// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2018 Intel Corporation

#include <linux/bitfield.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/peci.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/uaccess.h>

/* Mask for getting minor revision number from DIB */
#define REVISION_NUM_MASK  GENMASK(15, 8)

/* CRC8 table for Assure Write Frame Check */
#define PECI_CRC8_POLYNOMIAL  0x07
DECLARE_CRC8_TABLE(peci_crc8_table);

static struct device_type peci_adapter_type;
static struct device_type peci_client_type;

/* Max number of peci cdev */
#define PECI_CDEV_MAX  16

static dev_t peci_devt;
static bool is_registered;

static DEFINE_MUTEX(core_lock);
static DEFINE_IDR(peci_adapter_idr);

static struct peci_adapter *peci_get_adapter(int nr)
{
	struct peci_adapter *adapter;

	mutex_lock(&core_lock);
	adapter = idr_find(&peci_adapter_idr, nr);
	if (!adapter)
		goto out_unlock;

	if (try_module_get(adapter->owner))
		get_device(&adapter->dev);
	else
		adapter = NULL;

out_unlock:
	mutex_unlock(&core_lock);
	return adapter;
}

static void peci_put_adapter(struct peci_adapter *adapter)
{
	if (!adapter)
		return;

	put_device(&adapter->dev);
	module_put(adapter->owner);
}

static ssize_t name_show(struct device *dev,
			 struct device_attribute *attr,
			 char *buf)
{
	return sprintf(buf, "%s\n", dev->type == &peci_client_type ?
		       to_peci_client(dev)->name : to_peci_adapter(dev)->name);
}
static DEVICE_ATTR_RO(name);

static void peci_client_dev_release(struct device *dev)
{
	struct peci_client *client = to_peci_client(dev);

	dev_dbg(dev, "%s: %s\n", __func__, client->name);
	peci_put_adapter(client->adapter);
	kfree(client);
}

static struct attribute *peci_device_attrs[] = {
	&dev_attr_name.attr,
	NULL
};
ATTRIBUTE_GROUPS(peci_device);

static struct device_type peci_client_type = {
	.groups		= peci_device_groups,
	.release	= peci_client_dev_release,
};

/**
 * peci_verify_client - return parameter as peci_client, or NULL
 * @dev: device, probably from some driver model iterator
 *
 * Return: pointer to peci_client on success, else NULL.
 */
struct peci_client *peci_verify_client(struct device *dev)
{
	return (dev->type == &peci_client_type)
			? to_peci_client(dev)
			: NULL;
}
EXPORT_SYMBOL_GPL(peci_verify_client);

static u8 peci_aw_fcs(u8 *data, int len)
{
	return crc8(peci_crc8_table, data, (size_t)len, 0);
}

static int __peci_xfer(struct peci_adapter *adapter, struct peci_xfer_msg *msg,
		       bool do_retry, bool has_aw_fcs)
{
	ktime_t start, end;
	s64 elapsed_ms;
	int rc = 0;

	/**
	 * For some commands, the PECI originator may need to retry a command if
	 * the processor PECI client responds with a 0x8x completion code. In
	 * each instance, the processor PECI client may have started the
	 * operation but not completed it yet. When the 'retry' bit is set, the
	 * PECI client will ignore a new request if it exactly matches a
	 * previous valid request.
	 */

	if (do_retry)
		start = ktime_get();

	do {
		rc = adapter->xfer(adapter, msg);

		if (!do_retry || rc)
			break;

		if (msg->rx_buf[0] == DEV_PECI_CC_SUCCESS)
			break;

		/* Retry is needed when completion code is 0x8x */
		if ((msg->rx_buf[0] & DEV_PECI_CC_RETRY_CHECK_MASK) !=
		    DEV_PECI_CC_NEED_RETRY) {
			rc = -EIO;
			break;
		}

		/* Set the retry bit to indicate a retry attempt */
		msg->tx_buf[1] |= DEV_PECI_RETRY_BIT;

		/* Recalculate the AW FCS if it has one */
		if (has_aw_fcs)
			msg->tx_buf[msg->tx_len - 1] = 0x80 ^
						peci_aw_fcs((u8 *)msg,
							    2 + msg->tx_len);

		/**
		 * Retry for at least 250ms before returning an error.
		 * Retry interval guideline:
		 *   No minimum < Retry Interval < No maximum
		 *                (recommend 10ms)
		 */
		end = ktime_get();
		elapsed_ms = ktime_to_ms(ktime_sub(end, start));
		if (elapsed_ms >= DEV_PECI_RETRY_TIME_MS) {
			dev_dbg(&adapter->dev, "Timeout retrying xfer!\n");
			rc = -ETIMEDOUT;
			break;
		}

		usleep_range((DEV_PECI_RETRY_INTERVAL_USEC >> 2) + 1,
			     DEV_PECI_RETRY_INTERVAL_USEC);
	} while (true);

	if (rc)
		dev_dbg(&adapter->dev, "xfer error, rc: %d\n", rc);

	return rc;
}

static int peci_xfer(struct peci_adapter *adapter, struct peci_xfer_msg *msg)
{
	return __peci_xfer(adapter, msg, false, false);
}

static int peci_xfer_with_retries(struct peci_adapter *adapter,
				  struct peci_xfer_msg *msg,
				  bool has_aw_fcs)
{
	return __peci_xfer(adapter, msg, true, has_aw_fcs);
}

static int peci_scan_cmd_mask(struct peci_adapter *adapter)
{
	struct peci_xfer_msg msg;
	u8 revision;
	int rc = 0;
	u64 dib;

	/* Update command mask just once */
	if (adapter->cmd_mask & BIT(PECI_CMD_XFER))
		return 0;

	msg.addr      = PECI_BASE_ADDR;
	msg.tx_len    = GET_DIB_WR_LEN;
	msg.rx_len    = GET_DIB_RD_LEN;
	msg.tx_buf[0] = GET_DIB_PECI_CMD;

	rc = peci_xfer(adapter, &msg);
	if (rc)
		return rc;

	dib = le64_to_cpup((__le64 *)msg.rx_buf);

