[RFC PATCH 1/5] phy: Add driver for Exynos MIPI CSIS/DSIM DPHYs

Hi Sylwester,

Looks good, but I added some nitpicks inline.

On Friday 14 of June 2013 19:45:47 Sylwester Nawrocki wrote:

I don't like this <soc_name> here. It sounds like any SoC name can be put 
here. IMHO just listing all supported compatible values should be enough.

and

 	  phy users can obtain reference to the PHY.
+
+if GENERIC_PHY
+
+config EXYNOS_VIDEO_MIPI_PHY
+	bool "S5P/EXYNOS MIPI CSI-2/DSI PHY driver"
+	depends on OF

Hmm. Is this driver designed only for OF-enabled boards?

I don't find this statement too readable. What about:

	void __iomem *addr = state->regs;

and below:

	/* CSIS 1 and DSIM 1 PHYs have separate register */
	if (id >= 2)
		addr += 4;

+	unsigned long flags;
+	u32 reg, reset;
+
+	pr_debug("%s(): id: %d, on: %d, addr: %#x, base: %#x\n",
+		 __func__, id, on, (u32)addr, (u32)state->regs);
+
+	if (WARN_ON(id > EXYNOS_MAX_VIDEO_PHYS))
+		return -EINVAL;
+
+	if (id & 1)

Nice trick ;), but not very readable. What about creating an enum of PHYs 
and using those defined values here:

	if (id == PHY_DSI0 || id == PHY_DSI1)

+		reset = EXYNOS_MIPI_PHY_MRESETN;
+	else
+		reset = EXYNOS_MIPI_PHY_SRESETN;
+
+	spin_lock_irqsave(&state->slock, flags);
+
+	reg = readl(addr);
+	if (on)
+		reg |= reset;
+	else
+		reg &= ~reset;
+	writel(reg, addr);
+
+	if (on)
+		reg |= EXYNOS_MIPI_PHY_ENABLE;

I believe this is a kind of reference counting, but a comment here would 
be nice.

+	else if (!(reg & EXYNOS_MIPI_PHY_RESET_MASK))
+		reg &= ~EXYNOS_MIPI_PHY_ENABLE;
+
+	writel(reg, addr);
+
+	spin_unlock_irqrestore(&state->slock, flags);
+	return 0;
+}
+
+static int exynos_video_phy_power_on(struct phy *phy)
+{
+	struct exynos_video_phy *state = dev_get_drvdata(&phy->dev);
+	return set_phy_state(state, phy->id, 1);
+}
+
+static int exynos_video_phy_power_off(struct phy *phy)
+{
+	struct exynos_video_phy *state = dev_get_drvdata(&phy->dev);
+	return set_phy_state(state, phy->id, 0);
+}
+
+static struct phy *exynos_video_phy_xlate(struct device *dev,
+					struct of_phandle_args *args)
+{
+	struct exynos_video_phy *state = dev_get_drvdata(dev);
+
+	if (WARN_ON(args->args[0] > EXYNOS_MAX_VIDEO_PHYS))
+		return NULL;
+
+	return state->phys[args->args[0]];
+}
+
+static struct phy_ops exynos_video_phy_ops = {
+	.power_on	= exynos_video_phy_power_on,
+	.power_off	= exynos_video_phy_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static int exynos_video_phy_probe(struct platform_device *pdev)
+{
+	struct exynos_video_phy *state;
+	struct device *dev = &pdev->dev;
+	struct resource res;
+	struct phy_provider *phy_provider;
+	int ret, i;
+
+	state = devm_kzalloc(dev, sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	ret = of_address_to_resource(dev->of_node, 0, &res);
+	if (ret < 0)
+		return ret;

You can use platform_get_resource() here to get a resource generated for 
you by of_platform_populate().

In addition you don't need to check the pointer returned by 
platform_get_resource() because it is checked in devm_ioremap_resource().

+
+	state->regs = devm_ioremap_resource(dev, &res);
+	if (IS_ERR(state->regs))
+		return PTR_ERR(state->regs);
+
+	dev_set_drvdata(dev, state);
+
+	phy_provider = devm_of_phy_provider_register(dev, THIS_MODULE,
+					    exynos_video_phy_xlate);
+	if (IS_ERR(phy_provider))
+		return PTR_ERR(phy_provider);
+
+	for (i = 0; i < EXYNOS_MAX_VIDEO_PHYS; i++) {
+		state->phys[i] = devm_phy_create(dev, i, 

&exynos_video_phy_ops,

+									

state);

+		if (IS_ERR(state->phys[i])) {
+			dev_err(dev, "failed to create PHY %d\n", i);
+			return PTR_ERR(state->phys[i]);
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id exynos_video_phy_of_match[] = {
+	{ .compatible = "samsung,s5pv210-video-phy" },
+	{ },
+};

IMHO a MODULE_DEVICE_TABLE should be added here.

Best regards,
Tomasz

+
+static struct platform_driver exynos_video_phy_driver = {
+	.probe	= exynos_video_phy_probe,
+	.driver = {
+		.of_match_table	= exynos_video_phy_of_match,
+		.name  = "exynos-video-phy",
+		.owner = THIS_MODULE,
+	}
+};
+module_platform_driver(exynos_video_phy_driver);
+
+MODULE_DESCRIPTION("Samsung S5P/EXYNOS SoC MIPI CSI-2/DSI DPHY
driver"); +MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sylwester Nawrocki [off-list ref]");