[PATCH 16/16] drivers/fsi: Add GPIO based FSI master

Hi Chris,

+static ssize_t store_scan(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf,
+				size_t count)
+{
+	struct fsi_master_gpio *master = dev_get_drvdata(dev);
+
+	fsi_master_gpio_init(master);
+
+	/* clear out any old scan data if present */
+	fsi_master_unregister(&master->master);
+	fsi_master_register(&master->master);
+
+	return count;
+}
+
+static DEVICE_ATTR(scan, 0200, NULL, store_scan);

I think it would make more sense to have the scan attribute populated by
the fsi core; we want this on all masters, not just GPIO.

Currently, the only GPIO-master-specific functionality here is the
fsi_master_gpio_init() - but isn't this something that we can do at
probe time instead?

+static int fsi_master_gpio_probe(struct platform_device *pdev)
+{
+	struct fsi_master_gpio *master;
+	struct gpio_desc *gpio;
+
+	master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return -ENOMEM;

We should be populating master->dev.parent, see

  https://github.com/jk-ozlabs/linux/commit/5225d6c47

+	/* Optional pins */
+
+	gpio = devm_gpiod_get(&pdev->dev, "trans", 0);
+	if (IS_ERR(gpio))
+		dev_dbg(&pdev->dev, "probe: failed to get trans pin\n");
+	else
+		master->gpio_trans = gpio;

I found devm_gpiod_get_optional(), which might make this a little
neater.

Cheers,


Jeremy