[Xen-devel] Re: [PATCH 1 of 3] xen: Automatically find serial port on PCI/PCIe and AMT devices

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 07.07.11 at 15:59, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> # HG changeset patch
> # User James Mckenzie <jamesmck@xxxxxxxxxxxxxxxxxxxx>
> # Date 1310047149 14400
> # Node ID 7cdc5770d13bbd7fc2b958ba7d74787ff4e20eef
> # Parent  2f63562df1c4230492a81793dce3672f93c93d9a
> xen: Automatically find serial port on PCI/PCIe and AMT devices.
> 
> Instead of having to manually look the right I/O port on the PCI
> devices or AMT devices, lets probe the card and find that
> automatically.
> 
> This means that you don't have to have this:
>  com1=115200,8n1,0xd800,0
> 
> But instead can have
>  com1=115200,8n1,magic
> 
> Or if you have AMT:
>  com1=19200,8n1,amt
> 
> Signed-off-by: James Mckenzie <jamesmck@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Signed-off-by: Tom Goetz <tom.goetz@xxxxxxxxxxxxxxxxxxx>
> 
> diff -r 2f63562df1c4 -r 7cdc5770d13b xen/drivers/char/ns16550.c
> --- a/xen/drivers/char/ns16550.c      Mon Jun 27 17:37:12 2011 +0100
> +++ b/xen/drivers/char/ns16550.c      Thu Jul 07 09:59:09 2011 -0400
> @@ -17,6 +17,8 @@
>  #include <xen/timer.h>
>  #include <xen/serial.h>
>  #include <xen/iocap.h>
> +#include <xen/pci.h>
> +#include <xen/pci_regs.h>
>  #include <asm/io.h>
>  
>  /*
> @@ -433,6 +435,64 @@ static int __init check_existence(struct
>      return (status == 0x90);
>  }
>  
> +static int
> +magic_uart_config (struct ns16550 *uart,int skip_amt)
> +{
> +  uint16_t class;
> +  uint32_t bar0, len;
> +  int b, d, f;
> +
> +/*Skanky hack - start at bus 1 to avoid AMT, a plug in card cannot be on bus 
> 1 */
> +
> +  if (skip_amt) b=1;
> +     else b=0;
> +
> +  for (; b < 0x100; ++b)
> +    {
> +    for (d = 0; d < 0x20; ++d)
> +        {
> +          for (f = 0; f < 0x8; ++f)
> +            {
> +
> +              class = pci_conf_read16 (b, d, f, PCI_CLASS_DEVICE);
> +              if (class != 0x700)
> +                continue;;
> +
> +              bar0 = pci_conf_read32 (b, d, f, PCI_BASE_ADDRESS_0);

Why would a serial port only be allowed to be on the port specified
with BAR0? E.g. if you have a serial card with multiple ports, multiple
BARs could be candidates.

Also, why would the first one found be it?

Jan

> +
> +              /* Not IO */
> +              if (!(bar0 & 1))
> +                continue;
> +
> +              pci_conf_write32 (b, d, f, PCI_BASE_ADDRESS_0, 0xffffffff);
> +              len = pci_conf_read32 (b, d, f, PCI_BASE_ADDRESS_0);
> +              pci_conf_write32 (b, d, f, PCI_BASE_ADDRESS_0, bar0);
> +
> +              /* Not 8 bytes */
> +              if ((len & 0xffff) != 0xfff9)
> +                continue;
> +
> +              uart->io_base = bar0 & 0xfffe;
> +              uart->irq = 0;

Hmm, I found that without use of an interrupt the output isn't very
reliable. But yes, getting the proper number could be pretty difficult,
especially this early.

Jan

> +
> +              return 0;
> +
> +            }
> +
> +        }
> +    }
> +
> +  if (!skip_amt)
> +     return -1;
> +
> +  uart->io_base = 0x3f8;
> +  uart->irq = 0;
> +  uart->clock_hz  = UART_CLOCK_HZ;
> +
> +  return 0;
> +}
> +
> +
>  #define PARSE_ERR(_f, _a...)                 \
>      do {                                     \
>          printk( "ERROR: " _f "\n" , ## _a ); \
> @@ -481,7 +541,18 @@ static void __init ns16550_parse_port_co
>      if ( *conf == ',' )
>      {
>          conf++;
> -        uart->io_base = simple_strtoul(conf, &conf, 0);
> +        
> +        if ( strncmp(conf,"magic",5) == 0 ) {
> +         if (magic_uart_config(uart,1)) 
> +             return;
> +         conf+=5;
> +        } else if ( strncmp(conf,"amt",3) == 0 ) {
> +         if (magic_uart_config(uart,0)) 
> +             return;
> +         conf+=3;
> +        } else {
> +            uart->io_base = simple_strtoul(conf, &conf, 0);
> +        }
>  
>          if ( *conf == ',' )
>          {




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