i2c: Driver to expose PowerNV platform i2c busses

The patch exposes the available i2c busses on the PowerNV platform
to the kernel and implements the bus driver to support i2c and
smbus commands.
The driver uses the platform device infrastructure to probe the busses
on the platform and registers them with the i2c driver framework.

Signed-off-by: Neelesh Gupta <neelegup@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de> (I2C part, excluding the bindings)
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

3 files changed, 306 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 917c3585f45b..71ad6e11efb7 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1044,4 +1044,15 @@ config SCx200_ACB
 	  This support is also available as a module.  If so, the module
 	  will be called scx200_acb.
 
+config I2C_OPAL
+	tristate "IBM OPAL I2C driver"
+	depends on PPC_POWERNV
+	default y
+	help
+	  This exposes the PowerNV platform i2c busses to the linux i2c layer,
+	  the driver is based on the OPAL interfaces.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called as i2c-opal.
+
 endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 78d56c54ba2b..e23ec815e21f 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -99,6 +99,7 @@ obj-$(CONFIG_I2C_ACORN)		+= i2c-acorn.o
 obj-$(CONFIG_I2C_BCM_KONA)	+= i2c-bcm-kona.o
 obj-$(CONFIG_I2C_CROS_EC_TUNNEL)	+= i2c-cros-ec-tunnel.o
 obj-$(CONFIG_I2C_ELEKTOR)	+= i2c-elektor.o
+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_SCx200_ACB)	+= scx200_acb.o
diff --git a/drivers/i2c/busses/i2c-opal.c b/drivers/i2c/busses/i2c-opal.c
new file mode 100644
index 000000000000..16f90b1a7508
--- /dev/null
+++ b/drivers/i2c/busses/i2c-opal.c
@@ -0,0 +1,294 @@
+/*
+ * IBM OPAL I2C driver
+ * Copyright (C) 2014 IBM
+ *
+ * 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.
+ */
+
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <asm/firmware.h>
+#include <asm/opal.h>
+
+static int i2c_opal_translate_error(int rc)
+{
+	switch (rc) {
+	case OPAL_NO_MEM:
+		return -ENOMEM;
+	case OPAL_PARAMETER:
+		return -EINVAL;
+	case OPAL_I2C_ARBT_LOST:
+		return -EAGAIN;
+	case OPAL_I2C_TIMEOUT:
+		return -ETIMEDOUT;
+	case OPAL_I2C_NACK_RCVD:
+		return -ENXIO;
+	case OPAL_I2C_STOP_ERR:
+		return -EBUSY;
+	default:
+		return -EIO;
+	}
+}
+
+static int i2c_opal_send_request(u32 bus_id, struct opal_i2c_request *req)
+{
+	struct opal_msg msg;
+	int token, rc;
+
+	token = opal_async_get_token_interruptible();
+	if (token < 0) {
+		if (token != -ERESTARTSYS)
+			pr_err("Failed to get the async token\n");
+
+		return token;
+	}
+
+	rc = opal_i2c_request(token, bus_id, req);
+	if (rc != OPAL_ASYNC_COMPLETION) {
+		rc = i2c_opal_translate_error(rc);
+		goto exit;
+	}
+
+	rc = opal_async_wait_response(token, &msg);
+	if (rc)
+		goto exit;
+
+	rc = be64_to_cpu(msg.params[1]);
+	if (rc != OPAL_SUCCESS) {
+		rc = i2c_opal_translate_error(rc);
+		goto exit;
+	}
+
+exit:
+	opal_async_release_token(token);
+	return rc;
+}
+
+static int i2c_opal_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+				int num)
+{
+	unsigned long opal_id = (unsigned long)adap->algo_data;
+	struct opal_i2c_request req;
+	int rc, i;
+
+	/* We only support fairly simple combinations here of one
+	 * or two messages
+	 */
+	memset(&req, 0, sizeof(req));
+	switch(num) {
+	case 0:
+		return 0;
+	case 1:
+		req.type = (msgs[0].flags & I2C_M_RD) ?
+			OPAL_I2C_RAW_READ : OPAL_I2C_RAW_WRITE;
+		req.addr = cpu_to_be16(msgs[0].addr);
+		req.size = cpu_to_be32(msgs[0].len);
+		req.buffer_ra = cpu_to_be64(__pa(msgs[0].buf));
+		break;
+	case 2:
+		/* For two messages, we basically support only simple
+		 * smbus transactions of a write plus a read. We might
+		 * want to allow also two writes but we'd have to bounce
+		 * the data into a single buffer.
+		 */
+		if ((msgs[0].flags & I2C_M_RD) || !(msgs[1].flags & I2C_M_RD))
+			return -EOPNOTSUPP;
+		if (msgs[0].len > 4)
+			return -EOPNOTSUPP;
+		if (msgs[0].addr != msgs[1].addr)
+			return -EOPNOTSUPP;
+		req.type = OPAL_I2C_SM_READ;
+		req.addr = cpu_to_be16(msgs[0].addr);
+		req.subaddr_sz = msgs[0].len;
+		for (i = 0; i < msgs[0].len; i++)
+			req.subaddr = (req.subaddr << 8) | msgs[0].buf[i];
+		req.subaddr = cpu_to_be32(req.subaddr);
+		req.size = cpu_to_be32(msgs[1].len);
+		req.buffer_ra = cpu_to_be64(__pa(msgs[1].buf));
