drivers/misc/ibmasm/uart.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 /*
   4  * IBM ASM Service Processor Device Driver
   5  *
   6  * Copyright (C) IBM Corporation, 2004
   7  *
   8  * Author: Max Asböck <amax@us.ibm.com>
   9  */
  10
  11 #include <linux/termios.h>
  12 #include <linux/tty.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/serial_reg.h>
  15 #include <linux/serial_8250.h>
  16 #include "ibmasm.h"
  17 #include "lowlevel.h"
  18
  19
  20 void ibmasm_register_uart(struct service_processor *sp)
  21 {
  22         struct uart_8250_port uart;
  23         void __iomem *iomem_base;
  24
  25         iomem_base = sp->base_address + SCOUT_COM_B_BASE;
  26
  27         /* read the uart scratch register to determine if the UART
  28          * is dedicated to the service processor or if the OS can use it
  29          */
  30         if (0 == readl(iomem_base + UART_SCR)) {
  31                 dev_info(sp->dev, "IBM SP UART not registered, owned by service processor\n");
  32                 sp->serial_line = -1;
  33                 return;
  34         }
  35
  36         memset(&uart, 0, sizeof(uart));
  37         uart.port.irq           = sp->irq;
  38         uart.port.uartclk       = 3686400;
  39         uart.port.flags         = UPF_SHARE_IRQ;
  40         uart.port.iotype        = UPIO_MEM;
  41         uart.port.membase       = iomem_base;
  42
  43         sp->serial_line = serial8250_register_8250_port(&uart);
  44         if (sp->serial_line < 0) {
  45                 dev_err(sp->dev, "Failed to register serial port\n");
  46                 return;
  47         }
  48         enable_uart_interrupts(sp->base_address);
  49 }
  50
  51 void ibmasm_unregister_uart(struct service_processor *sp)
  52 {
  53         if (sp->serial_line < 0)
  54                 return;
  55
  56         disable_uart_interrupts(sp->base_address);
  57         serial8250_unregister_port(sp->serial_line);
  58 }