[patch 2/2] i2c: mux: mellanox: add driver

[vadimp]

From: Vadim Pasternak <vadimp@xxxxxxxxxxxx>

This driver allows I2C routing controlled through CPLD select registers on
wide range of Mellanox systems (CPLD Lattice device).
MUX selection is provided by digital and analog HW. Analog part is not
under SW control.
Digital part is under CPLD control (channel selection/de-selection).

Connectivity schema.
i2c-mlxcpld                                 Digital               Analog
driver
*--------*                                 * -> mux1 (virt bus2) -> mux ->|
| I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux ->|
| bridge | bus 1                 *---------*                              |
| logic  |---------------------> * mux reg *                              |
| in CPLD|                       *---------*                              |
*--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux ->|
    |        driver                   |                                   |
    |        *---------------*        |                             Devices
    |        * CPLD (LPC bus)* select |
    |        * registers for *--------*
    |        * mux selection * deselect
    |        *---------------*
    |                 |
<-------->     <----------->
i2c cntrl      Board cntrl reg
reg space      space (mux select,
    |          IO, LED, WD, info)
    |                 |                  *-----*   *-----*
    *------------- LPC bus --------------| PCH |---| CPU |
                                         *-----*   *-----*

i2c-mux-mlxpcld does not necessary required i2c-mlxcpld. It can be use
along with another bus driver, and still control i2c routing through CPLD
mux selection, in case the system is equipped with CPLD capable of mux
selection control.

The Kconfig currently controlling compilation of this code is:
drivers/i2c/muxes/Kconfig:config I2C_MUX_MLXCPLD

Signed-off-by: Michael Shych <michaelsh@xxxxxxxxxxxx>
Signed-off-by: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
Reviewed-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
---
 MAINTAINERS                         |   8 +
 drivers/i2c/muxes/Kconfig           |  11 ++
 drivers/i2c/muxes/Makefile          |   1 +
 drivers/i2c/muxes/i2c-mux-mlxcpld.c | 326 ++++++++++++++++++++++++++++++++++++
 include/linux/i2c/mlxcpld.h         |  57 +++++++
 5 files changed, 403 insertions(+)
 create mode 100644 drivers/i2c/muxes/i2c-mux-mlxcpld.c
 create mode 100644 include/linux/i2c/mlxcpld.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 8b3f8d7..a994455 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7664,6 +7664,14 @@ W:	http://www.mellanox.com
 F:	drivers/i2c/busses/i2c-mlxcpld.c
 F:	Documentation/i2c/busses/i2c-mlxcpld
 
+MELLANOX MLXCPLD I2C MUX DRIVER
+M:	Vadim Pasternak <vadimp@xxxxxxxxxxxx>
+M:	Michael Shych <michaelsh@xxxxxxxxxxxx>
+L:	linux-kernel@xxxxxxxxxxxxxxx
+S:	Supported
+W:	http://www.mellanox.com
+F:	drivers/i2c/muxes/i2c-mux-mlxcpld.c
+
 SOFT-ROCE DRIVER (rxe)
 M:	Moni Shoua <monis@xxxxxxxxxxxx>
 L:	linux-rdma@xxxxxxxxxxxxxxx
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index e280c8e..b7ab144 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -81,4 +81,15 @@ config I2C_DEMUX_PINCTRL
 	  demultiplexer that uses the pinctrl subsystem. This is useful if you
 	  want to change the I2C master at run-time depending on features.
 
