// SPDX-License-Identifier: GPL-2.0+
// Copyright IBM Corp 2019

#include <linux/device.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/fsi-occ.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/string.h>
#include <linux/sysfs.h>

#include "common.h"

#define OCC_CHECKSUM_RETRIES    3

struct p9_sbe_occ {
        struct occ occ;
        bool sbe_error;
        void *ffdc;
        size_t ffdc_len;
        size_t ffdc_size;
        struct mutex sbe_error_lock;    /* lock access to ffdc data */
        struct device *sbe;
};

#define to_p9_sbe_occ(x)        container_of((x), struct p9_sbe_occ, occ)

static ssize_t ffdc_read(struct file *filp, struct kobject *kobj,
                         const struct bin_attribute *battr, char *buf, loff_t pos,
                         size_t count)
{
        ssize_t rc = 0;
        struct occ *occ = dev_get_drvdata(kobj_to_dev(kobj));
        struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);

        mutex_lock(&ctx->sbe_error_lock);
        if (ctx->sbe_error) {
                rc = memory_read_from_buffer(buf, count, &pos, ctx->ffdc,
                                             ctx->ffdc_len);
                if (pos >= ctx->ffdc_len)
                        ctx->sbe_error = false;
        }
        mutex_unlock(&ctx->sbe_error_lock);

        return rc;
}
static const BIN_ATTR_RO(ffdc, OCC_MAX_RESP_WORDS * 4);

static bool p9_sbe_occ_save_ffdc(struct p9_sbe_occ *ctx, const void *resp,
                                 size_t resp_len)
{
        bool notify = false;

        mutex_lock(&ctx->sbe_error_lock);
        if (!ctx->sbe_error) {
                if (resp_len > ctx->ffdc_size) {
                        kvfree(ctx->ffdc);
                        ctx->ffdc = kvmalloc(resp_len, GFP_KERNEL);
                        if (!ctx->ffdc) {
                                ctx->ffdc_len = 0;
                                ctx->ffdc_size = 0;
                                goto done;
                        }

                        ctx->ffdc_size = resp_len;
                }

                notify = true;
                ctx->sbe_error = true;
                ctx->ffdc_len = resp_len;
                memcpy(ctx->ffdc, resp, resp_len);
        }

done:
        mutex_unlock(&ctx->sbe_error_lock);
        return notify;
}

static int p9_sbe_occ_send_cmd(struct occ *occ, u8 *cmd, size_t len,
                               void *resp, size_t resp_len)
{
        size_t original_resp_len = resp_len;
        struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);
        int rc, i;

        for (i = 0; i < OCC_CHECKSUM_RETRIES; ++i) {
                rc = fsi_occ_submit(ctx->sbe, cmd, len, resp, &resp_len);
                if (rc >= 0)
                        break;
                if (resp_len) {
                        if (p9_sbe_occ_save_ffdc(ctx, resp, resp_len))
                                sysfs_notify(&occ->bus_dev->kobj, NULL,
                                             bin_attr_ffdc.attr.name);
                        return rc;
                }
                if (rc != -EBADE)
                        return rc;
                resp_len = original_resp_len;
        }

        switch (((struct occ_response *)resp)->return_status) {
        case OCC_RESP_CMD_IN_PRG:
                rc = -ETIMEDOUT;
                break;
        case OCC_RESP_SUCCESS:
                rc = 0;
                break;
        case OCC_RESP_CMD_INVAL:
        case OCC_RESP_CMD_LEN_INVAL:
        case OCC_RESP_DATA_INVAL:
        case OCC_RESP_CHKSUM_ERR:
                rc = -EINVAL;
                break;
        case OCC_RESP_INT_ERR:
        case OCC_RESP_BAD_STATE:
        case OCC_RESP_CRIT_EXCEPT:
        case OCC_RESP_CRIT_INIT:
        case OCC_RESP_CRIT_WATCHDOG:
        case OCC_RESP_CRIT_OCB:
        case OCC_RESP_CRIT_HW:
                rc = -EREMOTEIO;
                break;
        default:
                rc = -EPROTO;
        }

        return rc;
}

static int p9_sbe_occ_probe(struct platform_device *pdev)
{
        int rc;
        struct occ *occ;
        struct p9_sbe_occ *ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx),
                                              GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        mutex_init(&ctx->sbe_error_lock);

        ctx->sbe = pdev->dev.parent;
        occ = &ctx->occ;
        occ->bus_dev = &pdev->dev;
        platform_set_drvdata(pdev, occ);

        occ->powr_sample_time_us = 500;
        occ->poll_cmd_data = 0x20;              /* P9 OCC poll data */
        occ->send_cmd = p9_sbe_occ_send_cmd;

        rc = occ_setup(occ);
        if (rc == -ESHUTDOWN)
                rc = -ENODEV;   /* Host is shutdown, don't spew errors */

        if (!rc) {
                rc = device_create_bin_file(occ->bus_dev, &bin_attr_ffdc);
                if (rc) {
                        dev_warn(occ->bus_dev,
                                 "failed to create SBE error ffdc file\n");
                        rc = 0;
                }
        }

        return rc;
}

static void p9_sbe_occ_remove(struct platform_device *pdev)
{
        struct occ *occ = platform_get_drvdata(pdev);
        struct p9_sbe_occ *ctx = to_p9_sbe_occ(occ);

        device_remove_bin_file(occ->bus_dev, &bin_attr_ffdc);

        ctx->sbe = NULL;
        occ_shutdown(occ);

        kvfree(ctx->ffdc);
}

static const struct of_device_id p9_sbe_occ_of_match[] = {
        { .compatible = "ibm,p9-occ-hwmon" },
        { .compatible = "ibm,p10-occ-hwmon" },
        {}
};
MODULE_DEVICE_TABLE(of, p9_sbe_occ_of_match);

static struct platform_driver p9_sbe_occ_driver = {
        .driver = {
                .name = "occ-hwmon",
                .of_match_table = p9_sbe_occ_of_match,
        },
        .probe = p9_sbe_occ_probe,
        .remove = p9_sbe_occ_remove,
};

module_platform_driver(p9_sbe_occ_driver);

MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
MODULE_DESCRIPTION("BMC P9 OCC hwmon driver");
MODULE_LICENSE("GPL");