i2c: add support for Diolan DLN-2 USB-I2C adapter

This patch adds support for the Diolan DLN-2 I2C master module. Due
to hardware limitations it does not support SMBUS quick commands.

Information about the USB protocol interface can be found in the
Programmer's Reference Manual [1], see section 6.2.2 for the I2C
master module commands and responses.

[1] https://www.diolan.com/downloads/dln-api-manual.pdf

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Octavian Purdila <octavian.purdila@intel.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Johan Hovold <johan@kernel.org>
[Lee: Fixed some whitespace issues in Kconfig]
Signed-off-by: Lee Jones <lee.jones@linaro.org>

3 files changed, 278 insertions, 0 deletions

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 917c3585f45b..b4d135cc2f39 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -881,6 +881,16 @@ config I2C_DIOLAN_U2C
           This driver can also be built as a module.  If so, the module
           will be called i2c-diolan-u2c.
 
+config I2C_DLN2
+       tristate "Diolan DLN-2 USB I2C adapter"
+       depends on MFD_DLN2
+       help
+         If you say yes to this option, support will be included for Diolan
+         DLN2, a USB to I2C interface.
+
+         This driver can also be built as a module.  If so, the module
+         will be called i2c-dln2.
+
 config I2C_PARPORT
         tristate "Parallel port adapter"
         depends on PARPORT
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 78d56c54ba2b..cdac7f15eab5 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 
 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_DIOLAN_U2C)    += i2c-diolan-u2c.o
+obj-$(CONFIG_I2C_DLN2)          += i2c-dln2.o
 obj-$(CONFIG_I2C_PARPORT)       += i2c-parport.o
 obj-$(CONFIG_I2C_PARPORT_LIGHT) += i2c-parport-light.o
 obj-$(CONFIG_I2C_ROBOTFUZZ_OSIF)        += i2c-robotfuzz-osif.o
diff --git a/drivers/i2c/busses/i2c-dln2.c b/drivers/i2c/busses/i2c-dln2.c
new file mode 100644
index 000000000000..010a5fa8c883
--- /dev/null
+++ b/drivers/i2c/busses/i2c-dln2.c
@@ -0,0 +1,267 @@
+/*
+ * Driver for the Diolan DLN-2 USB-I2C adapter
+ *
+ * Copyright (c) 2014 Intel Corporation
+ *
+ * Derived from:
+ *  i2c-diolan-u2c.c
+ *  Copyright (c) 2010-2011 Ericsson AB
+ *
+ * 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, version 2.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/dln2.h>
+
+#define DLN2_I2C_MODULE_ID              0x03
+#define DLN2_I2C_CMD(cmd)               DLN2_CMD(cmd, DLN2_I2C_MODULE_ID)
+
+/* I2C commands */
+#define DLN2_I2C_GET_PORT_COUNT         DLN2_I2C_CMD(0x00)
+#define DLN2_I2C_ENABLE                 DLN2_I2C_CMD(0x01)
+#define DLN2_I2C_DISABLE                DLN2_I2C_CMD(0x02)
+#define DLN2_I2C_IS_ENABLED             DLN2_I2C_CMD(0x03)
+#define DLN2_I2C_WRITE                  DLN2_I2C_CMD(0x06)
+#define DLN2_I2C_READ                   DLN2_I2C_CMD(0x07)
+#define DLN2_I2C_SCAN_DEVICES           DLN2_I2C_CMD(0x08)
+#define DLN2_I2C_PULLUP_ENABLE          DLN2_I2C_CMD(0x09)
+#define DLN2_I2C_PULLUP_DISABLE         DLN2_I2C_CMD(0x0A)
+#define DLN2_I2C_PULLUP_IS_ENABLED      DLN2_I2C_CMD(0x0B)
+#define DLN2_I2C_TRANSFER               DLN2_I2C_CMD(0x0C)
+#define DLN2_I2C_SET_MAX_REPLY_COUNT    DLN2_I2C_CMD(0x0D)
+#define DLN2_I2C_GET_MAX_REPLY_COUNT    DLN2_I2C_CMD(0x0E)
+
+#define DLN2_I2C_MAX_XFER_SIZE          256
+#define DLN2_I2C_BUF_SIZE               (DLN2_I2C_MAX_XFER_SIZE + 16)
+
+struct dln2_i2c {
+        struct platform_device *pdev;
+        struct i2c_adapter adapter;
+        u8 port;
+        /*
+         * Buffer to hold the packet for read or write transfers. One is enough
+         * since we can't have multiple transfers in parallel on the i2c bus.
+         */
+        void *buf;
+};
+
+static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
+{
+        int ret;
+        u16 cmd;
+        struct {
+                u8 port;
+        } tx;
+
+        tx.port = dln2->port;
+
+        if (enable)
+                cmd = DLN2_I2C_ENABLE;
+        else
+                cmd = DLN2_I2C_DISABLE;
+
+        ret = dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
+        if (ret < 0)
+                return ret;
+
+        return 0;
+}
+
+static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
+                          u8 *data, u16 data_len)
+{
+        int ret;
+        struct {
+                u8 port;
+                u8 addr;
+                u8 mem_addr_len;
+                __le32 mem_addr;
+                __le16 buf_len;
+                u8 buf[DLN2_I2C_MAX_XFER_SIZE];
+        } __packed *tx = dln2->buf;
+        unsigned len;
+
+        BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);
+
+        tx->port = dln2->port;
+        tx->addr = addr;
+        tx->mem_addr_len = 0;
+        tx->mem_addr = 0;
+        tx->buf_len = cpu_to_le16(data_len);
+        memcpy(tx->buf, data, data_len);
+
+        len = sizeof(*tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
+        ret = dln2_transfer_tx(dln2->pdev, DLN2_I2C_WRITE, tx, len);
