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![Brent Casavant](/assets/img/avatar_default.png)
Several hardware features of SGI's IOC4 I/O controller chip require timing-related driver calculations dependent upon the PCI bus speed. This patch enables the core IOC4 driver code to detect the actual bus speed and store a value that can later be used by the IOC4 subdrivers as needed. Signed-off-by: Brent Casavant <bcasavan@sgi.com> Acked-by: Pat Gefre <pfg@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
427 lines
12 KiB
C
427 lines
12 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2005 Silicon Graphics, Inc. All Rights Reserved.
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*/
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/* This file contains the master driver module for use by SGI IOC4 subdrivers.
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*
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* It allocates any resources shared between multiple subdevices, and
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* provides accessor functions (where needed) and the like for those
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* resources. It also provides a mechanism for the subdevice modules
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* to support loading and unloading.
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*
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* Non-shared resources (e.g. external interrupt A_INT_OUT register page
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* alias, serial port and UART registers) are handled by the subdevice
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* modules themselves.
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*
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* This is all necessary because IOC4 is not implemented as a multi-function
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* PCI device, but an amalgamation of disparate registers for several
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* types of device (ATA, serial, external interrupts). The normal
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* resource management in the kernel doesn't have quite the right interfaces
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* to handle this situation (e.g. multiple modules can't claim the same
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* PCI ID), thus this IOC4 master module.
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*/
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/ioc4.h>
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#include <linux/mmtimer.h>
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#include <linux/rtc.h>
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#include <linux/rwsem.h>
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#include <asm/sn/addrs.h>
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#include <asm/sn/clksupport.h>
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#include <asm/sn/shub_mmr.h>
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/***************
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* Definitions *
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***************/
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/* Tweakable values */
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/* PCI bus speed detection/calibration */
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#define IOC4_CALIBRATE_COUNT 63 /* Calibration cycle period */
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#define IOC4_CALIBRATE_CYCLES 256 /* Average over this many cycles */
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#define IOC4_CALIBRATE_DISCARD 2 /* Discard first few cycles */
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#define IOC4_CALIBRATE_LOW_MHZ 25 /* Lower bound on bus speed sanity */
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#define IOC4_CALIBRATE_HIGH_MHZ 75 /* Upper bound on bus speed sanity */
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#define IOC4_CALIBRATE_DEFAULT_MHZ 66 /* Assumed if sanity check fails */
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/************************
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* Submodule management *
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************************/
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static LIST_HEAD(ioc4_devices);
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static DECLARE_RWSEM(ioc4_devices_rwsem);
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static LIST_HEAD(ioc4_submodules);
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static DECLARE_RWSEM(ioc4_submodules_rwsem);
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/* Register an IOC4 submodule */
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int
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ioc4_register_submodule(struct ioc4_submodule *is)
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{
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struct ioc4_driver_data *idd;
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down_write(&ioc4_submodules_rwsem);
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list_add(&is->is_list, &ioc4_submodules);
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up_write(&ioc4_submodules_rwsem);
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/* Initialize submodule for each IOC4 */
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if (!is->is_probe)
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return 0;
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down_read(&ioc4_devices_rwsem);
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list_for_each_entry(idd, &ioc4_devices, idd_list) {
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if (is->is_probe(idd)) {
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printk(KERN_WARNING
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"%s: IOC4 submodule %s probe failed "
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"for pci_dev %s",
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__FUNCTION__, module_name(is->is_owner),
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pci_name(idd->idd_pdev));
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}
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}
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up_read(&ioc4_devices_rwsem);
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return 0;
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}
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/* Unregister an IOC4 submodule */
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void
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ioc4_unregister_submodule(struct ioc4_submodule *is)
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{
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struct ioc4_driver_data *idd;
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down_write(&ioc4_submodules_rwsem);
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list_del(&is->is_list);
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up_write(&ioc4_submodules_rwsem);
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/* Remove submodule for each IOC4 */
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if (!is->is_remove)
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return;
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down_read(&ioc4_devices_rwsem);
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list_for_each_entry(idd, &ioc4_devices, idd_list) {
