/*
 * System Control and Power Interface (SCPI) Message Protocol driver
 *
 * Copyright (C) 2014 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/err.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/mailbox_client.h>
#include <linux/scpi_protocol.h>
#include <linux/slab.h>

#include "arm_mhu.h"

#define CMD_ID_SHIFT		0
#define CMD_ID_MASK		0xff
#define CMD_SENDER_ID_SHIFT	8
#define CMD_SENDER_ID_MASK	0xff
#define CMD_DATA_SIZE_SHIFT	20
#define CMD_DATA_SIZE_MASK	0x1ff
#define PACK_SCPI_CMD(cmd, sender, txsz)				\
	((((cmd) & CMD_ID_MASK) << CMD_ID_SHIFT) |			\
	(((sender) & CMD_SENDER_ID_MASK) << CMD_SENDER_ID_SHIFT) |	\
	(((txsz) & CMD_DATA_SIZE_MASK) << CMD_DATA_SIZE_SHIFT))

#define MAX_DVFS_DOMAINS	3
#define MAX_DVFS_OPPS		8
#define DVFS_LATENCY(hdr)	((hdr) >> 16)
#define DVFS_OPP_COUNT(hdr)	(((hdr) >> 8) & 0xff)

enum scpi_error_codes {
	SCPI_SUCCESS = 0, /* Success */
	SCPI_ERR_PARAM = 1, /* Invalid parameter(s) */
	SCPI_ERR_ALIGN = 2, /* Invalid alignment */
	SCPI_ERR_SIZE = 3, /* Invalid size */
	SCPI_ERR_HANDLER = 4, /* Invalid handler/callback */
	SCPI_ERR_ACCESS = 5, /* Invalid access/permission denied */
	SCPI_ERR_RANGE = 6, /* Value out of range */
	SCPI_ERR_TIMEOUT = 7, /* Timeout has occurred */
	SCPI_ERR_NOMEM = 8, /* Invalid memory area or pointer */
	SCPI_ERR_PWRSTATE = 9, /* Invalid power state */
	SCPI_ERR_SUPPORT = 10, /* Not supported or disabled */
	SCPI_ERR_DEVICE = 11, /* Device error */
	SCPI_ERR_MAX
};

enum scpi_client_id {
	SCPI_CL_NONE,
	SCPI_CL_CLOCKS,
	SCPI_CL_DVFS,
	SCPI_CL_POWER,
	SCPI_MAX,
};

enum scpi_std_cmd {
	SCPI_CMD_INVALID		= 0x00,
	SCPI_CMD_SCPI_READY		= 0x01,
	SCPI_CMD_SCPI_CAPABILITIES	= 0x02,
	SCPI_CMD_EVENT			= 0x03,
	SCPI_CMD_SET_CSS_PWR_STATE	= 0x04,
	SCPI_CMD_GET_CSS_PWR_STATE	= 0x05,
	SCPI_CMD_CFG_PWR_STATE_STAT	= 0x06,
	SCPI_CMD_GET_PWR_STATE_STAT	= 0x07,
	SCPI_CMD_SYS_PWR_STATE		= 0x08,
	SCPI_CMD_L2_READY		= 0x09,
	SCPI_CMD_SET_AP_TIMER		= 0x0a,
	SCPI_CMD_CANCEL_AP_TIME		= 0x0b,
	SCPI_CMD_DVFS_CAPABILITIES	= 0x0c,
	SCPI_CMD_GET_DVFS_INFO		= 0x0d,
	SCPI_CMD_SET_DVFS		= 0x0e,
	SCPI_CMD_GET_DVFS		= 0x0f,
	SCPI_CMD_GET_DVFS_STAT		= 0x10,
	SCPI_CMD_SET_RTC		= 0x11,
	SCPI_CMD_GET_RTC		= 0x12,
	SCPI_CMD_CLOCK_CAPABILITIES	= 0x13,
	SCPI_CMD_SET_CLOCK_INDEX	= 0x14,
	SCPI_CMD_SET_CLOCK_VALUE	= 0x15,
	SCPI_CMD_GET_CLOCK_VALUE	= 0x16,
	SCPI_CMD_PSU_CAPABILITIES	= 0x17,
	SCPI_CMD_SET_PSU		= 0x18,
	SCPI_CMD_GET_PSU		= 0x19,
	SCPI_CMD_SENSOR_CAPABILITIES	= 0x1a,
	SCPI_CMD_SENSOR_INFO		= 0x1b,
	SCPI_CMD_SENSOR_VALUE		= 0x1c,
	SCPI_CMD_SENSOR_CFG_PERIODIC	= 0x1d,
	SCPI_CMD_SENSOR_CFG_BOUNDS	= 0x1e,
	SCPI_CMD_SENSOR_ASYNC_VALUE	= 0x1f,
	SCPI_CMD_COUNT
};

