/*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 2005-2006 Silicon Graphics, Inc.  All Rights Reserved.
   */
  
  /* This file contains the master driver module for use by SGI IOC4 subdrivers.
   *
   * It allocates any resources shared between multiple subdevices, and
   * provides accessor functions (where needed) and the like for those
   * resources.  It also provides a mechanism for the subdevice modules
   * to support loading and unloading.
   *
   * Non-shared resources (e.g. external interrupt A_INT_OUT register page
   * alias, serial port and UART registers) are handled by the subdevice
   * modules themselves.
   *
   * This is all necessary because IOC4 is not implemented as a multi-function
   * PCI device, but an amalgamation of disparate registers for several
   * types of device (ATA, serial, external interrupts).  The normal
   * resource management in the kernel doesn't have quite the right interfaces
   * to handle this situation (e.g. multiple modules can't claim the same
   * PCI ID), thus this IOC4 master module.
   */
  
  #include <linux/errno.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include <linux/ioc4.h>
  #include <linux/ktime.h>
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/time.h>
  #include <asm/io.h>
  
  /***************
   * Definitions *
   ***************/
  
  /* Tweakable values */
  
  /* PCI bus speed detection/calibration */
  #define IOC4_CALIBRATE_COUNT 63		/* Calibration cycle period */
  #define IOC4_CALIBRATE_CYCLES 256	/* Average over this many cycles */
  #define IOC4_CALIBRATE_DISCARD 2	/* Discard first few cycles */
  #define IOC4_CALIBRATE_LOW_MHZ 25	/* Lower bound on bus speed sanity */
  #define IOC4_CALIBRATE_HIGH_MHZ 75	/* Upper bound on bus speed sanity */
  #define IOC4_CALIBRATE_DEFAULT_MHZ 66	/* Assumed if sanity check fails */
  
  /************************
   * Submodule management *
   ************************/
  
  static DEFINE_MUTEX(ioc4_mutex);
  
  static LIST_HEAD(ioc4_devices);
  static LIST_HEAD(ioc4_submodules);
  
  /* Register an IOC4 submodule */
  int
  ioc4_register_submodule(struct ioc4_submodule *is)
  {
  	struct ioc4_driver_data *idd;
  
  	mutex_lock(&ioc4_mutex);
  	list_add(&is->is_list, &ioc4_submodules);
  
  	/* Initialize submodule for each IOC4 */
  	if (!is->is_probe)
  		goto out;
  
  	list_for_each_entry(idd, &ioc4_devices, idd_list) {
  		if (is->is_probe(idd)) {
  			printk(KERN_WARNING
  			       "%s: IOC4 submodule %s probe failed "
  			       "for pci_dev %s",
  			       __func__, module_name(is->is_owner),
  			       pci_name(idd->idd_pdev));
  		}
  	}
   out:
  	mutex_unlock(&ioc4_mutex);
  	return 0;
  }
  
  /* Unregister an IOC4 submodule */
  void
  ioc4_unregister_submodule(struct ioc4_submodule *is)
  {
  	struct ioc4_driver_data *idd;
  
  	mutex_lock(&ioc4_mutex);
  	list_del(&is->is_list);
  
  	/* Remove submodule for each IOC4 */
  	if (!is->is_remove)
  		goto out;
  
  	list_for_each_entry(idd, &ioc4_devices, idd_list) {
  		if (is->is_remove(idd)) {
  			printk(KERN_WARNING
  			       "%s: IOC4 submodule %s remove failed "
  			       "for pci_dev %s.
  ",
  			       __func__, module_name(is->is_owner),
  			       pci_name(idd->idd_pdev));
  		}
  	}
   out:
  	mutex_unlock(&ioc4_mutex);
  }
  
  /*********************
   * Device management *
   *********************/
  
  #define IOC4_CALIBRATE_LOW_LIMIT \
  	(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_LOW_MHZ)
  #define IOC4_CALIBRATE_HIGH_LIMIT \
  	(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_HIGH_MHZ)
  #define IOC4_CALIBRATE_DEFAULT \
  	(1000*IOC4_EXTINT_COUNT_DIVISOR/IOC4_CALIBRATE_DEFAULT_MHZ)
  