	/* Check special case for Get DIB command */
	if (dib == 0) {
		dev_dbg(&adapter->dev, "DIB read as 0\n");
		return -EIO;
	}

	/**
	 * Setting up the supporting commands based on minor revision number.
	 * See PECI Spec Table 3-1.
	 */
	revision = FIELD_GET(REVISION_NUM_MASK, dib);
	if (revision >= 0x36) /* Rev. 3.6 */
		adapter->cmd_mask |= BIT(PECI_CMD_WR_IA_MSR);
	if (revision >= 0x35) /* Rev. 3.5 */
		adapter->cmd_mask |= BIT(PECI_CMD_WR_PCI_CFG);
	if (revision >= 0x34) /* Rev. 3.4 */
		adapter->cmd_mask |= BIT(PECI_CMD_RD_PCI_CFG);
	if (revision >= 0x33) { /* Rev. 3.3 */
		adapter->cmd_mask |= BIT(PECI_CMD_RD_PCI_CFG_LOCAL);
		adapter->cmd_mask |= BIT(PECI_CMD_WR_PCI_CFG_LOCAL);
	}
	if (revision >= 0x32) /* Rev. 3.2 */
		adapter->cmd_mask |= BIT(PECI_CMD_RD_IA_MSR);
	if (revision >= 0x31) { /* Rev. 3.1 */
		adapter->cmd_mask |= BIT(PECI_CMD_RD_PKG_CFG);
		adapter->cmd_mask |= BIT(PECI_CMD_WR_PKG_CFG);
	}

	adapter->cmd_mask |= BIT(PECI_CMD_XFER);
	adapter->cmd_mask |= BIT(PECI_CMD_GET_TEMP);
	adapter->cmd_mask |= BIT(PECI_CMD_GET_DIB);
	adapter->cmd_mask |= BIT(PECI_CMD_PING);

	return rc;
}

static int peci_cmd_support(struct peci_adapter *adapter, enum peci_cmd cmd)
{
	if (!(adapter->cmd_mask & BIT(PECI_CMD_PING)) &&
	    peci_scan_cmd_mask(adapter) < 0) {
		dev_dbg(&adapter->dev, "Failed to scan command mask\n");
		return -EIO;
	}

	if (!(adapter->cmd_mask & BIT(cmd))) {
		dev_dbg(&adapter->dev, "Command %d is not supported\n", cmd);
		return -EINVAL;
	}

	return 0;
}

static int peci_ioctl_xfer(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_xfer_msg *msg = vmsg;

	return peci_xfer(adapter, msg);
}

static int peci_ioctl_ping(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_ping_msg *umsg = vmsg;
	struct peci_xfer_msg msg;

	msg.addr   = umsg->addr;
	msg.tx_len = 0;
	msg.rx_len = 0;

	return peci_xfer(adapter, &msg);
}

static int peci_ioctl_get_dib(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_get_dib_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc;

	msg.addr      = umsg->addr;
	msg.tx_len    = GET_DIB_WR_LEN;
	msg.rx_len    = GET_DIB_RD_LEN;
	msg.tx_buf[0] = GET_DIB_PECI_CMD;

	rc = peci_xfer(adapter, &msg);
	if (rc)
		return rc;

	umsg->dib = le64_to_cpup((__le64 *)msg.rx_buf);

	return 0;
}

static int peci_ioctl_get_temp(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_get_temp_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc;

	msg.addr      = umsg->addr;
	msg.tx_len    = GET_TEMP_WR_LEN;
	msg.rx_len    = GET_TEMP_RD_LEN;
	msg.tx_buf[0] = GET_TEMP_PECI_CMD;

	rc = peci_xfer(adapter, &msg);
	if (rc)
		return rc;

	umsg->temp_raw = le16_to_cpup((__le16 *)msg.rx_buf);

	return 0;
}

static int peci_ioctl_rd_pkg_cfg(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_rd_pkg_cfg_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc = 0;

	/* Per the PECI spec, the read length must be a byte, word, or dword */
	if (umsg->rx_len != 1 && umsg->rx_len != 2 && umsg->rx_len != 4) {
		dev_dbg(&adapter->dev, "Invalid read length, rx_len: %d\n",
			umsg->rx_len);
		return -EINVAL;
	}

	msg.addr = umsg->addr;
	msg.tx_len = RDPKGCFG_WRITE_LEN;
	/* read lengths of 1 and 2 result in an error, so only use 4 for now */
	msg.rx_len = RDPKGCFG_READ_LEN_BASE + umsg->rx_len;
	msg.tx_buf[0] = RDPKGCFG_PECI_CMD;
	msg.tx_buf[1] = 0;         /* request byte for Host ID | Retry bit */
				   /* Host ID is 0 for PECI 3.0 */
	msg.tx_buf[2] = umsg->index;            /* RdPkgConfig index */
	msg.tx_buf[3] = (u8)umsg->param;        /* LSB - Config parameter */
	msg.tx_buf[4] = (u8)(umsg->param >> 8); /* MSB - Config parameter */

	rc = peci_xfer_with_retries(adapter, &msg, false);
	if (!rc)
		memcpy(umsg->pkg_config, &msg.rx_buf[1], umsg->rx_len);

	return rc;
}

static int peci_ioctl_wr_pkg_cfg(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_wr_pkg_cfg_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc = 0, i;

	/* Per the PECI spec, the write length must be a dword */
	if (umsg->tx_len != 4) {
		dev_dbg(&adapter->dev, "Invalid write length, tx_len: %d\n",
			umsg->tx_len);
		return -EINVAL;
	}

	msg.addr = umsg->addr;
	msg.tx_len = WRPKGCFG_WRITE_LEN_BASE + umsg->tx_len;
	/* read lengths of 1 and 2 result in an error, so only use 4 for now */
	msg.rx_len = WRPKGCFG_READ_LEN;
	msg.tx_buf[0] = WRPKGCFG_PECI_CMD;
	msg.tx_buf[1] = 0;         /* request byte for Host ID | Retry bit */
				   /* Host ID is 0 for PECI 3.0 */
	msg.tx_buf[2] = umsg->index;            /* RdPkgConfig index */
	msg.tx_buf[3] = (u8)umsg->param;        /* LSB - Config parameter */
	msg.tx_buf[4] = (u8)(umsg->param >> 8); /* MSB - Config parameter */
	for (i = 0; i < umsg->tx_len; i++)
		msg.tx_buf[5 + i] = (u8)(umsg->value >> (i << 3));

