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    Subject[PATCH v3 2/3] i2c: add support for Diolan DLN-2 USB-I2C adapter
    Date
    From: Laurentiu Palcu <laurentiu.palcu@intel.com>

    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>
    ---
    drivers/i2c/busses/Kconfig | 10 ++
    drivers/i2c/busses/Makefile | 1 +
    drivers/i2c/busses/i2c-dln2.c | 301 ++++++++++++++++++++++++++++++++++++++++++
    3 files changed, 312 insertions(+)
    create mode 100644 drivers/i2c/busses/i2c-dln2.c

    diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
    index 2ac87fa..4873161 100644
    --- a/drivers/i2c/busses/Kconfig
    +++ b/drivers/i2c/busses/Kconfig
    @@ -1021,4 +1021,14 @@ config SCx200_ACB
    This support is also available as a module. If so, the module
    will be called scx200_acb.

    +config I2C_DLN2
    + tristate "Diolan DLN-2 USB I2C adapter"
    + depends on USB && 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.
    +
    endmenu
    diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
    index 49bf07e..3118fea 100644
    --- a/drivers/i2c/busses/Makefile
    +++ b/drivers/i2c/busses/Makefile
    @@ -100,5 +100,6 @@ obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o
    obj-$(CONFIG_I2C_PCA_ISA) += i2c-pca-isa.o
    obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o
    obj-$(CONFIG_SCx200_ACB) += scx200_acb.o
    +obj-$(CONFIG_I2C_DLN2) += i2c-dln2.o

    ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
    diff --git a/drivers/i2c/busses/i2c-dln2.c b/drivers/i2c/busses/i2c-dln2.c
    new file mode 100644
    index 0000000..93e85ff
    --- /dev/null
    +++ b/drivers/i2c/busses/i2c-dln2.c
    @@ -0,0 +1,301 @@
    +/*
    + * 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/errno.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 DRIVER_NAME "dln2-i2c"
    +
    +#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_SET_FREQUENCY DLN2_I2C_CMD(0x04)
    +#define DLN2_I2C_GET_FREQUENCY DLN2_I2C_CMD(0x05)
    +#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_GET_MIN_FREQUENCY DLN2_I2C_CMD(0x40)
    +#define DLN2_I2C_GET_MAX_FREQUENCY DLN2_I2C_CMD(0x41)
    +
    +#define DLN2_I2C_FREQ_FAST 400000
    +#define DLN2_I2C_FREQ_STD 100000
    +
    +#define DLN2_I2C_MAX_XFER_SIZE 256
    +
    +struct dln2_i2c {
    + struct platform_device *pdev;
    + struct i2c_adapter adapter;
    +};
    +
    +static uint frequency = DLN2_I2C_FREQ_STD; /* I2C clock frequency in Hz */
    +
    +module_param(frequency, uint, S_IRUGO | S_IWUSR);
    +MODULE_PARM_DESC(frequency, "I2C clock frequency in hertz");
    +
    +static int dln2_i2c_set_state(struct dln2_i2c *dln2, u8 state)
    +{
    + int ret;
    + u8 port = 0;
    +
    + ret = dln2_transfer(dln2->pdev,
    + state ? DLN2_I2C_ENABLE : DLN2_I2C_DISABLE,
    + &port, sizeof(port), NULL, NULL);
    +
    + if (ret < 0)
    + return ret;
    +
    + return 0;
    +}
    +
    +#define dln2_i2c_enable(dln2) dln2_i2c_set_state(dln2, 1)
    +#define dln2_i2c_disable(dln2) dln2_i2c_set_state(dln2, 0)
    +
    +static int dln2_i2c_set_frequency(struct dln2_i2c *dln2, u32 freq)
    +{
    + int ret;
    + struct tx_data {
    + u8 port;
    + __le32 freq;
    + } __packed tx;
    +
    + tx.port = 0;
    + tx.freq = cpu_to_le32(freq);
    +
    + ret = dln2_transfer(dln2->pdev, DLN2_I2C_SET_FREQUENCY, &tx, sizeof(tx),
    + NULL, NULL);
    + 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, len;
    + struct tx_data {
    + u8 port;
    + u8 addr;
    + u8 mem_addr_len;
    + __le32 mem_addr;
    + __le16 buf_len;
    + u8 buf[DLN2_I2C_MAX_XFER_SIZE];
    + } __packed tx;
    +
    + if (data_len > DLN2_I2C_MAX_XFER_SIZE)
    + return -ENOSPC;
    +
    + tx.port = 0;
    + 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(dln2->pdev, DLN2_I2C_WRITE, &tx, len,
    + NULL, NULL);
    + if (ret < 0)
    + return ret;
    +
    + return data_len;
    +}
    +
    +static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
    + u16 data_len)
    +{
    + struct tx_data {
    + u8 port;
    + u8 addr;
    + u8 mem_addr_len;
    + __le32 mem_addr;
    + __le16 buf_len;
    + } __packed tx;
    + struct rx_data {
    + __le16 buf_len;
    + u8 buf[DLN2_I2C_MAX_XFER_SIZE];
    + } __packed rx;
    + int ret, buf_len, rx_len = sizeof(rx);
    +
    + tx.port = 0;
    + 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 < 2)
    + return -EPROTO;
    +
    + buf_len = le16_to_cpu(rx.buf_len);
    + if (rx_len + sizeof(__le16) < buf_len)
    + return -EPROTO;
    +
    + memcpy(data, rx.buf, buf_len);
    +
    + return buf_len;
    +}
    +
    +static int dln2_i2c_setup(struct dln2_i2c *dln2)
    +{
    + int ret;
    +
    + ret = dln2_i2c_disable(dln2);
    + if (ret < 0)
    + return ret;
    +
    + /* Set I2C frequency */
    + ret = dln2_i2c_set_frequency(dln2, frequency);
    + if (ret < 0)
    + return ret;
    +
    + ret = dln2_i2c_enable(dln2);
    +
    + return ret;
    +}
    +
    +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;
    + int i;
    + int ret = 0;
    +
    + for (i = 0; i < num; i++) {
    + pmsg = &msgs[i];
    +
    + if (pmsg->len > DLN2_I2C_MAX_XFER_SIZE)
    + return -EINVAL;
    +
    + 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;
    +}
    +
    +/*
    + * Return list of supported functionality.
    + */
    +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,
    +};
    +
    +/* device layer */
    +
    +static int dln2_i2c_probe(struct platform_device *pdev)
    +{
    + int ret;
    + struct device *dev = &pdev->dev;
    + struct dln2_i2c *dln2 = kzalloc(sizeof(*dln2), GFP_KERNEL);
    +
    + if (!dln2)
    + return -ENOMEM;
    +
    + dln2->pdev = pdev;
    +
    + /* 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), DRIVER_NAME);
    +
    + /* initialize the i2c interface */
    + ret = dln2_i2c_setup(dln2);
    + if (ret < 0) {
    + dev_err(dev, "failed to initialize adapter\n");
    + goto error_free;
    + }
    +
    + /* and finally attach to i2c layer */
    + ret = i2c_add_adapter(&dln2->adapter);
    + if (ret < 0) {
    + dev_err(dev, "failed to add I2C adapter\n");
    + goto error_free;
    + }
    +
    + platform_set_drvdata(pdev, dln2);
    +
    + return 0;
    +
    +error_free:
    + kfree(dln2);
    +
    + return ret;
    +}
    +
    +static int dln2_i2c_remove(struct platform_device *pdev)
    +{
    + struct dln2_i2c *dln2 = platform_get_drvdata(pdev);
    +
    + i2c_del_adapter(&dln2->adapter);
    +
    + return 0;
    +}
    +
    +static struct platform_driver dln2_i2c_driver = {
    + .driver.name = DRIVER_NAME,
    + .driver.owner = THIS_MODULE,
    + .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_NAME " driver");
    +MODULE_LICENSE("GPL");
    --
    1.9.1


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