  #define IOC4_CALIBRATE_END \
  	(IOC4_CALIBRATE_CYCLES + IOC4_CALIBRATE_DISCARD)
  
  #define IOC4_INT_OUT_MODE_TOGGLE 0x7	/* Toggle INT_OUT every COUNT+1 ticks */
  
  /* Determines external interrupt output clock period of the PCI bus an
   * IOC4 is attached to.  This value can be used to determine the PCI
   * bus speed.
   *
   * IOC4 has a design feature that various internal timers are derived from
   * the PCI bus clock.  This causes IOC4 device drivers to need to take the
   * bus speed into account when setting various register values (e.g. INT_OUT
   * register COUNT field, UART divisors, etc).  Since this information is
   * needed by several subdrivers, it is determined by the main IOC4 driver,
   * even though the following code utilizes external interrupt registers
   * to perform the speed calculation.
   */
  static void
  ioc4_clock_calibrate(struct ioc4_driver_data *idd)
  {
  	union ioc4_int_out int_out;
  	union ioc4_gpcr gpcr;
  	unsigned int state, last_state = 1;
  	struct timespec start_ts, end_ts;
  	uint64_t start, end, period;
  	unsigned int count = 0;
  
  	/* Enable output */
  	gpcr.raw = 0;
  	gpcr.fields.dir = IOC4_GPCR_DIR_0;
  	gpcr.fields.int_out_en = 1;
  	writel(gpcr.raw, &idd->idd_misc_regs->gpcr_s.raw);
  
  	/* Reset to power-on state */
  	writel(0, &idd->idd_misc_regs->int_out.raw);
  	mmiowb();
  
  	/* Set up square wave */
  	int_out.raw = 0;
  	int_out.fields.count = IOC4_CALIBRATE_COUNT;
  	int_out.fields.mode = IOC4_INT_OUT_MODE_TOGGLE;
  	int_out.fields.diag = 0;
  	writel(int_out.raw, &idd->idd_misc_regs->int_out.raw);
  	mmiowb();
  
  	/* Check square wave period averaged over some number of cycles */
  	do {
  		int_out.raw = readl(&idd->idd_misc_regs->int_out.raw);
  		state = int_out.fields.int_out;
  		if (!last_state && state) {
  			count++;
  			if (count == IOC4_CALIBRATE_END) {
  				ktime_get_ts(&end_ts);
  				break;
  			} else if (count == IOC4_CALIBRATE_DISCARD)
  				ktime_get_ts(&start_ts);
  		}
  		last_state = state;
  	} while (1);
  
  	/* Calculation rearranged to preserve intermediate precision.
  	 * Logically:
  	 * 1. "end - start" gives us the measurement period over all
  	 *    the square wave cycles.
  	 * 2. Divide by number of square wave cycles to get the period
  	 *    of a square wave cycle.
  	 * 3. Divide by 2*(int_out.fields.count+1), which is the formula
  	 *    by which the IOC4 generates the square wave, to get the
  	 *    period of an IOC4 INT_OUT count.
  	 */
  	end = end_ts.tv_sec * NSEC_PER_SEC + end_ts.tv_nsec;
  	start = start_ts.tv_sec * NSEC_PER_SEC + start_ts.tv_nsec;
  	period = (end - start) /
  		(IOC4_CALIBRATE_CYCLES * 2 * (IOC4_CALIBRATE_COUNT + 1));
  
