/*
   * X-Gene SLIMpro I2C Driver
   *
   * Copyright (c) 2014, Applied Micro Circuits Corporation
   * Author: Feng Kan <fkan@apm.com>
   * Author: Hieu Le <hnle@apm.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of
   * the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that 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/>.
   *
   * This driver provides support for X-Gene SLIMpro I2C device access
   * using the APM X-Gene SLIMpro mailbox driver.
   *
   */
  #include <linux/acpi.h>
  #include <linux/dma-mapping.h>
  #include <linux/i2c.h>
  #include <linux/interrupt.h>
  #include <linux/mailbox_client.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/version.h>
  
  #define MAILBOX_OP_TIMEOUT		1000	/* Operation time out in ms */
  #define MAILBOX_I2C_INDEX		0
  #define SLIMPRO_IIC_BUS			1	/* Use I2C bus 1 only */
  
  #define SMBUS_CMD_LEN			1
  #define BYTE_DATA			1
  #define WORD_DATA			2
  #define BLOCK_DATA			3
  
  #define SLIMPRO_IIC_I2C_PROTOCOL	0
  #define SLIMPRO_IIC_SMB_PROTOCOL	1
  
  #define SLIMPRO_IIC_READ		0
  #define SLIMPRO_IIC_WRITE		1
  
  #define IIC_SMB_WITHOUT_DATA_LEN	0
  #define IIC_SMB_WITH_DATA_LEN		1
  
  #define SLIMPRO_DEBUG_MSG		0
  #define SLIMPRO_MSG_TYPE_SHIFT		28
  #define SLIMPRO_DBG_SUBTYPE_I2C1READ	4
  #define SLIMPRO_DBGMSG_TYPE_SHIFT	24
  #define SLIMPRO_DBGMSG_TYPE_MASK	0x0F000000U
  #define SLIMPRO_IIC_DEV_SHIFT		23
  #define SLIMPRO_IIC_DEV_MASK		0x00800000U
  #define SLIMPRO_IIC_DEVID_SHIFT		13
  #define SLIMPRO_IIC_DEVID_MASK		0x007FE000U
  #define SLIMPRO_IIC_RW_SHIFT		12
  #define SLIMPRO_IIC_RW_MASK		0x00001000U
  #define SLIMPRO_IIC_PROTO_SHIFT		11
  #define SLIMPRO_IIC_PROTO_MASK		0x00000800U
  #define SLIMPRO_IIC_ADDRLEN_SHIFT	8
  #define SLIMPRO_IIC_ADDRLEN_MASK	0x00000700U
  #define SLIMPRO_IIC_DATALEN_SHIFT	0
  #define SLIMPRO_IIC_DATALEN_MASK	0x000000FFU
  
  /*
   * SLIMpro I2C message encode
   *
   * dev		- Controller number (0-based)
   * chip		- I2C chip address
   * op		- SLIMPRO_IIC_READ or SLIMPRO_IIC_WRITE
   * proto	- SLIMPRO_IIC_SMB_PROTOCOL or SLIMPRO_IIC_I2C_PROTOCOL
   * addrlen	- Length of the address field
   * datalen	- Length of the data field
   */
  #define SLIMPRO_IIC_ENCODE_MSG(dev, chip, op, proto, addrlen, datalen) \
  	((SLIMPRO_DEBUG_MSG << SLIMPRO_MSG_TYPE_SHIFT) | \
  	((SLIMPRO_DBG_SUBTYPE_I2C1READ << SLIMPRO_DBGMSG_TYPE_SHIFT) & \
  	SLIMPRO_DBGMSG_TYPE_MASK) | \
  	((dev << SLIMPRO_IIC_DEV_SHIFT) & SLIMPRO_IIC_DEV_MASK) | \
  	((chip << SLIMPRO_IIC_DEVID_SHIFT) & SLIMPRO_IIC_DEVID_MASK) | \
  	((op << SLIMPRO_IIC_RW_SHIFT) & SLIMPRO_IIC_RW_MASK) | \
  	((proto << SLIMPRO_IIC_PROTO_SHIFT) & SLIMPRO_IIC_PROTO_MASK) | \
  	((addrlen << SLIMPRO_IIC_ADDRLEN_SHIFT) & SLIMPRO_IIC_ADDRLEN_MASK) | \
  	((datalen << SLIMPRO_IIC_DATALEN_SHIFT) & SLIMPRO_IIC_DATALEN_MASK))
  