	/* Add an Assure Write Frame Check Sequence byte */
	msg.tx_buf[5 + i] = 0x80 ^
			    peci_aw_fcs((u8 *)&msg, 8 + umsg->tx_len);

	rc = peci_xfer_with_retries(adapter, &msg, true);

	return rc;
}

static int peci_ioctl_rd_ia_msr(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_rd_ia_msr_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc = 0;

	msg.addr = umsg->addr;
	msg.tx_len = RDIAMSR_WRITE_LEN;
	msg.rx_len = RDIAMSR_READ_LEN;
	msg.tx_buf[0] = RDIAMSR_PECI_CMD;
	msg.tx_buf[1] = 0;
	msg.tx_buf[2] = umsg->thread_id;
	msg.tx_buf[3] = (u8)umsg->address;
	msg.tx_buf[4] = (u8)(umsg->address >> 8);

	rc = peci_xfer_with_retries(adapter, &msg, false);
	if (!rc)
		memcpy(&umsg->value, &msg.rx_buf[1], sizeof(uint64_t));

	return rc;
}

static int peci_ioctl_rd_pci_cfg(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_rd_pci_cfg_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	u32 address;
	int rc = 0;

	address = umsg->reg;                  /* [11:0]  - Register */
	address |= (u32)umsg->function << 12; /* [14:12] - Function */
	address |= (u32)umsg->device << 15;   /* [19:15] - Device   */
	address |= (u32)umsg->bus << 20;      /* [27:20] - Bus      */
					      /* [31:28] - Reserved */
	msg.addr = umsg->addr;
	msg.tx_len = RDPCICFG_WRITE_LEN;
	msg.rx_len = RDPCICFG_READ_LEN;
	msg.tx_buf[0] = RDPCICFG_PECI_CMD;
	msg.tx_buf[1] = 0;         /* request byte for Host ID | Retry bit */
				   /* Host ID is 0 for PECI 3.0 */
	msg.tx_buf[2] = (u8)address;         /* LSB - PCI Config Address */
	msg.tx_buf[3] = (u8)(address >> 8);  /* PCI Config Address */
	msg.tx_buf[4] = (u8)(address >> 16); /* PCI Config Address */
	msg.tx_buf[5] = (u8)(address >> 24); /* MSB - PCI Config Address */

	rc = peci_xfer_with_retries(adapter, &msg, false);
	if (!rc)
		memcpy(umsg->pci_config, &msg.rx_buf[1], 4);

	return rc;
}

static int peci_ioctl_rd_pci_cfg_local(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_rd_pci_cfg_local_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	u32 address;
	int rc = 0;

	/* Per the PECI spec, the read length must be a byte, word, or dword */
	if (umsg->rx_len != 1 && umsg->rx_len != 2 && umsg->rx_len != 4) {
		dev_dbg(&adapter->dev, "Invalid read length, rx_len: %d\n",
			umsg->rx_len);
		return -EINVAL;
	}

	address = umsg->reg;                  /* [11:0]  - Register */
	address |= (u32)umsg->function << 12; /* [14:12] - Function */
	address |= (u32)umsg->device << 15;   /* [19:15] - Device   */
	address |= (u32)umsg->bus << 20;      /* [23:20] - Bus      */

	msg.addr = umsg->addr;
	msg.tx_len = RDPCICFGLOCAL_WRITE_LEN;
	msg.rx_len = RDPCICFGLOCAL_READ_LEN_BASE + umsg->rx_len;
	msg.tx_buf[0] = RDPCICFGLOCAL_PECI_CMD;
	msg.tx_buf[1] = 0;         /* request byte for Host ID | Retry bit */
				   /* Host ID is 0 for PECI 3.0 */
	msg.tx_buf[2] = (u8)address;       /* LSB - PCI Configuration Address */
	msg.tx_buf[3] = (u8)(address >> 8);  /* PCI Configuration Address */
	msg.tx_buf[4] = (u8)(address >> 16); /* PCI Configuration Address */

	rc = peci_xfer_with_retries(adapter, &msg, false);
	if (!rc)
		memcpy(umsg->pci_config, &msg.rx_buf[1], umsg->rx_len);

	return rc;
}

static int peci_ioctl_wr_pci_cfg_local(struct peci_adapter *adapter, void *vmsg)
{
	struct peci_wr_pci_cfg_local_msg *umsg = vmsg;
	struct peci_xfer_msg msg;
	int rc = 0, i;
	u32 address;

	/* Per the PECI spec, the write length must be a byte, word, or dword */
	if (umsg->tx_len != 1 && umsg->tx_len != 2 && umsg->tx_len != 4) {
		dev_dbg(&adapter->dev, "Invalid write length, tx_len: %d\n",
			umsg->tx_len);
		return -EINVAL;
	}

	address = umsg->reg;                  /* [11:0]  - Register */
	address |= (u32)umsg->function << 12; /* [14:12] - Function */
	address |= (u32)umsg->device << 15;   /* [19:15] - Device   */
	address |= (u32)umsg->bus << 20;      /* [23:20] - Bus      */

	msg.addr = umsg->addr;
	msg.tx_len = WRPCICFGLOCAL_WRITE_LEN_BASE + umsg->tx_len;
	msg.rx_len = WRPCICFGLOCAL_READ_LEN;
	msg.tx_buf[0] = WRPCICFGLOCAL_PECI_CMD;
	msg.tx_buf[1] = 0;         /* request byte for Host ID | Retry bit */
				   /* Host ID is 0 for PECI 3.0 */
	msg.tx_buf[2] = (u8)address;       /* LSB - PCI Configuration Address */
	msg.tx_buf[3] = (u8)(address >> 8);  /* PCI Configuration Address */
	msg.tx_buf[4] = (u8)(address >> 16); /* PCI Configuration Address */
	for (i = 0; i < umsg->tx_len; i++)
		msg.tx_buf[5 + i] = (u8)(umsg->value >> (i << 3));

