treewide: remove redundant IS_ERR() before error code check

[linux/fpc-iii.git] / drivers / rapidio / rio-scan.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * RapidIO enumeration and discovery support
 *
 * Copyright 2005 MontaVista Software, Inc.
 * Matt Porter <mporter@kernel.crashing.org>
 *
 * Copyright 2009 Integrated Device Technology, Inc.
 * Alex Bounine <alexandre.bounine@idt.com>
 * - Added Port-Write/Error Management initialization and handling
 *
 * Copyright 2009 Sysgo AG
 * Thomas Moll <thomas.moll@sysgo.com>
 * - Added Input- Output- enable functionality, to allow full communication
 */

#include <linux/types.h>
#include <linux/kernel.h>

#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/rio.h>
#include <linux/rio_drv.h>
#include <linux/rio_ids.h>
#include <linux/rio_regs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/jiffies.h>
#include <linux/slab.h>

#include "rio.h"

static void rio_init_em(struct rio_dev *rdev);

struct rio_id_table {
        u16 start;      /* logical minimal id */
        u32 max;        /* max number of IDs in table */
        spinlock_t lock;
        unsigned long table[0];
};

static int next_destid = 0;
static int next_comptag = 1;

/**
 * rio_destid_alloc - Allocate next available destID for given network
 * @net: RIO network
 *
 * Returns next available device destination ID for the specified RIO network.
 * Marks allocated ID as one in use.
 * Returns RIO_INVALID_DESTID if new destID is not available.
 */
static u16 rio_destid_alloc(struct rio_net *net)
{
        int destid;
        struct rio_id_table *idtab = (struct rio_id_table *)net->enum_data;

        spin_lock(&idtab->lock);
        destid = find_first_zero_bit(idtab->table, idtab->max);

        if (destid < idtab->max) {
                set_bit(destid, idtab->table);
                destid += idtab->start;
        } else
                destid = RIO_INVALID_DESTID;

        spin_unlock(&idtab->lock);
        return (u16)destid;
}

/**
 * rio_destid_reserve - Reserve the specified destID
 * @net: RIO network
 * @destid: destID to reserve
 *
 * Tries to reserve the specified destID.
 * Returns 0 if successful.
 */
static int rio_destid_reserve(struct rio_net *net, u16 destid)
{
        int oldbit;
        struct rio_id_table *idtab = (struct rio_id_table *)net->enum_data;

        destid -= idtab->start;
        spin_lock(&idtab->lock);
        oldbit = test_and_set_bit(destid, idtab->table);
        spin_unlock(&idtab->lock);
        return oldbit;
}

/**
 * rio_destid_free - free a previously allocated destID
 * @net: RIO network
 * @destid: destID to free
 *
 * Makes the specified destID available for use.
 */
static void rio_destid_free(struct rio_net *net, u16 destid)
{
        struct rio_id_table *idtab = (struct rio_id_table *)net->enum_data;

        destid -= idtab->start;
        spin_lock(&idtab->lock);
        clear_bit(destid, idtab->table);
        spin_unlock(&idtab->lock);
}

/**
 * rio_destid_first - return first destID in use
 * @net: RIO network
 */
static u16 rio_destid_first(struct rio_net *net)
{
        int destid;
        struct rio_id_table *idtab = (struct rio_id_table *)net->enum_data;

        spin_lock(&idtab->lock);
        destid = find_first_bit(idtab->table, idtab->max);
        if (destid >= idtab->max)
                destid = RIO_INVALID_DESTID;
        else
                destid += idtab->start;
        spin_unlock(&idtab->lock);
        return (u16)destid;
}

/**
 * rio_destid_next - return next destID in use
 * @net: RIO network
 * @from: destination ID from which search shall continue
 */
static u16 rio_destid_next(struct rio_net *net, u16 from)
{
        int destid;
        struct rio_id_table *idtab = (struct rio_id_table *)net->enum_data;

        spin_lock(&idtab->lock);
        destid = find_next_bit(idtab->table, idtab->max, from);
        if (destid >= idtab->max)
                destid = RIO_INVALID_DESTID;
        else
                destid += idtab->start;
        spin_unlock(&idtab->lock);
        return (u16)destid;
}

/**
 * rio_get_device_id - Get the base/extended device id for a device
 * @port: RIO master port
 * @destid: Destination ID of device
 * @hopcount: Hopcount to device
 *
 * Reads the base/extended device id from a device. Returns the
 * 8/16-bit device ID.
 */
static u16 rio_get_device_id(struct rio_mport *port, u16 destid, u8 hopcount)
{
        u32 result;

        rio_mport_read_config_32(port, destid, hopcount, RIO_DID_CSR, &result);

        return RIO_GET_DID(port->sys_size, result);
}

/**
 * rio_set_device_id - Set the base/extended device id for a device
 * @port: RIO master port
 * @destid: Destination ID of device
 * @hopcount: Hopcount to device
 * @did: Device ID value to be written
 *
 * Writes the base/extended device id from a device.
 */
static void rio_set_device_id(struct rio_mport *port, u16 destid, u8 hopcount, u16 did)
{
        rio_mport_write_config_32(port, destid, hopcount, RIO_DID_CSR,
                                  RIO_SET_DID(port->sys_size, did));
}

