Re: [RFC][Patch] IBM Real-Time "SMI Free" mode driver -v5

Vernon Mauery
2010-09-24T21:30:14Z

On 24-Sep-2010 02:20 PM, Randy Dunlap wrote:
>On Fri, 24 Sep 2010 14:06:42 -0700 Vernon Mauery wrote:
>
>> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
>> index cff7cc2..5fba368 100644
>> --- a/drivers/platform/x86/Kconfig
>> +++ b/drivers/platform/x86/Kconfig
>> @@ -590,4 +590,20 @@ config INTEL_IPS
>> functionality. If in doubt, say Y here; it will only load on
>> supported platforms.
>>
>> +config IBM_RTL
>> + tristate "Device driver to enable PRTL support"
>> + depends on X86 && PCI
>> + ---help---
>> + Enable support for IBM Premium Real Time Mode (PRTM).
>> + This module will allow you the enter and exit PRTM in the BIOS via
>> + sysfs on platforms that support this feature. System in PRTM will
>> + not recive CPU-generated SMIs for recoverable errors. Use of this
>
> receive (again/still)

Ack. Again.

>> + feature without proper support may void your hardware warranty.
>> +
>> + If the proper BIOS support is found the driver will load and create
>> + /sys/devices/system/ibm_rtl/. The "state" variable will indicate
>> + whether or not the BIOS is in PRTM.
[snip]
>> +#include <linux/delay.h>
>> +#include <linux/module.h>
>> +#include <linux/io.h>
>> +#include <linux/sysdev.h>
>> +#include <linux/dmi.h>
>> +#include <linux/mutex.h>
>> +#include <asm/bios_ebda.h>
>> +
>> +static int force;
>
>s/int/bool/
>
>> +module_param(force, bool, 0);
>> +MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
>> +
>> +static int debug;
>
>s/int/bool/

Ack.

>> +module_param(debug, bool, 0644);
>> +MODULE_PARM_DESC(debug, "Show debug output");
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
>> +MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");
>> +
>> +#define RTL_ADDR_TYPE_IO 1
>> +#define RTL_ADDR_TYPE_MMIO 2
>> +
>> +#define RTL_CMD_ENTER_PRTM 1
>> +#define RTL_CMD_EXIT_PRTM 2
>> +
>> +/* The RTL table as presented by the EBDA: */
>> +struct ibm_rtl_table {
>> + char signature[5];
>
>Question: are all 5 bytes of signature[] used? It looks like the search code
>only checks for 32 bits of signature (and the last byte can be garbage?).

Technically, the 5 bytes are supposed to be "_RTL_", but it is a lot
easier to just check _RTL since we can do that with a single read. I
suppose I could do a 64-bit read and mask the bits that matter. Do you
have an opinion on the matter?

>> + u8 version;
>> + u8 rt_status;
>> + u8 command;
>> + u8 command_status;
>> + u8 cmd_address_type;
>> + u8 cmd_granularity;
>> + u8 cmd_offset;
>> + u16 reserve1;
>> + u32 cmd_port_address; /* platform dependent address */
>> + u32 cmd_port_value; /* platform dependent value */
>> +} __attribute__((packed));
>> +
>> +#define RTL_SIGNATURE (('L'<<24)|('T'<<16)|('R'<<8)|'_')
>> +
>> +#define RTL_DEBUG(A, ...) do { \
>> + if (debug) \
>> + pr_info("ibm-rtl: " A, ##__VA_ARGS__ ); \
>> +} while (0)
>> +
>> +static DEFINE_MUTEX(rtl_lock);
>> +static struct ibm_rtl_table __iomem *rtl_table;
>> +static void __iomem *ebda_map;
>> +static void __iomem *rtl_cmd_addr;
>> +static u8 rtl_cmd_type;
>> +static u8 rtl_cmd_width;
>
>...
>
>> +static int __init ibm_rtl_init(void) {
>> + unsigned long ebda_addr, ebda_size;
>> + unsigned int ebda_kb;
>> + int ret = -ENODEV, i;
>> +
>> + if (force)
>> + pr_warning("ibm-rtl: module loaded by force!\n");
>
>Please drop the '!'.

Ack.

--Vernon