  /*
   * Encode for upper address for block data
   */
  #define SLIMPRO_IIC_ENCODE_FLAG_BUFADDR			0x80000000
  #define SLIMPRO_IIC_ENCODE_FLAG_WITH_DATA_LEN(a)	((u32) (((a) << 30) \
  								& 0x40000000))
  #define SLIMPRO_IIC_ENCODE_UPPER_BUFADDR(a)		((u32) (((a) >> 12) \
  								& 0x3FF00000))
  #define SLIMPRO_IIC_ENCODE_ADDR(a)			((a) & 0x000FFFFF)
  
  struct slimpro_i2c_dev {
  	struct i2c_adapter adapter;
  	struct device *dev;
  	struct mbox_chan *mbox_chan;
  	struct mbox_client mbox_client;
  	struct completion rd_complete;
  	u8 dma_buffer[I2C_SMBUS_BLOCK_MAX + 1]; /* dma_buffer[0] is used for length */
  	u32 *resp_msg;
  };
  
  #define to_slimpro_i2c_dev(cl)	\
  		container_of(cl, struct slimpro_i2c_dev, mbox_client)
  
  static void slimpro_i2c_rx_cb(struct mbox_client *cl, void *mssg)
  {
  	struct slimpro_i2c_dev *ctx = to_slimpro_i2c_dev(cl);
  
  	/*
  	 * Response message format:
  	 * mssg[0] is the return code of the operation
  	 * mssg[1] is the first data word
  	 * mssg[2] is NOT used
  	 */
  	if (ctx->resp_msg)
  		*ctx->resp_msg = ((u32 *)mssg)[1];
  
  	if (ctx->mbox_client.tx_block)
  		complete(&ctx->rd_complete);
  }
  
  static int start_i2c_msg_xfer(struct slimpro_i2c_dev *ctx)
  {
  	if (ctx->mbox_client.tx_block) {
  		if (!wait_for_completion_timeout(&ctx->rd_complete,
  						 msecs_to_jiffies(MAILBOX_OP_TIMEOUT)))
  			return -ETIMEDOUT;
  	}
  
  	/* Check of invalid data or no device */
  	if (*ctx->resp_msg == 0xffffffff)
  		return -ENODEV;
  
  	return 0;
  }
  
  static int slimpro_i2c_rd(struct slimpro_i2c_dev *ctx, u32 chip,
  			  u32 addr, u32 addrlen, u32 protocol,
  			  u32 readlen, u32 *data)
  {
  	u32 msg[3];
  	int rc;
  
  	msg[0] = SLIMPRO_IIC_ENCODE_MSG(SLIMPRO_IIC_BUS, chip,
  					SLIMPRO_IIC_READ, protocol, addrlen, readlen);
  	msg[1] = SLIMPRO_IIC_ENCODE_ADDR(addr);
  	msg[2] = 0;
  	ctx->resp_msg = data;
  	rc = mbox_send_message(ctx->mbox_chan, &msg);
  	if (rc < 0)
  		goto err;
  
  	rc = start_i2c_msg_xfer(ctx);
  err:
  	ctx->resp_msg = NULL;
  	return rc;
  }
  
  static int slimpro_i2c_wr(struct slimpro_i2c_dev *ctx, u32 chip,
  			  u32 addr, u32 addrlen, u32 protocol, u32 writelen,
  			  u32 data)
  {
  	u32 msg[3];
  	int rc;
  
