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    SubjectRe: [PATCH 2/3] i2c: Add Congatec CGEB I2C driver
    Christian Gmeiner, MSc



    2012/2/1 Sascha Hauer <s.hauer@pengutronix.de>:
    > This driver provides a I2C bus driver for the CGEB interface
    > found on some Congatec x86 modules. No devices are registered
    > on the bus, the user has to do this via the i2c device /sys
    > interface.
    >
    > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
    > ---
    >  drivers/i2c/busses/Kconfig             |    7 +
    >  drivers/i2c/busses/Makefile            |    1 +
    >  drivers/i2c/busses/i2c-congatec-cgeb.c |  206 ++++++++++++++++++++++++++++++++
    >  3 files changed, 214 insertions(+), 0 deletions(-)
    >  create mode 100644 drivers/i2c/busses/i2c-congatec-cgeb.c
    >
    > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
    > index a3afac4..cc8eb22 100644
    > --- a/drivers/i2c/busses/Kconfig
    > +++ b/drivers/i2c/busses/Kconfig
    > @@ -696,6 +696,13 @@ config I2C_EG20T
    >          ML7213/ML7223 is companion chip for Intel Atom E6xx series.
    >          ML7213/ML7223 is completely compatible for Intel EG20T PCH.
    >
    > +config I2C_CONGATEC_CGEB
    > +       tristate "Congatec CGEB I2C driver"
    > +       depends on MFD_CONGATEC_CGEB
    > +       help
    > +         This driver provides support for the I2C busses accssable via
    > +         the Congatec CGEB interface found on Congatec boards.
    > +
    >  comment "External I2C/SMBus adapter drivers"
    >
    >  config I2C_DIOLAN_U2C
    > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
    > index fba6da6..4aab659 100644
    > --- a/drivers/i2c/busses/Makefile
    > +++ b/drivers/i2c/busses/Makefile
    > @@ -69,6 +69,7 @@ obj-$(CONFIG_I2C_VERSATILE)   += i2c-versatile.o
    >  obj-$(CONFIG_I2C_OCTEON)       += i2c-octeon.o
    >  obj-$(CONFIG_I2C_XILINX)       += i2c-xiic.o
    >  obj-$(CONFIG_I2C_EG20T)         += i2c-eg20t.o
    > +obj-$(CONFIG_I2C_CONGATEC_CGEB)        += i2c-congatec-cgeb.o
    >
    >  # External I2C/SMBus adapter drivers
    >  obj-$(CONFIG_I2C_DIOLAN_U2C)   += i2c-diolan-u2c.o
    > diff --git a/drivers/i2c/busses/i2c-congatec-cgeb.c b/drivers/i2c/busses/i2c-congatec-cgeb.c
    > new file mode 100644
    > index 0000000..a387662
    > --- /dev/null
    > +++ b/drivers/i2c/busses/i2c-congatec-cgeb.c
    > @@ -0,0 +1,206 @@
    > +/*
    > + * CGEB i2c driver
    > + *
    > + * (c) 2011 Sascha Hauer, Pengutronix
    > + *
    > + * 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 of the License.
    > + *
    > + * 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.
    > + */
    > +#include <linux/module.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/slab.h>
    > +#include <linux/i2c.h>
    > +#include <linux/mfd/congatec-cgeb.h>
    > +
    > +#define CG_I2C_FLAG_START   0x00080    /* send START condition */
    > +#define CG_I2C_FLAG_STOP    0x00040    /* send STOP condition */
    > +#define CG_I2C_FLAG_ALL_ACK 0x08000    /* send ACK on all read bytes */
    > +#define CG_I2C_FLAG_ALL_NAK 0x04000    /* send NAK on all read bytes */
    > +
    > +struct cgeb_i2c_priv {
    > +       struct cgeb_board_data          *board;
    > +       struct i2c_adapter      adapter;
    > +       int unit;
    > +};
    > +
    > +static u32 cgeb_i2c_func(struct i2c_adapter *adapter)
    > +{
    > +       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
    > +}
    > +
    > +static int cgeb_i2c_set_speed(struct cgeb_i2c_priv *priv, int speed)
    > +{
    > +       struct cgeb_function_parameters fps;
    > +
    > +       memset(&fps, 0, sizeof(fps));
    > +
    > +       fps.unit = priv->unit;
    > +       fps.pars[0] = speed;
    > +
    > +       return cgeb_call(priv->board, &fps, CgebI2CSetFrequency);
    > +}
    > +
    > +static int cgeb_i2c_xfer(struct i2c_adapter *adapter,
    > +               struct i2c_msg *msgs, int num)
    > +{
    > +       struct cgeb_function_parameters fps;
    > +       int i, ret;
    > +       unsigned long flags = CG_I2C_FLAG_START;
    > +       struct cgeb_i2c_priv *priv = i2c_get_adapdata(adapter);
    > +       unsigned long rdlen, wrlen;
    > +       unsigned char *rdbuf, *wrbuf, *raw_wrbuf;
    > +       unsigned short lmax = 0;
    > +
    > +       /*
    > +        * With cgeb the I2C address is part of the write data
    > +        * buffer, so allocate a buffer with the length of the
    > +        * longest write buffer + 1
    > +        */
    > +       for (i = 0; i < num; i++)
    > +               if (!(msgs[i].flags & I2C_M_RD))
    > +                       lmax = max(lmax, msgs[i].len);
    > +
    > +       raw_wrbuf = kmalloc(lmax + 1, GFP_KERNEL);
    > +       if (!raw_wrbuf)
    > +               return -ENOMEM;
    > +
    > +       for (i = 0; i < num; i++) {
    > +
    > +               if (msgs[i].flags & I2C_M_RD) {