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if (is->is_remove(idd)) {
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printk(KERN_WARNING
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"%s: IOC4 submodule %s remove failed "
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"for pci_dev %s.\n",
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__FUNCTION__, module_name(is->is_owner),
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pci_name(idd->idd_pdev));
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}
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}
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up_read(&ioc4_devices_rwsem);
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}
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/*********************
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* Device management *
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*********************/
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#define IOC4_CALIBRATE_LOW_LIMIT \
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(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_LOW_MHZ)
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#define IOC4_CALIBRATE_HIGH_LIMIT \
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(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_HIGH_MHZ)
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#define IOC4_CALIBRATE_DEFAULT \
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(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_DEFAULT_MHZ)
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#define IOC4_CALIBRATE_END \
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(IOC4_CALIBRATE_CYCLES + IOC4_CALIBRATE_DISCARD)
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#define IOC4_INT_OUT_MODE_TOGGLE 0x7 /* Toggle INT_OUT every COUNT+1 ticks */
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/* Determines external interrupt output clock period of the PCI bus an
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* IOC4 is attached to. This value can be used to determine the PCI
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* bus speed.
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*
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* IOC4 has a design feature that various internal timers are derived from
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* the PCI bus clock. This causes IOC4 device drivers to need to take the
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* bus speed into account when setting various register values (e.g. INT_OUT
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* register COUNT field, UART divisors, etc). Since this information is
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* needed by several subdrivers, it is determined by the main IOC4 driver,
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* even though the following code utilizes external interrupt registers
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* to perform the speed calculation.
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*/
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static void
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ioc4_clock_calibrate(struct ioc4_driver_data *idd)
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{
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extern unsigned long sn_rtc_cycles_per_second;
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union ioc4_int_out int_out;
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union ioc4_gpcr gpcr;
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unsigned int state, last_state = 1;
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uint64_t start = 0, end, period;
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unsigned int count = 0;
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/* Enable output */
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gpcr.raw = 0;
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gpcr.fields.dir = IOC4_GPCR_DIR_0;
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gpcr.fields.int_out_en = 1;
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writel(gpcr.raw, &idd->idd_misc_regs->gpcr_s.raw);
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/* Reset to power-on state */
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writel(0, &idd->idd_misc_regs->int_out.raw);
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mmiowb();
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printk(KERN_INFO
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"%s: Calibrating PCI bus speed "
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"for pci_dev %s ... ", __FUNCTION__, pci_name(idd->idd_pdev));
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/* Set up square wave */
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int_out.raw = 0;
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int_out.fields.count = IOC4_CALIBRATE_COUNT;
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int_out.fields.mode = IOC4_INT_OUT_MODE_TOGGLE;
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int_out.fields.diag = 0;
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writel(int_out.raw, &idd->idd_misc_regs->int_out.raw);
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mmiowb();
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/* Check square wave period averaged over some number of cycles */
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do {
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int_out.raw = readl(&idd->idd_misc_regs->int_out.raw);
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state = int_out.fields.int_out;
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if (!last_state && state) {
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count++;
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if (count == IOC4_CALIBRATE_END) {
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end = rtc_time();
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break;
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} else if (count == IOC4_CALIBRATE_DISCARD)
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start = rtc_time();
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}
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last_state = state;
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} while (1);
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/* Calculation rearranged to preserve intermediate precision.
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* Logically:
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* 1. "end - start" gives us number of RTC cycles over all the
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* square wave cycles measured.
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* 2. Divide by number of square wave cycles to get number of
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* RTC cycles per square wave cycle.
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* 3. Divide by 2*(int_out.fields.count+1), which is the formula
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* by which the IOC4 generates the square wave, to get the
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* number of RTC cycles per IOC4 INT_OUT count.
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* 4. Divide by sn_rtc_cycles_per_second to get seconds per
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* count.
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* 5. Multiply by 1E9 to get nanoseconds per count.