/**
 * rio_clear_locks- Release all host locks and signal enumeration complete
 * @net: RIO network to run on
 *
 * Marks the component tag CSR on each device with the enumeration
 * complete flag. When complete, it then release the host locks on
 * each device. Returns 0 on success or %-EINVAL on failure.
 */
static int rio_clear_locks(struct rio_net *net)
{
        struct rio_mport *port = net->hport;
        struct rio_dev *rdev;
        u32 result;
        int ret = 0;

        /* Release host device id locks */
        rio_local_write_config_32(port, RIO_HOST_DID_LOCK_CSR,
                                  port->host_deviceid);
        rio_local_read_config_32(port, RIO_HOST_DID_LOCK_CSR, &result);
        if ((result & 0xffff) != 0xffff) {
                printk(KERN_INFO
                       "RIO: badness when releasing host lock on master port, result %8.8x\n",
                       result);
                ret = -EINVAL;
        }
        list_for_each_entry(rdev, &net->devices, net_list) {
                rio_write_config_32(rdev, RIO_HOST_DID_LOCK_CSR,
                                    port->host_deviceid);
                rio_read_config_32(rdev, RIO_HOST_DID_LOCK_CSR, &result);
                if ((result & 0xffff) != 0xffff) {
                        printk(KERN_INFO
                               "RIO: badness when releasing host lock on vid %4.4x did %4.4x\n",
                               rdev->vid, rdev->did);
                        ret = -EINVAL;
                }

                /* Mark device as discovered and enable master */
                rio_read_config_32(rdev,
                                   rdev->phys_efptr + RIO_PORT_GEN_CTL_CSR,
                                   &result);
                result |= RIO_PORT_GEN_DISCOVERED | RIO_PORT_GEN_MASTER;
                rio_write_config_32(rdev,
                                    rdev->phys_efptr + RIO_PORT_GEN_CTL_CSR,
                                    result);
        }

        return ret;
}

/**
 * rio_enum_host- Set host lock and initialize host destination ID
 * @port: Master port to issue transaction
 *
 * Sets the local host master port lock and destination ID register
 * with the host device ID value. The host device ID value is provided
 * by the platform. Returns %0 on success or %-1 on failure.
 */
static int rio_enum_host(struct rio_mport *port)
{
        u32 result;

        /* Set master port host device id lock */
        rio_local_write_config_32(port, RIO_HOST_DID_LOCK_CSR,
                                  port->host_deviceid);

        rio_local_read_config_32(port, RIO_HOST_DID_LOCK_CSR, &result);
        if ((result & 0xffff) != port->host_deviceid)
                return -1;

        /* Set master port destid and init destid ctr */
        rio_local_set_device_id(port, port->host_deviceid);
        return 0;
}

/**
 * rio_device_has_destid- Test if a device contains a destination ID register
 * @port: Master port to issue transaction
 * @src_ops: RIO device source operations
 * @dst_ops: RIO device destination operations
 *
 * Checks the provided @src_ops and @dst_ops for the necessary transaction
 * capabilities that indicate whether or not a device will implement a
 * destination ID register. Returns 1 if true or 0 if false.
 */
static int rio_device_has_destid(struct rio_mport *port, int src_ops,
                                 int dst_ops)
{
        u32 mask = RIO_OPS_READ | RIO_OPS_WRITE | RIO_OPS_ATOMIC_TST_SWP | RIO_OPS_ATOMIC_INC | RIO_OPS_ATOMIC_DEC | RIO_OPS_ATOMIC_SET | RIO_OPS_ATOMIC_CLR;

        return !!((src_ops | dst_ops) & mask);
}

/**
 * rio_release_dev- Frees a RIO device struct
 * @dev: LDM device associated with a RIO device struct
 *
 * Gets the RIO device struct associated a RIO device struct.
 * The RIO device struct is freed.
 */
static void rio_release_dev(struct device *dev)
{
        struct rio_dev *rdev;

        rdev = to_rio_dev(dev);
        kfree(rdev);
}

/**
 * rio_is_switch- Tests if a RIO device has switch capabilities
 * @rdev: RIO device
 *
 * Gets the RIO device Processing Element Features register
 * contents and tests for switch capabilities. Returns 1 if
 * the device is a switch or 0 if it is not a switch.
 * The RIO device struct is freed.
 */
static int rio_is_switch(struct rio_dev *rdev)
{
        if (rdev->pef & RIO_PEF_SWITCH)
                return 1;
        return 0;
}

