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linux/drivers/net/irda/mcs7780.h
David Howells 7d12e780e0 IRQ: Maintain regs pointer globally rather than passing to IRQ handlers 
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)
2006-10-05 15:10:12 +01:00

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/*****************************************************************************
*
* Filename: mcs7780.h
* Version: 0.2-alpha
* Description: Irda MosChip USB Dongle
* Status: Experimental
* Authors: Lukasz Stelmach <stlman@poczta.fm>
* Brian Pugh <bpugh@cs.pdx.edu>
*
* Copyright (C) 2005, Lukasz Stelmach <stlman@poczta.fm>
* Copyright (C) 2005, Brian Pugh <bpugh@cs.pdx.edu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*****************************************************************************/
#ifndef _MCS7780_H
#define _MCS7780_H
#define MCS_MODE_SIR 0
#define MCS_MODE_MIR 1
#define MCS_MODE_FIR 2
#define MCS_CTRL_TIMEOUT 500
#define MCS_XMIT_TIMEOUT 500
/* Possible transceiver types */
#define MCS_TSC_VISHAY 0 /* Vishay TFD, default choice */
#define MCS_TSC_AGILENT 1 /* Agilent 3602/3600 */
#define MCS_TSC_SHARP 2 /* Sharp GP2W1000YP */
/* Requests */
#define MCS_RD_RTYPE 0xC0
#define MCS_WR_RTYPE 0x40
#define MCS_RDREQ 0x0F
#define MCS_WRREQ 0x0E
/* Register 0x00 */
#define MCS_MODE_REG 0
#define MCS_FIR ((__u16)0x0001)
#define MCS_SIR16US ((__u16)0x0002)
#define MCS_BBTG ((__u16)0x0004)
#define MCS_ASK ((__u16)0x0008)
#define MCS_PARITY ((__u16)0x0010)
/* SIR/MIR speed constants */
#define MCS_SPEED_SHIFT 5
#define MCS_SPEED_MASK ((__u16)0x00E0)
#define MCS_SPEED(x) ((x & MCS_SPEED_MASK) >> MCS_SPEED_SHIFT)
#define MCS_SPEED_2400 ((0 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_9600 ((1 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_19200 ((2 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_38400 ((3 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_57600 ((4 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_115200 ((5 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_576000 ((6 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_SPEED_1152000 ((7 << MCS_SPEED_SHIFT) & MCS_SPEED_MASK)
#define MCS_PLLPWDN ((__u16)0x0100)
#define MCS_DRIVER ((__u16)0x0200)
#define MCS_DTD ((__u16)0x0400)
#define MCS_DIR ((__u16)0x0800)
#define MCS_SIPEN ((__u16)0x1000)
#define MCS_SENDSIP ((__u16)0x2000)
#define MCS_CHGDIR ((__u16)0x4000)
#define MCS_RESET ((__u16)0x8000)
/* Register 0x02 */
#define MCS_XCVR_REG 2
#define MCS_MODE0 ((__u16)0x0001)
#define MCS_STFIR ((__u16)0x0002)
#define MCS_XCVR_CONF ((__u16)0x0004)
#define MCS_RXFAST ((__u16)0x0008)
/* TXCUR [6:4] */
#define MCS_TXCUR_SHIFT 4
#define MCS_TXCUR_MASK ((__u16)0x0070)
#define MCS_TXCUR(x) ((x & MCS_TXCUR_MASK) >> MCS_TXCUR_SHIFT)
#define MCS_SETTXCUR(x,y) \
((x & ~MCS_TXCUR_MASK) | (y << MCS_TXCUR_SHIFT) & MCS_TXCUR_MASK)
#define MCS_MODE1 ((__u16)0x0080)
#define MCS_SMODE0 ((__u16)0x0100)
#define MCS_SMODE1 ((__u16)0x0200)
#define MCS_INVTX ((__u16)0x0400)
#define MCS_INVRX ((__u16)0x0800)
#define MCS_MINRXPW_REG 4
#define MCS_RESV_REG 7
#define MCS_IRINTX ((__u16)0x0001)
#define MCS_IRINRX ((__u16)0x0002)
struct mcs_cb {
struct usb_device *usbdev; /* init: probe_irda */
struct net_device *netdev; /* network layer */
struct irlap_cb *irlap; /* The link layer we are binded to */
struct net_device_stats stats; /* network statistics */
struct qos_info qos;
unsigned int speed; /* Current speed */
unsigned int new_speed; /* new speed */
struct work_struct work; /* Change speed work */
struct sk_buff *tx_pending;
char in_buf[4096]; /* transmit/receive buffer */
char out_buf[4096]; /* transmit/receive buffer */
__u8 *fifo_status;
iobuff_t rx_buff; /* receive unwrap state machine */
struct timeval rx_time;
spinlock_t lock;
int receiving;
__u8 ep_in;
__u8 ep_out;
struct urb *rx_urb;
struct urb *tx_urb;
int transceiver_type;
int sir_tweak;
int receive_mode;
};
static int mcs_set_reg(struct mcs_cb *mcs, __u16 reg, __u16 val);
static int mcs_get_reg(struct mcs_cb *mcs, __u16 reg, __u16 * val);
static inline int mcs_setup_transceiver_vishay(struct mcs_cb *mcs);
static inline int mcs_setup_transceiver_agilent(struct mcs_cb *mcs);
static inline int mcs_setup_transceiver_sharp(struct mcs_cb *mcs);
static inline int mcs_setup_transceiver(struct mcs_cb *mcs);
static inline int mcs_wrap_sir_skb(struct sk_buff *skb, __u8 * buf);
static unsigned mcs_wrap_fir_skb(const struct sk_buff *skb, __u8 *buf);
static unsigned mcs_wrap_mir_skb(const struct sk_buff *skb, __u8 *buf);
static void mcs_unwrap_mir(struct mcs_cb *mcs, __u8 *buf, int len);
static void mcs_unwrap_fir(struct mcs_cb *mcs, __u8 *buf, int len);
static inline int mcs_setup_urbs(struct mcs_cb *mcs);
static inline int mcs_receive_start(struct mcs_cb *mcs);
static inline int mcs_find_endpoints(struct mcs_cb *mcs,
struct usb_host_endpoint *ep, int epnum);
static int mcs_speed_change(struct mcs_cb *mcs);
static int mcs_net_ioctl(struct net_device *netdev, struct ifreq *rq, int cmd);
static int mcs_net_close(struct net_device *netdev);
static int mcs_net_open(struct net_device *netdev);
static struct net_device_stats *mcs_net_get_stats(struct net_device *netdev);
static void mcs_receive_irq(struct urb *urb);
static void mcs_send_irq(struct urb *urb);
static int mcs_hard_xmit(struct sk_buff *skb, struct net_device *netdev);
static int mcs_probe(struct usb_interface *intf,
const struct usb_device_id *id);
static void mcs_disconnect(struct usb_interface *intf);
#endif /* _MCS7780_H */
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