// 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/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,
			 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 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 int 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);

	return 0;
}

static struct platform_driver p9_sbe_occ_driver = {
	.driver = {
		.name = "occ-hwmon",
	},
	.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");