+config I2C_MUX_MLXCPLD
+        tristate "Mellanox CPLD based I2C multiplexer"
+        help
+          If you say yes to this option, support will be included for a
+          CPLD based I2C multiplexer. This driver provides access to
+          I2C busses connected through a MUX, which is controlled
+          by a CPLD registers.
+
+          This driver can also be built as a module.  If so, the module
+          will be called i2c-mux-mlxcpld.
+
 endmenu
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 7c267c2..e5c990e 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -10,5 +10,6 @@ obj-$(CONFIG_I2C_MUX_PCA9541)	+= i2c-mux-pca9541.o
 obj-$(CONFIG_I2C_MUX_PCA954x)	+= i2c-mux-pca954x.o
 obj-$(CONFIG_I2C_MUX_PINCTRL)	+= i2c-mux-pinctrl.o
 obj-$(CONFIG_I2C_MUX_REG)	+= i2c-mux-reg.o
+obj-$(CONFIG_I2C_MUX_MLXCPLD)	+= i2c-mux-mlxcpld.o
 
 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/i2c-mux-mlxcpld.c b/drivers/i2c/muxes/i2c-mux-mlxcpld.c
new file mode 100644
index 0000000..9624613
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-mlxcpld.c
@@ -0,0 +1,326 @@
+/*
+ * drivers/i2c/muxes/i2c-mux-mlxcpld.c
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Michael Shych <michaels@xxxxxxxxxxxx>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/i2c/mlxcpld.h>
+
+#define CPLD_MUX_MAX_NCHANS	8
+#define CPLD_MUX_EXT_MAX_NCHANS	24
+
+/*
+ * mlxcpld_mux types - kind of mux supported by driver:
+ * @mlxcpld_mux_tor - LPC access; 8 channels.
+ * @mlxcpld_mux_mgmt - LPC access; 8 channels.
+ * @mlxcpld_mux_mgmt_ext - LPC access; 24 channels.
+ * @mlxcpld_mux_module - I2C access; 8 channels/legs.
+ */
+enum mlxcpld_mux_type {
+	mlxcpld_mux_tor,
+	mlxcpld_mux_mgmt,
+	mlxcpld_mux_mgmt_ext,
+	mlxcpld_mux_module,
+};
+
+/* mlxcpld_mux_type - underlying physical bus, to which device is connected:
+ * @lpc_access - LPC connected CPLD device
+ * @i2c_access - I2C connected CPLD device
+ */
+enum mlxcpld_mux_access_type {
+	lpc_access,
+	i2c_access,
+};
+
+/* mlxcpld_mux - mux control structure:
+ * @type - mux type
+ * @last_chan - last register value
+ * @client - I2C device client
+ */
+struct mlxcpld_mux {
+	enum mlxcpld_mux_type type;
+	u8 last_chan;
+	struct i2c_client *client;
+};
+
+/* mlxcpld_mux_desc - mux descriptor structure:
+ * @nchans - number of channels
+ * @muxtype - physical mux type (LPC or I2C)
+ */
+struct mlxcpld_mux_desc {
+	u8 nchans;
+	enum mlxcpld_mux_access_type muxtype;
+};
+
+/* MUX logic description.
+ * This logic can be applied for LPC attached CPLD and fro I2C attached CPLD.
+ * Driver can support different mux control logic, according to CPLD
+ * implementation.
+ *
+ * Connectivity schema.
+ *
+ * i2c-mlxcpld                                 Digital               Analog
+ * driver
+ * *--------*                                 * -> mux1 (virt bus2) -> mux -> |
+ * | I2CLPC | i2c physical                    * -> mux2 (virt bus3) -> mux -> |
+ * | bridge | bus 1                 *---------*                               |
+ * | logic  |---------------------> * mux reg *                               |
+ * | in CPLD|                       *---------*                               |
+ * *--------*   i2c-mux-mlxpcld          ^    * -> muxn (virt busn) -> mux -> |
+ *     |        driver                   |                                    |
