FreeBSD/Linux Kernel Cross Reference
sys/dev/imcsmb/imcsmb_pci.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Authors: Joe Kloss; Ravi Pokala (rpokala@freebsd.org)
      *
      * Copyright (c) 2017-2018 Panasas
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/endian.h>
    #include <sys/errno.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/syslog.h>
    #include <sys/bus.h>
    
    #include <machine/bus.h>
    #include <machine/atomic.h>
    
    #include <dev/pci/pcivar.h>
    #include <dev/pci/pcireg.h>
    
    #include <dev/smbus/smbconf.h>
    
    #include "imcsmb_reg.h"
    #include "imcsmb_var.h"
    
    /* (Sandy,Ivy)bridge-Xeon and (Has,Broad)well-Xeon CPUs contain one or two
     * "Integrated Memory Controllers" (iMCs), and each iMC contains two separate
     * SMBus controllers. These are used for reading SPD data from the DIMMs, and
     * for reading the "Thermal Sensor on DIMM" (TSODs). The iMC SMBus controllers
     * are very simple devices, and have limited functionality compared to
     * full-fledged SMBus controllers, like the one in Intel ICHs and PCHs.
     *
     * The publicly available documentation for the iMC SMBus controllers can be
     * found in the CPU datasheets for (Sandy,Ivy)bridge-Xeon and
     * (Has,broad)well-Xeon, respectively:
     *
     * https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/
     *      Sandybridge     xeon-e5-1600-2600-vol-2-datasheet.pdf
     *      Ivybridge       xeon-e5-v2-datasheet-vol-2.pdf
     *      Haswell         xeon-e5-v3-datasheet-vol-2.pdf
     *      Broadwell       xeon-e5-v4-datasheet-vol-2.pdf
     *
     * Another useful resource is the Linux driver. It is not in the main tree.
     *
     * https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg840043.html
     *
     * The iMC SMBus controllers do not support interrupts (thus, they must be
     * polled for IO completion). All of the iMC registers are in PCI configuration
     * space; there is no support for PIO or MMIO. As a result, this driver does
     * not need to perform and newbus resource manipulation.
     *
     * Because there are multiple SMBus controllers sharing the same PCI device,
     * this driver is actually *two* drivers:
     *
     * - "imcsmb" is an smbus(4)-compliant SMBus controller driver
     *
     * - "imcsmb_pci" recognizes the PCI device and assigns the appropriate set of
     *    PCI config registers to a specific "imcsmb" instance.
     */
    
    /* Depending on the motherboard and firmware, the TSODs might be polled by
     * firmware. Therefore, when this driver accesses these SMBus controllers, the
     * firmware polling must be disabled as part of requesting the bus, and
     * re-enabled when releasing the bus. Unfortunately, the details of how to do
     * this are vendor-specific. Contact your motherboard vendor to get the
     * information you need to do proper implementations.
     *
     * For NVDIMMs which conform to the ACPI "NFIT" standard, the ACPI firmware
     * manages the NVDIMM; for those which pre-date the standard, the operating
     * system interacts with the NVDIMM controller using a vendor-proprietary API
     * over the SMBus. In that case, the NVDIMM driver would be an SMBus slave
    * device driver, and would interface with the hardware via an SMBus controller
    * driver such as this one.
    */
   
   /* PCIe device IDs for (Sandy,Ivy)bridge)-Xeon and (Has,Broad)well-Xeon */
   #define PCI_VENDOR_INTEL                0x8086
   #define IMCSMB_PCI_DEV_ID_IMC0_SBX      0x3ca8
   #define IMCSMB_PCI_DEV_ID_IMC0_IBX      0x0ea8
   #define IMCSMB_PCI_DEV_ID_IMC0_HSX      0x2fa8
   #define IMCSMB_PCI_DEV_ID_IMC0_BDX      0x6fa8
   /* (Sandy,Ivy)bridge-Xeon only have a single memory controller per socket */
   #define IMCSMB_PCI_DEV_ID_IMC1_HSX      0x2f68
   #define IMCSMB_PCI_DEV_ID_IMC1_BDX      0x6f68
   
   /* There are two SMBus controllers in each device. These define the registers
    * for each of these devices.
    */
   static struct imcsmb_reg_set imcsmb_regs[] = {
           {
                   .smb_stat = IMCSMB_REG_STATUS0,
                   .smb_cmd = IMCSMB_REG_COMMAND0,
                   .smb_cntl = IMCSMB_REG_CONTROL0
           },
           {
                   .smb_stat = IMCSMB_REG_STATUS1,
                   .smb_cmd = IMCSMB_REG_COMMAND1,
                   .smb_cntl = IMCSMB_REG_CONTROL1
           },
   };
   
   static struct imcsmb_pci_device {
           uint16_t        id;
           char            *name;
   } imcsmb_pci_devices[] = {
           {IMCSMB_PCI_DEV_ID_IMC0_SBX,
               "Intel Sandybridge Xeon iMC 0 SMBus controllers"    },
           {IMCSMB_PCI_DEV_ID_IMC0_IBX,
               "Intel Ivybridge Xeon iMC 0 SMBus controllers"      },
           {IMCSMB_PCI_DEV_ID_IMC0_HSX,
               "Intel Haswell Xeon iMC 0 SMBus controllers"        },
           {IMCSMB_PCI_DEV_ID_IMC1_HSX,
               "Intel Haswell Xeon iMC 1 SMBus controllers"        },
           {IMCSMB_PCI_DEV_ID_IMC0_BDX,
               "Intel Broadwell Xeon iMC 0 SMBus controllers"      },
           {IMCSMB_PCI_DEV_ID_IMC1_BDX,
               "Intel Broadwell Xeon iMC 1 SMBus controllers"      },
           {0, NULL},
   };
   