struct scpi_data_buf {
	int client_id;
	struct mhu_data_buf *data;
	struct completion complete;
};

static int high_priority_cmds[] = {
	SCPI_CMD_GET_CSS_PWR_STATE,
	SCPI_CMD_CFG_PWR_STATE_STAT,
	SCPI_CMD_GET_PWR_STATE_STAT,
	SCPI_CMD_SET_DVFS,
	SCPI_CMD_GET_DVFS,
	SCPI_CMD_SET_RTC,
	SCPI_CMD_GET_RTC,
	SCPI_CMD_SET_CLOCK_INDEX,
	SCPI_CMD_SET_CLOCK_VALUE,
	SCPI_CMD_GET_CLOCK_VALUE,
	SCPI_CMD_SET_PSU,
	SCPI_CMD_GET_PSU,
	SCPI_CMD_SENSOR_VALUE,
	SCPI_CMD_SENSOR_CFG_PERIODIC,
	SCPI_CMD_SENSOR_CFG_BOUNDS,
};

static struct scpi_opp *scpi_opps[MAX_DVFS_DOMAINS];

static int scpi_linux_errmap[SCPI_ERR_MAX] = {
	0, -EINVAL, -ENOEXEC, -EMSGSIZE,
	-EINVAL, -EACCES, -ERANGE, -ETIMEDOUT,
	-ENOMEM, -EINVAL, -EOPNOTSUPP, -EIO,
};

static inline int scpi_to_linux_errno(int errno)
{
	if (errno >= SCPI_SUCCESS && errno < SCPI_ERR_MAX)
		return scpi_linux_errmap[errno];
	return -EIO;
}

static bool high_priority_chan_supported(int cmd)
{
	int idx;
	for (idx = 0; idx < ARRAY_SIZE(high_priority_cmds); idx++)
		if (cmd == high_priority_cmds[idx])
			return true;
	return false;
}

static void scpi_rx_callback(struct mbox_client *cl, void *msg)
{
	struct mhu_data_buf *data = (struct mhu_data_buf *)msg;
	struct scpi_data_buf *scpi_buf = data->cl_data;
	complete(&scpi_buf->complete);
}

static int send_scpi_cmd(struct scpi_data_buf *scpi_buf, bool high_priority)
{
	struct mbox_chan *chan;
	struct mbox_client cl = {0};
	struct mhu_data_buf *data = scpi_buf->data;
	u32 status;

	cl.dev = the_scpi_device;
	cl.rx_callback = scpi_rx_callback;

	chan = mbox_request_channel(&cl, high_priority);
	if (IS_ERR(chan))
		return PTR_ERR(chan);

	init_completion(&scpi_buf->complete);
	if (mbox_send_message(chan, (void *)data) < 0) {
		status = SCPI_ERR_TIMEOUT;
		goto free_channel;
	}

	wait_for_completion(&scpi_buf->complete);
	status = *(u32 *)(data->rx_buf); /* read first word */

free_channel:
	mbox_free_channel(chan);

	return scpi_to_linux_errno(status);
}

#define SCPI_SETUP_DBUF(scpi_buf, mhu_buf, _client_id,\
			_cmd, _tx_buf, _rx_buf) \
do {						\
	struct mhu_data_buf *pdata = &mhu_buf;	\
	pdata->cmd = _cmd;			\
	pdata->tx_buf = &_tx_buf;		\
	pdata->tx_size = sizeof(_tx_buf);	\
	pdata->rx_buf = &_rx_buf;		\
	pdata->rx_size = sizeof(_rx_buf);	\
	scpi_buf.client_id = _client_id;	\
	scpi_buf.data = pdata;			\
} while (0)

static int scpi_execute_cmd(struct scpi_data_buf *scpi_buf)
{
	struct mhu_data_buf *data;
	bool high_priority;

	if (!scpi_buf || !scpi_buf->data)
		return -EINVAL;

	data = scpi_buf->data;
	high_priority = high_priority_chan_supported(data->cmd);
	data->cmd = PACK_SCPI_CMD(data->cmd, scpi_buf->client_id,
				  data->tx_size);
	data->cl_data = scpi_buf;

	return send_scpi_cmd(scpi_buf, high_priority);
}

unsigned long scpi_clk_get_val(u16 clk_id)
{
	struct scpi_data_buf sdata;
	struct mhu_data_buf mdata;
	struct __packed {
		u32 status;
		u32 clk_rate;
	} buf;