/**
 * rio_setup_device- Allocates and sets up a RIO device
 * @net: RIO network
 * @port: Master port to send transactions
 * @destid: Current destination ID
 * @hopcount: Current hopcount
 * @do_enum: Enumeration/Discovery mode flag
 *
 * Allocates a RIO device and configures fields based on configuration
 * space contents. If device has a destination ID register, a destination
 * ID is either assigned in enumeration mode or read from configuration
 * space in discovery mode.  If the device has switch capabilities, then
 * a switch is allocated and configured appropriately. Returns a pointer
 * to a RIO device on success or NULL on failure.
 *
 */
static struct rio_dev *rio_setup_device(struct rio_net *net,
                                        struct rio_mport *port, u16 destid,
                                        u8 hopcount, int do_enum)
{
        int ret = 0;
        struct rio_dev *rdev;
        struct rio_switch *rswitch = NULL;
        int result, rdid;
        size_t size;
        u32 swpinfo = 0;

        size = sizeof(struct rio_dev);
        if (rio_mport_read_config_32(port, destid, hopcount,
                                     RIO_PEF_CAR, &result))
                return NULL;

        if (result & (RIO_PEF_SWITCH | RIO_PEF_MULTIPORT)) {
                rio_mport_read_config_32(port, destid, hopcount,
                                         RIO_SWP_INFO_CAR, &swpinfo);
                if (result & RIO_PEF_SWITCH) {
                        size += (RIO_GET_TOTAL_PORTS(swpinfo) *
                                sizeof(rswitch->nextdev[0])) + sizeof(*rswitch);
                }
        }

        rdev = kzalloc(size, GFP_KERNEL);
        if (!rdev)
                return NULL;

        rdev->net = net;
        rdev->pef = result;
        rdev->swpinfo = swpinfo;
        rio_mport_read_config_32(port, destid, hopcount, RIO_DEV_ID_CAR,
                                 &result);
        rdev->did = result >> 16;
        rdev->vid = result & 0xffff;
        rio_mport_read_config_32(port, destid, hopcount, RIO_DEV_INFO_CAR,
                                 &rdev->device_rev);
        rio_mport_read_config_32(port, destid, hopcount, RIO_ASM_ID_CAR,
                                 &result);
        rdev->asm_did = result >> 16;
        rdev->asm_vid = result & 0xffff;
        rio_mport_read_config_32(port, destid, hopcount, RIO_ASM_INFO_CAR,
                                 &result);
        rdev->asm_rev = result >> 16;
        if (rdev->pef & RIO_PEF_EXT_FEATURES) {
                rdev->efptr = result & 0xffff;
                rdev->phys_efptr = rio_mport_get_physefb(port, 0, destid,
                                                hopcount, &rdev->phys_rmap);
                pr_debug("RIO: %s Register Map %d device\n",
                         __func__, rdev->phys_rmap);

                rdev->em_efptr = rio_mport_get_feature(port, 0, destid,
                                                hopcount, RIO_EFB_ERR_MGMNT);
                if (!rdev->em_efptr)
                        rdev->em_efptr = rio_mport_get_feature(port, 0, destid,
                                                hopcount, RIO_EFB_ERR_MGMNT_HS);
        }

        rio_mport_read_config_32(port, destid, hopcount, RIO_SRC_OPS_CAR,
                                 &rdev->src_ops);
        rio_mport_read_config_32(port, destid, hopcount, RIO_DST_OPS_CAR,
                                 &rdev->dst_ops);

        if (do_enum) {
                /* Assign component tag to device */
                if (next_comptag >= 0x10000) {
                        pr_err("RIO: Component Tag Counter Overflow\n");
                        goto cleanup;
                }
                rio_mport_write_config_32(port, destid, hopcount,
                                          RIO_COMPONENT_TAG_CSR, next_comptag);
                rdev->comp_tag = next_comptag++;
                rdev->do_enum = true;
        }  else {
                rio_mport_read_config_32(port, destid, hopcount,
                                         RIO_COMPONENT_TAG_CSR,
                                         &rdev->comp_tag);
        }

        if (rio_device_has_destid(port, rdev->src_ops, rdev->dst_ops)) {
                if (do_enum) {
                        rio_set_device_id(port, destid, hopcount, next_destid);
                        rdev->destid = next_destid;
                        next_destid = rio_destid_alloc(net);
                } else
                        rdev->destid = rio_get_device_id(port, destid, hopcount);

                rdev->hopcount = 0xff;
        } else {
                /* Switch device has an associated destID which
                 * will be adjusted later
                 */
                rdev->destid = destid;
                rdev->hopcount = hopcount;
        }