  	msg[0] = SLIMPRO_IIC_ENCODE_MSG(SLIMPRO_IIC_BUS, chip,
  					SLIMPRO_IIC_WRITE, protocol, addrlen, writelen);
  	msg[1] = SLIMPRO_IIC_ENCODE_ADDR(addr);
  	msg[2] = data;
  	ctx->resp_msg = msg;
  
  	rc = mbox_send_message(ctx->mbox_chan, &msg);
  	if (rc < 0)
  		goto err;
  
  	rc = start_i2c_msg_xfer(ctx);
  err:
  	ctx->resp_msg = NULL;
  	return rc;
  }
  
  static int slimpro_i2c_blkrd(struct slimpro_i2c_dev *ctx, u32 chip, u32 addr,
  			     u32 addrlen, u32 protocol, u32 readlen,
  			     u32 with_data_len, void *data)
  {
  	dma_addr_t paddr;
  	u32 msg[3];
  	int rc;
  
  	paddr = dma_map_single(ctx->dev, ctx->dma_buffer, readlen, DMA_FROM_DEVICE);
  	if (dma_mapping_error(ctx->dev, paddr)) {
  		dev_err(&ctx->adapter.dev, "Error in mapping dma buffer %p
  ",
  			ctx->dma_buffer);
  		rc = -ENOMEM;
  		goto err;
  	}
  
  	msg[0] = SLIMPRO_IIC_ENCODE_MSG(SLIMPRO_IIC_BUS, chip, SLIMPRO_IIC_READ,
  					protocol, addrlen, readlen);
  	msg[1] = SLIMPRO_IIC_ENCODE_FLAG_BUFADDR |
  		 SLIMPRO_IIC_ENCODE_FLAG_WITH_DATA_LEN(with_data_len) |
  		 SLIMPRO_IIC_ENCODE_UPPER_BUFADDR(paddr) |
  		 SLIMPRO_IIC_ENCODE_ADDR(addr);
  	msg[2] = (u32)paddr;
  	ctx->resp_msg = msg;
  
  	rc = mbox_send_message(ctx->mbox_chan, &msg);
  	if (rc < 0)
  		goto err_unmap;
  
  	rc = start_i2c_msg_xfer(ctx);
  
  	/* Copy to destination */
  	memcpy(data, ctx->dma_buffer, readlen);
  
  err_unmap:
  	dma_unmap_single(ctx->dev, paddr, readlen, DMA_FROM_DEVICE);
  err:
  	ctx->resp_msg = NULL;
  	return rc;
  }
  
  static int slimpro_i2c_blkwr(struct slimpro_i2c_dev *ctx, u32 chip,
  			     u32 addr, u32 addrlen, u32 protocol, u32 writelen,
  			     void *data)
  {
  	dma_addr_t paddr;
  	u32 msg[3];
  	int rc;
  
  	memcpy(ctx->dma_buffer, data, writelen);
  	paddr = dma_map_single(ctx->dev, ctx->dma_buffer, writelen,
  			       DMA_TO_DEVICE);
  	if (dma_mapping_error(ctx->dev, paddr)) {
  		dev_err(&ctx->adapter.dev, "Error in mapping dma buffer %p
  ",
  			ctx->dma_buffer);
  		rc = -ENOMEM;
  		goto err;
  	}
  
  	msg[0] = SLIMPRO_IIC_ENCODE_MSG(SLIMPRO_IIC_BUS, chip, SLIMPRO_IIC_WRITE,
  					protocol, addrlen, writelen);
  	msg[1] = SLIMPRO_IIC_ENCODE_FLAG_BUFADDR |
  		 SLIMPRO_IIC_ENCODE_UPPER_BUFADDR(paddr) |
  		 SLIMPRO_IIC_ENCODE_ADDR(addr);
  	msg[2] = (u32)paddr;
  	ctx->resp_msg = msg;
  
  	if (ctx->mbox_client.tx_block)
  		reinit_completion(&ctx->rd_complete);
  
  	rc = mbox_send_message(ctx->mbox_chan, &msg);
  	if (rc < 0)
  		goto err_unmap;
  
  	rc = start_i2c_msg_xfer(ctx);
  
