FreeBSD/Linux Kernel Cross Reference
sys/dev/imcsmb/imcsmb.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.
     *
     * $FreeBSD$
     */
    
    /* A detailed description of this device is present in imcsmb_pci.c */
    
    #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"
    
    /* Device methods */
    static int imcsmb_attach(device_t dev);
    static int imcsmb_detach(device_t dev);
    static int imcsmb_probe(device_t dev);
    
    /* SMBus methods */
    static int imcsmb_callback(device_t dev, int index, void *data);
    static int imcsmb_readb(device_t dev, u_char slave, char cmd, char *byte);
    static int imcsmb_readw(device_t dev, u_char slave, char cmd, short *word);
    static int imcsmb_writeb(device_t dev, u_char slave, char cmd, char byte);
    static int imcsmb_writew(device_t dev, u_char slave, char cmd, short word);
    
    /* All the read/write methods wrap around this. */
    static int imcsmb_transfer(device_t dev, u_char slave, char cmd, void *data,
        int word_op, int write_op);
    
    /**
     * device_attach() method. Set up the softc, including getting the set of the
     * parent imcsmb_pci's registers that we will use. Create the smbus(4) device,
     * which any SMBus slave device drivers will connect to.
     *
     * @author rpokala
     *
     * @param[in,out] dev
     *      Device being attached.
     */
    static int
    imcsmb_attach(device_t dev)
    {
            struct imcsmb_softc *sc;
            int rc;
    
            /* Initialize private state */
            sc = device_get_softc(dev);
            sc->dev = dev;
            sc->imcsmb_pci = device_get_parent(dev);
            sc->regs = device_get_ivars(dev);
    
            /* Create the smbus child */
            sc->smbus = device_add_child(dev, "smbus", -1);
            if (sc->smbus == NULL) {
                    /* Nothing has been allocated, so there's no cleanup. */
                    device_printf(dev, "Child smbus not added\n");
                    rc = ENXIO;
                   goto out;
           }
   
           /* Attach the smbus child. */
           if ((rc = bus_generic_attach(dev)) != 0) {
                   device_printf(dev, "Failed to attach smbus: %d\n", rc);
           }
   
   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_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. All the actual probing was done by the imcsmb_pci
    * parent, so just report success.
    *
    * @author Joe Kloss
    *
    * @param[in,out] dev
    *      Device being probed.
    */
   static int
   imcsmb_probe(device_t dev)
   {
   
           device_set_desc(dev, "iMC SMBus controller");
           return (BUS_PROBE_DEFAULT);
   }
   
   /**
    * smbus_callback() method. Call the parent imcsmb_pci's request or release
    * function to quiesce / restart firmware tasks which might use the SMBus.
    *
    * @author rpokala
    *
    * @param[in] dev
    *      Device being requested or released.
    *
    * @param[in] index
    *      Either SMB_REQUEST_BUS or SMB_RELEASE_BUS.
    *
    * @param[in] data
    *      Tell's the rest of the SMBus subsystem to allow or disallow waiting;
    *      this driver only works with SMB_DONTWAIT.
    */
   static int
   imcsmb_callback(device_t dev, int index, void *data)
   {
           struct imcsmb_softc *sc;
           int *how;
           int rc;
   
           sc = device_get_softc(dev);
           how = (int *) data;
   
           switch (index) {
           case SMB_REQUEST_BUS: {
                   if (*how != SMB_DONTWAIT) {
                           rc = EINVAL;
                           goto out;
                   }
                   rc = imcsmb_pci_request_bus(sc->imcsmb_pci);
                   break;
           }
           case SMB_RELEASE_BUS:
                   imcsmb_pci_release_bus(sc->imcsmb_pci);
                   rc = 0;
                   break;
           default:
                   rc = EINVAL;
                   break;
           }
   