        /* If a PE has both switch and other functions, show it as a switch */
        if (rio_is_switch(rdev)) {
                rswitch = rdev->rswitch;
                rswitch->port_ok = 0;
                spin_lock_init(&rswitch->lock);
                rswitch->route_table =
                        kzalloc(RIO_MAX_ROUTE_ENTRIES(port->sys_size),
                                GFP_KERNEL);
                if (!rswitch->route_table)
                        goto cleanup;
                /* Initialize switch route table */
                for (rdid = 0; rdid < RIO_MAX_ROUTE_ENTRIES(port->sys_size);
                                rdid++)
                        rswitch->route_table[rdid] = RIO_INVALID_ROUTE;
                dev_set_name(&rdev->dev, "%02x:s:%04x", rdev->net->id,
                             rdev->comp_tag & RIO_CTAG_UDEVID);

                if (do_enum)
                        rio_route_clr_table(rdev, RIO_GLOBAL_TABLE, 0);
        } else {
                if (do_enum)
                        /*Enable Input Output Port (transmitter receiver)*/
                        rio_enable_rx_tx_port(port, 0, destid, hopcount, 0);

                dev_set_name(&rdev->dev, "%02x:e:%04x", rdev->net->id,
                             rdev->comp_tag & RIO_CTAG_UDEVID);
        }

        rdev->dev.parent = &net->dev;
        rio_attach_device(rdev);
        rdev->dev.release = rio_release_dev;
        rdev->dma_mask = DMA_BIT_MASK(32);
        rdev->dev.dma_mask = &rdev->dma_mask;
        rdev->dev.coherent_dma_mask = DMA_BIT_MASK(32);

        if (rdev->dst_ops & RIO_DST_OPS_DOORBELL)
                rio_init_dbell_res(&rdev->riores[RIO_DOORBELL_RESOURCE],
                                   0, 0xffff);

        ret = rio_add_device(rdev);
        if (ret)
                goto cleanup;

        rio_dev_get(rdev);

        return rdev;

cleanup:
        if (rswitch)
                kfree(rswitch->route_table);

        kfree(rdev);
        return NULL;
}

/**
 * rio_sport_is_active- Tests if a switch port has an active connection.
 * @rdev: RapidIO device object
 * @sp: Switch port number
 *
 * Reads the port error status CSR for a particular switch port to
 * determine if the port has an active link.  Returns
 * %RIO_PORT_N_ERR_STS_PORT_OK if the port is active or %0 if it is
 * inactive.
 */
static int
rio_sport_is_active(struct rio_dev *rdev, int sp)
{
        u32 result = 0;

        rio_read_config_32(rdev, RIO_DEV_PORT_N_ERR_STS_CSR(rdev, sp),
                           &result);

        return result & RIO_PORT_N_ERR_STS_PORT_OK;
}

/**
 * rio_get_host_deviceid_lock- Reads the Host Device ID Lock CSR on a device
 * @port: Master port to send transaction
 * @hopcount: Number of hops to the device
 *
 * Used during enumeration to read the Host Device ID Lock CSR on a
 * RIO device. Returns the value of the lock register.
 */
static u16 rio_get_host_deviceid_lock(struct rio_mport *port, u8 hopcount)
{
        u32 result;

        rio_mport_read_config_32(port, RIO_ANY_DESTID(port->sys_size), hopcount,
                                 RIO_HOST_DID_LOCK_CSR, &result);

        return (u16) (result & 0xffff);
}

/**
 * rio_enum_peer- Recursively enumerate a RIO network through a master port
 * @net: RIO network being enumerated
 * @port: Master port to send transactions
 * @hopcount: Number of hops into the network
 * @prev: Previous RIO device connected to the enumerated one
 * @prev_port: Port on previous RIO device
 *
 * Recursively enumerates a RIO network.  Transactions are sent via the
 * master port passed in @port.
 */
static int rio_enum_peer(struct rio_net *net, struct rio_mport *port,
                         u8 hopcount, struct rio_dev *prev, int prev_port)
{
        struct rio_dev *rdev;
        u32 regval;
        int tmp;

        if (rio_mport_chk_dev_access(port,
                        RIO_ANY_DESTID(port->sys_size), hopcount)) {
                pr_debug("RIO: device access check failed\n");
                return -1;
        }

        if (rio_get_host_deviceid_lock(port, hopcount) == port->host_deviceid) {
                pr_debug("RIO: PE already discovered by this host\n");
                /*
                 * Already discovered by this host. Add it as another
                 * link to the existing device.
                 */
                rio_mport_read_config_32(port, RIO_ANY_DESTID(port->sys_size),
                                hopcount, RIO_COMPONENT_TAG_CSR, &regval);

                if (regval) {
                        rdev = rio_get_comptag((regval & 0xffff), NULL);

