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 = of_get_property(np, "current-speed", NULL);
  33         clk = of_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                 | UPF_FIXED_PORT;
  53         port->dev = &ofdev->dev;
  54         port->custom_divisor = *clk / (16 * (*spd));
  55
  56         return 0;
  57 }
  58
  59 /*
  60  * Try to register a serial port
  61  */
  62 static int __devinit of_platform_serial_probe(struct of_device *ofdev,
  63                                                 const struct of_device_id *id)
  64 {
  65         struct uart_port port;
  66         int port_type;
  67         int ret;
  68
  69         if (of_find_property(ofdev->node, "used-by-rtas", NULL))
  70                 return -EBUSY;
  71
  72         port_type = (unsigned long)id->data;
  73         ret = of_platform_serial_setup(ofdev, port_type, &port);
  74         if (ret)
  75                 goto out;
  76
  77         switch (port_type) {
  78         case PORT_UNKNOWN:
  79                 dev_info(&ofdev->dev, "Unknown serial port found, "
  80                         "attempting to use 8250 driver\n");
  81                 /* fallthrough */
  82         case PORT_8250 ... PORT_MAX_8250:
  83                 ret = serial8250_register_port(&port);
  84                 break;
  85         default:
  86                 /* need to add code for these */
  87                 ret = -ENODEV;
  88                 break;
  89         }
  90         if (ret < 0)
  91                 goto out;
  92
  93         ofdev->dev.driver_data = (void *)(unsigned long)ret;
  94         return 0;
  95 out:
  96         irq_dispose_mapping(port.irq);
  97         return ret;
  98 }
  99
 100 /*
 101  * Release a line
 102  */
 103 static int of_platform_serial_remove(struct of_device *ofdev)
 104 {
 105         int line = (unsigned long)ofdev->dev.driver_data;
 106         serial8250_unregister_port(line);
 107         return 0;
 108 }
 109
 110 /*
 111  * A few common types, add more as needed.
 112  */
 113 static struct of_device_id __devinitdata of_platform_serial_table[] = {
 114         { .type = "serial", .compatible = "ns8250",   .data = (void *)PORT_8250, },
 115         { .type = "serial", .compatible = "ns16450",  .data = (void *)PORT_16450, },
 116         { .type = "serial", .compatible = "ns16550",  .data = (void *)PORT_16550, },
 117         { .type = "serial", .compatible = "ns16750",  .data = (void *)PORT_16750, },
 118         { .type = "serial",                           .data = (void *)PORT_UNKNOWN, },
 119         { /* end of list */ },
 120 };
 121
 122 static struct of_platform_driver __devinitdata of_platform_serial_driver = {
 123         .owner = THIS_MODULE,
 124         .name = "of_serial",
 125         .probe = of_platform_serial_probe,
 126         .remove = of_platform_serial_remove,
 127         .match_table = of_platform_serial_table,
 128 };
 129
 130 static int __init of_platform_serial_init(void)
 131 {
 132         return of_register_platform_driver(&of_platform_serial_driver);
 133 }
 134 module_init(of_platform_serial_init);
 135
 136 static void __exit of_platform_serial_exit(void)
 137 {
 138         return of_unregister_platform_driver(&of_platform_serial_driver);
 139 };
 140 module_exit(of_platform_serial_exit);
 141
 142 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
 143 MODULE_LICENSE("GPL");
 144 MODULE_DESCRIPTION("Serial Port driver for Open Firmware platform devices");