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![David Howells](/assets/img/avatar_default.png)
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)
293 lines
7.4 KiB
C
293 lines
7.4 KiB
C
/* Low-level parallel port routines for the Amiga built-in port
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*
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* Author: Joerg Dorchain <joerg@dorchain.net>
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*
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* This is a complete rewrite of the code, but based heaviy upon the old
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* lp_intern. code.
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*
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* The built-in Amiga parallel port provides one port at a fixed address
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* with 8 bidirectional data lines (D0 - D7) and 3 bidirectional status
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* lines (BUSY, POUT, SEL), 1 output control line /STROBE (raised automatically
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* in hardware when the data register is accessed), and 1 input control line
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* /ACK, able to cause an interrupt, but both not directly settable by
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* software.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/parport.h>
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#include <linux/ioport.h>
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#include <linux/interrupt.h>
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#include <asm/setup.h>
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#include <asm/amigahw.h>
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#include <asm/irq.h>
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#include <asm/io.h>
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#include <asm/amigaints.h>
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#undef DEBUG
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#ifdef DEBUG
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#define DPRINTK printk
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#else
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#define DPRINTK(x...) do { } while (0)
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#endif
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static struct parport *this_port = NULL;
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static void amiga_write_data(struct parport *p, unsigned char data)
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{
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DPRINTK(KERN_DEBUG "write_data %c\n",data);
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/* Triggers also /STROBE. This behavior cannot be changed */
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ciaa.prb = data;
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mb();
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}
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static unsigned char amiga_read_data(struct parport *p)
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{
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/* Triggers also /STROBE. This behavior cannot be changed */
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return ciaa.prb;
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}
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#if 0
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static unsigned char control_pc_to_amiga(unsigned char control)
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{
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unsigned char ret = 0;
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if (control & PARPORT_CONTROL_SELECT) /* XXX: What is SELECP? */
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;
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if (control & PARPORT_CONTROL_INIT) /* INITP */
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/* reset connected to cpu reset pin */;
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if (control & PARPORT_CONTROL_AUTOFD) /* AUTOLF */
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/* Not connected */;
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if (control & PARPORT_CONTROL_STROBE) /* Strobe */
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/* Handled only directly by hardware */;
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return ret;
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}
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#endif
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static unsigned char control_amiga_to_pc(unsigned char control)
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{
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return PARPORT_CONTROL_SELECT |
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PARPORT_CONTROL_AUTOFD | PARPORT_CONTROL_STROBE;
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/* fake value: interrupt enable, select in, no reset,
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no autolf, no strobe - seems to be closest the wiring diagram */
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}
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static void amiga_write_control(struct parport *p, unsigned char control)
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{
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DPRINTK(KERN_DEBUG "write_control %02x\n",control);
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/* No implementation possible */
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}
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static unsigned char amiga_read_control( struct parport *p)
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{
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DPRINTK(KERN_DEBUG "read_control \n");
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return control_amiga_to_pc(0);
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}
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static unsigned char amiga_frob_control( struct parport *p, unsigned char mask, unsigned char val)
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{
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unsigned char old;
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DPRINTK(KERN_DEBUG "frob_control mask %02x, value %02x\n",mask,val);
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old = amiga_read_control(p);
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amiga_write_control(p, (old & ~mask) ^ val);
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return old;
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}
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#if 0 /* currently unused */
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static unsigned char status_pc_to_amiga(unsigned char status)
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{
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unsigned char ret = 1;
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if (status & PARPORT_STATUS_BUSY) /* Busy */
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ret &= ~1;
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if (status & PARPORT_STATUS_ACK) /* Ack */
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/* handled in hardware */;
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if (status & PARPORT_STATUS_PAPEROUT) /* PaperOut */
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ret |= 2;
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if (status & PARPORT_STATUS_SELECT) /* select */
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ret |= 4;
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if (status & PARPORT_STATUS_ERROR) /* error */
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/* not connected */;
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return ret;
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}
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#endif
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static unsigned char status_amiga_to_pc(unsigned char status)
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{
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unsigned char ret = PARPORT_STATUS_BUSY | PARPORT_STATUS_ACK | PARPORT_STATUS_ERROR;
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if (status & 1) /* Busy */
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ret &= ~PARPORT_STATUS_BUSY;
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if (status & 2) /* PaperOut */
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ret |= PARPORT_STATUS_PAPEROUT;
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if (status & 4) /* Selected */
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ret |= PARPORT_STATUS_SELECT;
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/* the rest is not connected or handled autonomously in hardware */
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return ret;
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}
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static unsigned char amiga_read_status(struct parport *p)
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{
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unsigned char status;
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status = status_amiga_to_pc(ciab.pra & 7);
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DPRINTK(KERN_DEBUG "read_status %02x\n", status);
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return status;
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}
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/* as this ports irq handling is already done, we use a generic funktion */
