// SPDX-License-Identifier: GPL-2.0+
/*
 * PowerNV OPAL IPMI driver
 *
 * Copyright 2014 IBM Corp.
 */

#define pr_fmt(fmt)        "ipmi-powernv: " fmt

#include <linux/ipmi_smi.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>

#include <asm/opal.h>


struct ipmi_smi_powernv {
        u64                     interface_id;
        struct ipmi_smi         *intf;
        unsigned int            irq;

        /**
         * We assume that there can only be one outstanding request, so
         * keep the pending message in cur_msg. We protect this from concurrent
         * updates through send & recv calls, (and consequently opal_msg, which
         * is in-use when cur_msg is set) with msg_lock
         */
        spinlock_t              msg_lock;
        struct ipmi_smi_msg     *cur_msg;
        struct opal_ipmi_msg    *opal_msg;
};

static int ipmi_powernv_start_processing(void *send_info, struct ipmi_smi *intf)
{
        struct ipmi_smi_powernv *smi = send_info;

        smi->intf = intf;
        return 0;
}

static void send_error_reply(struct ipmi_smi_powernv *smi,
                struct ipmi_smi_msg *msg, u8 completion_code)
{
        msg->rsp[0] = msg->data[0] | 0x4;
        msg->rsp[1] = msg->data[1];
        msg->rsp[2] = completion_code;
        msg->rsp_size = 3;
        ipmi_smi_msg_received(smi->intf, msg);
}

static int ipmi_powernv_send(void *send_info, struct ipmi_smi_msg *msg)
{
        struct ipmi_smi_powernv *smi = send_info;
        struct opal_ipmi_msg *opal_msg;
        unsigned long flags;
        int comp, rc;
        size_t size;

        /* ensure data_len will fit in the opal_ipmi_msg buffer... */
        if (msg->data_size > IPMI_MAX_MSG_LENGTH) {
                comp = IPMI_REQ_LEN_EXCEEDED_ERR;
                goto err;
        }

        /* ... and that we at least have netfn and cmd bytes */
        if (msg->data_size < 2) {
                comp = IPMI_REQ_LEN_INVALID_ERR;
                goto err;
        }

        spin_lock_irqsave(&smi->msg_lock, flags);

        if (smi->cur_msg) {
                comp = IPMI_NODE_BUSY_ERR;
                goto err_unlock;
        }

        /* format our data for the OPAL API */
        opal_msg = smi->opal_msg;
        opal_msg->version = OPAL_IPMI_MSG_FORMAT_VERSION_1;
        opal_msg->netfn = msg->data[0];
        opal_msg->cmd = msg->data[1];
        if (msg->data_size > 2)
                memcpy(opal_msg->data, msg->data + 2, msg->data_size - 2);

        /* data_size already includes the netfn and cmd bytes */
        size = sizeof(*opal_msg) + msg->data_size - 2;

        pr_devel("%s: opal_ipmi_send(0x%llx, %p, %ld)\n", __func__,
                        smi->interface_id, opal_msg, size);
        rc = opal_ipmi_send(smi->interface_id, opal_msg, size);
        pr_devel("%s:  -> %d\n", __func__, rc);
        if (rc) {
                comp = IPMI_ERR_UNSPECIFIED;
                goto err_unlock;
        }

        smi->cur_msg = msg;
        spin_unlock_irqrestore(&smi->msg_lock, flags);
        return IPMI_CC_NO_ERROR;

err_unlock:
        spin_unlock_irqrestore(&smi->msg_lock, flags);
err:
        return comp;
}

static int ipmi_powernv_recv(struct ipmi_smi_powernv *smi)
{
        struct opal_ipmi_msg *opal_msg;
        struct ipmi_smi_msg *msg;
        unsigned long flags;
        uint64_t size;
        int rc;

        pr_devel("%s: opal_ipmi_recv(%llx, msg, sz)\n", __func__,
                        smi->interface_id);

        spin_lock_irqsave(&smi->msg_lock, flags);

        if (!smi->cur_msg) {
                spin_unlock_irqrestore(&smi->msg_lock, flags);
                pr_warn("no current message?\n");
                return 0;
        }

        msg = smi->cur_msg;
        opal_msg = smi->opal_msg;

        size = cpu_to_be64(sizeof(*opal_msg) + IPMI_MAX_MSG_LENGTH);

        rc = opal_ipmi_recv(smi->interface_id,
                        opal_msg,
                        &size);
        size = be64_to_cpu(size);
        pr_devel("%s:   -> %d (size %lld)\n", __func__,
                        rc, rc == 0 ? size : 0);
        if (rc) {
                /* If came via the poll, and response was not yet ready */
                if (rc == OPAL_EMPTY) {
                        spin_unlock_irqrestore(&smi->msg_lock, flags);
                        return 0;
                }

                smi->cur_msg = NULL;
                spin_unlock_irqrestore(&smi->msg_lock, flags);
                send_error_reply(smi, msg, IPMI_ERR_UNSPECIFIED);
                return 0;
        }

        if (size < sizeof(*opal_msg)) {
                spin_unlock_irqrestore(&smi->msg_lock, flags);
                pr_warn("unexpected IPMI message size %lld\n", size);
                return 0;
        }