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	rc = i2c_opal_send_request(opal_id, &req);
+	if (rc)
+		return rc;
+
+	return num;
+}
+
+static int i2c_opal_smbus_xfer(struct i2c_adapter *adap, u16 addr,
+			       unsigned short flags, char read_write,
+			       u8 command, int size, union i2c_smbus_data *data)
+{
+	unsigned long opal_id = (unsigned long)adap->algo_data;
+	struct opal_i2c_request req;
+	u8 local[2];
+	int rc;
+
+	memset(&req, 0, sizeof(req));
+
+	req.addr = cpu_to_be16(addr);
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+		req.buffer_ra = cpu_to_be64(__pa(&data->byte));
+		req.size = cpu_to_be32(1);
+		/* Fall through */
+	case I2C_SMBUS_QUICK:
+		req.type = (read_write == I2C_SMBUS_READ) ?
+			OPAL_I2C_RAW_READ : OPAL_I2C_RAW_WRITE;
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		req.buffer_ra = cpu_to_be64(__pa(&data->byte));
+		req.size = cpu_to_be32(1);
+		req.subaddr = cpu_to_be32(command);
+		req.subaddr_sz = 1;
+		req.type = (read_write == I2C_SMBUS_READ) ?
+			OPAL_I2C_SM_READ : OPAL_I2C_SM_WRITE;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		if (!read_write) {
+			local[0] = data->word & 0xff;
+			local[1] = (data->word >> 8) & 0xff;
+		}
+		req.buffer_ra = cpu_to_be64(__pa(local));
+		req.size = cpu_to_be32(2);
+		req.subaddr = cpu_to_be32(command);
+		req.subaddr_sz = 1;
+		req.type = (read_write == I2C_SMBUS_READ) ?
+			OPAL_I2C_SM_READ : OPAL_I2C_SM_WRITE;
+		break;
+	case I2C_SMBUS_I2C_BLOCK_DATA:
+		req.buffer_ra = cpu_to_be64(__pa(&data->block[1]));
+		req.size = cpu_to_be32(data->block[0]);
+		req.subaddr = cpu_to_be32(command);
+		req.subaddr_sz = 1;
+		req.type = (read_write == I2C_SMBUS_READ) ?
+			OPAL_I2C_SM_READ : OPAL_I2C_SM_WRITE;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	rc = i2c_opal_send_request(opal_id, &req);
+	if (!rc && read_write && size == I2C_SMBUS_WORD_DATA) {
+		data->word = ((u16)local[1]) << 8;
+		data->word |= local[0];
+	}
+
+	return rc;
+}
+
+static u32 i2c_opal_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
+	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
+	       I2C_FUNC_SMBUS_I2C_BLOCK;
+}
+
+static const struct i2c_algorithm i2c_opal_algo = {
+	.master_xfer	= i2c_opal_master_xfer,
+	.smbus_xfer	= i2c_opal_smbus_xfer,
+	.functionality	= i2c_opal_func,
+};
+
+static int i2c_opal_probe(struct platform_device *pdev)
+{
+	struct i2c_adapter	*adapter;
+	const char		*pname;
+	u32			opal_id;
+	int			rc;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	rc = of_property_read_u32(pdev->dev.of_node, "ibm,opal-id", &opal_id);
+	if (rc) {
+		dev_err(&pdev->dev, "Missing ibm,opal-id property !\n");
+		return -EIO;
+	}
+
+	adapter = devm_kzalloc(&pdev->dev, sizeof(*adapter), GFP_KERNEL);
+	if (!adapter)
+		return -ENOMEM;
+
+	adapter->algo = &i2c_opal_algo;
+	adapter->algo_data = (void *)(unsigned long)opal_id;
+	adapter->dev.parent = &pdev->dev;
+	adapter->dev.of_node = of_node_get(pdev->dev.of_node);
+	pname = of_get_property(pdev->dev.of_node, "ibm,port-name", NULL);
+	if (pname)
+		strlcpy(adapter->name, pname, sizeof(adapter->name));
+	else
+		strlcpy(adapter->name, "opal", sizeof(adapter->name));
+
+	platform_set_drvdata(pdev, adapter);
+	rc = i2c_add_adapter(adapter);
+	if (rc)
+		dev_err(&pdev->dev, "Failed to register the i2c adapter\n");
+
+	return rc;
+}
+
+static int i2c_opal_remove(struct platform_device *pdev)
+{
+	struct i2c_adapter *adapter = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(adapter);
+
+	return 0;
+}
+
+static const struct of_device_id i2c_opal_of_match[] = {
+	{
+		.compatible = "ibm,opal-i2c",
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, i2c_opal_of_match);
+
+static struct platform_driver i2c_opal_driver = {
+	.probe	= i2c_opal_probe,
+	.remove	= i2c_opal_remove,
+	.driver	= {
+		.name		= "i2c-opal",
+		.of_match_table	= i2c_opal_of_match,
+	},
+};
+
+static int __init i2c_opal_init(void)
+{
+	if (!firmware_has_feature(FW_FEATURE_OPAL))
+		return -ENODEV;
+
+	return platform_driver_register(&i2c_opal_driver);
+}
+module_init(i2c_opal_init);
+
+static void __exit i2c_opal_exit(void)
+{
+	return platform_driver_unregister(&i2c_opal_driver);
+}
+module_exit(i2c_opal_exit);
+
+MODULE_AUTHOR("Neelesh Gupta <neelegup@linux.vnet.ibm.com>");
+MODULE_DESCRIPTION("IBM OPAL I2C driver");
+MODULE_LICENSE("GPL");