+ *     |        *---------------*        |                              Devices
+ *     |        * CPLD (LPC bus)* select |
+ *     |        * registers for *--------*
+ *     |        * mux selection * deselect
+ *     |        *---------------*
+ *     |                 |
+ * <-------->     <----------->
+ * i2c cntrl      Board cntrl reg
+ * reg space      space (mux select,
+ *     |          IO, LED, WD, info)
+ *     |                 |                  *-----*   *-----*
+ *     *------------- LPC bus --------------| PCH |---| CPU |
+ *                                          *-----*   *-----*
+ *
+ */
+static const struct mlxcpld_mux_desc muxes[] = {
+	[mlxcpld_mux_tor] = {
+		.nchans = CPLD_MUX_MAX_NCHANS,
+		.muxtype = lpc_access,
+	},
+	[mlxcpld_mux_mgmt] = {
+		.nchans = CPLD_MUX_MAX_NCHANS,
+		.muxtype = lpc_access,
+	},
+	[mlxcpld_mux_mgmt_ext] = {
+		.nchans = CPLD_MUX_EXT_MAX_NCHANS,
+		.muxtype = lpc_access,
+	},
+	[mlxcpld_mux_module] = {
+		.nchans = CPLD_MUX_MAX_NCHANS,
+		.muxtype = i2c_access,
+	},
+};
+
+static const struct i2c_device_id mlxcpld_mux_id[] = {
+	{ "mlxcpld_mux_tor", mlxcpld_mux_tor },
+	{ "mlxcpld_mux_mgmt", mlxcpld_mux_mgmt },
+	{ "mlxcpld_mux_mgmt_ext", mlxcpld_mux_mgmt_ext },
+	{ "mlxcpld_mux_module", mlxcpld_mux_module },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id);
+
+/* Write to mux register. Don't use i2c_transfer() and
+ * i2c_smbus_xfer() for this as they will try to lock adapter a second time
+ */
+static int mlxcpld_mux_reg_write(struct i2c_adapter *adap,
+				 struct i2c_client *client, u8 val,
+				 enum mlxcpld_mux_access_type muxtype)
+{
+	struct mlxcpld_mux_platform_data *pdata =
+						dev_get_platdata(&client->dev);
+	int ret = -ENODEV;
+
+	switch (muxtype) {
+	case lpc_access:
+		outb(val, pdata->addr); /* addr = CPLD base + offset */
+		ret = 1;
+		break;
+
+	case i2c_access:
+		if (adap->algo->master_xfer) {
+			struct i2c_msg msg;
+			u8 msgbuf[] = {pdata->sel_reg_addr, val};
+
+			msg.addr = pdata->addr;
+			msg.flags = 0;
+			msg.len = 2;
+			msg.buf = msgbuf;
+			return __i2c_transfer(adap, &msg, 1);
+		}
+		dev_err(&client->dev, "SMBus isn't supported on this adapter\n");
+		break;
+
+	default:
+		dev_err(&client->dev, "Incorrect muxtype %d\n", muxtype);
+	}
+
+	return ret;
+}
+
+static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mlxcpld_mux *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	struct mlxcpld_mux_platform_data *pdata =
+						dev_get_platdata(&client->dev);
+	const struct mlxcpld_mux_desc *mux = &muxes[data->type];
+	u8 regval;
+	int err = 0;
+
+	switch (data->type) {
+	case mlxcpld_mux_tor:
+		regval = pdata->first_channel + chan;
+		break;
+
+	case mlxcpld_mux_mgmt:
+	case mlxcpld_mux_mgmt_ext:
+	case mlxcpld_mux_module:
+		regval = chan + 1;
+		break;
+
+	default:
+		return -ENXIO;
+	}
+
+	/* Only select the channel if its different from the last channel */
+	if (data->last_chan != regval) {
+		err = mlxcpld_mux_reg_write(muxc->parent, client, regval,
+					    mux->muxtype);
+		data->last_chan = regval;
+	}
+
+	return err;
+}
+
+static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct mlxcpld_mux *data = i2c_mux_priv(muxc);
+	struct i2c_client *client = data->client;
+	const struct mlxcpld_mux_desc *mux = &muxes[data->type];
+
+	/* Deselect active channel */
+	data->last_chan = 0;