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*/
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period = ((end - start) * 1000000000) /
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(IOC4_CALIBRATE_CYCLES * 2 * (IOC4_CALIBRATE_COUNT + 1)
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* sn_rtc_cycles_per_second);
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/* Bounds check the result. */
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if (period > IOC4_CALIBRATE_LOW_LIMIT ||
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period < IOC4_CALIBRATE_HIGH_LIMIT) {
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printk("failed. Assuming PCI clock ticks are %d ns.\n",
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IOC4_CALIBRATE_DEFAULT / IOC4_EXTINT_COUNT_DIVISOR);
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period = IOC4_CALIBRATE_DEFAULT;
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} else {
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printk("succeeded. PCI clock ticks are %ld ns.\n",
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period / IOC4_EXTINT_COUNT_DIVISOR);
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}
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/* Remember results. We store the extint clock period rather
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* than the PCI clock period so that greater precision is
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* retained. Divide by IOC4_EXTINT_COUNT_DIVISOR to get
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* PCI clock period.
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*/
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idd->count_period = period;
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}
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/* Adds a new instance of an IOC4 card */
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static int
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ioc4_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
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{
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struct ioc4_driver_data *idd;
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struct ioc4_submodule *is;
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uint32_t pcmd;
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int ret;
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/* Enable IOC4 and take ownership of it */
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if ((ret = pci_enable_device(pdev))) {
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printk(KERN_WARNING
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"%s: Failed to enable IOC4 device for pci_dev %s.\n",
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__FUNCTION__, pci_name(pdev));
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goto out;
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}
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pci_set_master(pdev);
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/* Set up per-IOC4 data */
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idd = kmalloc(sizeof(struct ioc4_driver_data), GFP_KERNEL);
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if (!idd) {
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printk(KERN_WARNING
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"%s: Failed to allocate IOC4 data for pci_dev %s.\n",
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__FUNCTION__, pci_name(pdev));
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ret = -ENODEV;
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goto out_idd;
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}
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idd->idd_pdev = pdev;
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idd->idd_pci_id = pci_id;
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/* Map IOC4 misc registers. These are shared between subdevices
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* so the main IOC4 module manages them.
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*/
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idd->idd_bar0 = pci_resource_start(idd->idd_pdev, 0);
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if (!idd->idd_bar0) {
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printk(KERN_WARNING
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"%s: Unable to find IOC4 misc resource "
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"for pci_dev %s.\n",
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__FUNCTION__, pci_name(idd->idd_pdev));
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ret = -ENODEV;
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goto out_pci;
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}
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if (!request_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs),
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"ioc4_misc")) {
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printk(KERN_WARNING
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"%s: Unable to request IOC4 misc region "
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"for pci_dev %s.\n",
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__FUNCTION__, pci_name(idd->idd_pdev));
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ret = -ENODEV;
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goto out_pci;
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}
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idd->idd_misc_regs = ioremap(idd->idd_bar0,
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sizeof(struct ioc4_misc_regs));
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if (!idd->idd_misc_regs) {
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printk(KERN_WARNING
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"%s: Unable to remap IOC4 misc region "
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"for pci_dev %s.\n",
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__FUNCTION__, pci_name(idd->idd_pdev));
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ret = -ENODEV;
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goto out_misc_region;
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}
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/* Failsafe portion of per-IOC4 initialization */
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/* Initialize IOC4 */
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pci_read_config_dword(idd->idd_pdev, PCI_COMMAND, &pcmd);
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pci_write_config_dword(idd->idd_pdev, PCI_COMMAND,
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pcmd | PCI_COMMAND_PARITY | PCI_COMMAND_SERR);
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/* Determine PCI clock */
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ioc4_clock_calibrate(idd);
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/* Disable/clear all interrupts. Need to do this here lest
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* one submodule request the shared IOC4 IRQ, but interrupt
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* is generated by a different subdevice.