                        if (rdev && prev && rio_is_switch(prev)) {
                                pr_debug("RIO: redundant path to %s\n",
                                         rio_name(rdev));
                                prev->rswitch->nextdev[prev_port] = rdev;
                        }
                }

                return 0;
        }

        /* Attempt to acquire device lock */
        rio_mport_write_config_32(port, RIO_ANY_DESTID(port->sys_size),
                                  hopcount,
                                  RIO_HOST_DID_LOCK_CSR, port->host_deviceid);
        while ((tmp = rio_get_host_deviceid_lock(port, hopcount))
               < port->host_deviceid) {
                /* Delay a bit */
                mdelay(1);
                /* Attempt to acquire device lock again */
                rio_mport_write_config_32(port, RIO_ANY_DESTID(port->sys_size),
                                          hopcount,
                                          RIO_HOST_DID_LOCK_CSR,
                                          port->host_deviceid);
        }

        if (rio_get_host_deviceid_lock(port, hopcount) > port->host_deviceid) {
                pr_debug(
                    "RIO: PE locked by a higher priority host...retreating\n");
                return -1;
        }

        /* Setup new RIO device */
        rdev = rio_setup_device(net, port, RIO_ANY_DESTID(port->sys_size),
                                        hopcount, 1);
        if (rdev) {
                rdev->prev = prev;
                if (prev && rio_is_switch(prev))
                        prev->rswitch->nextdev[prev_port] = rdev;
        } else
                return -1;

        if (rio_is_switch(rdev)) {
                int sw_destid;
                int cur_destid;
                int sw_inport;
                u16 destid;
                int port_num;

                sw_inport = RIO_GET_PORT_NUM(rdev->swpinfo);
                rio_route_add_entry(rdev, RIO_GLOBAL_TABLE,
                                    port->host_deviceid, sw_inport, 0);
                rdev->rswitch->route_table[port->host_deviceid] = sw_inport;

                destid = rio_destid_first(net);
                while (destid != RIO_INVALID_DESTID && destid < next_destid) {
                        if (destid != port->host_deviceid) {
                                rio_route_add_entry(rdev, RIO_GLOBAL_TABLE,
                                                    destid, sw_inport, 0);
                                rdev->rswitch->route_table[destid] = sw_inport;
                        }
                        destid = rio_destid_next(net, destid + 1);
                }
                pr_debug(
                    "RIO: found %s (vid %4.4x did %4.4x) with %d ports\n",
                    rio_name(rdev), rdev->vid, rdev->did,
                    RIO_GET_TOTAL_PORTS(rdev->swpinfo));
                sw_destid = next_destid;
                for (port_num = 0;
                     port_num < RIO_GET_TOTAL_PORTS(rdev->swpinfo);
                     port_num++) {
                        if (sw_inport == port_num) {
                                rio_enable_rx_tx_port(port, 0,
                                              RIO_ANY_DESTID(port->sys_size),
                                              hopcount, port_num);
                                rdev->rswitch->port_ok |= (1 << port_num);
                                continue;
                        }

                        cur_destid = next_destid;

                        if (rio_sport_is_active(rdev, port_num)) {
                                pr_debug(
                                    "RIO: scanning device on port %d\n",
                                    port_num);
                                rio_enable_rx_tx_port(port, 0,
                                              RIO_ANY_DESTID(port->sys_size),
                                              hopcount, port_num);
                                rdev->rswitch->port_ok |= (1 << port_num);
                                rio_route_add_entry(rdev, RIO_GLOBAL_TABLE,
                                                RIO_ANY_DESTID(port->sys_size),
                                                port_num, 0);

                                if (rio_enum_peer(net, port, hopcount + 1,
                                                  rdev, port_num) < 0)
                                        return -1;

                                /* Update routing tables */
                                destid = rio_destid_next(net, cur_destid + 1);
                                if (destid != RIO_INVALID_DESTID) {
                                        for (destid = cur_destid;
                                             destid < next_destid;) {
                                                if (destid != port->host_deviceid) {
                                                        rio_route_add_entry(rdev,
                                                                    RIO_GLOBAL_TABLE,
                                                                    destid,
                                                                    port_num,
                                                                    0);
                                                        rdev->rswitch->
                                                                route_table[destid] =
                                                                port_num;
                                                }
                                                destid = rio_destid_next(net,
                                                                destid + 1);
                                        }
                                }
                        } else {
                                /* If switch supports Error Management,
                                 * set PORT_LOCKOUT bit for unused port
                                 */
                                if (rdev->em_efptr)
                                        rio_set_port_lockout(rdev, port_num, 1);

                                rdev->rswitch->port_ok &= ~(1 << port_num);
                        }
                }

                /* Direct Port-write messages to the enumeratiing host */
                if ((rdev->src_ops & RIO_SRC_OPS_PORT_WRITE) &&
                    (rdev->em_efptr)) {
                        rio_write_config_32(rdev,
                                        rdev->em_efptr + RIO_EM_PW_TGT_DEVID,
                                        (port->host_deviceid << 16) |
                                        (port->sys_size << 15));
                }

                rio_init_em(rdev);

