i2c: add SLIMpro I2C device driver on APM X-Gene platform

Add SLIMpro I2C device driver on APM X-Gene platform. This I2C
device driver use the SLIMpro Mailbox driver to tunnel message to
the SLIMpro coprocessor to do the work of accessing I2C components.

Signed-off-by: Feng Kan <[e-mail]>
Signed-off-by: Hieu Le <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

Documentation/devicetree/bindings/i2c/i2c-xgene-slimpro.txt

···
+APM X-Gene SLIMpro Mailbox I2C Driver
+
+An I2C controller accessed over the "SLIMpro" mailbox.
+
+Required properties :
+
+ - compatible : should be "apm,xgene-slimpro-i2c"
+ - mboxes : use the label reference for the mailbox as the first parameter.
+	    The second parameter is the channel number.
+
+Example :
+	i2cslimpro {
+		compatible = "apm,xgene-slimpro-i2c";
+		mboxes = <&mailbox 0>;
+	};

drivers/i2c/busses/Kconfig

···
 	  connected there. This will work whatever the interface used to
 	  talk to the EC (SPI, I2C or LPC).
 
+config I2C_XGENE_SLIMPRO
+	tristate "APM X-Gene SoC I2C SLIMpro devices support"
+	depends on ARCH_XGENE && MAILBOX
+	help
+	  Enable I2C bus access using the APM X-Gene SoC SLIMpro
+	  co-processor. The I2C device access the I2C bus via the X-Gene
+	  to SLIMpro (On chip coprocessor) mailbox mechanism.
+	  If unsure, say N.
+
 config SCx200_ACB
 	tristate "Geode ACCESS.bus support"
 	depends on X86_32 && PCI

drivers/i2c/busses/Makefile

···
 obj-$(CONFIG_I2C_OPAL)		+= i2c-opal.o
 obj-$(CONFIG_I2C_PCA_ISA)	+= i2c-pca-isa.o
 obj-$(CONFIG_I2C_SIBYTE)	+= i2c-sibyte.o
+obj-$(CONFIG_I2C_XGENE_SLIMPRO) += i2c-xgene-slimpro.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 
 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG

drivers/i2c/busses/i2c-xgene-slimpro.c

···
+/*
+ * X-Gene SLIMpro I2C Driver
+ *
+ * Copyright (c) 2014, Applied Micro Circuits Corporation
+ * Author: Feng Kan <[e-mail]>
+ * Author: Hieu Le <[e-mail]>
+ *
+ * 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];
+	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);
+	rc = dma_mapping_error(ctx->dev, paddr);
+	if (rc) {
+		dev_err(&ctx->adapter.dev, "Error in mapping dma buffer %p\n",
+			ctx->dma_buffer);
+		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);
+	rc = dma_mapping_error(ctx->dev, paddr);
+	if (rc) {
+		dev_err(&ctx->adapter.dev, "Error in mapping dma buffer %p\n",
+			ctx->dma_buffer);
+		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 __init 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\n");
+		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\n");
+
+	/* 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\n");
+		return rc;
+	}
+
+	dev_info(&pdev->dev, "Mailbox I2C Adapter registered\n");
+	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 <[e-mail]>");
+MODULE_AUTHOR("Hieu Le <[e-mail]>");
+MODULE_LICENSE("GPL");