On Tue, Sep 03, 2013 at 05:49:29PM +0100, Ian Molton wrote:
> Add a driver for the EMMA mobile I2C block.
>
> The driver supports low and high-speed interrupt driven PIO transfers.
>
> Signed-off-by: Ian Molton <ian.molton@xxxxxxxxxxxxxxx>
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -777,6 +777,16 @@ config I2C_RCAR
> This driver can also be built as a module. If so, the module
> will be called i2c-rcar.
>
> +config I2C_EM
> + tristate "EMMA Mobile series I2C adapter"
> + depends on I2C && HAVE_CLK
> + help
> + If you say yes to this option, support will be included for the
> + I2C interface on the Renesas Electronics EM/EV family of processors.
> +
> + This driver can also be built as a module. If so, the module
> + will be called i2c-em
> +
Please keep it sorted.
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-em.c
> @@ -0,0 +1,501 @@
> +/*
> + * Copyright 2013 Codethink Ltd.
> + * Parts Copyright 2010 Renesas Electronics Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software Foundation,
> + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA.
> + */
Skip the address please.
> +static int em_i2c_xfer(struct i2c_adapter *, struct i2c_msg[], int);
You can skip this forward declaration by reordering.
> +
> +struct em_i2c_device {
> + struct i2c_adapter adap;
> + wait_queue_head_t i2c_wait;
> + void __iomem *membase;
> + struct clk *clk;
> + struct clk *sclk;
> + int irq;
> + int flags;
> + int pending;
> + spinlock_t irq_lock;
> +};
> +
> +#define to_em_i2c(adap) (struct em_i2c_device *)i2c_get_adapdata(adap)
> +
> +static u32 em_i2c_func(struct i2c_adapter *adap)
> +{
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
Have you tried SMBUS_QUICK (via 'i2cdetect -q')?
> +
> +static struct i2c_algorithm em_i2c_algo = {
> + .master_xfer = em_i2c_xfer,
> + .smbus_xfer = NULL,
No need to specify the NULL.
> + .functionality = em_i2c_func,
> +};
> +
> +static int em_i2c_wait_for_event(struct em_i2c_device *i2c_dev, u16 *status)
> +{
> + int interrupted;
> +
> + do {
> + interrupted = wait_event_interruptible_timeout(
> + i2c_dev->i2c_wait, i2c_dev->pending,
> + i2c_dev->adap.timeout);
Have you tested signals extensively? It can be done right, yet it is
complex. Most drivers decide to skip the interruptible.
> +
> + if (i2c_dev->pending) {
> + spin_lock_irq(&i2c_dev->irq_lock);
> + i2c_dev->pending = 0;
> + spin_unlock_irq(&i2c_dev->irq_lock);
> + *status = readl(i2c_dev->membase + I2C_OFS_IICSE0);
> + return 0;
> + }
> +
> + } while (interrupted);
> +
> + *status = 0;
> +
> + return -ETIMEDOUT;
> +}
> +
> +static int em_i2c_stop(struct em_i2c_device *i2c_dev)
> +{
> + u16 status;
> +
> + /* Send Stop condition */
> + writel((readl(i2c_dev->membase + I2C_OFS_IICC0) | I2C_BIT_SPT0 |
> + I2C_BIT_SPIE0), i2c_dev->membase + I2C_OFS_IICC0);
I'd think a em_set_bit() function would make the code more readable.
> +
> + /* Wait for stop condition */
> + em_i2c_wait_for_event(i2c_dev, &status);
> + /* FIXME - check status? */
What about the FIXME?
> +
> + if ((readl(i2c_dev->membase + I2C_OFS_IICSE0) & I2C_BIT_SPD0) != 0)
!= 0 is superfluous, same for == 1 later.