	/* Add an Assure Write Frame Check Sequence byte */
	msg.tx_buf[5 + i] = 0x80 ^
			    peci_aw_fcs((u8 *)&msg, 8 + umsg->tx_len);

	rc = peci_xfer_with_retries(adapter, &msg, true);

	return rc;
}

typedef int (*peci_ioctl_fn_type)(struct peci_adapter *, void *);

static const peci_ioctl_fn_type peci_ioctl_fn[PECI_CMD_MAX] = {
	peci_ioctl_xfer,
	peci_ioctl_ping,
	peci_ioctl_get_dib,
	peci_ioctl_get_temp,
	peci_ioctl_rd_pkg_cfg,
	peci_ioctl_wr_pkg_cfg,
	peci_ioctl_rd_ia_msr,
	NULL, /* Reserved */
	peci_ioctl_rd_pci_cfg,
	NULL, /* Reserved */
	peci_ioctl_rd_pci_cfg_local,
	peci_ioctl_wr_pci_cfg_local,
};

/**
 * peci_command - transfer function of a PECI command
 * @adapter: pointer to peci_adapter
 * @vmsg: pointer to PECI messages
 * Context: can sleep
 *
 * This performs a transfer of a PECI command using PECI messages parameter
 * which has various formats on each command.
 *
 * Return: zero on success, else a negative error code.
 */
int peci_command(struct peci_adapter *adapter, enum peci_cmd cmd, void *vmsg)
{
	int rc = 0;

	if (cmd >= PECI_CMD_MAX || cmd < PECI_CMD_XFER)
		return -EINVAL;

	dev_dbg(&adapter->dev, "%s, cmd=0x%02x\n", __func__, cmd);

	if (!peci_ioctl_fn[cmd])
		return -EINVAL;

	rt_mutex_lock(&adapter->bus_lock);

	rc = peci_cmd_support(adapter, cmd);
	if (!rc)
		rc = peci_ioctl_fn[cmd](adapter, vmsg);

	rt_mutex_unlock(&adapter->bus_lock);

	return rc;
}
EXPORT_SYMBOL_GPL(peci_command);

static long peci_ioctl(struct file *file, unsigned int iocmd, unsigned long arg)
{
	struct peci_adapter *adapter = file->private_data;
	void __user *argp = (void __user *)arg;
	unsigned int msg_len;
	enum peci_cmd cmd;
	int rc = 0;
	u8 *msg;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	dev_dbg(&adapter->dev, "ioctl, cmd=0x%x, arg=0x%lx\n", iocmd, arg);

	switch (iocmd) {
	case PECI_IOC_XFER:
	case PECI_IOC_PING:
	case PECI_IOC_GET_DIB:
	case PECI_IOC_GET_TEMP:
	case PECI_IOC_RD_PKG_CFG:
	case PECI_IOC_WR_PKG_CFG:
	case PECI_IOC_RD_IA_MSR:
	case PECI_IOC_RD_PCI_CFG:
	case PECI_IOC_RD_PCI_CFG_LOCAL:
	case PECI_IOC_WR_PCI_CFG_LOCAL:
		cmd = _IOC_NR(iocmd);
		msg_len = _IOC_SIZE(iocmd);
		break;

	default:
		dev_dbg(&adapter->dev, "Invalid ioctl cmd : 0x%x\n", iocmd);
		return -ENOTTY;
	}

	if (!access_ok(argp, msg_len))
		return -EFAULT;

	msg = memdup_user(argp, msg_len);
	if (IS_ERR(msg))
		return PTR_ERR(msg);

	rc = peci_command(adapter, cmd, msg);

	if (!rc && copy_to_user(argp, msg, msg_len))
		rc = -EFAULT;

	kfree(msg);
	return (long)rc;
}

static int peci_open(struct inode *inode, struct file *file)
{
	unsigned int minor = iminor(inode);
	struct peci_adapter *adapter;

	adapter = peci_get_adapter(minor);
	if (!adapter)
		return -ENODEV;

	file->private_data = adapter;

	return 0;
}

static int peci_release(struct inode *inode, struct file *file)
{
	struct peci_adapter *adapter = file->private_data;

	peci_put_adapter(adapter);
	file->private_data = NULL;

	return 0;
}

static const struct file_operations peci_fops = {
	.owner          = THIS_MODULE,
	.unlocked_ioctl = peci_ioctl,
	.open           = peci_open,
	.release        = peci_release,
};

static int peci_detect(struct peci_adapter *adapter, u8 addr)
{
	struct peci_ping_msg msg;

	msg.addr = addr;

	return peci_command(adapter, PECI_CMD_PING, &msg);
}

static const struct of_device_id *
peci_of_match_device(const struct of_device_id *matches,
		     struct peci_client *client)
{
#if IS_ENABLED(CONFIG_OF)
	if (!(client && matches))
		return NULL;

	return of_match_device(matches, &client->dev);
#else
	return NULL;
#endif
}

static const struct peci_device_id *
peci_match_id(const struct peci_device_id *id, struct peci_client *client)
{
	if (!(id && client))
		return NULL;

	while (id->name[0]) {
		if (!strncmp(client->name, id->name, PECI_NAME_SIZE))
			return id;
		id++;
	}

	return NULL;
}

static int peci_device_match(struct device *dev, struct device_driver *drv)
{
	struct peci_client *client = peci_verify_client(dev);
	struct peci_driver *driver;

	/* Attempt an OF style match */
	if (peci_of_match_device(drv->of_match_table, client))
		return 1;

	driver = to_peci_driver(drv);

