drivers/serial/of_serial.c

   1 /*
   2  *  Serial Port driver for Open Firmware platform devices
   3  *
   4  *    Copyright (C) 2006 Arnd Bergmann <arnd@arndb.de>, IBM Corp.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  *
  11  */
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/serial_core.h>
  15 #include <linux/serial_8250.h>
  16
  17 #include <asm/of_platform.h>
  18 #include <asm/prom.h>
  19
  20 /*
  21  * Fill a struct uart_port for a given device node
  22  */
  23 static int __devinit of_platform_serial_setup(struct of_device *ofdev,
  24                                         int type, struct uart_port *port)
  25 {
  26         struct resource resource;
  27         struct device_node *np = ofdev->node;
  28         const unsigned int *clk, *spd;
  29         int ret;
  30
  31         memset(port, 0, sizeof *port);
  32         spd = get_property(np, "current-speed", NULL);
  33         clk = get_property(np, "clock-frequency", NULL);
  34         if (!clk) {
  35                 dev_warn(&ofdev->dev, "no clock-frequency property set\n");
  36                 return -ENODEV;
  37         }
  38
  39         ret = of_address_to_resource(np, 0, &resource);
  40         if (ret) {
  41                 dev_warn(&ofdev->dev, "invalid address\n");
  42                 return ret;
  43         }
  44
  45         spin_lock_init(&port->lock);
  46         port->mapbase = resource.start;
  47         port->irq = irq_of_parse_and_map(np, 0);
  48         port->iotype = UPIO_MEM;
  49         port->type = type;
  50         port->uartclk = *clk;
  51         port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP;
  52         port->dev = &ofdev->dev;
  53         port->custom_divisor = *clk / (16 * (*spd));
  54
  55         return 0;
  56 }
  57
  58 /*
  59  * Try to register a serial port
  60  */
  61 static int __devinit of_platform_serial_probe(struct of_device *ofdev,
  62                                                 const struct of_device_id *id)
  63 {
  64         struct uart_port port;
  65         int port_type;
  66         int ret;
  67
  68         if (of_find_property(ofdev->node, "used-by-rtas", NULL))
  69                 return -EBUSY;
  70
  71         port_type = (unsigned long)id->data;
  72         ret = of_platform_serial_setup(ofdev, port_type, &port);
  73         if (ret)
  74                 goto out;
  75
  76         switch (port_type) {
  77         case PORT_UNKNOWN:
  78                 dev_info(&ofdev->dev, "Unknown serial port found, "
  79                         "attempting to use 8250 driver\n");
  80                 /* fallthrough */
  81         case PORT_8250 ... PORT_MAX_8250:
  82                 ret = serial8250_register_port(&port);
  83                 break;
  84         default:
  85                 /* need to add code for these */
  86                 ret = -ENODEV;
  87                 break;
  88         }
  89         if (ret < 0)
  90                 goto out;
  91
  92         ofdev->dev.driver_data = (void *)(unsigned long)ret;
  93         return 0;
  94 out:
  95         irq_dispose_mapping(port.irq);
  96         return ret;
  97 }
  98
  99 /*
 100  * Release a line
 101  */
 102 static int of_platform_serial_remove(struct of_device *ofdev)
 103 {
 104         int line = (unsigned long)ofdev->dev.driver_data;
 105         serial8250_unregister_port(line);
 106         return 0;
 107 }
 108
 109 /*
 110  * A few common types, add more as needed.
 111  */
 112 static struct of_device_id __devinitdata of_platform_serial_table[] = {
 113         { .type = "serial", .compatible = "ns8250",   .data = (void *)PORT_8250, },
 114         { .type = "serial", .compatible = "ns16450",  .data = (void *)PORT_16450, },
 115         { .type = "serial", .compatible = "ns16550",  .data = (void *)PORT_16550, },
 116         { .type = "serial", .compatible = "ns16750",  .data = (void *)PORT_16750, },
 117         { .type = "serial",                           .data = (void *)PORT_UNKNOWN, },
 118         { /* end of list */ },
 119 };
 120
 121 static struct of_platform_driver __devinitdata of_platform_serial_driver = {
 122         .owner = THIS_MODULE,
 123         .name = "of_serial",
 124         .probe = of_platform_serial_probe,
 125         .remove = of_platform_serial_remove,
 126         .match_table = of_platform_serial_table,
 127 };
 128
 129 static int __init of_platform_serial_init(void)
 130 {
 131         return of_register_platform_driver(&of_platform_serial_driver);
 132 }
 133 module_init(of_platform_serial_init);
 134
 135 static void __exit of_platform_serial_exit(void)
 136 {
 137         return of_unregister_platform_driver(&of_platform_serial_driver);
 138 };
 139 module_exit(of_platform_serial_exit);
 140
 141 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
 142 MODULE_LICENSE("GPL");
 143 MODULE_DESCRIPTION("Serial Port driver for Open Firmware platform devices");