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

Hi Ezequiel,

On 05.11.2014 22:21, Ezequiel Garcia wrote:

From: James Hogan <redacted>

Add support for the IMG I2C Serial Control Bus (SCB) found on the
Pistachio and TZ1090 SoCs.

Signed-off-by: James Hogan <redacted>
[Ezequiel: code cleaning and rebasing]
Signed-off-by: Ezequiel Garcia <redacted>
---
 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 [off-list ref]");
+MODULE_DESCRIPTION("IMG host I2C driver");
+MODULE_LICENSE("GPL");

--
With best wishes,
Vladimir