![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)
276 lines
6.3 KiB
C
276 lines
6.3 KiB
C
/*
|
|
* Driver for the ADB controller in the Mac I/O (Hydra) chip.
|
|
*/
|
|
#include <stdarg.h>
|
|
#include <linux/types.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/interrupt.h>
|
|
#include <asm/prom.h>
|
|
#include <linux/adb.h>
|
|
#include <asm/io.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/hydra.h>
|
|
#include <asm/irq.h>
|
|
#include <asm/system.h>
|
|
#include <linux/init.h>
|
|
#include <linux/ioport.h>
|
|
|
|
struct preg {
|
|
unsigned char r;
|
|
char pad[15];
|
|
};
|
|
|
|
struct adb_regs {
|
|
struct preg intr;
|
|
struct preg data[9];
|
|
struct preg intr_enb;
|
|
struct preg dcount;
|
|
struct preg error;
|
|
struct preg ctrl;
|
|
struct preg autopoll;
|
|
struct preg active_hi;
|
|
struct preg active_lo;
|
|
struct preg test;
|
|
};
|
|
|
|
/* Bits in intr and intr_enb registers */
|
|
#define DFB 1 /* data from bus */
|
|
#define TAG 2 /* transfer access grant */
|
|
|
|
/* Bits in dcount register */
|
|
#define HMB 0x0f /* how many bytes */
|
|
#define APD 0x10 /* auto-poll data */
|
|
|
|
/* Bits in error register */
|
|
#define NRE 1 /* no response error */
|
|
#define DLE 2 /* data lost error */
|
|
|
|
/* Bits in ctrl register */
|
|
#define TAR 1 /* transfer access request */
|
|
#define DTB 2 /* data to bus */
|
|
#define CRE 4 /* command response expected */
|
|
#define ADB_RST 8 /* ADB reset */
|
|
|
|
/* Bits in autopoll register */
|
|
#define APE 1 /* autopoll enable */
|
|
|
|
static volatile struct adb_regs __iomem *adb;
|
|
static struct adb_request *current_req, *last_req;
|
|
static DEFINE_SPINLOCK(macio_lock);
|
|
|
|
static int macio_probe(void);
|
|
static int macio_init(void);
|
|
static irqreturn_t macio_adb_interrupt(int irq, void *arg);
|
|
static int macio_send_request(struct adb_request *req, int sync);
|
|
static int macio_adb_autopoll(int devs);
|
|
static void macio_adb_poll(void);
|
|
static int macio_adb_reset_bus(void);
|
|
|
|
struct adb_driver macio_adb_driver = {
|
|
"MACIO",
|
|
macio_probe,
|
|
macio_init,
|
|
macio_send_request,
|
|
/*macio_write,*/
|
|
macio_adb_autopoll,
|
|
macio_adb_poll,
|
|
macio_adb_reset_bus
|
|
};
|
|
|
|
int macio_probe(void)
|
|
{
|
|
return find_compatible_devices("adb", "chrp,adb0")? 0: -ENODEV;
|
|
}
|
|
|
|
int macio_init(void)
|
|
{
|
|
struct device_node *adbs;
|
|
struct resource r;
|
|
unsigned int irq;
|
|
|
|
adbs = find_compatible_devices("adb", "chrp,adb0");
|
|
if (adbs == 0)
|
|
return -ENXIO;
|
|
|
|
if (of_address_to_resource(adbs, 0, &r))
|
|
return -ENXIO;
|
|
adb = ioremap(r.start, sizeof(struct adb_regs));
|
|
|
|
out_8(&adb->ctrl.r, 0);
|
|
out_8(&adb->intr.r, 0);
|
|
out_8(&adb->error.r, 0);
|
|
out_8(&adb->active_hi.r, 0xff); /* for now, set all devices active */
|
|
out_8(&adb->active_lo.r, 0xff);
|
|
out_8(&adb->autopoll.r, APE);
|
|
|
|
irq = irq_of_parse_and_map(adbs, 0);
|
|
if (request_irq(irq, macio_adb_interrupt, 0, "ADB", (void *)0)) {
|
|
printk(KERN_ERR "ADB: can't get irq %d\n", irq);
|
|
return -EAGAIN;
|
|
}
|
|
out_8(&adb->intr_enb.r, DFB | TAG);
|
|
|
|
printk("adb: mac-io driver 1.0 for unified ADB\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int macio_adb_autopoll(int devs)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&macio_lock, flags);
|
|
out_8(&adb->active_hi.r, devs >> 8);
|
|
out_8(&adb->active_lo.r, devs);
|
|
out_8(&adb->autopoll.r, devs? APE: 0);
|
|
spin_unlock_irqrestore(&macio_lock, flags);
|
|
return 0;
|
|
}
|
|
|
|
static int macio_adb_reset_bus(void)
|
|
{
|
|
unsigned long flags;
|
|
int timeout = 1000000;
|
|
|
|
/* Hrm... we may want to not lock interrupts for so
|
|
* long ... oh well, who uses that chip anyway ? :)
|
|
* That function will be seldomly used during boot
|
|
* on rare machines, so...