  	/* Bounds check the result. */
  	if (period > IOC4_CALIBRATE_LOW_LIMIT ||
  	    period < IOC4_CALIBRATE_HIGH_LIMIT) {
  		printk(KERN_INFO
  		       "IOC4 %s: Clock calibration failed.  Assuming"
  		       "PCI clock is %d ns.
  ",
  		       pci_name(idd->idd_pdev),
  		       IOC4_CALIBRATE_DEFAULT / IOC4_EXTINT_COUNT_DIVISOR);
  		period = IOC4_CALIBRATE_DEFAULT;
  	} else {
  		u64 ns = period;
  
  		do_div(ns, IOC4_EXTINT_COUNT_DIVISOR);
  		printk(KERN_DEBUG
  		       "IOC4 %s: PCI clock is %llu ns.
  ",
  		       pci_name(idd->idd_pdev), (unsigned long long)ns);
  	}
  
  	/* Remember results.  We store the extint clock period rather
  	 * than the PCI clock period so that greater precision is
  	 * retained.  Divide by IOC4_EXTINT_COUNT_DIVISOR to get
  	 * PCI clock period.
  	 */
  	idd->count_period = period;
  }
  
  /* There are three variants of IOC4 cards: IO9, IO10, and PCI-RT.
   * Each brings out different combinations of IOC4 signals, thus.
   * the IOC4 subdrivers need to know to which we're attached.
   *
   * We look for the presence of a SCSI (IO9) or SATA (IO10) controller
   * on the same PCI bus at slot number 3 to differentiate IO9 from IO10.
   * If neither is present, it's a PCI-RT.
   */
  static unsigned int
  ioc4_variant(struct ioc4_driver_data *idd)
  {
  	struct pci_dev *pdev = NULL;
  	int found = 0;
  
  	/* IO9: Look for a QLogic ISP 12160 at the same bus and slot 3. */
  	do {
  		pdev = pci_get_device(PCI_VENDOR_ID_QLOGIC,
  				      PCI_DEVICE_ID_QLOGIC_ISP12160, pdev);
  		if (pdev &&
  		    idd->idd_pdev->bus->number == pdev->bus->number &&
  		    3 == PCI_SLOT(pdev->devfn))
  			found = 1;
  	} while (pdev && !found);
  	if (NULL != pdev) {
  		pci_dev_put(pdev);
  		return IOC4_VARIANT_IO9;
  	}
  
  	/* IO10: Look for a Vitesse VSC 7174 at the same bus and slot 3. */
  	pdev = NULL;
  	do {
  		pdev = pci_get_device(PCI_VENDOR_ID_VITESSE,
  				      PCI_DEVICE_ID_VITESSE_VSC7174, pdev);
  		if (pdev &&
  		    idd->idd_pdev->bus->number == pdev->bus->number &&
  		    3 == PCI_SLOT(pdev->devfn))
  			found = 1;
  	} while (pdev && !found);
  	if (NULL != pdev) {
  		pci_dev_put(pdev);
  		return IOC4_VARIANT_IO10;
  	}
  
  	/* PCI-RT: No SCSI/SATA controller will be present */
  	return IOC4_VARIANT_PCI_RT;
  }
  
  static void
  ioc4_load_modules(struct work_struct *work)
  {
  	request_module("sgiioc4");
  }
  
  static DECLARE_WORK(ioc4_load_modules_work, ioc4_load_modules);
  
  /* Adds a new instance of an IOC4 card */
  static int
  ioc4_probe(struct pci_dev *pdev, const struct pci_device_id *pci_id)
  {
  	struct ioc4_driver_data *idd;
  	struct ioc4_submodule *is;
  	uint32_t pcmd;
  	int ret;
  
  	/* Enable IOC4 and take ownership of it */
  	if ((ret = pci_enable_device(pdev))) {
  		printk(KERN_WARNING
  		       "%s: Failed to enable IOC4 device for pci_dev %s.
  ",
  		       __func__, pci_name(pdev));
  		goto out;
  	}
  	pci_set_master(pdev);
  
  	/* Set up per-IOC4 data */
  	idd = kmalloc(sizeof(struct ioc4_driver_data), GFP_KERNEL);
  	if (!idd) {
  		printk(KERN_WARNING
  		       "%s: Failed to allocate IOC4 data for pci_dev %s.
  ",
  		       __func__, pci_name(pdev));
  		ret = -ENODEV;
  		goto out_idd;
  	}
  	idd->idd_pdev = pdev;
  	idd->idd_pci_id = pci_id;
  