	/* Finally an ID match */
	if (peci_match_id(driver->id_table, client))
		return 1;

	return 0;
}

static int peci_device_probe(struct device *dev)
{
	struct peci_client *client = peci_verify_client(dev);
	struct peci_driver *driver;
	int status = -EINVAL;

	if (!client)
		return 0;

	driver = to_peci_driver(dev->driver);

	if (!driver->id_table &&
	    !peci_of_match_device(dev->driver->of_match_table, client))
		return -ENODEV;

	dev_dbg(dev, "%s: name:%s\n", __func__, client->name);

	status = dev_pm_domain_attach(&client->dev, true);
	if (status == -EPROBE_DEFER)
		return status;

	if (driver->probe)
		status = driver->probe(client);
	else
		status = -EINVAL;

	if (status)
		goto err_detach_pm_domain;

	return 0;

err_detach_pm_domain:
	dev_pm_domain_detach(&client->dev, true);
	return status;
}

static int peci_device_remove(struct device *dev)
{
	struct peci_client *client = peci_verify_client(dev);
	struct peci_driver *driver;
	int status = 0;

	if (!client || !dev->driver)
		return 0;

	driver = to_peci_driver(dev->driver);
	if (driver->remove) {
		dev_dbg(dev, "%s: name:%s\n", __func__, client->name);
		status = driver->remove(client);
	}

	dev_pm_domain_detach(&client->dev, true);

	return status;
}

static void peci_device_shutdown(struct device *dev)
{
	struct peci_client *client = peci_verify_client(dev);
	struct peci_driver *driver;

	if (!client || !dev->driver)
		return;

	dev_dbg(dev, "%s: name:%s\n", __func__, client->name);

	driver = to_peci_driver(dev->driver);
	if (driver->shutdown)
		driver->shutdown(client);
}

static struct bus_type peci_bus_type = {
	.name		= "peci",
	.match		= peci_device_match,
	.probe		= peci_device_probe,
	.remove		= peci_device_remove,
	.shutdown	= peci_device_shutdown,
};

static int peci_check_addr_validity(u8 addr)
{
	if (addr < PECI_BASE_ADDR && addr > PECI_BASE_ADDR + PECI_OFFSET_MAX)
		return -EINVAL;

	return 0;
}

static int peci_check_client_busy(struct device *dev, void *client_new_p)
{
	struct peci_client *client = peci_verify_client(dev);
	struct peci_client *client_new = client_new_p;

	if (client && client->addr == client_new->addr)
		return -EBUSY;

	return 0;
}

/**
 * peci_get_cpu_id - read CPU ID from the Package Configuration Space of CPU
 * @adapter: pointer to peci_adapter
 * @addr: address of the PECI client CPU
 * @cpu_id: where the CPU ID will be stored
 * Context: can sleep
 *
 * Return: zero on success, else a negative error code.
 */
int peci_get_cpu_id(struct peci_adapter *adapter, u8 addr, u32 *cpu_id)
{
	struct peci_rd_pkg_cfg_msg msg;
	int rc;

	msg.addr = addr;
	msg.index = MBX_INDEX_CPU_ID;
	msg.param = PKG_ID_CPU_ID;
	msg.rx_len = 4;

	rc = peci_command(adapter, PECI_CMD_RD_PKG_CFG, &msg);
	if (!rc)
		*cpu_id = le32_to_cpup((__le32 *)msg.pkg_config);

	return rc;
}
EXPORT_SYMBOL_GPL(peci_get_cpu_id);

static struct peci_client *peci_new_device(struct peci_adapter *adapter,
					   struct peci_board_info const *info)
{
	struct peci_client *client;
	int rc;

	/* Increase reference count for the adapter assigned */
	if (!peci_get_adapter(adapter->nr))
		return NULL;

	client = kzalloc(sizeof(*client), GFP_KERNEL);
	if (!client)
		goto err_put_adapter;

	client->adapter = adapter;
	client->addr = info->addr;
	strlcpy(client->name, info->type, sizeof(client->name));

	rc = peci_check_addr_validity(client->addr);
	if (rc) {
		dev_err(&adapter->dev, "Invalid PECI CPU address 0x%02hx\n",
			client->addr);
		goto err_free_client_silent;
	}

	/* Check online status of client */
	rc = peci_detect(adapter, client->addr);
	if (rc)
		goto err_free_client;

	rc = device_for_each_child(&adapter->dev, client,
				   peci_check_client_busy);
	if (rc)
		goto err_free_client;

	client->dev.parent = &client->adapter->dev;
	client->dev.bus = &peci_bus_type;
	client->dev.type = &peci_client_type;
	client->dev.of_node = info->of_node;
	dev_set_name(&client->dev, "%d-%02x", adapter->nr, client->addr);

	rc = device_register(&client->dev);
	if (rc)
		goto err_free_client;

	dev_dbg(&adapter->dev, "client [%s] registered with bus id %s\n",
		client->name, dev_name(&client->dev));

	return client;

err_free_client:
	dev_err(&adapter->dev,
		"Failed to register peci client %s at 0x%02x (%d)\n",
		client->name, client->addr, rc);
err_free_client_silent:
	kfree(client);
err_put_adapter:
	peci_put_adapter(adapter);
	return NULL;
}

static void peci_unregister_device(struct peci_client *client)
{
	if (!client)
		return;

	if (client->dev.of_node)
		of_node_clear_flag(client->dev.of_node, OF_POPULATED);

	device_unregister(&client->dev);
}

static int peci_unregister_client(struct device *dev, void *dummy)
{
	struct peci_client *client = peci_verify_client(dev);

	peci_unregister_device(client);

	return 0;
}

static void peci_adapter_dev_release(struct device *dev)
{
	struct peci_adapter *adapter = to_peci_adapter(dev);

	dev_dbg(dev, "%s: %s\n", __func__, adapter->name);
	mutex_destroy(&adapter->userspace_clients_lock);
	rt_mutex_destroy(&adapter->bus_lock);
	kfree(adapter);
}

static ssize_t peci_sysfs_new_device(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf, size_t count)
{
	struct peci_adapter *adapter = to_peci_adapter(dev);
	struct peci_board_info info = {};
	struct peci_client *client;
	char *blank, end;
	int rc;