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*/
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/* Disable */
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writel(~0, &idd->idd_misc_regs->other_iec.raw);
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writel(~0, &idd->idd_misc_regs->sio_iec);
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/* Clear (i.e. acknowledge) */
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writel(~0, &idd->idd_misc_regs->other_ir.raw);
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writel(~0, &idd->idd_misc_regs->sio_ir);
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/* Track PCI-device specific data */
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idd->idd_serial_data = NULL;
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pci_set_drvdata(idd->idd_pdev, idd);
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down_write(&ioc4_devices_rwsem);
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list_add(&idd->idd_list, &ioc4_devices);
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up_write(&ioc4_devices_rwsem);
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/* Add this IOC4 to all submodules */
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down_read(&ioc4_submodules_rwsem);
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list_for_each_entry(is, &ioc4_submodules, is_list) {
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if (is->is_probe && is->is_probe(idd)) {
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printk(KERN_WARNING
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"%s: IOC4 submodule 0x%s probe failed "
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"for pci_dev %s.\n",
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__FUNCTION__, module_name(is->is_owner),
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pci_name(idd->idd_pdev));
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}
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}
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up_read(&ioc4_submodules_rwsem);
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return 0;
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out_misc_region:
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release_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));
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out_pci:
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kfree(idd);
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out_idd:
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pci_disable_device(pdev);
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out:
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return ret;
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}
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/* Removes a particular instance of an IOC4 card. */
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static void
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ioc4_remove(struct pci_dev *pdev)
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{
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struct ioc4_submodule *is;
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struct ioc4_driver_data *idd;
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idd = pci_get_drvdata(pdev);
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/* Remove this IOC4 from all submodules */
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down_read(&ioc4_submodules_rwsem);
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list_for_each_entry(is, &ioc4_submodules, is_list) {
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if (is->is_remove && is->is_remove(idd)) {
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printk(KERN_WARNING
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"%s: IOC4 submodule 0x%s remove failed "
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"for pci_dev %s.\n",
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__FUNCTION__, module_name(is->is_owner),
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pci_name(idd->idd_pdev));
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}
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}
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up_read(&ioc4_submodules_rwsem);
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/* Release resources */
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iounmap(idd->idd_misc_regs);
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if (!idd->idd_bar0) {
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printk(KERN_WARNING
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"%s: Unable to get IOC4 misc mapping for pci_dev %s. "
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"Device removal may be incomplete.\n",
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__FUNCTION__, pci_name(idd->idd_pdev));
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}
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release_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));
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/* Disable IOC4 and relinquish */
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pci_disable_device(pdev);
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/* Remove and free driver data */
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down_write(&ioc4_devices_rwsem);
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list_del(&idd->idd_list);
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up_write(&ioc4_devices_rwsem);
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kfree(idd);
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}
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static struct pci_device_id ioc4_id_table[] = {
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{PCI_VENDOR_ID_SGI, PCI_DEVICE_ID_SGI_IOC4, PCI_ANY_ID,
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PCI_ANY_ID, 0x0b4000, 0xFFFFFF},
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{0}
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};
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static struct pci_driver __devinitdata ioc4_driver = {
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.name = "IOC4",
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.id_table = ioc4_id_table,
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.probe = ioc4_probe,
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.remove = ioc4_remove,
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};
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MODULE_DEVICE_TABLE(pci, ioc4_id_table);
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/*********************
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* Module management *
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*********************/
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/* Module load */
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static int __devinit
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ioc4_init(void)
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{
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return pci_register_driver(&ioc4_driver);
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}
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/* Module unload */
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static void __devexit
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ioc4_exit(void)
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{
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pci_unregister_driver(&ioc4_driver);
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}
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module_init(ioc4_init);
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module_exit(ioc4_exit);
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MODULE_AUTHOR("Brent Casavant - Silicon Graphics, Inc. <bcasavan@sgi.com>");
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MODULE_DESCRIPTION("PCI driver master module for SGI IOC4 Base-IO Card");
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MODULE_LICENSE("GPL");
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EXPORT_SYMBOL(ioc4_register_submodule);
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EXPORT_SYMBOL(ioc4_unregister_submodule);
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