        if (opal_msg->version != OPAL_IPMI_MSG_FORMAT_VERSION_1) {
                spin_unlock_irqrestore(&smi->msg_lock, flags);
                pr_warn("unexpected IPMI message format (version %d)\n",
                                opal_msg->version);
                return 0;
        }

        msg->rsp[0] = opal_msg->netfn;
        msg->rsp[1] = opal_msg->cmd;
        if (size > sizeof(*opal_msg))
                memcpy(&msg->rsp[2], opal_msg->data, size - sizeof(*opal_msg));
        msg->rsp_size = 2 + size - sizeof(*opal_msg);

        smi->cur_msg = NULL;
        spin_unlock_irqrestore(&smi->msg_lock, flags);
        ipmi_smi_msg_received(smi->intf, msg);
        return 0;
}

static void ipmi_powernv_request_events(void *send_info)
{
}

static void ipmi_powernv_set_run_to_completion(void *send_info,
                bool run_to_completion)
{
}

static void ipmi_powernv_poll(void *send_info)
{
        struct ipmi_smi_powernv *smi = send_info;

        ipmi_powernv_recv(smi);
}

static const struct ipmi_smi_handlers ipmi_powernv_smi_handlers = {
        .owner                  = THIS_MODULE,
        .start_processing       = ipmi_powernv_start_processing,
        .sender                 = ipmi_powernv_send,
        .request_events         = ipmi_powernv_request_events,
        .set_run_to_completion  = ipmi_powernv_set_run_to_completion,
        .poll                   = ipmi_powernv_poll,
};

static irqreturn_t ipmi_opal_event(int irq, void *data)
{
        struct ipmi_smi_powernv *smi = data;

        ipmi_powernv_recv(smi);
        return IRQ_HANDLED;
}

static int ipmi_powernv_probe(struct platform_device *pdev)
{
        struct ipmi_smi_powernv *ipmi;
        struct device *dev;
        u32 prop;
        int rc;

        if (!pdev || !pdev->dev.of_node)
                return -ENODEV;

        dev = &pdev->dev;

        ipmi = devm_kzalloc(dev, sizeof(*ipmi), GFP_KERNEL);
        if (!ipmi)
                return -ENOMEM;

        spin_lock_init(&ipmi->msg_lock);

        rc = of_property_read_u32(dev->of_node, "ibm,ipmi-interface-id",
                        &prop);
        if (rc) {
                dev_warn(dev, "No interface ID property\n");
                goto err_free;
        }
        ipmi->interface_id = prop;

        rc = of_property_read_u32(dev->of_node, "interrupts", &prop);
        if (rc) {
                dev_warn(dev, "No interrupts property\n");
                goto err_free;
        }

        ipmi->irq = irq_of_parse_and_map(dev->of_node, 0);
        if (!ipmi->irq) {
                dev_info(dev, "Unable to map irq from device tree\n");
                ipmi->irq = opal_event_request(prop);
        }

        rc = request_irq(ipmi->irq, ipmi_opal_event, IRQ_TYPE_LEVEL_HIGH,
                         "opal-ipmi", ipmi);
        if (rc) {
                dev_warn(dev, "Unable to request irq\n");
                goto err_dispose;
        }

        ipmi->opal_msg = devm_kmalloc(dev,
                        sizeof(*ipmi->opal_msg) + IPMI_MAX_MSG_LENGTH,
                        GFP_KERNEL);
        if (!ipmi->opal_msg) {
                rc = -ENOMEM;
                goto err_unregister;
        }

        rc = ipmi_register_smi(&ipmi_powernv_smi_handlers, ipmi, dev, 0);
        if (rc) {
                dev_warn(dev, "IPMI SMI registration failed (%d)\n", rc);
                goto err_free_msg;
        }

        dev_set_drvdata(dev, ipmi);
        return 0;

err_free_msg:
        devm_kfree(dev, ipmi->opal_msg);
err_unregister:
        free_irq(ipmi->irq, ipmi);
err_dispose:
        irq_dispose_mapping(ipmi->irq);
err_free:
        devm_kfree(dev, ipmi);
        return rc;
}

static void ipmi_powernv_remove(struct platform_device *pdev)
{
        struct ipmi_smi_powernv *smi = dev_get_drvdata(&pdev->dev);

        ipmi_unregister_smi(smi->intf);
        free_irq(smi->irq, smi);
        irq_dispose_mapping(smi->irq);
}

static const struct of_device_id ipmi_powernv_match[] = {
        { .compatible = "ibm,opal-ipmi" },
        { },
};


static struct platform_driver powernv_ipmi_driver = {
        .driver = {
                .name           = "ipmi-powernv",
                .of_match_table = ipmi_powernv_match,
        },
        .probe  = ipmi_powernv_probe,
        .remove = ipmi_powernv_remove,
};


module_platform_driver(powernv_ipmi_driver);

MODULE_DEVICE_TABLE(of, ipmi_powernv_match);
MODULE_DESCRIPTION("powernv IPMI driver");
MODULE_AUTHOR("Jeremy Kerr <jk@ozlabs.org>");
MODULE_LICENSE("GPL");