|
|
*/
|
|
spin_lock_irqsave(&macio_lock, flags);
|
|
out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | ADB_RST);
|
|
while ((in_8(&adb->ctrl.r) & ADB_RST) != 0) {
|
|
if (--timeout == 0) {
|
|
out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) & ~ADB_RST);
|
|
return -1;
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&macio_lock, flags);
|
|
return 0;
|
|
}
|
|
|
|
/* Send an ADB command */
|
|
static int macio_send_request(struct adb_request *req, int sync)
|
|
{
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
if (req->data[0] != ADB_PACKET)
|
|
return -EINVAL;
|
|
|
|
for (i = 0; i < req->nbytes - 1; ++i)
|
|
req->data[i] = req->data[i+1];
|
|
--req->nbytes;
|
|
|
|
req->next = NULL;
|
|
req->sent = 0;
|
|
req->complete = 0;
|
|
req->reply_len = 0;
|
|
|
|
spin_lock_irqsave(&macio_lock, flags);
|
|
if (current_req != 0) {
|
|
last_req->next = req;
|
|
last_req = req;
|
|
} else {
|
|
current_req = last_req = req;
|
|
out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
|
|
}
|
|
spin_unlock_irqrestore(&macio_lock, flags);
|
|
|
|
if (sync) {
|
|
while (!req->complete)
|
|
macio_adb_poll();
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static irqreturn_t macio_adb_interrupt(int irq, void *arg)
|
|
{
|
|
int i, n, err;
|
|
struct adb_request *req = NULL;
|
|
unsigned char ibuf[16];
|
|
int ibuf_len = 0;
|
|
int complete = 0;
|
|
int autopoll = 0;
|
|
int handled = 0;
|
|
|
|
spin_lock(&macio_lock);
|
|
if (in_8(&adb->intr.r) & TAG) {
|
|
handled = 1;
|
|
if ((req = current_req) != 0) {
|
|
/* put the current request in */
|
|
for (i = 0; i < req->nbytes; ++i)
|
|
out_8(&adb->data[i].r, req->data[i]);
|
|
out_8(&adb->dcount.r, req->nbytes & HMB);
|
|
req->sent = 1;
|
|
if (req->reply_expected) {
|
|
out_8(&adb->ctrl.r, DTB + CRE);
|
|
} else {
|
|
out_8(&adb->ctrl.r, DTB);
|
|
current_req = req->next;
|
|
complete = 1;
|
|
if (current_req)
|
|
out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
|
|
}
|
|
}
|
|
out_8(&adb->intr.r, 0);
|
|
}
|
|
|
|
if (in_8(&adb->intr.r) & DFB) {
|
|
handled = 1;
|
|
err = in_8(&adb->error.r);
|
|
if (current_req && current_req->sent) {
|
|
/* this is the response to a command */
|
|
req = current_req;
|
|
if (err == 0) {
|
|
req->reply_len = in_8(&adb->dcount.r) & HMB;
|
|
for (i = 0; i < req->reply_len; ++i)
|
|
req->reply[i] = in_8(&adb->data[i].r);
|
|
}
|
|
current_req = req->next;
|
|
complete = 1;
|
|
if (current_req)
|
|
out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
|
|
} else if (err == 0) {
|
|
/* autopoll data */
|
|
n = in_8(&adb->dcount.r) & HMB;
|
|
for (i = 0; i < n; ++i)
|
|
ibuf[i] = in_8(&adb->data[i].r);
|
|
ibuf_len = n;
|
|
autopoll = (in_8(&adb->dcount.r) & APD) != 0;
|
|
}
|
|
out_8(&adb->error.r, 0);
|
|
out_8(&adb->intr.r, 0);
|
|
}
|
|
spin_unlock(&macio_lock);
|
|
if (complete && req) {
|
|
void (*done)(struct adb_request *) = req->done;
|
|
mb();
|
|
req->complete = 1;
|
|
/* Here, we assume that if the request has a done member, the
|
|
* struct request will survive to setting req->complete to 1
|
|
*/
|
|
if (done)
|
|
(*done)(req);
|
|
}
|
|
if (ibuf_len)
|
|
adb_input(ibuf, ibuf_len, autopoll);
|
|
|
|
return IRQ_RETVAL(handled);
|
|
}
|
|
|
|
static void macio_adb_poll(void)
|
|
{
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
if (in_8(&adb->intr.r) != 0)
|
|
macio_adb_interrupt(0, NULL, NULL);
|
|
local_irq_restore(flags);
|
|
}
|