  	/* Map IOC4 misc registers.  These are shared between subdevices
  	 * so the main IOC4 module manages them.
  	 */
  	idd->idd_bar0 = pci_resource_start(idd->idd_pdev, 0);
  	if (!idd->idd_bar0) {
  		printk(KERN_WARNING
  		       "%s: Unable to find IOC4 misc resource "
  		       "for pci_dev %s.
  ",
  		       __func__, pci_name(idd->idd_pdev));
  		ret = -ENODEV;
  		goto out_pci;
  	}
  	if (!request_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs),
  			    "ioc4_misc")) {
  		printk(KERN_WARNING
  		       "%s: Unable to request IOC4 misc region "
  		       "for pci_dev %s.
  ",
  		       __func__, pci_name(idd->idd_pdev));
  		ret = -ENODEV;
  		goto out_pci;
  	}
  	idd->idd_misc_regs = ioremap(idd->idd_bar0,
  				     sizeof(struct ioc4_misc_regs));
  	if (!idd->idd_misc_regs) {
  		printk(KERN_WARNING
  		       "%s: Unable to remap IOC4 misc region "
  		       "for pci_dev %s.
  ",
  		       __func__, pci_name(idd->idd_pdev));
  		ret = -ENODEV;
  		goto out_misc_region;
  	}
  
  	/* Failsafe portion of per-IOC4 initialization */
  
  	/* Detect card variant */
  	idd->idd_variant = ioc4_variant(idd);
  	printk(KERN_INFO "IOC4 %s: %s card detected.
  ", pci_name(pdev),
  	       idd->idd_variant == IOC4_VARIANT_IO9 ? "IO9" :
  	       idd->idd_variant == IOC4_VARIANT_PCI_RT ? "PCI-RT" :
  	       idd->idd_variant == IOC4_VARIANT_IO10 ? "IO10" : "unknown");
  
  	/* Initialize IOC4 */
  	pci_read_config_dword(idd->idd_pdev, PCI_COMMAND, &pcmd);
  	pci_write_config_dword(idd->idd_pdev, PCI_COMMAND,
  			       pcmd | PCI_COMMAND_PARITY | PCI_COMMAND_SERR);
  
  	/* Determine PCI clock */
  	ioc4_clock_calibrate(idd);
  
  	/* Disable/clear all interrupts.  Need to do this here lest
  	 * one submodule request the shared IOC4 IRQ, but interrupt
  	 * is generated by a different subdevice.
  	 */
  	/* Disable */
  	writel(~0, &idd->idd_misc_regs->other_iec.raw);
  	writel(~0, &idd->idd_misc_regs->sio_iec);
  	/* Clear (i.e. acknowledge) */
  	writel(~0, &idd->idd_misc_regs->other_ir.raw);
  	writel(~0, &idd->idd_misc_regs->sio_ir);
  
  	/* Track PCI-device specific data */
  	idd->idd_serial_data = NULL;
  	pci_set_drvdata(idd->idd_pdev, idd);
  
  	mutex_lock(&ioc4_mutex);
  	list_add_tail(&idd->idd_list, &ioc4_devices);
  
  	/* Add this IOC4 to all submodules */
  	list_for_each_entry(is, &ioc4_submodules, is_list) {
  		if (is->is_probe && is->is_probe(idd)) {
  			printk(KERN_WARNING
  			       "%s: IOC4 submodule 0x%s probe failed "
  			       "for pci_dev %s.
  ",
  			       __func__, module_name(is->is_owner),
  			       pci_name(idd->idd_pdev));
  		}
  	}
  	mutex_unlock(&ioc4_mutex);
  