   out:
           return (rc);
   }
   
   /**
    * smbus_readb() method. Thin wrapper around imcsmb_transfer().
    *
    * @author Joe Kloss
    *
    * @param[in] dev
    *
    * @param[in] slave
    *      The SMBus address of the target device.
    *
    * @param[in] cmd
    *      The SMBus command for the target device; this is the offset for SPDs,
    *      or the register number for TSODs.
    *
    * @param[out] byte
    *      The byte which was read.
    */
   static int
   imcsmb_readb(device_t dev, u_char slave, char cmd, char *byte)
   {
   
           return (imcsmb_transfer(dev, slave, cmd, byte, FALSE, FALSE));
   }
   
   /**
    * smbus_readw() method. Thin wrapper around imcsmb_transfer().
    *
    * @author Joe Kloss
    *
    * @param[in] dev
    *
    * @param[in] slave
    *      The SMBus address of the target device.
    *
    * @param[in] cmd
    *      The SMBus command for the target device; this is the offset for SPDs,
    *      or the register number for TSODs.
    *
    * @param[out] word
    *      The word which was read.
    */
   static int
   imcsmb_readw(device_t dev, u_char slave, char cmd, short *word)
   {
   
           return (imcsmb_transfer(dev, slave, cmd, word, TRUE, FALSE));
   }
   
   /**
    * smbus_writeb() method. Thin wrapper around imcsmb_transfer().
    *
    * @author Joe Kloss
    *
    * @param[in] dev
    *
    * @param[in] slave
    *      The SMBus address of the target device.
    *
    * @param[in] cmd
    *      The SMBus command for the target device; this is the offset for SPDs,
    *      or the register number for TSODs.
    *
    * @param[in] byte
    *      The byte to write.
    */
   static int
   imcsmb_writeb(device_t dev, u_char slave, char cmd, char byte)
   {
   
           return (imcsmb_transfer(dev, slave, cmd, &byte, FALSE, TRUE));
   }
   
   /**
    * smbus_writew() method. Thin wrapper around imcsmb_transfer().
    *
    * @author Joe Kloss
    *
    * @param[in] dev
    *
    * @param[in] slave
    *      The SMBus address of the target device.
    *
    * @param[in] cmd
    *      The SMBus command for the target device; this is the offset for SPDs,
    *      or the register number for TSODs.
    *
    * @param[in] word
    *      The word to write.
    */
   static int
   imcsmb_writew(device_t dev, u_char slave, char cmd, short word)
   {
   
           return (imcsmb_transfer(dev, slave, cmd, &word, TRUE, TRUE));
   }
   
   /**
    * Manipulate the PCI control registers to read data from or write data to the
    * SMBus controller.
    *
    * @author Joe Kloss, rpokala
    *
    * @param[in] dev
    *
    * @param[in] slave
    *      The SMBus address of the target device.
    *
    * @param[in] cmd
    *      The SMBus command for the target device; this is the offset for SPDs,
    *      or the register number for TSODs.
    *
    * @param[in,out] data
    *      Pointer to either the value to be written, or where to place the value
    *      which was read.
    *
    * @param[in] word_op
    *      Bool: is this a word operation?
    *
    * @param[in] write_op
    *      Bool: is this a write operation?
    */
   static int
   imcsmb_transfer(device_t dev, u_char slave, char cmd, void *data, int word_op,
       int write_op)
   {
           struct imcsmb_softc *sc;
           int i;
           int rc;
           uint32_t cmd_val;
           uint32_t cntl_val;
           uint32_t orig_cntl_val;
           uint32_t stat_val;
           uint16_t *word;
           uint16_t lword;
           uint8_t *byte;
           uint8_t lbyte;
   
           sc = device_get_softc(dev);
           byte = data;
           word = data;
           lbyte = *byte;
           lword = *word;
   
           /* We modify the value of the control register; save the original, so
            * we can restore it later
            */
           orig_cntl_val = pci_read_config(sc->imcsmb_pci,
               sc->regs->smb_cntl, 4);
           cntl_val = orig_cntl_val;
   
