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Maintain a per-CPU global "struct pt_regs *" variable which can be used instead
of passing regs around manually through all ~1800 interrupt handlers in the
Linux kernel.
The regs pointer is used in few places, but it potentially costs both stack
space and code to pass it around. On the FRV arch, removing the regs parameter
from all the genirq function results in a 20% speed up of the IRQ exit path
(ie: from leaving timer_interrupt() to leaving do_IRQ()).
Where appropriate, an arch may override the generic storage facility and do
something different with the variable. On FRV, for instance, the address is
maintained in GR28 at all times inside the kernel as part of general exception
handling.
Having looked over the code, it appears that the parameter may be handed down
through up to twenty or so layers of functions. Consider a USB character
device attached to a USB hub, attached to a USB controller that posts its
interrupts through a cascaded auxiliary interrupt controller. A character
device driver may want to pass regs to the sysrq handler through the input
layer which adds another few layers of parameter passing.
I've build this code with allyesconfig for x86_64 and i386. I've runtested the
main part of the code on FRV and i386, though I can't test most of the drivers.
I've also done partial conversion for powerpc and MIPS - these at least compile
with minimal configurations.
This will affect all archs. Mostly the changes should be relatively easy.
Take do_IRQ(), store the regs pointer at the beginning, saving the old one:
struct pt_regs *old_regs = set_irq_regs(regs);
And put the old one back at the end:
set_irq_regs(old_regs);
Don't pass regs through to generic_handle_irq() or __do_IRQ().
In timer_interrupt(), this sort of change will be necessary:
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING, regs);
+ update_process_times(user_mode(get_irq_regs()));
+ profile_tick(CPU_PROFILING);
I'd like to move update_process_times()'s use of get_irq_regs() into itself,
except that i386, alone of the archs, uses something other than user_mode().
Some notes on the interrupt handling in the drivers:
(*) input_dev() is now gone entirely. The regs pointer is no longer stored in
the input_dev struct.
(*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does
something different depending on whether it's been supplied with a regs
pointer or not.
(*) Various IRQ handler function pointers have been moved to type
irq_handler_t.
Signed-Off-By: David Howells <dhowells@redhat.com>
(cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
119 lines
4.5 KiB
C
119 lines
4.5 KiB
C
/* to be used by qlogicfas and qlogic_cs */
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#ifndef __QLOGICFAS408_H
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#define __QLOGICFAS408_H
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/*----------------------------------------------------------------*/
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/* Configuration */
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/* Set the following to max out the speed of the PIO PseudoDMA transfers,
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again, 0 tends to be slower, but more stable. */
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#define QL_TURBO_PDMA 1
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/* This should be 1 to enable parity detection */
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#define QL_ENABLE_PARITY 1
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/* This will reset all devices when the driver is initialized (during bootup).
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The other linux drivers don't do this, but the DOS drivers do, and after
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using DOS or some kind of crash or lockup this will bring things back
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without requiring a cold boot. It does take some time to recover from a
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reset, so it is slower, and I have seen timeouts so that devices weren't
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recognized when this was set. */
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#define QL_RESET_AT_START 0
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/* crystal frequency in megahertz (for offset 5 and 9)
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Please set this for your card. Most Qlogic cards are 40 Mhz. The
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Control Concepts ISA (not VLB) is 24 Mhz */
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#define XTALFREQ 40
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/**********/
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/* DANGER! modify these at your own risk */
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/* SLOWCABLE can usually be reset to zero if you have a clean setup and
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proper termination. The rest are for synchronous transfers and other
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advanced features if your device can transfer faster than 5Mb/sec.
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If you are really curious, email me for a quick howto until I have
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something official */
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/**********/
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/*****/
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/* config register 1 (offset 8) options */
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/* This needs to be set to 1 if your cabling is long or noisy */
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#define SLOWCABLE 1
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/*****/
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/* offset 0xc */
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/* This will set fast (10Mhz) synchronous timing when set to 1
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For this to have an effect, FASTCLK must also be 1 */
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#define FASTSCSI 0
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/* This when set to 1 will set a faster sync transfer rate */
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#define FASTCLK 0 /*(XTALFREQ>25?1:0)*/
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/*****/
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/* offset 6 */
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/* This is the sync transfer divisor, XTALFREQ/X will be the maximum
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achievable data rate (assuming the rest of the system is capable
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and set properly) */
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#define SYNCXFRPD 5 /*(XTALFREQ/5)*/
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/*****/
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/* offset 7 */
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/* This is the count of how many synchronous transfers can take place
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i.e. how many reqs can occur before an ack is given.
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The maximum value for this is 15, the upper bits can modify
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REQ/ACK assertion and deassertion during synchronous transfers
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If this is 0, the bus will only transfer asynchronously */
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#define SYNCOFFST 0
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/* for the curious, bits 7&6 control the deassertion delay in 1/2 cycles
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of the 40Mhz clock. If FASTCLK is 1, specifying 01 (1/2) will
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cause the deassertion to be early by 1/2 clock. Bits 5&4 control
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the assertion delay, also in 1/2 clocks (FASTCLK is ignored here). */
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/*----------------------------------------------------------------*/
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struct qlogicfas408_priv {
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int qbase; /* Port */
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int qinitid; /* initiator ID */
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int qabort; /* Flag to cause an abort */
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int qlirq; /* IRQ being used */
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int int_type; /* type of irq, 2 for ISA board, 0 for PCMCIA */
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char qinfo[80]; /* description */
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Scsi_Cmnd *qlcmd; /* current command being processed */
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struct Scsi_Host *shost; /* pointer back to host */
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struct qlogicfas408_priv *next; /* next private struct */
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};
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/* The qlogic card uses two register maps - These macros select which one */
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#define REG0 ( outb( inb( qbase + 0xd ) & 0x7f , qbase + 0xd ), outb( 4 , qbase + 0xd ))
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#define REG1 ( outb( inb( qbase + 0xd ) | 0x80 , qbase + 0xd ), outb( 0xb4 | int_type, qbase + 0xd ))
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/* following is watchdog timeout in microseconds */
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#define WATCHDOG 5000000
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/*----------------------------------------------------------------*/
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/* the following will set the monitor border color (useful to find
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where something crashed or gets stuck at and as a simple profiler) */
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#define rtrc(i) {}
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#define get_priv_by_cmd(x) (struct qlogicfas408_priv *)&((x)->device->host->hostdata[0])
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#define get_priv_by_host(x) (struct qlogicfas408_priv *)&((x)->hostdata[0])
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irqreturn_t qlogicfas408_ihandl(int irq, void *dev_id);
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int qlogicfas408_queuecommand(Scsi_Cmnd * cmd, void (*done) (Scsi_Cmnd *));
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int qlogicfas408_biosparam(struct scsi_device * disk,
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struct block_device *dev,
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sector_t capacity, int ip[]);
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int qlogicfas408_abort(Scsi_Cmnd * cmd);
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int qlogicfas408_bus_reset(Scsi_Cmnd * cmd);
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const char *qlogicfas408_info(struct Scsi_Host *host);
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int qlogicfas408_get_chip_type(int qbase, int int_type);
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void qlogicfas408_setup(int qbase, int id, int int_type);
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int qlogicfas408_detect(int qbase, int int_type);
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void qlogicfas408_disable_ints(struct qlogicfas408_priv *priv);
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#endif /* __QLOGICFAS408_H */
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