  err_unmap:
  	dma_unmap_single(ctx->dev, paddr, writelen, DMA_TO_DEVICE);
  err:
  	ctx->resp_msg = NULL;
  	return rc;
  }
  
  static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
  				  unsigned short flags, char read_write,
  				  u8 command, int size,
  				  union i2c_smbus_data *data)
  {
  	struct slimpro_i2c_dev *ctx = i2c_get_adapdata(adap);
  	int ret = -EOPNOTSUPP;
  	u32 val;
  
  	switch (size) {
  	case I2C_SMBUS_BYTE:
  		if (read_write == I2C_SMBUS_READ) {
  			ret = slimpro_i2c_rd(ctx, addr, 0, 0,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     BYTE_DATA, &val);
  			data->byte = val;
  		} else {
  			ret = slimpro_i2c_wr(ctx, addr, command, SMBUS_CMD_LEN,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     0, 0);
  		}
  		break;
  	case I2C_SMBUS_BYTE_DATA:
  		if (read_write == I2C_SMBUS_READ) {
  			ret = slimpro_i2c_rd(ctx, addr, command, SMBUS_CMD_LEN,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     BYTE_DATA, &val);
  			data->byte = val;
  		} else {
  			val = data->byte;
  			ret = slimpro_i2c_wr(ctx, addr, command, SMBUS_CMD_LEN,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     BYTE_DATA, val);
  		}
  		break;
  	case I2C_SMBUS_WORD_DATA:
  		if (read_write == I2C_SMBUS_READ) {
  			ret = slimpro_i2c_rd(ctx, addr, command, SMBUS_CMD_LEN,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     WORD_DATA, &val);
  			data->word = val;
  		} else {
  			val = data->word;
  			ret = slimpro_i2c_wr(ctx, addr, command, SMBUS_CMD_LEN,
  					     SLIMPRO_IIC_SMB_PROTOCOL,
  					     WORD_DATA, val);
  		}
  		break;
  	case I2C_SMBUS_BLOCK_DATA:
  		if (read_write == I2C_SMBUS_READ) {
  			ret = slimpro_i2c_blkrd(ctx, addr, command,
  						SMBUS_CMD_LEN,
  						SLIMPRO_IIC_SMB_PROTOCOL,
  						I2C_SMBUS_BLOCK_MAX + 1,
  						IIC_SMB_WITH_DATA_LEN,
  						&data->block[0]);
  
  		} else {
  			ret = slimpro_i2c_blkwr(ctx, addr, command,
  						SMBUS_CMD_LEN,
  						SLIMPRO_IIC_SMB_PROTOCOL,
  						data->block[0] + 1,
  						&data->block[0]);
  		}
  		break;
  	case I2C_SMBUS_I2C_BLOCK_DATA:
  		if (read_write == I2C_SMBUS_READ) {
  			ret = slimpro_i2c_blkrd(ctx, addr,
  						command,
  						SMBUS_CMD_LEN,
  						SLIMPRO_IIC_I2C_PROTOCOL,
  						I2C_SMBUS_BLOCK_MAX,
  						IIC_SMB_WITHOUT_DATA_LEN,
  						&data->block[1]);
  		} else {
  			ret = slimpro_i2c_blkwr(ctx, addr, command,
  						SMBUS_CMD_LEN,
  						SLIMPRO_IIC_I2C_PROTOCOL,
  						data->block[0],
  						&data->block[1]);
  		}
  		break;
  	default:
  		break;
  	}
  	return ret;
  }
  
  /*
  * Return list of supported functionality.
  */
  static u32 xgene_slimpro_i2c_func(struct i2c_adapter *adapter)
  {
  	return I2C_FUNC_SMBUS_BYTE |
  		I2C_FUNC_SMBUS_BYTE_DATA |
  		I2C_FUNC_SMBUS_WORD_DATA |
  		I2C_FUNC_SMBUS_BLOCK_DATA |
  		I2C_FUNC_SMBUS_I2C_BLOCK;
  }
  
  static struct i2c_algorithm xgene_slimpro_i2c_algorithm = {
  	.smbus_xfer = xgene_slimpro_i2c_xfer,
  	.functionality = xgene_slimpro_i2c_func,
  };
  
  static int xgene_slimpro_i2c_probe(struct platform_device *pdev)
  {
  	struct slimpro_i2c_dev *ctx;
  	struct i2c_adapter *adapter;
  	struct mbox_client *cl;
  	int rc;
  