	/* Parse device type */
	blank = strchr(buf, ' ');
	if (!blank) {
		dev_err(dev, "%s: Missing parameters\n", "new_device");
		return -EINVAL;
	}
	if (blank - buf > PECI_NAME_SIZE - 1) {
		dev_err(dev, "%s: Invalid device type\n", "new_device");
		return -EINVAL;
	}
	memcpy(info.type, buf, blank - buf);

	/* Parse remaining parameters, reject extra parameters */
	rc = sscanf(++blank, "%hi%c", &info.addr, &end);
	if (rc < 1) {
		dev_err(dev, "%s: Can't parse client address\n", "new_device");
		return -EINVAL;
	}
	if (rc > 1  && end != '\n') {
		dev_err(dev, "%s: Extra parameters\n", "new_device");
		return -EINVAL;
	}

	client = peci_new_device(adapter, &info);
	if (!client)
		return -EINVAL;

	/* Keep track of the added device */
	mutex_lock(&adapter->userspace_clients_lock);
	list_add_tail(&client->detected, &adapter->userspace_clients);
	mutex_unlock(&adapter->userspace_clients_lock);
	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
		 info.type, info.addr);

	return count;
}
static DEVICE_ATTR(new_device, 0200, NULL, peci_sysfs_new_device);

static ssize_t peci_sysfs_delete_device(struct device *dev,
					struct device_attribute *attr,
					const char *buf, size_t count)
{
	struct peci_adapter *adapter = to_peci_adapter(dev);
	struct peci_client *client, *next;
	struct peci_board_info info = {};
	struct peci_driver *driver;
	char *blank, end;
	int rc;

	/* Parse device type */
	blank = strchr(buf, ' ');
	if (!blank) {
		dev_err(dev, "%s: Missing parameters\n", "delete_device");
		return -EINVAL;
	}
	if (blank - buf > PECI_NAME_SIZE - 1) {
		dev_err(dev, "%s: Invalid device type\n", "delete_device");
		return -EINVAL;
	}
	memcpy(info.type, buf, blank - buf);

	/* Parse remaining parameters, reject extra parameters */
	rc = sscanf(++blank, "%hi%c", &info.addr, &end);
	if (rc < 1) {
		dev_err(dev, "%s: Can't parse client address\n",
			"delete_device");
		return -EINVAL;
	}
	if (rc > 1  && end != '\n') {
		dev_err(dev, "%s: Extra parameters\n", "delete_device");
		return -EINVAL;
	}

	/* Make sure the device was added through sysfs */
	rc = -ENOENT;
	mutex_lock(&adapter->userspace_clients_lock);
	list_for_each_entry_safe(client, next, &adapter->userspace_clients,
				 detected) {
		driver = to_peci_driver(client->dev.driver);

		if (client->addr == info.addr &&
		    !strncmp(client->name, info.type, PECI_NAME_SIZE)) {
			dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
				 "delete_device", client->name, client->addr);
			list_del(&client->detected);
			peci_unregister_device(client);
			rc = count;
			break;
		}
	}
	mutex_unlock(&adapter->userspace_clients_lock);

	if (rc < 0)
		dev_err(dev, "%s: Can't find device in list\n",
			"delete_device");

	return rc;
}
static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, 0200, NULL,
				  peci_sysfs_delete_device);

static struct attribute *peci_adapter_attrs[] = {
	&dev_attr_name.attr,
	&dev_attr_new_device.attr,
	&dev_attr_delete_device.attr,
	NULL
};
ATTRIBUTE_GROUPS(peci_adapter);

static struct device_type peci_adapter_type = {
	.groups		= peci_adapter_groups,
	.release	= peci_adapter_dev_release,
};

/**
 * peci_verify_adapter - return parameter as peci_adapter, or NULL
 * @dev: device, probably from some driver model iterator
 *
 * Return: pointer to peci_adapter on success, else NULL.
 */
struct peci_adapter *peci_verify_adapter(struct device *dev)
{
	return (dev->type == &peci_adapter_type)
			? to_peci_adapter(dev)
			: NULL;
}
EXPORT_SYMBOL_GPL(peci_verify_adapter);

#if IS_ENABLED(CONFIG_OF)
static struct peci_client *peci_of_register_device(struct peci_adapter *adapter,
						   struct device_node *node)
{
	struct peci_board_info info = {};
	struct peci_client *result;
	const __be32 *addr_be;
	int len;

	dev_dbg(&adapter->dev, "register %pOF\n", node);

	if (of_modalias_node(node, info.type, sizeof(info.type)) < 0) {
		dev_err(&adapter->dev, "modalias failure on %pOF\n", node);
		return ERR_PTR(-EINVAL);
	}

	addr_be = of_get_property(node, "reg", &len);
	if (!addr_be || len < sizeof(*addr_be)) {
		dev_err(&adapter->dev, "invalid reg on %pOF\n", node);
		return ERR_PTR(-EINVAL);
	}

	info.addr = be32_to_cpup(addr_be);
	info.of_node = of_node_get(node);

	result = peci_new_device(adapter, &info);
	if (!result)
		result = ERR_PTR(-EINVAL);

	of_node_put(node);
	return result;
}

static void peci_of_register_devices(struct peci_adapter *adapter)
{
	struct device_node *bus, *node;
	struct peci_client *client;

	/* Only register child devices if the adapter has a node pointer set */
	if (!adapter->dev.of_node)
		return;

	bus = of_get_child_by_name(adapter->dev.of_node, "peci-bus");
	if (!bus)
		bus = of_node_get(adapter->dev.of_node);

	for_each_available_child_of_node(bus, node) {
		if (of_node_test_and_set_flag(node, OF_POPULATED))
			continue;

		client = peci_of_register_device(adapter, node);
		if (IS_ERR(client)) {
			dev_warn(&adapter->dev,
				 "Failed to create PECI device for %pOF\n",
				 node);
			of_node_clear_flag(node, OF_POPULATED);
		}
	}

	of_node_put(bus);
}
#else
static void peci_of_register_devices(struct peci_adapter *adapter) { }
#endif /* CONFIG_OF */

#if IS_ENABLED(CONFIG_OF_DYNAMIC)
static int peci_of_match_node(struct device *dev, void *data)
{
	return dev->of_node == data;
}