+        if (ret < 0)
+                return ret;
+
+        return data_len;
+}
+
+static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
+                         u16 data_len)
+{
+        int ret;
+        struct {
+                u8 port;
+                u8 addr;
+                u8 mem_addr_len;
+                __le32 mem_addr;
+                __le16 buf_len;
+        } __packed tx;
+        struct {
+                __le16 buf_len;
+                u8 buf[DLN2_I2C_MAX_XFER_SIZE];
+        } __packed *rx = dln2->buf;
+        unsigned rx_len = sizeof(*rx);
+
+        BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);
+
+        tx.port = dln2->port;
+        tx.addr = addr;
+        tx.mem_addr_len = 0;
+        tx.mem_addr = 0;
+        tx.buf_len = cpu_to_le16(data_len);
+
+        ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
+                            rx, &rx_len);
+        if (ret < 0)
+                return ret;
+        if (rx_len < sizeof(rx->buf_len) + data_len)
+                return -EPROTO;
+        if (le16_to_cpu(rx->buf_len) != data_len)
+                return -EPROTO;
+
+        memcpy(data, rx->buf, data_len);
+
+        return data_len;
+}
+
+static int dln2_i2c_xfer(struct i2c_adapter *adapter,
+                         struct i2c_msg *msgs, int num)
+{
+        struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
+        struct i2c_msg *pmsg;
+        struct device *dev = &dln2->adapter.dev;
+        int i;
+
+        for (i = 0; i < num; i++) {
+                int ret;
+
+                pmsg = &msgs[i];
+
+                if (pmsg->len > DLN2_I2C_MAX_XFER_SIZE) {
+                        dev_warn(dev, "maximum transfer size exceeded\n");
+                        return -EOPNOTSUPP;
+                }
+
+                if (pmsg->flags & I2C_M_RD) {
+                        ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
+                                            pmsg->len);
+                        if (ret < 0)
+                                return ret;
+
+                        pmsg->len = ret;
+                } else {
+                        ret = dln2_i2c_write(dln2, pmsg->addr, pmsg->buf,
+                                             pmsg->len);
+                        if (ret != pmsg->len)
+                                return -EPROTO;
+                }
+        }
+
+        return num;
+}
+
+static u32 dln2_i2c_func(struct i2c_adapter *a)
+{
+        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
+                I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
+                I2C_FUNC_SMBUS_I2C_BLOCK;
+}
+
+static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
+        .master_xfer = dln2_i2c_xfer,
+        .functionality = dln2_i2c_func,
+};
+
+static int dln2_i2c_probe(struct platform_device *pdev)
+{
+        int ret;
+        struct dln2_i2c *dln2;
+        struct device *dev = &pdev->dev;
+        struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
+
+        dln2 = devm_kzalloc(dev, sizeof(*dln2), GFP_KERNEL);
+        if (!dln2)
+                return -ENOMEM;
+
+        dln2->buf = devm_kmalloc(dev, DLN2_I2C_BUF_SIZE, GFP_KERNEL);
+        if (!dln2->buf)
+                return -ENOMEM;
+
+        dln2->pdev = pdev;
+        dln2->port = pdata->port;
+
+        /* setup i2c adapter description */
+        dln2->adapter.owner = THIS_MODULE;
+        dln2->adapter.class = I2C_CLASS_HWMON;
+        dln2->adapter.algo = &dln2_i2c_usb_algorithm;
+        dln2->adapter.dev.parent = dev;
+        i2c_set_adapdata(&dln2->adapter, dln2);
+        snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
+                 "dln2-i2c", dev_name(pdev->dev.parent), dln2->port);
+
+        platform_set_drvdata(pdev, dln2);
+
+        /* initialize the i2c interface */
+        ret = dln2_i2c_enable(dln2, true);
+        if (ret < 0) {
+                dev_err(dev, "failed to initialize adapter: %d\n", ret);
+                return ret;
+        }
+
+        /* and finally attach to i2c layer */
+        ret = i2c_add_adapter(&dln2->adapter);
+        if (ret < 0) {
+                dev_err(dev, "failed to add I2C adapter: %d\n", ret);
+                goto out_disable;
+        }
+
+        return 0;
+
+out_disable:
+        dln2_i2c_enable(dln2, false);
+
+        return ret;
+}
+
+static int dln2_i2c_remove(struct platform_device *pdev)
+{
+        struct dln2_i2c *dln2 = platform_get_drvdata(pdev);
+
+        i2c_del_adapter(&dln2->adapter);
+        dln2_i2c_enable(dln2, false);
+
+        return 0;
+}
+
+static struct platform_driver dln2_i2c_driver = {
+        .driver.name    = "dln2-i2c",
+        .probe          = dln2_i2c_probe,
+        .remove         = dln2_i2c_remove,
+};
+
+module_platform_driver(dln2_i2c_driver);
+
+MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
+MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C master interface");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:dln2-i2c");