> + return 0;
> +
> + return -EBUSY;
> +}
> +
> + /* Send / receive data */
> + do {
> + /* Arbitration, Extension mode or Slave mode are errors*/
> + if (status & (I2C_BIT_EXC0 | I2C_BIT_COI0 | I2C_BIT_ALD0)
> + || !(status & I2C_BIT_MSTS0))
> + goto out_reset;
> +
> + if (!(status & I2C_BIT_TRC0)) { /* Read transaction */
> +
> + /* msg->flags is Write type */
> + if (!(msg->flags & I2C_M_RD))
> + goto out_reset;
> +
> + if (count == msg->len)
> + break;
> +
> + msg->buf[count++] =
> + readl(i2c_dev->membase + I2C_OFS_IIC0);
> +
> +
> + writel((readl(i2c_dev->membase + I2C_OFS_IICC0)
> + | I2C_BIT_WREL0),
> + i2c_dev->membase + I2C_OFS_IICC0);
> +
> + } else { /* Write transaction */
> +
> + /* msg->flags is Read type */
> + if ((msg->flags & I2C_M_RD))
> + goto out_reset;
> +
> + /* Recieved No ACK */
> + if (!(status & I2C_BIT_ACKD0)) {
> + em_i2c_stop(i2c_dev);
> + goto out;
> + }
> +
> + if (count == msg->len)
> + break;
> +
> + /* Write data */
> + writel(msg->buf[count++], i2c_dev->membase
> + + I2C_OFS_IIC0);
> + }
> +
> + /* Wait for R/W transaction */
> + if (em_i2c_wait_for_event(i2c_dev, &status))
> + goto out_reset;
> +
> + } while (1);
Have you tried using another loop than this endless do/while?
> +
> + if (stop)
> + em_i2c_stop(i2c_dev);
> +
> + return count;
> +
> +out_reset:
> + em_i2c_reset(adap);
> +out:
> + return -EREMOTEIO;
> +}
> +
> +static int em_i2c_wait_free(struct i2c_adapter *adap)
> +{
> + struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> + int timeout = adap->timeout;
> + int status;
> +
> + /* wait until I2C bus free */
> + while ((readl(i2c_dev->membase + I2C_OFS_IICF0) & I2C_BIT_IICBSY)
> + && timeout--) {
> + schedule_timeout_uninterruptible(1);
> + }
Are you sure you want to loop with a 1 jiffy granularity?
> +
> + status = (timeout <= 0);
> +
> + if (status)
> + dev_info(&adap->dev, "I2C bus is busy\n");
> +
> + return status;
> +}
> +
> +static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> + int num)
> +{
> + struct em_i2c_device *i2c_dev = to_em_i2c(adap);
> + int ret = 0;
> + int i;
> +
> + em_i2c_enable_clock(i2c_dev);
> + em_i2c_reset(adap);
You reset the adapter before every transfer?
> +
> + /* Attempt to gain control of the adapter */
> + i = 0;
> + while (em_i2c_wait_free(adap)) {
> + switch (i) {
> + case 0:
> + if (!(readl(i2c_dev->membase + I2C_OFS_IICSE0)
> + & I2C_BIT_MSTS0)) {
> + /* Slave mode -> Error */
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + em_i2c_stop(i2c_dev);
> + break;
> + case 1:
> + em_i2c_reset(adap);
...and here again?
> + break;
> + case 2:
> + ret = -EREMOTEIO;
> + goto out;
> + }
> + i++;
> + }
> +
> + /* Send messages */
> + for (i = 0; i < num; i++) {
> + ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1)));
> + if (ret < 0)
> + goto out;
> + }
> +
> + /* I2C transfer completed */
> + ret = i;
> +
> +out:
> + em_i2c_disable_clock(i2c_dev);
> +
> + return ret;
> +}
> +
> + spin_lock_init(&i2c_dev->irq_lock);
> +
> + if (of_find_property(pdev->dev.of_node, "high-speed", NULL))
> + i2c_dev->flags |= I2C_BIT_SMC0;
Please derive this from the standard property "clock-frequency" which
configures the bus speed for I2C.
> + of_i2c_register_devices(&i2c_dev->adap);
The core does this for you.
> +static int em_i2c_remove(struct platform_device *dev)
> +{
> + struct em_i2c_device *i2c_dev = platform_get_drvdata(dev);
> +
> + i2c_del_adapter(&i2c_dev->adap);
> +
> + clk_disable(i2c_dev->clk);
Aren't the clocks off already?
> + clk_unprepare(i2c_dev->clk);
> +
> + return 0;
> +}
> +
> +
> +MODULE_LICENSE("GPLv2");
GPL v2
> +MODULE_DESCRIPTION("EMEV2 I2C bus driver");
> +MODULE_AUTHOR("Ian Molton");
Email address?
> +
> --
> 1.7.10.4
>
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