           /*
            * Set up the SMBCNTL register
            */
   
           /* [31:28] Clear the existing value of the DTI bits, then set them to
            * the four high bits of the slave address.
            */
           cntl_val &= ~IMCSMB_CNTL_DTI_MASK;
           cntl_val |= ((uint32_t) slave & 0xf0) << 24;
   
           /* [27:27] Set the CLK_OVERRIDE bit, to enable normal operation */
           cntl_val |= IMCSMB_CNTL_CLK_OVERRIDE;
   
           /* [26:26] Clear the WRITE_DISABLE bit; the datasheet says this isn't
            * necessary, but empirically, it is.
            */
           cntl_val &= ~IMCSMB_CNTL_WRITE_DISABLE_BIT;
   
           /* [9:9] Clear the POLL_EN bit, to stop the hardware TSOD polling. */
           cntl_val &= ~IMCSMB_CNTL_POLL_EN;
   
           /*
            * Set up the SMBCMD register
            */
   
           /* [31:31] Set the TRIGGER bit; when this gets written, the controller
            * will issue the command.
            */
           cmd_val = IMCSMB_CMD_TRIGGER_BIT;
   
           /* [29:29] For word operations, set the WORD_ACCESS bit. */
           if (word_op) {
                   cmd_val |= IMCSMB_CMD_WORD_ACCESS;
           }
   
           /* [27:27] For write operations, set the WRITE bit. */
           if (write_op) {
                   cmd_val |= IMCSMB_CMD_WRITE_BIT;
           }
   
           /* [26:24] The three non-DTI, non-R/W bits of the slave address. */
           cmd_val |= (uint32_t) ((slave & 0xe) << 23);
   
           /* [23:16] The command (offset in the case of an EEPROM, or register in
            * the case of TSOD or NVDIMM controller).
            */
           cmd_val |= (uint32_t) ((uint8_t) cmd << 16);
   
           /* [15:0] The data to be written for a write operation. */
           if (write_op) {
                   if (word_op) {
                           /* The datasheet says the controller uses different
                            * endianness for word operations on I2C vs SMBus!
                            *      I2C: [15:8] = MSB; [7:0] = LSB
                            *      SMB: [15:8] = LSB; [7:0] = MSB
                            * As a practical matter, this controller is very
                            * specifically for use with DIMMs, the SPD (and
                            * NVDIMM controllers) are only accessed as bytes,
                            * the temperature sensor is only accessed as words, and
                            * the temperature sensors are I2C. Thus, byte-swap the
                            * word.
                            */
                           lword = htobe16(lword);
                   } else {
                           /* For byte operations, the data goes in the LSB, and
                            * the MSB is a don't care.
                            */
                           lword = (uint16_t) (lbyte & 0xff);
                   }
                   cmd_val |= lword;
           }
   
           /* Write the updated value to the control register first, to disable
            * the hardware TSOD polling.
            */
           pci_write_config(sc->imcsmb_pci, sc->regs->smb_cntl, cntl_val, 4);
   
           /* Poll on the BUSY bit in the status register until clear, or timeout.
            * We just cleared the auto-poll bit, so we need to make sure the device
            * is idle before issuing a command. We can safely timeout after 35 ms,
            * as this is the maximum time the SMBus spec allows for a transaction.
            */
           for (i = 4; i != 0; i--) {
                   stat_val = pci_read_config(sc->imcsmb_pci, sc->regs->smb_stat,
                       4);
                   if ((stat_val & IMCSMB_STATUS_BUSY_BIT) == 0) {
                           break;
                   }
                   pause("imcsmb", 10 * hz / 1000);
           }
   
           if (i == 0) {
                   device_printf(sc->dev,
                       "transfer: timeout waiting for device to settle\n");
           }
   
           /* Now that polling has stopped, we can write the command register. This
            * starts the SMBus command.
            */
           pci_write_config(sc->imcsmb_pci, sc->regs->smb_cmd, cmd_val, 4);
   
