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    Subject[PATCH v2 2/4] i2c: Kontron PLD i2c bus driver
    Date
    Add i2c support for the on-board PLD found on some Kontron embedded
    modules.

    Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
    Signed-off-by: Michael Brunner <michael.brunner@kontron.com>
    Acked-by: Guenter Roeck <linux@roeck-us.net>
    Acked-by: Darren Hart <dvhart@linux.intel.com>
    ---
    drivers/i2c/busses/Kconfig | 10 +
    drivers/i2c/busses/Makefile | 1 +
    drivers/i2c/busses/i2c-kempld.c | 410 +++++++++++++++++++++++++++++++++++++++
    3 files changed, 421 insertions(+)
    create mode 100644 drivers/i2c/busses/i2c-kempld.c

    diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
    index adfee98..3e1457d 100644
    --- a/drivers/i2c/busses/Kconfig
    +++ b/drivers/i2c/busses/Kconfig
    @@ -494,6 +494,16 @@ config I2C_IOP3XX
    This driver can also be built as a module. If so, the module
    will be called i2c-iop3xx.

    +config I2C_KEMPLD
    + tristate "Kontron COM I2C Controller"
    + depends on MFD_KEMPLD
    + help
    + This enables support for the I2C bus interface on some Kontron ETX
    + and COMexpress (ETXexpress) modules.
    +
    + This driver can also be built as a module. If so, the module
    + will be called i2c-kempld.
    +
    config I2C_MPC
    tristate "MPC107/824x/85xx/512x/52xx/83xx/86xx"
    depends on PPC
    diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
    index 8f4fc23..150fa15 100644
    --- a/drivers/i2c/busses/Makefile
    +++ b/drivers/i2c/busses/Makefile
    @@ -48,6 +48,7 @@ obj-$(CONFIG_I2C_IBM_IIC) += i2c-ibm_iic.o
    obj-$(CONFIG_I2C_IMX) += i2c-imx.o
    obj-$(CONFIG_I2C_INTEL_MID) += i2c-intel-mid.o
    obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o
    +obj-$(CONFIG_I2C_KEMPLD) += i2c-kempld.o
    obj-$(CONFIG_I2C_MPC) += i2c-mpc.o
    obj-$(CONFIG_I2C_MV64XXX) += i2c-mv64xxx.o
    obj-$(CONFIG_I2C_MXS) += i2c-mxs.o
    diff --git a/drivers/i2c/busses/i2c-kempld.c b/drivers/i2c/busses/i2c-kempld.c
    new file mode 100644
    index 0000000..ccec916
    --- /dev/null
    +++ b/drivers/i2c/busses/i2c-kempld.c
    @@ -0,0 +1,410 @@
    +/*
    + * I2C bus driver for Kontron COM modules
    + *
    + * Copyright (c) 2010-2013 Kontron Europe GmbH
    + * Author: Michael Brunner <michael.brunner@kontron.com>
    + *
    + * The driver is based on the i2c-ocores driver by Peter Korsgaard.
    + *
    + * This program is free software; you can redistribute it and/or modify
    + * it under the terms of the GNU General Public License 2 as published
    + * by the Free Software Foundation.
    + *
    + * 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/i2c.h>
    +#include <linux/delay.h>
    +#include <linux/mfd/kempld.h>
    +
    +#define KEMPLD_I2C_PRELOW 0x0b
    +#define KEMPLD_I2C_PREHIGH 0x0c
    +#define KEMPLD_I2C_DATA 0x0e
    +
    +#define KEMPLD_I2C_CTRL 0x0d
    +#define I2C_CTRL_IEN 0x40
    +#define I2C_CTRL_EN 0x80
    +
    +#define KEMPLD_I2C_STAT 0x0f
    +#define I2C_STAT_IF 0x01
    +#define I2C_STAT_TIP 0x02
    +#define I2C_STAT_ARBLOST 0x20
    +#define I2C_STAT_BUSY 0x40
    +#define I2C_STAT_NACK 0x80
    +
    +#define KEMPLD_I2C_CMD 0x0f
    +#define I2C_CMD_START 0x91
    +#define I2C_CMD_STOP 0x41
    +#define I2C_CMD_READ 0x21
    +#define I2C_CMD_WRITE 0x11
    +#define I2C_CMD_READ_ACK 0x21
    +#define I2C_CMD_READ_NACK 0x29
    +#define I2C_CMD_IACK 0x01
    +
    +#define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
    +#define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */
    +
    +enum {
    + STATE_DONE = 0,
    + STATE_INIT,
    + STATE_ADDR,
    + STATE_ADDR10,
    + STATE_START,
    + STATE_WRITE,
    + STATE_READ,
    + STATE_ERROR,
    +};
    +
    +struct kempld_i2c_data {
    + struct device *dev;
    + struct kempld_device_data *pld;
    + struct i2c_adapter adap;
    + struct i2c_msg *msg;
    + int pos;
    + int nmsgs;
    + int state;
    + bool was_active;
    +};
    +
    +static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
    +module_param(bus_frequency, uint, 0);
    +MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
    + __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
    +
    +static int i2c_bus = -1;
    +module_param(i2c_bus, int, 0);
    +MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
    +
    +static bool i2c_gpio_mux;
    +module_param(i2c_gpio_mux, bool, 0);
    +MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
    +
    +/*
    + * kempld_get_mutex must be called prior to calling this function.
