS422 BIT(KUART_MODE_RS422)
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#define KUART_CAPABILITY_RS232 BIT(KUART_MODE_RS232)
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#define KUART_CAPABILITY_MASK GENMASK(3, 0)
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/* Additional Control Register DTR line configuration */
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#define UART_ACR_DTRLC_MASK 0x18
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#define UART_ACR_DTRLC_COMPAT 0x00
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#define UART_ACR_DTRLC_ENABLE_LOW 0x10
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struct kuart {
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struct keba_uart_auxdev *auxdev;
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void __iomem *base;
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unsigned int line;
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unsigned int flags;
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u8 capability;
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enum kuart_mode mode;
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};
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static void kuart_set_phy_mode(struct kuart *kuart, enum kuart_mode mode)
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{
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iowrite8(mode, kuart->base + KUART_CONTROL);
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}
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static void kuart_enhanced_mode(struct uart_8250_port *up, bool enable)
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{
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u8 lcr, efr;
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/* backup LCR register */
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lcr = serial_in(up, UART_LCR);
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/* enable 650 compatible register set (EFR, ...) */
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serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
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/* enable/disable enhanced mode with indexed control registers */
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efr = serial_in(up, UART_EFR);
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if (enable)
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efr |= UART_EFR_ECB;
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else
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efr &= ~UART_EFR_ECB;
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serial_out(up, UART_EFR, efr);
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/* disable 650 compatible register set, restore LCR */
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serial_out(up, UART_LCR, lcr);
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}
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static void kuart_dtr_line_config(struct uart_8250_port *up, u8 dtrlc)
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{
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u8 acr;
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/* set index register to 0 to access ACR register */
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serial_out(up, UART_SCR, UART_ACR);
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/* set value register to 0x10 writing DTR mode (1,0) */
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acr = serial_in(up, UART_LSR);
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acr &= ~UART_ACR_DTRLC_MASK;
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acr |= dtrlc;
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serial_out(up, UART_LSR, acr);
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}
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static int kuart_rs485_config(struct uart_port *port, struct ktermios *termios,
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struct serial_rs485 *rs485)
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{
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struct uart_8250_port *up = up_to_u8250p(port);
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struct kuart *kuart = port->private_data;
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enum kuart_mode mode;
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u8 dtrlc;
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if (rs485->flags & SER_RS485_ENABLED) {
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if (rs485->flags & SER_RS485_MODE_RS422)
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mode = KUART_MODE_RS422;
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else
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mode = KUART_MODE_RS485;
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} else {
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mode = KUART_MODE_RS232;
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}
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if (mode == kuart->mode)
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return 0;
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if (kuart->flags & KUART_USE_CAPABILITY) {
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/* deactivate physical interface, break before make */
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kuart_set_phy_mode(kuart, KUART_MODE_NONE);
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}
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if (mode == KUART_MODE_RS485) {
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/*
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* Set DTR line configuration of 95x UART to DTR mode (1,0).
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* In this mode the DTR pin drives the active-low enable pin of
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* an external RS485 buffer. The DTR pin will be forced low
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* whenever the transmitter is not empty, otherwise DTR pin is
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* high.
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*/
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dtrlc = UART_ACR_DTRLC_ENABLE_LOW;
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} else {
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/*
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* Set DTR line configuration of 95x UART to DTR mode (0,0).
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* In this mode the DTR pin is compatible with 16C450, 16C550,
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* 16C650 and 16c670 (i.e. normal).
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*/
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dtrlc = UART_ACR_DTRLC_COMPAT;
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}
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kuart_enhanced_mode(up, true);
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kuart_dtr_line_config(up, dtrlc);
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kuart_enhanced_mode(up, false);
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if (kuart->flags & KUART_USE_CAPABILITY) {
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/* activate selected physical interface */
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kuart_set_phy_mode(kuart, mode);
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}
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kuart->mode = mode;
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return 0;
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}
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static int kuart_probe(struct auxiliary_device *auxdev,
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const struct auxiliary_device_id *id)
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{
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struct device *dev = &auxdev->dev;
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struct uart_8250_port uart = {};
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struct resource res;
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struct kuart *kuart;
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int retval;
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kuart = devm_kzalloc(dev, sizeof(*kuart), GFP_KERNEL);
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if (!kuart)
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return -ENOMEM;
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kuart->auxdev = container_of(auxdev, struct keba_uart_auxdev, auxdev);
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kuart->flags = id->driver_data;
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auxiliary_set_drvdata(auxdev, kuart);
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/*
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* map only memory in front of UART registers, UART registers will be
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* mapped by serial port
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*/
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res = kuart->auxdev->io;
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res.end = res.start + KUART_BASE - 1;