  	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
  	if (!ctx)
  		return -ENOMEM;
  
  	ctx->dev = &pdev->dev;
  	platform_set_drvdata(pdev, ctx);
  	cl = &ctx->mbox_client;
  
  	/* Request mailbox channel */
  	cl->dev = &pdev->dev;
  	cl->rx_callback = slimpro_i2c_rx_cb;
  	cl->tx_block = true;
  	init_completion(&ctx->rd_complete);
  	cl->tx_tout = MAILBOX_OP_TIMEOUT;
  	cl->knows_txdone = false;
  	ctx->mbox_chan = mbox_request_channel(cl, MAILBOX_I2C_INDEX);
  	if (IS_ERR(ctx->mbox_chan)) {
  		dev_err(&pdev->dev, "i2c mailbox channel request failed
  ");
  		return PTR_ERR(ctx->mbox_chan);
  	}
  
  	rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
  	if (rc)
  		dev_warn(&pdev->dev, "Unable to set dma mask
  ");
  
  	/* Setup I2C adapter */
  	adapter = &ctx->adapter;
  	snprintf(adapter->name, sizeof(adapter->name), "MAILBOX I2C");
  	adapter->algo = &xgene_slimpro_i2c_algorithm;
  	adapter->class = I2C_CLASS_HWMON;
  	adapter->dev.parent = &pdev->dev;
  	i2c_set_adapdata(adapter, ctx);
  	rc = i2c_add_adapter(adapter);
  	if (rc) {
  		dev_err(&pdev->dev, "Adapter registeration failed
  ");
  		mbox_free_channel(ctx->mbox_chan);
  		return rc;
  	}
  
  	dev_info(&pdev->dev, "Mailbox I2C Adapter registered
  ");
  	return 0;
  }
  
  static int xgene_slimpro_i2c_remove(struct platform_device *pdev)
  {
  	struct slimpro_i2c_dev *ctx = platform_get_drvdata(pdev);
  
  	i2c_del_adapter(&ctx->adapter);
  
  	mbox_free_channel(ctx->mbox_chan);
  
  	return 0;
  }
  
  static const struct of_device_id xgene_slimpro_i2c_dt_ids[] = {
  	{.compatible = "apm,xgene-slimpro-i2c" },
  	{},
  };
  MODULE_DEVICE_TABLE(of, xgene_slimpro_i2c_dt_ids);
  
  #ifdef CONFIG_ACPI
  static const struct acpi_device_id xgene_slimpro_i2c_acpi_ids[] = {
  	{"APMC0D40", 0},
  	{}
  };
  MODULE_DEVICE_TABLE(acpi, xgene_slimpro_i2c_acpi_ids);
  #endif
  
  static struct platform_driver xgene_slimpro_i2c_driver = {
  	.probe	= xgene_slimpro_i2c_probe,
  	.remove	= xgene_slimpro_i2c_remove,
  	.driver	= {
  		.name	= "xgene-slimpro-i2c",
  		.of_match_table = of_match_ptr(xgene_slimpro_i2c_dt_ids),
  		.acpi_match_table = ACPI_PTR(xgene_slimpro_i2c_acpi_ids)
  	},
  };
  
  module_platform_driver(xgene_slimpro_i2c_driver);
  
  MODULE_DESCRIPTION("APM X-Gene SLIMpro I2C driver");
  MODULE_AUTHOR("Feng Kan <fkan@apm.com>");
  MODULE_AUTHOR("Hieu Le <hnle@apm.com>");
  MODULE_LICENSE("GPL");