  	/* Request sgiioc4 IDE driver on boards that bring that functionality
  	 * off of IOC4.  The root filesystem may be hosted on a drive connected
  	 * to IOC4, so we need to make sure the sgiioc4 driver is loaded as it
  	 * won't be picked up by modprobes due to the ioc4 module owning the
  	 * PCI device.
  	 */
  	if (idd->idd_variant != IOC4_VARIANT_PCI_RT) {
  		/* Request the module from a work procedure as the modprobe
  		 * goes out to a userland helper and that will hang if done
  		 * directly from ioc4_probe().
  		 */
  		printk(KERN_INFO "IOC4 loading sgiioc4 submodule
  ");
  		schedule_work(&ioc4_load_modules_work);
  	}
  
  	return 0;
  
  out_misc_region:
  	release_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));
  out_pci:
  	kfree(idd);
  out_idd:
  	pci_disable_device(pdev);
  out:
  	return ret;
  }
  
  /* Removes a particular instance of an IOC4 card. */
  static void
  ioc4_remove(struct pci_dev *pdev)
  {
  	struct ioc4_submodule *is;
  	struct ioc4_driver_data *idd;
  
  	idd = pci_get_drvdata(pdev);
  
  	/* Remove this IOC4 from all submodules */
  	mutex_lock(&ioc4_mutex);
  	list_for_each_entry(is, &ioc4_submodules, is_list) {
  		if (is->is_remove && is->is_remove(idd)) {
  			printk(KERN_WARNING
  			       "%s: IOC4 submodule 0x%s remove failed "
  			       "for pci_dev %s.
  ",
  			       __func__, module_name(is->is_owner),
  			       pci_name(idd->idd_pdev));
  		}
  	}
  	mutex_unlock(&ioc4_mutex);
  
  	/* Release resources */
  	iounmap(idd->idd_misc_regs);
  	if (!idd->idd_bar0) {
  		printk(KERN_WARNING
  		       "%s: Unable to get IOC4 misc mapping for pci_dev %s. "
  		       "Device removal may be incomplete.
  ",
  		       __func__, pci_name(idd->idd_pdev));
  	}
  	release_mem_region(idd->idd_bar0, sizeof(struct ioc4_misc_regs));
  
  	/* Disable IOC4 and relinquish */
  	pci_disable_device(pdev);
  
  	/* Remove and free driver data */
  	mutex_lock(&ioc4_mutex);
  	list_del(&idd->idd_list);
  	mutex_unlock(&ioc4_mutex);
  	kfree(idd);
  }
  
  static struct pci_device_id ioc4_id_table[] = {
  	{PCI_VENDOR_ID_SGI, PCI_DEVICE_ID_SGI_IOC4, PCI_ANY_ID,
  	 PCI_ANY_ID, 0x0b4000, 0xFFFFFF},
  	{0}
  };
  
  static struct pci_driver ioc4_driver = {
  	.name = "IOC4",
  	.id_table = ioc4_id_table,
  	.probe = ioc4_probe,
  	.remove = ioc4_remove,
  };
  
  MODULE_DEVICE_TABLE(pci, ioc4_id_table);
  
  /*********************
   * Module management *
   *********************/
  
  /* Module load */
  static int __init
  ioc4_init(void)
  {
  	return pci_register_driver(&ioc4_driver);
  }
  
  /* Module unload */
  static void __exit
  ioc4_exit(void)
  {
  	/* Ensure ioc4_load_modules() has completed before exiting */
  	flush_work(&ioc4_load_modules_work);
  	pci_unregister_driver(&ioc4_driver);
  }
  
  module_init(ioc4_init);
  module_exit(ioc4_exit);
  
  MODULE_AUTHOR("Brent Casavant - Silicon Graphics, Inc. <bcasavan@sgi.com>");
  MODULE_DESCRIPTION("PCI driver master module for SGI IOC4 Base-IO Card");
  MODULE_LICENSE("GPL");
  
  EXPORT_SYMBOL(ioc4_register_submodule);
  EXPORT_SYMBOL(ioc4_unregister_submodule);