+
+	return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan,
+				     mux->muxtype);
+}
+
+/* I2C init/probing/exit functions */
+static int mlxcpld_mux_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+	struct mlxcpld_mux_platform_data *pdata =
+						dev_get_platdata(&client->dev);
+	struct i2c_mux_core *muxc;
+	int num, force;
+	u8 nchans;
+	struct mlxcpld_mux *data;
+	int err;
+
+	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+		return -ENODEV;
+
+	switch (id->driver_data) {
+	case mlxcpld_mux_tor:
+	case mlxcpld_mux_mgmt:
+	case mlxcpld_mux_mgmt_ext:
+	case mlxcpld_mux_module:
+		nchans = muxes[id->driver_data].nchans;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	muxc = i2c_mux_alloc(adap, &client->dev, nchans, sizeof(*data), 0,
+			     mlxcpld_mux_select_chan, mlxcpld_mux_deselect);
+	if (!muxc)
+		return -ENOMEM;
+
+	data = i2c_mux_priv(muxc);
+	i2c_set_clientdata(client, muxc);
+	data->client = client;
+	data->type = id->driver_data;
+	data->last_chan = 0; /* force the first selection */
+
+	/* Only in mlxcpld_mux_tor first_channel can be different.
+	 * In other mlxcpld_mux types channel numbering begin from 1
+	 * Now create an adapter for each channel
+	 */
+	for (num = 0; num < muxes[data->type].nchans; num++) {
+		force = 0; /* dynamic adap number */
+		if (pdata) {
+			if (num < pdata->num_adaps)
+				force = pdata->adap_ids[num];
+			else
+				/* discard unconfigured channels */
+				break;
+		}
+
+		err = i2c_mux_add_adapter(muxc, force, num, 0);
+		if (err) {
+			dev_err(&client->dev, "failed to register multiplexed adapter %d as bus %d\n",
+				num, force);
+			goto virt_reg_failed;
+		}
+	}
+
+	return 0;
+
+virt_reg_failed:
+	i2c_mux_del_adapters(muxc);
+	return err;
+}
+
+static int mlxcpld_mux_remove(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	i2c_mux_del_adapters(muxc);
+	return 0;
+}
+
+static struct i2c_driver mlxcpld_mux_driver = {
+	.driver		= {
+		.name	= "mlxcpld-mux",
+	},
+	.probe		= mlxcpld_mux_probe,
+	.remove		= mlxcpld_mux_remove,
+	.id_table	= mlxcpld_mux_id,
+};
+
+module_i2c_driver(mlxcpld_mux_driver);
+
+MODULE_AUTHOR("Michael Shych (michaels@xxxxxxxxxxxx)");
+MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-mux-mlxcpld");
diff --git a/include/linux/i2c/mlxcpld.h b/include/linux/i2c/mlxcpld.h
new file mode 100644
index 0000000..6f7d4c5
--- /dev/null
+++ b/include/linux/i2c/mlxcpld.h
@@ -0,0 +1,57 @@
+/*
+ * mlxcpld.h - Mellanox I2C multiplexer support in CPLD
+ *
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Michael Shych <michaels@xxxxxxxxxxxx>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _LINUX_I2C_MLXCPLD_H
+#define _LINUX_I2C_MLXCPLD_H
+
+/* Platform data for the CPLD I2C multiplexers */
+
+/* mlxcpld_mux_platform_data - per mux data, used with i2c_register_board_info
+ * @adap_ids - adapter array
+ * @num_adaps - number of adapters
+ * @sel_reg_addr - mux select register offset in CPLD space
+ * @first_channel - first channel to start virtual busses vector
+ * @addr - address of mux device - set to mux select register offset on LPC
+ *	   connected CPLDs or to I2C address on I2C conncted CPLDs
+ */
+struct mlxcpld_mux_platform_data {
+	int *adap_ids;
+	int num_adaps;
+	int sel_reg_addr;
+	int first_channel;
+	unsigned short addr;
+};
+
+#endif /* _LINUX_I2C_MLXCPLD_H */
-- 
2.1.4