    + */
    +static int kempld_i2c_process(struct kempld_i2c_data *i2c)
    +{
    + struct kempld_device_data *pld = i2c->pld;
    + u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
    + struct i2c_msg *msg = i2c->msg;
    + u8 addr;
    +
    + /* Ready? */
    + if (stat & I2C_STAT_TIP)
    + return -EBUSY;
    +
    + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
    + /* Stop has been sent */
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
    + if (i2c->state == STATE_ERROR)
    + return -EIO;
    + return 0;
    + }
    +
    + /* Error? */
    + if (stat & I2C_STAT_ARBLOST) {
    + i2c->state = STATE_ERROR;
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
    + return -EAGAIN;
    + }
    +
    + if (i2c->state == STATE_INIT) {
    + if (stat & I2C_STAT_BUSY)
    + return -EBUSY;
    +
    + i2c->state = STATE_ADDR;
    + }
    +
    + if (i2c->state == STATE_ADDR) {
    + /* 10 bit address? */
    + if (i2c->msg->flags & I2C_M_TEN) {
    + addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
    + i2c->state = STATE_ADDR10;
    + } else {
    + addr = (i2c->msg->addr << 1);
    + i2c->state = STATE_START;
    + }
    +
    + /* Set read bit if necessary */
    + addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
    +
    + kempld_write8(pld, KEMPLD_I2C_DATA, addr);
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
    +
    + return 0;
    + }
    +
    + /* Second part of 10 bit addressing */
    + if (i2c->state == STATE_ADDR10) {
    + kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
    +
    + i2c->state = STATE_START;
    + return 0;
    + }
    +
    + if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
    + i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
    +
    + if (stat & I2C_STAT_NACK) {
    + i2c->state = STATE_ERROR;
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
    + return -ENXIO;
    + }
    + } else {
    + msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
    + }
    +
    + if (i2c->pos >= msg->len) {
    + i2c->nmsgs--;
    + i2c->msg++;
    + i2c->pos = 0;
    + msg = i2c->msg;
    +
    + if (i2c->nmsgs) {
    + if (!(msg->flags & I2C_M_NOSTART)) {
    + i2c->state = STATE_ADDR;
    + return 0;
    + } else {
    + i2c->state = (msg->flags & I2C_M_RD)
    + ? STATE_READ : STATE_WRITE;
    + }
    + } else {
    + i2c->state = STATE_DONE;
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
    + return 0;
    + }
    + }
    +
    + if (i2c->state == STATE_READ) {
    + kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
    + I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
    + } else {
    + kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
    + }
    +
    + return 0;
    +}
    +
    +static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
    + int num)
    +{
    + struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
    + struct kempld_device_data *pld = i2c->pld;
    + unsigned long timeout = jiffies + HZ;
    + int ret;
    +
    + i2c->msg = msgs;
    + i2c->pos = 0;
    + i2c->nmsgs = num;
    + i2c->state = STATE_INIT;
    +
    + /* Handle the transfer */
    + while (time_before(jiffies, timeout)) {
    + kempld_get_mutex(pld);
    + ret = kempld_i2c_process(i2c);
    + kempld_release_mutex(pld);
    +
    + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
    + return (i2c->state == STATE_DONE) ? num : ret;
    +
    + if (ret == 0)
    + timeout = jiffies + HZ;
    +
    + usleep_range(5, 15);
    + }
    +
    + i2c->state = STATE_ERROR;
    +
    + return -ETIMEDOUT;
    +}
    +
    +/*
    + * kempld_get_mutex must be called prior to calling this function.