                /* Check for empty switch */
                if (next_destid == sw_destid)
                        next_destid = rio_destid_alloc(net);

                rdev->destid = sw_destid;
        } else
                pr_debug("RIO: found %s (vid %4.4x did %4.4x)\n",
                    rio_name(rdev), rdev->vid, rdev->did);

        return 0;
}

/**
 * rio_enum_complete- Tests if enumeration of a network is complete
 * @port: Master port to send transaction
 *
 * Tests the PGCCSR discovered bit for non-zero value (enumeration
 * complete flag). Return %1 if enumeration is complete or %0 if
 * enumeration is incomplete.
 */
static int rio_enum_complete(struct rio_mport *port)
{
        u32 regval;

        rio_local_read_config_32(port, port->phys_efptr + RIO_PORT_GEN_CTL_CSR,
                                 &regval);
        return (regval & RIO_PORT_GEN_DISCOVERED) ? 1 : 0;
}

/**
 * rio_disc_peer- Recursively discovers a RIO network through a master port
 * @net: RIO network being discovered
 * @port: Master port to send transactions
 * @destid: Current destination ID in network
 * @hopcount: Number of hops into the network
 * @prev: previous rio_dev
 * @prev_port: previous port number
 *
 * Recursively discovers a RIO network.  Transactions are sent via the
 * master port passed in @port.
 */
static int
rio_disc_peer(struct rio_net *net, struct rio_mport *port, u16 destid,
              u8 hopcount, struct rio_dev *prev, int prev_port)
{
        u8 port_num, route_port;
        struct rio_dev *rdev;
        u16 ndestid;

        /* Setup new RIO device */
        if ((rdev = rio_setup_device(net, port, destid, hopcount, 0))) {
                rdev->prev = prev;
                if (prev && rio_is_switch(prev))
                        prev->rswitch->nextdev[prev_port] = rdev;
        } else
                return -1;

        if (rio_is_switch(rdev)) {
                /* Associated destid is how we accessed this switch */
                rdev->destid = destid;

                pr_debug(
                    "RIO: found %s (vid %4.4x did %4.4x) with %d ports\n",
                    rio_name(rdev), rdev->vid, rdev->did,
                    RIO_GET_TOTAL_PORTS(rdev->swpinfo));
                for (port_num = 0;
                     port_num < RIO_GET_TOTAL_PORTS(rdev->swpinfo);
                     port_num++) {
                        if (RIO_GET_PORT_NUM(rdev->swpinfo) == port_num)
                                continue;

                        if (rio_sport_is_active(rdev, port_num)) {
                                pr_debug(
                                    "RIO: scanning device on port %d\n",
                                    port_num);

                                rio_lock_device(port, destid, hopcount, 1000);

                                for (ndestid = 0;
                                     ndestid < RIO_ANY_DESTID(port->sys_size);
                                     ndestid++) {
                                        rio_route_get_entry(rdev,
                                                            RIO_GLOBAL_TABLE,
                                                            ndestid,
                                                            &route_port, 0);
                                        if (route_port == port_num)
                                                break;
                                }

                                if (ndestid == RIO_ANY_DESTID(port->sys_size))
                                        continue;
                                rio_unlock_device(port, destid, hopcount);
                                if (rio_disc_peer(net, port, ndestid,
                                        hopcount + 1, rdev, port_num) < 0)
                                        return -1;
                        }
                }
        } else
                pr_debug("RIO: found %s (vid %4.4x did %4.4x)\n",
                    rio_name(rdev), rdev->vid, rdev->did);

        return 0;
}

/**
 * rio_mport_is_active- Tests if master port link is active
 * @port: Master port to test
 *
 * Reads the port error status CSR for the master port to
 * determine if the port has an active link.  Returns
 * %RIO_PORT_N_ERR_STS_PORT_OK if the  master port is active
 * or %0 if it is inactive.
 */
static int rio_mport_is_active(struct rio_mport *port)
{
        u32 result = 0;

        rio_local_read_config_32(port,
                port->phys_efptr +
                        RIO_PORT_N_ERR_STS_CSR(port->index, port->phys_rmap),
                &result);
        return result & RIO_PORT_N_ERR_STS_PORT_OK;
}

static void rio_scan_release_net(struct rio_net *net)
{
        pr_debug("RIO-SCAN: %s: net_%d\n", __func__, net->id);
        kfree(net->enum_data);
}

static void rio_scan_release_dev(struct device *dev)
{
        struct rio_net *net;

        net = to_rio_net(dev);
        pr_debug("RIO-SCAN: %s: net_%d\n", __func__, net->id);
        kfree(net);
}

