Re: [PATCH v3 1/2] i2c: Add Imagination Technologies I2C SCB driver

[Vladimir Zapolskiy <vladimir_zapolskiy-nmGgyN9QBj3QT0dZR+AlfA@public.gmane.org>]

Hi Ezequiel,

On 05.11.2014 22:21, Ezequiel Garcia wrote:
> From: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> 
> Add support for the IMG I2C Serial Control Bus (SCB) found on the
> Pistachio and TZ1090 SoCs.
> 
> Signed-off-by: James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> [Ezequiel: code cleaning and rebasing]
> Signed-off-by: Ezequiel Garcia <ezequiel.garcia-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
> ---
>  drivers/i2c/busses/Kconfig       |   10 +
>  drivers/i2c/busses/Makefile      |    1 +
>  drivers/i2c/busses/i2c-img-scb.c | 1397 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1408 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-img-scb.c
> 

[snip]

> +static int img_i2c_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
> +			int num)
> +{
> +	struct img_i2c *i2c = i2c_get_adapdata(i2c_adap);
> +	bool atomic = false;
> +	int i;
> +
> +	if (i2c->mode == MODE_SUSPEND) {
> +		WARN(1, "refusing to service transaction in suspended state\n");
> +		return -EIO;
> +	}
> +
> +	if (i2c->mode == MODE_FATAL)
> +		return -EIO;
> +
> +	for (i = 0; i < num; i++) {
> +		if (likely(msgs[i].len))
> +			continue;
> +		/*
> +		 * 0 byte reads are not possible because the slave could try
> +		 * and pull the data line low, preventing a stop bit.
> +		 */
> +		if (unlikely(msgs[i].flags & I2C_M_RD))
> +			return -EIO;
> +		/*
> +		 * 0 byte writes are possible and used for probing, but we
> +		 * cannot do them in automatic mode, so use atomic mode
> +		 * instead.
> +		 */
> +		atomic = true;
> +	}
> +
> +	clk_prepare_enable(i2c->scb_clk);

Does it make sense to add a check for returned error here?

> +	for (i = 0; i < num; i++) {
> +		struct i2c_msg *msg = &msgs[i];
> +		unsigned long flags;
> +
> +		spin_lock_irqsave(&i2c->lock, flags);
> +
> +		/*
> +		 * Make a copy of the message struct. We mustn't modify the
> +		 * original or we'll confuse drivers and i2c-dev.
> +		 */
> +		i2c->msg = *msg;
> +		i2c->msg_status = 0;
> +
> +		/*

[snip]

> +
> +static int img_i2c_resume(struct device *dev)
> +{
> +	struct img_i2c *i2c = dev_get_drvdata(dev);
> +
> +	clk_enable(i2c->sys_clk);

Same question as above.

> +	img_i2c_init(i2c);
> +
> +	return 0;
> +}
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static SIMPLE_DEV_PM_OPS(img_i2c_pm, img_i2c_suspend, img_i2c_resume);
> +
> +static const struct of_device_id img_scb_i2c_match[] = {
> +	{ .compatible = "img,scb-i2c" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, img_scb_i2c_match);
> +
> +static struct platform_driver img_scb_i2c_driver = {
> +	.driver = {
> +		.name		= "img-i2c-scb",
> +		.of_match_table	= img_scb_i2c_match,
> +		.pm		= &img_i2c_pm,
> +	},
> +	.probe = img_i2c_probe,
> +	.remove = img_i2c_remove,
> +};
> +module_platform_driver(img_scb_i2c_driver);
> +
> +MODULE_AUTHOR("James Hogan <james.hogan-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>");
> +MODULE_DESCRIPTION("IMG host I2C driver");
> +MODULE_LICENSE("GPL");
> 

--
With best wishes,
Vladimir