    > +                       rdbuf = msgs[i].buf;
    > +                       rdlen = msgs[i].len;
    > +                       wrbuf = NULL;
    > +                       wrlen = 0;
    > +               } else {
    > +                       rdbuf = NULL;
    > +                       rdlen = 0;
    > +                       wrbuf = msgs[i].buf;
    > +                       wrlen = msgs[i].len;
    > +               }
    > +
    > +               raw_wrbuf[0] = msgs[i].addr << 1;
    > +               if (wrlen)
    > +                       memcpy(&raw_wrbuf[1], wrbuf, wrlen);
    > +
    > +               if (msgs[i].flags & I2C_M_RD)
    > +                       raw_wrbuf[0] |= 1;
    > +
    > +               if (i == num - 1)
    > +                       flags |= CG_I2C_FLAG_STOP;
    > +
    > +               dev_dbg(&adapter->dev,
    > +                               "%s: rd: %p/%ld wr: %p/%ld flags: 0x%08lx %s\n",
    > +                               __func__, rdbuf, rdlen, raw_wrbuf, wrlen + 1,
    > +                               flags,
    > +                               msgs[i].flags & I2C_M_RD ? "READ" : "WRITE");
    > +
    > +               memset(&fps, 0, sizeof(fps));
    > +
    > +               fps.unit = priv->unit;
    > +               fps.pars[0] = wrlen + 1;
    > +               fps.pars[1] = rdlen;
    > +               fps.pars[2] = flags;
    > +               fps.iptr = raw_wrbuf;
    > +               fps.optr = rdbuf;
    > +
    > +               ret = cgeb_call(priv->board, &fps, CgebI2CTransfer);
    > +               if (ret) {
    > +                       ret = -EREMOTEIO;
    > +                       goto out;
    > +               }
    > +       }
    > +
    > +       ret = num;
    > +
    > +out:
    > +       kfree(raw_wrbuf);
    > +
    > +       return ret;
    > +
    > +}
    > +
    > +static struct i2c_algorithm cgeb_i2c_algo = {
    > +       .master_xfer    = cgeb_i2c_xfer,
    > +       .functionality  = cgeb_i2c_func,
    > +};
    > +
    > +static int __devinit cgeb_i2c_probe(struct platform_device *pdev)
    > +{
    > +       struct cgeb_i2c_priv *priv;
    > +       struct cgeb_pdata *pdata = pdev->dev.platform_data;
    > +       int ret;
    > +
    > +       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    > +       if (!priv)
    > +               return -ENOMEM;
    > +
    > +       strcpy(priv->adapter.name, pdev->name);
    > +       priv->adapter.owner             = THIS_MODULE;
    > +       priv->adapter.algo              = &cgeb_i2c_algo;
    > +       priv->adapter.dev.parent        = &pdev->dev;
    > +       priv->unit = pdata->unit;
    > +       priv->board = pdata->board;
    > +       i2c_set_adapdata(&priv->adapter, priv);
    > +
    > +       platform_set_drvdata(pdev, priv);
    > +
    > +       ret = cgeb_i2c_set_speed(priv, 400000);
    > +       if (ret)
    > +               /*
    > +                * not a critical error, we can continue with the default speed.
    > +                */
    > +               dev_warn(&pdev->dev, "Could not set speed to 400KHz\n");
    > +
    > +       ret = i2c_add_adapter(&priv->adapter);
    > +       if (ret < 0) {
    > +               dev_err(&pdev->dev, "registration failed\n");
    > +               return ret;
    > +       }
    > +
    > +       dev_info(&pdev->dev, "registered\n");
    > +
    > +       return 0;
    > +};
    > +
    > +static int __devexit cgeb_i2c_remove(struct platform_device *pdev)
    > +{
    > +       struct cgeb_i2c_priv *priv = platform_get_drvdata(pdev);
    > +
    > +       i2c_del_adapter(&priv->adapter);
    > +
    > +       platform_set_drvdata(pdev, NULL);
    > +
    > +       return 0;
    > +}
    > +
    > +static struct platform_driver cgeb_i2c_driver = {
    > +       .probe          = cgeb_i2c_probe,
    > +       .remove         = __exit_p(cgeb_i2c_remove),
    > +       .driver = {
    > +               .name   = "cgeb-i2c",
    > +               .owner  = THIS_MODULE,
    > +       },
    > +};
    > +
    > +static int __init cgeb_i2c_driver_init(void)
    > +{
    > +       return platform_driver_register(&cgeb_i2c_driver);
    > +}
    > +
    > +static void __exit cgeb_i2c_driver_exit(void)
    > +{
    > +       platform_driver_unregister(&cgeb_i2c_driver);
    > +}
    > +
    > +module_init(cgeb_i2c_driver_init);
    > +module_exit(cgeb_i2c_driver_exit);
    > +
    > +MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
    > +MODULE_DESCRIPTION("cgeb i2c driver");
    > +MODULE_LICENSE("GPL");
    > --
    > 1.7.2.5
    >

    Patch looks good and runs nicely with some i2c devices (eeprom, io
    expander, temp sensors,...)

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    Tested-by: Christian Gmeiner <christian.gmeiner@gmail.com>
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