/* must call put_device() when done with returned peci_client device */
static struct peci_client *peci_of_find_device(struct device_node *node)
{
	struct peci_client *client;
	struct device *dev;

	dev = bus_find_device(&peci_bus_type, NULL, node, peci_of_match_node);
	if (!dev)
		return NULL;

	client = peci_verify_client(dev);
	if (!client)
		put_device(dev);

	return client;
}

/* must call put_device() when done with returned peci_adapter device */
static struct peci_adapter *peci_of_find_adapter(struct device_node *node)
{
	struct peci_adapter *adapter;
	struct device *dev;

	dev = bus_find_device(&peci_bus_type, NULL, node, peci_of_match_node);
	if (!dev)
		return NULL;

	adapter = peci_verify_adapter(dev);
	if (!adapter)
		put_device(dev);

	return adapter;
}

static int peci_of_notify(struct notifier_block *nb,
			  unsigned long action,
			  void *arg)
{
	struct of_reconfig_data *rd = arg;
	struct peci_adapter *adapter;
	struct peci_client *client;

	switch (of_reconfig_get_state_change(action, rd)) {
	case OF_RECONFIG_CHANGE_ADD:
		adapter = peci_of_find_adapter(rd->dn->parent);
		if (!adapter)
			return NOTIFY_OK;	/* not for us */

		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
			put_device(&adapter->dev);
			return NOTIFY_OK;
		}

		client = peci_of_register_device(adapter, rd->dn);
		put_device(&adapter->dev);

		if (IS_ERR(client)) {
			dev_err(&adapter->dev,
				"failed to create client for '%pOF'\n", rd->dn);
			of_node_clear_flag(rd->dn, OF_POPULATED);
			return notifier_from_errno(PTR_ERR(client));
		}
		break;
	case OF_RECONFIG_CHANGE_REMOVE:
		/* already depopulated? */
		if (!of_node_check_flag(rd->dn, OF_POPULATED))
			return NOTIFY_OK;

		/* find our device by node */
		client = peci_of_find_device(rd->dn);
		if (!client)
			return NOTIFY_OK;	/* no? not meant for us */

		/* unregister takes one ref away */
		peci_unregister_device(client);

		/* and put the reference of the find */
		put_device(&client->dev);
		break;
	}

	return NOTIFY_OK;
}

static struct notifier_block peci_of_notifier = {
	.notifier_call = peci_of_notify,
};
#else
extern struct notifier_block peci_of_notifier;
#endif /* CONFIG_OF_DYNAMIC */

/**
 * peci_alloc_adapter - allocate a PECI adapter
 * @dev: the adapter, possibly using the platform_bus
 * @size: how much zeroed driver-private data to allocate; the pointer to this
 *	memory is in the driver_data field of the returned device,
 *	accessible with peci_get_adapdata().
 * Context: can sleep
 *
 * This call is used only by PECI adapter drivers, which are the only ones
 * directly touching chip registers.  It's how they allocate a peci_adapter
 * structure, prior to calling peci_add_adapter().
 *
 * This must be called from context that can sleep.
 *
 * The caller is responsible for initializing the adapter's methods before
 * calling peci_add_adapter(); and (after errors while adding the device)
 * calling put_device() to prevent a memory leak.
 *
 * Return: the peci_adapter structure on success, else NULL.
 */
struct peci_adapter *peci_alloc_adapter(struct device *dev, unsigned int size)
{
	struct peci_adapter *adapter;

	if (!dev)
		return NULL;

	adapter = kzalloc(size + sizeof(*adapter), GFP_KERNEL);
	if (!adapter)
		return NULL;

	device_initialize(&adapter->dev);
	adapter->dev.parent = dev;
	adapter->dev.bus = &peci_bus_type;
	adapter->dev.type = &peci_adapter_type;
	peci_set_adapdata(adapter, &adapter[1]);

	return adapter;
}
EXPORT_SYMBOL_GPL(peci_alloc_adapter);

static int peci_register_adapter(struct peci_adapter *adapter)
{
	int rc = -EINVAL;

	/* Can't register until after driver model init */
	if (WARN_ON(!is_registered))
		goto err_free_idr;

	if (WARN(!adapter->name[0], "peci adapter has no name"))
		goto err_free_idr;

	if (WARN(!adapter->xfer, "peci adapter has no xfer function\n"))
		goto err_free_idr;

	rt_mutex_init(&adapter->bus_lock);
	mutex_init(&adapter->userspace_clients_lock);
	INIT_LIST_HEAD(&adapter->userspace_clients);

	dev_set_name(&adapter->dev, "peci-%d", adapter->nr);

	/* cdev */
	cdev_init(&adapter->cdev, &peci_fops);
	adapter->cdev.owner = THIS_MODULE;
	adapter->dev.devt = MKDEV(MAJOR(peci_devt), adapter->nr);
	rc = cdev_add(&adapter->cdev, adapter->dev.devt, 1);
	if (rc) {
		pr_err("adapter '%s': can't add cdev (%d)\n",
		       adapter->name, rc);
		goto err_free_idr;
	}
	rc = device_add(&adapter->dev);
	if (rc) {
		pr_err("adapter '%s': can't add device (%d)\n",
		       adapter->name, rc);
		goto err_del_cdev;
	}

	dev_dbg(&adapter->dev, "adapter [%s] registered\n", adapter->name);

	pm_runtime_no_callbacks(&adapter->dev);
	pm_suspend_ignore_children(&adapter->dev, true);
	pm_runtime_enable(&adapter->dev);