           /* Wait for WRITE_DATA_DONE/READ_DATA_VALID to be set, or timeout and
            * fail. We wait up to 35ms.
            */
           for (i = 35000; i != 0; i -= 10)
           {
                   DELAY(10);
                   stat_val = pci_read_config(sc->imcsmb_pci, sc->regs->smb_stat,
                       4);
                   /* For a write, the bits holding the data contain the data being
                    * written. You'd think that would cause the READ_DATA_VALID bit
                    * to be cleared, because the data bits no longer contain valid
                    * data from the most recent read operation. While that would be
                    * logical, that's not the case here: READ_DATA_VALID is only
                    * cleared when starting a read operation, and WRITE_DATA_DONE
                    * is only cleared when starting a write operation.
                    */
                   if (write_op) {
                           if ((stat_val & IMCSMB_STATUS_WRITE_DATA_DONE) != 0) {
                                   break;
                           }
                   } else {
                           if ((stat_val & IMCSMB_STATUS_READ_DATA_VALID) != 0) {
                                   break;
                           }
                   }
           }
           if (i == 0) {
                   rc = SMB_ETIMEOUT;
                   device_printf(dev, "transfer timeout\n");
                   goto out;
           }
   
           /* It is generally the case that this bit indicates non-ACK, but it
            * could also indicate other bus errors. There's no way to tell the
            * difference.
            */
           if ((stat_val & IMCSMB_STATUS_BUS_ERROR_BIT) != 0) {
                   /* While it is not documented, empirically, SPD page-change
                    * commands (writes with DTI = 0x60) always complete with the
                    * error bit set. So, ignore it in those cases.
                    */
                   if ((slave & 0xf0) != 0x60) {
                           rc = SMB_ENOACK;
                           goto out;
                   }
           }
   
           /* For a read operation, copy the data out */
           if (write_op == 0) {
                   if (word_op) {
                           /* The data is returned in bits [15:0]; as discussed
                            * above, byte-swap.
                            */
                           lword = (uint16_t) (stat_val & 0xffff);
                           lword = htobe16(lword);
                           *word = lword;
                   } else {
                           /* The data is returned in bits [7:0] */
                           lbyte = (uint8_t) (stat_val & 0xff);
                           *byte = lbyte;
                   }
           }
   
           /* A lack of an error is, de facto, success. */
           rc = SMB_ENOERR;
   
   out:
           /* Restore the original value of the control register. */
           pci_write_config(sc->imcsmb_pci, sc->regs->smb_cntl, orig_cntl_val, 4);
           return (rc);
   }
   
   /* Device methods */
   static device_method_t imcsmb_methods[] = {
           /* Device interface */
           DEVMETHOD(device_attach,        imcsmb_attach),
           DEVMETHOD(device_detach,        imcsmb_detach),
           DEVMETHOD(device_probe,         imcsmb_probe),
   
           /* smbus methods */
           DEVMETHOD(smbus_callback,       imcsmb_callback),
           DEVMETHOD(smbus_readb,          imcsmb_readb),
           DEVMETHOD(smbus_readw,          imcsmb_readw),
           DEVMETHOD(smbus_writeb,         imcsmb_writeb),
           DEVMETHOD(smbus_writew,         imcsmb_writew),
   
           DEVMETHOD_END
   };
   
   static driver_t imcsmb_driver = {
           .name = "imcsmb",
           .methods = imcsmb_methods,
           .size = sizeof(struct imcsmb_softc),
   };
   
   DRIVER_MODULE(imcsmb, imcsmb_pci, imcsmb_driver, 0, 0);
   MODULE_DEPEND(imcsmb, smbus, SMBUS_MINVER, SMBUS_PREFVER, SMBUS_MAXVER);
   MODULE_VERSION(imcsmb, 1);
   
   DRIVER_MODULE(smbus, imcsmb, smbus_driver, 0, 0);
   
   /* vi: set ts=8 sw=4 sts=8 noet: */

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