    + */
    +static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
    +{
    + struct kempld_device_data *pld = i2c->pld;
    + u16 prescale_corr;
    + long prescale;
    + u8 ctrl;
    + u8 stat;
    + u8 cfg;
    +
    + /* Make sure the device is disabled */
    + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
    + ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
    + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
    +
    + if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
    + bus_frequency = KEMPLD_I2C_FREQ_MAX;
    +
    + if (pld->info.spec_major == 1)
    + prescale = pld->pld_clock / bus_frequency * 5 - 1000;
    + else
    + prescale = pld->pld_clock / bus_frequency * 4 - 3000;
    +
    + if (prescale < 0)
    + prescale = 0;
    +
    + /* Round to the best matching value */
    + prescale_corr = prescale / 1000;
    + if (prescale % 1000 >= 500)
    + prescale_corr++;
    +
    + kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
    + kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
    +
    + /* Activate I2C bus output on GPIO pins */
    + cfg = kempld_read8(pld, KEMPLD_CFG);
    + if (i2c_gpio_mux)
    + cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
    + else
    + cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
    + kempld_write8(pld, KEMPLD_CFG, cfg);
    +
    + /* Enable the device */
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
    + ctrl |= I2C_CTRL_EN;
    + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
    +
    + stat = kempld_read8(pld, KEMPLD_I2C_STAT);
    + if (stat & I2C_STAT_BUSY)
    + kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
    +}
    +
    +static u32 kempld_i2c_func(struct i2c_adapter *adap)
    +{
    + return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
    +}
    +
    +static const struct i2c_algorithm kempld_i2c_algorithm = {
    + .master_xfer = kempld_i2c_xfer,
    + .functionality = kempld_i2c_func,
    +};
    +
    +static struct i2c_adapter kempld_i2c_adapter = {
    + .owner = THIS_MODULE,
    + .name = "i2c-kempld",
    + .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
    + .algo = &kempld_i2c_algorithm,
    +};
    +
    +static int kempld_i2c_probe(struct platform_device *pdev)
    +{
    + struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
    + struct kempld_i2c_data *i2c;
    + int ret;
    + u8 ctrl;
    +
    + i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
    + if (!i2c)
    + return -ENOMEM;
    +
    + i2c->pld = pld;
    + i2c->dev = &pdev->dev;
    + i2c->adap = kempld_i2c_adapter;
    + i2c->adap.dev.parent = i2c->dev;
    + i2c_set_adapdata(&i2c->adap, i2c);
    + platform_set_drvdata(pdev, i2c);
    +
    + kempld_get_mutex(pld);
    + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
    +
    + if (ctrl & I2C_CTRL_EN)
    + i2c->was_active = true;
    +
    + kempld_i2c_device_init(i2c);
    + kempld_release_mutex(pld);
    +
    + /* Add I2C adapter to I2C tree */
    + if (i2c_bus >= -1)
    + i2c->adap.nr = i2c_bus;
    + ret = i2c_add_numbered_adapter(&i2c->adap);
    + if (ret)
    + return ret;
    +
    + dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
    + bus_frequency);
    +
    + return 0;
    +}
    +
    +static int kempld_i2c_remove(struct platform_device *pdev)
    +{
    + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
    + struct kempld_device_data *pld = i2c->pld;
    + u8 ctrl;
    +
    + kempld_get_mutex(pld);
    + /*
    + * Disable I2C logic if it was not activated before the
    + * driver loaded
    + */
    + if (!i2c->was_active) {
    + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
    + ctrl &= ~I2C_CTRL_EN;
    + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
    + }
    + kempld_release_mutex(pld);
    +
    + i2c_del_adapter(&i2c->adap);
    +
    + return 0;
    +}
    +
    +#ifdef CONFIG_PM
    +static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
    +{
    + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
    + struct kempld_device_data *pld = i2c->pld;
    + u8 ctrl;
    +
    + kempld_get_mutex(pld);
    + ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
    + ctrl &= ~I2C_CTRL_EN;
    + kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
    + kempld_release_mutex(pld);
    +
    + return 0;
    +}
    +
    +static int kempld_i2c_resume(struct platform_device *pdev)
    +{
    + struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
    + struct kempld_device_data *pld = i2c->pld;
    +
    + kempld_get_mutex(pld);
    + kempld_i2c_device_init(i2c);
    + kempld_release_mutex(pld);
    +
    + return 0;
    +}
    +#else
    +#define kempld_i2c_suspend NULL
    +#define kempld_i2c_resume NULL
    +#endif
    +
    +static struct platform_driver kempld_i2c_driver = {
    + .driver = {
    + .name = "kempld-i2c",
    + .owner = THIS_MODULE,
    + },
    + .probe = kempld_i2c_probe,
    + .remove = kempld_i2c_remove,
    + .suspend = kempld_i2c_suspend,
    + .resume = kempld_i2c_resume,
    +};
    +
    +module_platform_driver(kempld_i2c_driver);
    +
    +MODULE_DESCRIPTION("KEM PLD I2C Driver");
    +MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
    +MODULE_LICENSE("GPL");
    +MODULE_ALIAS("platform:kempld_i2c");
    --
    1.7.9.5


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