/* ------------------------------------------------------------
 * rpa_vscsi.c
 * (C) Copyright IBM Corporation 1994, 2003
 * Authors: Colin DeVilbiss (devilbis@us.ibm.com)
 *          Santiago Leon (santil@us.ibm.com)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 *
 * ------------------------------------------------------------
 * RPA-specific functions of the SCSI host adapter for Virtual I/O devices
 *
 * This driver allows the Linux SCSI peripheral drivers to directly
 * access devices in the hosting partition, either on an iSeries
 * hypervisor system or a converged hypervisor system.
 */

#include <asm/vio.h>
#include <asm/prom.h>
#include <asm/iommu.h>
#include <asm/hvcall.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include "ibmvscsi.h"

static char partition_name[97] = "UNKNOWN";
static unsigned int partition_number = -1;

/* ------------------------------------------------------------
 * Routines for managing the command/response queue
 */
/**
 * rpavscsi_handle_event: - Interrupt handler for crq events
 * @irq:        number of irq to handle, not used
 * @dev_instance: ibmvscsi_host_data of host that received interrupt
 *
 * Disables interrupts and schedules srp_task
 * Always returns IRQ_HANDLED
 */
static irqreturn_t rpavscsi_handle_event(int irq, void *dev_instance)
{
        struct ibmvscsi_host_data *hostdata =
            (struct ibmvscsi_host_data *)dev_instance;
        vio_disable_interrupts(to_vio_dev(hostdata->dev));
        tasklet_schedule(&hostdata->srp_task);
        return IRQ_HANDLED;
}

/**
 * release_crq_queue: - Deallocates data and unregisters CRQ
 * @queue:      crq_queue to initialize and register
 * @host_data:  ibmvscsi_host_data of host
 *
 * Frees irq, deallocates a page for messages, unmaps dma, and unregisters
 * the crq with the hypervisor.
 */
static void rpavscsi_release_crq_queue(struct crq_queue *queue,
                                       struct ibmvscsi_host_data *hostdata,
                                       int max_requests)
{
        long rc;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);
        free_irq(vdev->irq, (void *)hostdata);
        tasklet_kill(&hostdata->srp_task);
        do {
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
        dma_unmap_single(hostdata->dev,
                         queue->msg_token,
                         queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
        free_page((unsigned long)queue->msgs);
}

/**
 * crq_queue_next_crq: - Returns the next entry in message queue
 * @queue:      crq_queue to use
 *
 * Returns pointer to next entry in queue, or NULL if there are no new 
 * entried in the CRQ.
 */
static struct viosrp_crq *crq_queue_next_crq(struct crq_queue *queue)
{
        struct viosrp_crq *crq;
        unsigned long flags;

        spin_lock_irqsave(&queue->lock, flags);
        crq = &queue->msgs[queue->cur];
        if (crq->valid & 0x80) {
                if (++queue->cur == queue->size)
                        queue->cur = 0;
        } else
                crq = NULL;
        spin_unlock_irqrestore(&queue->lock, flags);

        return crq;
}

/**
 * rpavscsi_send_crq: - Send a CRQ
 * @hostdata:   the adapter
 * @word1:      the first 64 bits of the data
 * @word2:      the second 64 bits of the data
 */
static int rpavscsi_send_crq(struct ibmvscsi_host_data *hostdata,
                             u64 word1, u64 word2)
{
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, word1, word2);
}

/**
 * rpavscsi_task: - Process srps asynchronously
 * @data:       ibmvscsi_host_data of host
 */
static void rpavscsi_task(void *data)
{
        struct ibmvscsi_host_data *hostdata = (struct ibmvscsi_host_data *)data;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);
        struct viosrp_crq *crq;
        int done = 0;

        while (!done) {
                /* Pull all the valid messages off the CRQ */
                while ((crq = crq_queue_next_crq(&hostdata->queue)) != NULL) {
                        ibmvscsi_handle_crq(crq, hostdata);
                        crq->valid = 0x00;
                }

                vio_enable_interrupts(vdev);
                if ((crq = crq_queue_next_crq(&hostdata->queue)) != NULL) {
                        vio_disable_interrupts(vdev);
                        ibmvscsi_handle_crq(crq, hostdata);
                        crq->valid = 0x00;
                } else {
                        done = 1;
                }
        }
}

static void gather_partition_info(void)
{
        struct device_node *rootdn;

        const char *ppartition_name;
        const unsigned int *p_number_ptr;

        /* Retrieve information about this partition */
        rootdn = of_find_node_by_path("/");
        if (!rootdn) {
                return;
        }

        ppartition_name = of_get_property(rootdn, "ibm,partition-name", NULL);
        if (ppartition_name)
                strncpy(partition_name, ppartition_name,
                                sizeof(partition_name));
        p_number_ptr = of_get_property(rootdn, "ibm,partition-no", NULL);
        if (p_number_ptr)
                partition_number = *p_number_ptr;
        of_node_put(rootdn);
}

static void set_adapter_info(struct ibmvscsi_host_data *hostdata)
{
        memset(&hostdata->madapter_info, 0x00,
                        sizeof(hostdata->madapter_info));

        dev_info(hostdata->dev, "SRP_VERSION: %s\n", SRP_VERSION);
        strcpy(hostdata->madapter_info.srp_version, SRP_VERSION);

        strncpy(hostdata->madapter_info.partition_name, partition_name,
                        sizeof(hostdata->madapter_info.partition_name));

        hostdata->madapter_info.partition_number = partition_number;

        hostdata->madapter_info.mad_version = 1;
        hostdata->madapter_info.os_type = 2;
}