/*
 * rio_scan_alloc_net - Allocate and configure a new RIO network
 * @mport: Master port associated with the RIO network
 * @do_enum: Enumeration/Discovery mode flag
 * @start: logical minimal start id for new net
 *
 * Allocates a new RIO network structure and initializes enumerator-specific
 * part of it (if required).
 * Returns a RIO network pointer on success or %NULL on failure.
 */
static struct rio_net *rio_scan_alloc_net(struct rio_mport *mport,
                                          int do_enum, u16 start)
{
        struct rio_net *net;

        net = rio_alloc_net(mport);

        if (net && do_enum) {
                struct rio_id_table *idtab;
                size_t size;

                size = sizeof(struct rio_id_table) +
                                BITS_TO_LONGS(
                                        RIO_MAX_ROUTE_ENTRIES(mport->sys_size)
                                        ) * sizeof(long);

                idtab = kzalloc(size, GFP_KERNEL);

                if (idtab == NULL) {
                        pr_err("RIO: failed to allocate destID table\n");
                        rio_free_net(net);
                        net = NULL;
                } else {
                        net->enum_data = idtab;
                        net->release = rio_scan_release_net;
                        idtab->start = start;
                        idtab->max = RIO_MAX_ROUTE_ENTRIES(mport->sys_size);
                        spin_lock_init(&idtab->lock);
                }
        }

        if (net) {
                net->id = mport->id;
                net->hport = mport;
                dev_set_name(&net->dev, "rnet_%d", net->id);
                net->dev.parent = &mport->dev;
                net->dev.release = rio_scan_release_dev;
                rio_add_net(net);
        }

        return net;
}

/**
 * rio_update_route_tables- Updates route tables in switches
 * @net: RIO network to run update on
 *
 * For each enumerated device, ensure that each switch in a system
 * has correct routing entries. Add routes for devices that where
 * unknown during the first enumeration pass through the switch.
 */
static void rio_update_route_tables(struct rio_net *net)
{
        struct rio_dev *rdev, *swrdev;
        struct rio_switch *rswitch;
        u8 sport;
        u16 destid;

        list_for_each_entry(rdev, &net->devices, net_list) {

                destid = rdev->destid;

                list_for_each_entry(rswitch, &net->switches, node) {

                        if (rio_is_switch(rdev) && (rdev->rswitch == rswitch))
                                continue;

                        if (RIO_INVALID_ROUTE == rswitch->route_table[destid]) {
                                swrdev = sw_to_rio_dev(rswitch);

                                /* Skip if destid ends in empty switch*/
                                if (swrdev->destid == destid)
                                        continue;

                                sport = RIO_GET_PORT_NUM(swrdev->swpinfo);

                                rio_route_add_entry(swrdev, RIO_GLOBAL_TABLE,
                                                    destid, sport, 0);
                                rswitch->route_table[destid] = sport;
                        }
                }
        }
}

/**
 * rio_init_em - Initializes RIO Error Management (for switches)
 * @rdev: RIO device
 *
 * For each enumerated switch, call device-specific error management
 * initialization routine (if supplied by the switch driver).
 */
static void rio_init_em(struct rio_dev *rdev)
{
        if (rio_is_switch(rdev) && (rdev->em_efptr) &&
            rdev->rswitch->ops && rdev->rswitch->ops->em_init) {
                rdev->rswitch->ops->em_init(rdev);
        }
}

/**
 * rio_enum_mport- Start enumeration through a master port
 * @mport: Master port to send transactions
 * @flags: Enumeration control flags
 *
 * Starts the enumeration process. If somebody has enumerated our
 * master port device, then give up. If not and we have an active
 * link, then start recursive peer enumeration. Returns %0 if
 * enumeration succeeds or %-EBUSY if enumeration fails.
 */
static int rio_enum_mport(struct rio_mport *mport, u32 flags)
{
        struct rio_net *net = NULL;
        int rc = 0;

        printk(KERN_INFO "RIO: enumerate master port %d, %s\n", mport->id,
               mport->name);

        /*
         * To avoid multiple start requests (repeat enumeration is not supported
         * by this method) check if enumeration/discovery was performed for this
         * mport: if mport was added into the list of mports for a net exit
         * with error.
         */
        if (mport->nnode.next || mport->nnode.prev)
                return -EBUSY;

        /* If somebody else enumerated our master port device, bail. */
        if (rio_enum_host(mport) < 0) {
                printk(KERN_INFO
                       "RIO: master port %d device has been enumerated by a remote host\n",
                       mport->id);
                rc = -EBUSY;
                goto out;
        }

        /* If master port has an active link, allocate net and enum peers */
        if (rio_mport_is_active(mport)) {
                net = rio_scan_alloc_net(mport, 1, 0);
                if (!net) {
                        printk(KERN_ERR "RIO: failed to allocate new net\n");
                        rc = -ENOMEM;
                        goto out;
                }

                /* reserve mport destID in new net */
                rio_destid_reserve(net, mport->host_deviceid);

                /* Enable Input Output Port (transmitter receiver) */
                rio_enable_rx_tx_port(mport, 1, 0, 0, 0);