	/* create pre-declared device nodes */
	peci_of_register_devices(adapter);

	return 0;

err_del_cdev:
	cdev_del(&adapter->cdev);
err_free_idr:
	mutex_lock(&core_lock);
	idr_remove(&peci_adapter_idr, adapter->nr);
	mutex_unlock(&core_lock);
	return rc;
}

static int peci_add_numbered_adapter(struct peci_adapter *adapter)
{
	int id;

	mutex_lock(&core_lock);
	id = idr_alloc(&peci_adapter_idr, adapter,
		       adapter->nr, adapter->nr + 1, GFP_KERNEL);
	mutex_unlock(&core_lock);
	if (WARN(id < 0, "couldn't get idr"))
		return id == -ENOSPC ? -EBUSY : id;

	return peci_register_adapter(adapter);
}

/**
 * peci_add_adapter - add a PECI adapter
 * @adapter: initialized adapter, originally from peci_alloc_adapter()
 * Context: can sleep
 *
 * PECI adapters connect to their drivers using some non-PECI bus,
 * such as the platform bus.  The final stage of probe() in that code
 * includes calling peci_add_adapter() to hook up to this PECI bus glue.
 *
 * This must be called from context that can sleep.
 *
 * It returns zero on success, else a negative error code (dropping the
 * adapter's refcount).  After a successful return, the caller is responsible
 * for calling peci_del_adapter().
 *
 * Return: zero on success, else a negative error code.
 */
int peci_add_adapter(struct peci_adapter *adapter)
{
	struct device *dev = &adapter->dev;
	int id;

	if (dev->of_node) {
		id = of_alias_get_id(dev->of_node, "peci");
		if (id >= 0) {
			adapter->nr = id;
			return peci_add_numbered_adapter(adapter);
		}
	}

	mutex_lock(&core_lock);
	id = idr_alloc(&peci_adapter_idr, adapter, 0, 0, GFP_KERNEL);
	mutex_unlock(&core_lock);
	if (WARN(id < 0, "couldn't get idr"))
		return id;

	adapter->nr = id;

	return peci_register_adapter(adapter);
}
EXPORT_SYMBOL_GPL(peci_add_adapter);

/**
 * peci_del_adapter - delete a PECI adapter
 * @adapter: the adpater being deleted
 * Context: can sleep
 *
 * This call is used only by PECI adpater drivers, which are the only ones
 * directly touching chip registers.
 *
 * This must be called from context that can sleep.
 *
 * Note that this function also drops a reference to the adapter.
 */
void peci_del_adapter(struct peci_adapter *adapter)
{
	struct peci_client *client, *next;
	struct peci_adapter *found;
	int nr;

	/* First make sure that this adapter was ever added */
	mutex_lock(&core_lock);
	found = idr_find(&peci_adapter_idr, adapter->nr);
	mutex_unlock(&core_lock);

	if (found != adapter)
		return;

	/* Remove devices instantiated from sysfs */
	mutex_lock(&adapter->userspace_clients_lock);
	list_for_each_entry_safe(client, next, &adapter->userspace_clients,
				 detected) {
		dev_dbg(&adapter->dev, "Removing %s at 0x%x\n", client->name,
			client->addr);
		list_del(&client->detected);
		peci_unregister_device(client);
	}
	mutex_unlock(&adapter->userspace_clients_lock);

	/**
	 * Detach any active clients. This can't fail, thus we do not
	 * check the returned value.
	 */
	device_for_each_child(&adapter->dev, NULL, peci_unregister_client);

	/* device name is gone after device_unregister */
	dev_dbg(&adapter->dev, "adapter [%s] unregistered\n", adapter->name);

	/* free cdev */
	cdev_del(&adapter->cdev);

	pm_runtime_disable(&adapter->dev);

	nr = adapter->nr;

	device_unregister(&adapter->dev);

	/* free bus id */
	mutex_lock(&core_lock);
	idr_remove(&peci_adapter_idr, nr);
	mutex_unlock(&core_lock);
}
EXPORT_SYMBOL_GPL(peci_del_adapter);

/**
 * peci_register_driver - register a PECI driver
 * @owner: owner module of the driver being registered
 * @driver: the driver being registered
 * Context: can sleep
 *
 * Return: zero on success, else a negative error code.
 */
int peci_register_driver(struct module *owner, struct peci_driver *driver)
{
	int rc;

	/* Can't register until after driver model init */
	if (WARN_ON(!is_registered))
		return -EAGAIN;

	/* add the driver to the list of peci drivers in the driver core */
	driver->driver.owner = owner;
	driver->driver.bus = &peci_bus_type;

	/**
	 * When registration returns, the driver core
	 * will have called probe() for all matching-but-unbound devices.
	 */
	rc = driver_register(&driver->driver);
	if (rc)
		return rc;

	pr_debug("driver [%s] registered\n", driver->driver.name);

	return 0;
}
EXPORT_SYMBOL_GPL(peci_register_driver);

/**
 * peci_del_driver - unregister a PECI driver
 * @driver: the driver being unregistered
 * Context: can sleep
 */
void peci_del_driver(struct peci_driver *driver)
{
	driver_unregister(&driver->driver);
	pr_debug("driver [%s] unregistered\n", driver->driver.name);
}
EXPORT_SYMBOL_GPL(peci_del_driver);

static int __init peci_init(void)
{
	int ret;

	ret = bus_register(&peci_bus_type);
	if (ret < 0) {
		pr_err("peci: Failed to register PECI bus type!\n");
		return ret;
	}

	ret = alloc_chrdev_region(&peci_devt, 0, PECI_CDEV_MAX, "peci");
	if (ret < 0) {
		pr_err("peci: Failed to allocate chr dev region!\n");
		bus_unregister(&peci_bus_type);
		return ret;
	}

	crc8_populate_msb(peci_crc8_table, PECI_CRC8_POLYNOMIAL);

	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
		WARN_ON(of_reconfig_notifier_register(&peci_of_notifier));

	is_registered = true;

	return 0;
}

static void __exit peci_exit(void)
{
	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
		WARN_ON(of_reconfig_notifier_unregister(&peci_of_notifier));

	unregister_chrdev_region(peci_devt, PECI_CDEV_MAX);
	bus_unregister(&peci_bus_type);
}

postcore_initcall(peci_init);
module_exit(peci_exit);

MODULE_AUTHOR("Jason M Biils <jason.m.bills@linux.intel.com>");
MODULE_AUTHOR("Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>");
MODULE_DESCRIPTION("PECI bus core module");
MODULE_LICENSE("GPL v2");