/**
 * reset_crq_queue: - resets a crq after a failure
 * @queue:      crq_queue to initialize and register
 * @hostdata:   ibmvscsi_host_data of host
 *
 */
static int rpavscsi_reset_crq_queue(struct crq_queue *queue,
                                    struct ibmvscsi_host_data *hostdata)
{
        int rc;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        /* Close the CRQ */
        do {
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));

        /* Clean out the queue */
        memset(queue->msgs, 0x00, PAGE_SIZE);
        queue->cur = 0;

        set_adapter_info(hostdata);

        /* And re-open it again */
        rc = plpar_hcall_norets(H_REG_CRQ,
                                vdev->unit_address,
                                queue->msg_token, PAGE_SIZE);
        if (rc == 2) {
                /* Adapter is good, but other end is not ready */
                dev_warn(hostdata->dev, "Partner adapter not ready\n");
        } else if (rc != 0) {
                dev_warn(hostdata->dev, "couldn't register crq--rc 0x%x\n", rc);
        }
        return rc;
}

/**
 * initialize_crq_queue: - Initializes and registers CRQ with hypervisor
 * @queue:      crq_queue to initialize and register
 * @hostdata:   ibmvscsi_host_data of host
 *
 * Allocates a page for messages, maps it for dma, and registers
 * the crq with the hypervisor.
 * Returns zero on success.
 */
static int rpavscsi_init_crq_queue(struct crq_queue *queue,
                                   struct ibmvscsi_host_data *hostdata,
                                   int max_requests)
{
        int rc;
        int retrc;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        queue->msgs = (struct viosrp_crq *)get_zeroed_page(GFP_KERNEL);

        if (!queue->msgs)
                goto malloc_failed;
        queue->size = PAGE_SIZE / sizeof(*queue->msgs);

        queue->msg_token = dma_map_single(hostdata->dev, queue->msgs,
                                          queue->size * sizeof(*queue->msgs),
                                          DMA_BIDIRECTIONAL);

        if (dma_mapping_error(queue->msg_token))
                goto map_failed;

        gather_partition_info();
        set_adapter_info(hostdata);

        retrc = rc = plpar_hcall_norets(H_REG_CRQ,
                                vdev->unit_address,
                                queue->msg_token, PAGE_SIZE);
        if (rc == H_RESOURCE)
                /* maybe kexecing and resource is busy. try a reset */
                rc = rpavscsi_reset_crq_queue(queue,
                                              hostdata);

        if (rc == 2) {
                /* Adapter is good, but other end is not ready */
                dev_warn(hostdata->dev, "Partner adapter not ready\n");
                retrc = 0;
        } else if (rc != 0) {
                dev_warn(hostdata->dev, "Error %d opening adapter\n", rc);
                goto reg_crq_failed;
        }

        if (request_irq(vdev->irq,
                        rpavscsi_handle_event,
                        0, "ibmvscsi", (void *)hostdata) != 0) {
                dev_err(hostdata->dev, "couldn't register irq 0x%x\n",
                        vdev->irq);
                goto req_irq_failed;
        }

        rc = vio_enable_interrupts(vdev);
        if (rc != 0) {
                dev_err(hostdata->dev, "Error %d enabling interrupts!!!\n", rc);
                goto req_irq_failed;
        }

        queue->cur = 0;
        spin_lock_init(&queue->lock);

        tasklet_init(&hostdata->srp_task, (void *)rpavscsi_task,
                     (unsigned long)hostdata);

        return retrc;

      req_irq_failed:
        do {
                rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
        } while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
      reg_crq_failed:
        dma_unmap_single(hostdata->dev,
                         queue->msg_token,
                         queue->size * sizeof(*queue->msgs), DMA_BIDIRECTIONAL);
      map_failed:
        free_page((unsigned long)queue->msgs);
      malloc_failed:
        return -1;
}

/**
 * reenable_crq_queue: - reenables a crq after
 * @queue:      crq_queue to initialize and register
 * @hostdata:   ibmvscsi_host_data of host
 *
 */
static int rpavscsi_reenable_crq_queue(struct crq_queue *queue,
                                       struct ibmvscsi_host_data *hostdata)
{
        int rc;
        struct vio_dev *vdev = to_vio_dev(hostdata->dev);

        /* Re-enable the CRQ */
        do {
                rc = plpar_hcall_norets(H_ENABLE_CRQ, vdev->unit_address);
        } while ((rc == H_IN_PROGRESS) || (rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));

        if (rc)
                dev_err(hostdata->dev, "Error %d enabling adapter\n", rc);
        return rc;
}

struct ibmvscsi_ops rpavscsi_ops = {
        .init_crq_queue = rpavscsi_init_crq_queue,
        .release_crq_queue = rpavscsi_release_crq_queue,
        .reset_crq_queue = rpavscsi_reset_crq_queue,
        .reenable_crq_queue = rpavscsi_reenable_crq_queue,
        .send_crq = rpavscsi_send_crq,
};