                /* Set component tag for host */
                rio_local_write_config_32(mport, RIO_COMPONENT_TAG_CSR,
                                          next_comptag++);

                next_destid = rio_destid_alloc(net);

                if (rio_enum_peer(net, mport, 0, NULL, 0) < 0) {
                        /* A higher priority host won enumeration, bail. */
                        printk(KERN_INFO
                               "RIO: master port %d device has lost enumeration to a remote host\n",
                               mport->id);
                        rio_clear_locks(net);
                        rc = -EBUSY;
                        goto out;
                }
                /* free the last allocated destID (unused) */
                rio_destid_free(net, next_destid);
                rio_update_route_tables(net);
                rio_clear_locks(net);
                rio_pw_enable(mport, 1);
        } else {
                printk(KERN_INFO "RIO: master port %d link inactive\n",
                       mport->id);
                rc = -EINVAL;
        }

      out:
        return rc;
}

/**
 * rio_build_route_tables- Generate route tables from switch route entries
 * @net: RIO network to run route tables scan on
 *
 * For each switch device, generate a route table by copying existing
 * route entries from the switch.
 */
static void rio_build_route_tables(struct rio_net *net)
{
        struct rio_switch *rswitch;
        struct rio_dev *rdev;
        int i;
        u8 sport;

        list_for_each_entry(rswitch, &net->switches, node) {
                rdev = sw_to_rio_dev(rswitch);

                rio_lock_device(net->hport, rdev->destid,
                                rdev->hopcount, 1000);
                for (i = 0;
                     i < RIO_MAX_ROUTE_ENTRIES(net->hport->sys_size);
                     i++) {
                        if (rio_route_get_entry(rdev, RIO_GLOBAL_TABLE,
                                                i, &sport, 0) < 0)
                                continue;
                        rswitch->route_table[i] = sport;
                }

                rio_unlock_device(net->hport, rdev->destid, rdev->hopcount);
        }
}

/**
 * rio_disc_mport- Start discovery through a master port
 * @mport: Master port to send transactions
 * @flags: discovery control flags
 *
 * Starts the discovery process. If we have an active link,
 * then wait for the signal that enumeration is complete (if wait
 * is allowed).
 * When enumeration completion is signaled, start recursive
 * peer discovery. Returns %0 if discovery succeeds or %-EBUSY
 * on failure.
 */
static int rio_disc_mport(struct rio_mport *mport, u32 flags)
{
        struct rio_net *net = NULL;
        unsigned long to_end;

        printk(KERN_INFO "RIO: discover master port %d, %s\n", mport->id,
               mport->name);

        /* If master port has an active link, allocate net and discover peers */
        if (rio_mport_is_active(mport)) {
                if (rio_enum_complete(mport))
                        goto enum_done;
                else if (flags & RIO_SCAN_ENUM_NO_WAIT)
                        return -EAGAIN;

                pr_debug("RIO: wait for enumeration to complete...\n");

                to_end = jiffies + CONFIG_RAPIDIO_DISC_TIMEOUT * HZ;
                while (time_before(jiffies, to_end)) {
                        if (rio_enum_complete(mport))
                                goto enum_done;
                        msleep(10);
                }

                pr_debug("RIO: discovery timeout on mport %d %s\n",
                         mport->id, mport->name);
                goto bail;
enum_done:
                pr_debug("RIO: ... enumeration done\n");

                net = rio_scan_alloc_net(mport, 0, 0);
                if (!net) {
                        printk(KERN_ERR "RIO: Failed to allocate new net\n");
                        goto bail;
                }

                /* Read DestID assigned by enumerator */
                rio_local_read_config_32(mport, RIO_DID_CSR,
                                         &mport->host_deviceid);
                mport->host_deviceid = RIO_GET_DID(mport->sys_size,
                                                   mport->host_deviceid);

                if (rio_disc_peer(net, mport, RIO_ANY_DESTID(mport->sys_size),
                                        0, NULL, 0) < 0) {
                        printk(KERN_INFO
                               "RIO: master port %d device has failed discovery\n",
                               mport->id);
                        goto bail;
                }

                rio_build_route_tables(net);
        }

        return 0;
bail:
        return -EBUSY;
}

static struct rio_scan rio_scan_ops = {
        .owner = THIS_MODULE,
        .enumerate = rio_enum_mport,
        .discover = rio_disc_mport,
};

static bool scan;
module_param(scan, bool, 0);
MODULE_PARM_DESC(scan, "Start RapidIO network enumeration/discovery "
                        "(default = 0)");

/**
 * rio_basic_attach:
 *
 * When this enumeration/discovery method is loaded as a module this function
 * registers its specific enumeration and discover routines for all available
 * RapidIO mport devices. The "scan" command line parameter controls ability of
 * the module to start RapidIO enumeration/discovery automatically.
 *
 * Returns 0 for success or -EIO if unable to register itself.
 *
 * This enumeration/discovery method cannot be unloaded and therefore does not
 * provide a matching cleanup_module routine.
 */

static int __init rio_basic_attach(void)
{
        if (rio_register_scan(RIO_MPORT_ANY, &rio_scan_ops))
                return -EIO;
        if (scan)
                rio_init_mports();
        return 0;
}

late_initcall(rio_basic_attach);

MODULE_DESCRIPTION("Basic RapidIO enumeration/discovery");
MODULE_LICENSE("GPL");