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kuart->base = devm_ioremap_resource(dev, &res);
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if (IS_ERR(kuart->base))
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return PTR_ERR(kuart->base);
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if (kuart->flags & KUART_USE_CAPABILITY) {
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/*
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* supported modes are read from capability register, at least
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* one mode other than none must be supported
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*/
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kuart->capability = ioread8(kuart->base + KUART_CAPABILITY) &
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KUART_CAPABILITY_MASK;
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if ((kuart->capability & ~KUART_CAPABILITY_NONE) == 0)
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return -EIO;
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}
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spin_lock_init(&uart.port.lock);
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uart.port.dev = dev;
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uart.port.mapbase = kuart->auxdev->io.start + KUART_BASE;
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uart.port.irq = kuart->auxdev->irq;
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uart.port.uartclk = KUART_CLK;
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uart.port.private_data = kuart;
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/* 8 bit registers are 32 bit aligned => shift register offset */
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uart.port.iotype = UPIO_MEM32;
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uart.port.regshift = KUART_REGSHIFT;
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/*
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* UART mixes 16550, 16750 and 16C950 (for RS485) standard => auto
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* configuration works best
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*/
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uart.port.flags = UPF_SKIP_TEST | UPF_BOOT_AUTOCONF | UPF_IOREMAP;
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/*
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* UART supports RS485, RS422 and RS232 with switching of physical
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* interface
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*/
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uart.port.rs485_config = kuart_rs485_config;
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if (kuart->flags & KUART_RS485) {
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uart.port.rs485_supported.flags = SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND;
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uart.port.rs485.flags = SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND;
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}
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if (kuart->flags & KUART_USE_CAPABILITY) {
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/* default mode priority is RS485 > RS422 > RS232 */
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if (kuart->capability & KUART_CAPABILITY_RS422) {
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uart.port.rs485_supported.flags |= SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND |
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SER_RS485_MODE_RS422;
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uart.port.rs485.flags = SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND |
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SER_RS485_MODE_RS422;
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}
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if (kuart->capability & KUART_CAPABILITY_RS485) {
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uart.port.rs485_supported.flags |= SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND;
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uart.port.rs485.flags = SER_RS485_ENABLED |
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SER_RS485_RTS_ON_SEND;
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}
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}
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retval = serial8250_register_8250_port(&uart);
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if (retval < 0) {
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dev_err(&auxdev->dev, "UART registration failed!\n");
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return retval;
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}
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kuart->line = retval;
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return 0;
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}
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static void kuart_remove(struct auxiliary_device *auxdev)
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{
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struct kuart *kuart = auxiliary_get_drvdata(auxdev);
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if (kuart->flags & KUART_USE_CAPABILITY)
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kuart_set_phy_mode(kuart, KUART_MODE_NONE);
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serial8250_unregister_port(kuart->line);
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}
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static const struct auxiliary_device_id kuart_devtype_aux[] = {
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{ .name = "keba.rs485-uart", .driver_data = KUART_RS485 },
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{ .name = "keba.rs232-uart", .driver_data = 0 },
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{ .name = "keba.uart", .driver_data = KUART_USE_CAPABILITY },
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{}
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};
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MODULE_DEVICE_TABLE(auxiliary, kuart_devtype_aux);
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static struct auxiliary_driver kuart_driver_aux = {
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.name = KUART,
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.id_table = kuart_devtype_aux,
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.probe = kuart_probe,
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.remove = kuart_remove,
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};
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module_auxiliary_driver(kuart_driver_aux);
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MODULE_AUTHOR("Gerhard Engleder <eg@keba.com>");
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MODULE_DESCRIPTION("KEBA 8250 serial port driver");
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MODULE_LICENSE("GPL");
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@ -413,6 +413,19 @@ config SERIAL_8250_IOC3
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behind the IOC3 device on those systems. Maximum baud speed is
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38400bps using this driver.
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config SERIAL_8250_KEBA
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tristate "Support for KEBA 8250 UART"
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depends on SERIAL_8250
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depends on KEBA_CP500
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help
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Selecting this option will add support for KEBA UARTs. These UARTs
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are used for the serial interfaces of KEBA PLCs.
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This driver can also be built as a module. If so, the module will
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be called 8250_keba.
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If unsure, say N.
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config SERIAL_8250_RT288X
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bool "Ralink RT288x/RT305x/RT3662/RT3883 serial port support"
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depends on SERIAL_8250
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@ -38,6 +38,7 @@ obj-$(CONFIG_SERIAL_8250_HP300) += 8250_hp300.o
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obj-$(CONFIG_SERIAL_8250_HUB6) += 8250_hub6.o
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obj-$(CONFIG_SERIAL_8250_INGENIC) += 8250_ingenic.o
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obj-$(CONFIG_SERIAL_8250_IOC3) += 8250_ioc3.o
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obj-$(CONFIG_SERIAL_8250_KEBA) += 8250_keba.o
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obj-$(CONFIG_SERIAL_8250_LPC18XX) += 8250_lpc18xx.o
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obj-$(CONFIG_SERIAL_8250_LPSS) += 8250_lpss.o
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obj-$(CONFIG_SERIAL_8250_MEN_MCB) += 8250_men_mcb.o
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