	SCPI_SETUP_DBUF(sdata, mdata, SCPI_CL_CLOCKS,
			SCPI_CMD_GET_CLOCK_VALUE, clk_id, buf);
	if (scpi_execute_cmd(&sdata))
		return 0;

	return buf.clk_rate;
}
EXPORT_SYMBOL_GPL(scpi_clk_get_val);

int scpi_clk_set_val(u16 clk_id, unsigned long rate)
{
	struct scpi_data_buf sdata;
	struct mhu_data_buf mdata;
	int stat;
	struct __packed {
		u32 clk_rate;
		u16 clk_id;
	} buf;

	buf.clk_rate = (u32)rate;
	buf.clk_id = clk_id;

	SCPI_SETUP_DBUF(sdata, mdata, SCPI_CL_CLOCKS,
			SCPI_CMD_SET_CLOCK_VALUE, buf, stat);
	return scpi_execute_cmd(&sdata);
}
EXPORT_SYMBOL_GPL(scpi_clk_set_val);

struct scpi_opp *scpi_dvfs_get_opps(u8 domain)
{
	struct scpi_data_buf sdata;
	struct mhu_data_buf mdata;
	struct __packed {
		u32 status;
		u32 header;
		struct scpi_opp_entry opp[MAX_DVFS_OPPS];
	} buf;
	struct scpi_opp *opps;
	size_t opps_sz;
	int count, ret;

	if (domain >= MAX_DVFS_DOMAINS)
		return ERR_PTR(-EINVAL);

	if (scpi_opps[domain])	/* data already populated */
		return scpi_opps[domain];

	SCPI_SETUP_DBUF(sdata, mdata, SCPI_CL_DVFS,
			SCPI_CMD_GET_DVFS_INFO, domain, buf);
	ret = scpi_execute_cmd(&sdata);
	if (ret)
		return ERR_PTR(ret);

	opps = kmalloc(sizeof(*opps), GFP_KERNEL);
	if (!opps)
		return ERR_PTR(-ENOMEM);

	count = DVFS_OPP_COUNT(buf.header);
	opps_sz = count * sizeof(*(opps->opp));

	opps->count = count;
	opps->latency = DVFS_LATENCY(buf.header);
	opps->opp = kmalloc(opps_sz, GFP_KERNEL);
	if (!opps->opp) {
		kfree(opps);
		return ERR_PTR(-ENOMEM);
	}

	memcpy(opps->opp, &buf.opp[0], opps_sz);
	scpi_opps[domain] = opps;

	return opps;
}
EXPORT_SYMBOL_GPL(scpi_dvfs_get_opps);

int scpi_dvfs_get_idx(u8 domain)
{
	struct scpi_data_buf sdata;
	struct mhu_data_buf mdata;
	struct __packed {
		u32 status;
		u8 dvfs_idx;
	} buf;
	int ret;

	if (domain >= MAX_DVFS_DOMAINS)
		return -EINVAL;

	SCPI_SETUP_DBUF(sdata, mdata, SCPI_CL_DVFS,
			SCPI_CMD_GET_DVFS, domain, buf);
	ret = scpi_execute_cmd(&sdata);

	if (!ret)
		ret = buf.dvfs_idx;
	return ret;
}
EXPORT_SYMBOL_GPL(scpi_dvfs_get_idx);

int scpi_dvfs_set_idx(u8 domain, u8 idx)
{
	struct scpi_data_buf sdata;
	struct mhu_data_buf mdata;
	struct __packed {
		u8 dvfs_domain;
		u8 dvfs_idx;
	} buf;
	int stat;

	buf.dvfs_idx = idx;
	buf.dvfs_domain = domain;

	if (domain >= MAX_DVFS_DOMAINS)
		return -EINVAL;

	SCPI_SETUP_DBUF(sdata, mdata, SCPI_CL_DVFS,
			SCPI_CMD_SET_DVFS, buf, stat);
	return scpi_execute_cmd(&sdata);
}
EXPORT_SYMBOL_GPL(scpi_dvfs_set_idx);