   /* Device methods. */
   static int imcsmb_pci_attach(device_t dev);
   static int imcsmb_pci_detach(device_t dev);
   static int imcsmb_pci_probe(device_t dev);
   
   /**
    * device_attach() method. Set up the PCI device's softc, then explicitly create
    * children for the actual imcsmbX controllers. Set up the child's ivars to
    * point to the proper set of the PCI device's config registers.
    *
    * @author Joe Kloss, rpokala
    *
    * @param[in,out] dev
    *      Device being attached.
    */
   static int
   imcsmb_pci_attach(device_t dev)
   {
           struct imcsmb_pci_softc *sc;
           device_t child;
           int rc;
           int unit;
   
           /* Initialize private state */
           sc = device_get_softc(dev);
           sc->dev = dev;
           sc->semaphore = 0;
   
           /* Create the imcsmbX children */
           for (unit = 0; unit < 2; unit++) {
                   child = device_add_child(dev, "imcsmb", -1);
                   if (child == NULL) {
                           /* Nothing has been allocated, so there's no cleanup. */
                           device_printf(dev, "Child imcsmb not added\n");
                           rc = ENXIO;
                           goto out;
                   }
                   /* Set the child's ivars to point to the appropriate set of
                    * the PCI device's registers.
                    */
                   device_set_ivars(child, &imcsmb_regs[unit]);
           }
   
           /* Attach the imcsmbX children. */
           if ((rc = bus_generic_attach(dev)) != 0) {
                   device_printf(dev, "failed to attach children: %d\n", rc);
                   goto out;
           }
   
   out:
           return (rc);
   }
   
   /**
    * device_detach() method. attach() didn't do any allocations, so all that's
    * needed here is to free up any downstream drivers and children.
    *
    * @author Joe Kloss
    *
    * @param[in] dev
    *      Device being detached.
    */
   static int
   imcsmb_pci_detach(device_t dev)
   {
           int rc;
   
           /* Detach any attached drivers */
           rc = bus_generic_detach(dev);
           if (rc == 0) {
                   /* Remove all children */
                   rc = device_delete_children(dev);
           }
   
           return (rc);
   }
   
   /**
    * device_probe() method. Look for the right PCI vendor/device IDs.
    *
    * @author Joe Kloss, rpokala
    *
    * @param[in,out] dev
    *      Device being probed.
    */
   static int
   imcsmb_pci_probe(device_t dev)
   {
           struct imcsmb_pci_device *pci_device;
           int rc;
           uint16_t pci_dev_id;
   
           rc = ENXIO;
   
           if (pci_get_vendor(dev) != PCI_VENDOR_INTEL) {
                   goto out;
           }
   
           pci_dev_id = pci_get_device(dev);
           for (pci_device = imcsmb_pci_devices;
               pci_device->name != NULL;
               pci_device++) {
                   if (pci_dev_id == pci_device->id) {
                           device_set_desc(dev, pci_device->name);
                           rc = BUS_PROBE_DEFAULT;
                           goto out;
                   }
           }
   
   out:
           return (rc);
   }
   
   /**
    * Invoked via smbus_callback() -> imcsmb_callback(); clear the semaphore, and
    * re-enable motherboard-specific DIMM temperature monitoring if needed. This
    * gets called after the transaction completes.
    *
    * @author Joe Kloss
    *
    * @param[in,out] dev
    *      The device whose busses to release.
    */
   void
   imcsmb_pci_release_bus(device_t dev)
   {
           struct imcsmb_pci_softc *sc;
   
           sc = device_get_softc(dev);
   
           /*
            * IF NEEDED, INSERT MOTHERBOARD-SPECIFIC CODE TO RE-ENABLE DIMM
            * TEMPERATURE MONITORING HERE.
            */
   
           atomic_store_rel_int(&sc->semaphore, 0);
   }
   
   /**
    * Invoked via smbus_callback() -> imcsmb_callback(); set the semaphore, and
    * disable motherboard-specific DIMM temperature monitoring if needed. This gets
    * called before the transaction starts.
    *
    * @author Joe Kloss
    *
    * @param[in,out] dev
    *      The device whose busses to request.
    */
   int
   imcsmb_pci_request_bus(device_t dev)
   {
           struct imcsmb_pci_softc *sc;
           int rc;
   
           sc = device_get_softc(dev);
           rc = 0;
   
           /* We don't want to block. Use a simple test-and-set semaphore to
            * protect the bus.
            */
           if (atomic_cmpset_acq_int(&sc->semaphore, 0, 1) == 0) {
                   rc = EWOULDBLOCK;
           }
   
           /*
            * IF NEEDED, INSERT MOTHERBOARD-SPECIFIC CODE TO DISABLE DIMM
            * TEMPERATURE MONITORING HERE.
            */
   
           return (rc);
   }
   
   /* Device methods */
   static device_method_t imcsmb_pci_methods[] = {
           /* Device interface */
           DEVMETHOD(device_attach,        imcsmb_pci_attach),
           DEVMETHOD(device_detach,        imcsmb_pci_detach),
           DEVMETHOD(device_probe,         imcsmb_pci_probe),
   
           DEVMETHOD_END
   };
   
   static driver_t imcsmb_pci_driver = {
           .name = "imcsmb_pci",
           .methods = imcsmb_pci_methods,
           .size = sizeof(struct imcsmb_pci_softc),
   };
   
   DRIVER_MODULE(imcsmb_pci, pci, imcsmb_pci_driver, 0, 0);
   MODULE_DEPEND(imcsmb_pci, pci, 1, 1, 1);
   MODULE_VERSION(imcsmb_pci, 1);
   
   /* vi: set ts=8 sw=4 sts=8 noet: */

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