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static irqreturn_t amiga_interrupt(int irq, void *dev_id)
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{
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parport_generic_irq(irq, (struct parport *) dev_id);
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return IRQ_HANDLED;
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}
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static void amiga_enable_irq(struct parport *p)
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{
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enable_irq(IRQ_AMIGA_CIAA_FLG);
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}
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static void amiga_disable_irq(struct parport *p)
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{
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disable_irq(IRQ_AMIGA_CIAA_FLG);
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}
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static void amiga_data_forward(struct parport *p)
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{
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DPRINTK(KERN_DEBUG "forward\n");
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ciaa.ddrb = 0xff; /* all pins output */
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mb();
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}
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static void amiga_data_reverse(struct parport *p)
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{
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DPRINTK(KERN_DEBUG "reverse\n");
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ciaa.ddrb = 0; /* all pins input */
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mb();
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}
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static void amiga_init_state(struct pardevice *dev, struct parport_state *s)
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{
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s->u.amiga.data = 0;
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s->u.amiga.datadir = 255;
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s->u.amiga.status = 0;
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s->u.amiga.statusdir = 0;
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}
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static void amiga_save_state(struct parport *p, struct parport_state *s)
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{
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mb();
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s->u.amiga.data = ciaa.prb;
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s->u.amiga.datadir = ciaa.ddrb;
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s->u.amiga.status = ciab.pra & 7;
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s->u.amiga.statusdir = ciab.ddra & 7;
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mb();
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}
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static void amiga_restore_state(struct parport *p, struct parport_state *s)
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{
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mb();
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ciaa.prb = s->u.amiga.data;
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ciaa.ddrb = s->u.amiga.datadir;
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ciab.pra |= (ciab.pra & 0xf8) | s->u.amiga.status;
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ciab.ddra |= (ciab.ddra & 0xf8) | s->u.amiga.statusdir;
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mb();
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}
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static struct parport_operations pp_amiga_ops = {
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.write_data = amiga_write_data,
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.read_data = amiga_read_data,
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.write_control = amiga_write_control,
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.read_control = amiga_read_control,
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.frob_control = amiga_frob_control,
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.read_status = amiga_read_status,
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.enable_irq = amiga_enable_irq,
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.disable_irq = amiga_disable_irq,
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.data_forward = amiga_data_forward,
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.data_reverse = amiga_data_reverse,
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.init_state = amiga_init_state,
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.save_state = amiga_save_state,
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.restore_state = amiga_restore_state,
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.epp_write_data = parport_ieee1284_epp_write_data,
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.epp_read_data = parport_ieee1284_epp_read_data,
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.epp_write_addr = parport_ieee1284_epp_write_addr,
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.epp_read_addr = parport_ieee1284_epp_read_addr,
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.ecp_write_data = parport_ieee1284_ecp_write_data,
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.ecp_read_data = parport_ieee1284_ecp_read_data,
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.ecp_write_addr = parport_ieee1284_ecp_write_addr,
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.compat_write_data = parport_ieee1284_write_compat,
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.nibble_read_data = parport_ieee1284_read_nibble,
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.byte_read_data = parport_ieee1284_read_byte,
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.owner = THIS_MODULE,
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};
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/* ----------- Initialisation code --------------------------------- */
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static int __init parport_amiga_init(void)
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{
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struct parport *p;
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int err;
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if (!MACH_IS_AMIGA || !AMIGAHW_PRESENT(AMI_PARALLEL))
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return -ENODEV;
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err = -EBUSY;
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if (!request_mem_region(CIAA_PHYSADDR-1+0x100, 0x100, "parallel"))
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goto out_mem;
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ciaa.ddrb = 0xff;
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ciab.ddra &= 0xf8;
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mb();
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p = parport_register_port((unsigned long)&ciaa.prb, IRQ_AMIGA_CIAA_FLG,
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PARPORT_DMA_NONE, &pp_amiga_ops);
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if (!p)
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goto out_port;
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err = request_irq(IRQ_AMIGA_CIAA_FLG, amiga_interrupt, 0, p->name, p);
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if (err)
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goto out_irq;
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this_port = p;
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printk(KERN_INFO "%s: Amiga built-in port using irq\n", p->name);
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/* XXX: set operating mode */
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parport_announce_port(p);
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return 0;
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out_irq:
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parport_put_port(p);
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out_port:
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release_mem_region(CIAA_PHYSADDR-1+0x100, 0x100);
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out_mem:
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return err;
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}
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static void __exit parport_amiga_exit(void)
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{
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parport_remove_port(this_port);
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if (this_port->irq != PARPORT_IRQ_NONE)
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free_irq(IRQ_AMIGA_CIAA_FLG, this_port);
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parport_put_port(this_port);
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release_mem_region(CIAA_PHYSADDR-1+0x100, 0x100);
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}
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MODULE_AUTHOR("Joerg Dorchain <joerg@dorchain.net>");
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MODULE_DESCRIPTION("Parport Driver for Amiga builtin Port");
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MODULE_SUPPORTED_DEVICE("Amiga builtin Parallel Port");
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MODULE_LICENSE("GPL");
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module_init(parport_amiga_init)
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module_exit(parport_amiga_exit)
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