static int p2wi_probe()

in busses/i2c-sun6i-p2wi.c [183:314]

• 104 lines of code
• 16 McCabe index (conditional complexity)

static int p2wi_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct device_node *childnp;
	unsigned long parent_clk_freq;
	u32 clk_freq = I2C_MAX_STANDARD_MODE_FREQ;
	struct p2wi *p2wi;
	u32 slave_addr;
	int clk_div;
	int irq;
	int ret;

	of_property_read_u32(np, "clock-frequency", &clk_freq);
	if (clk_freq > P2WI_MAX_FREQ) {
		dev_err(dev,
			"required clock-frequency (%u Hz) is too high (max = 6MHz)",
			clk_freq);
		return -EINVAL;
	}

	if (of_get_child_count(np) > 1) {
		dev_err(dev, "P2WI only supports one slave device\n");
		return -EINVAL;
	}

	p2wi = devm_kzalloc(dev, sizeof(struct p2wi), GFP_KERNEL);
	if (!p2wi)
		return -ENOMEM;

	p2wi->slave_addr = -1;

	/*
	 * Authorize a p2wi node without any children to be able to use an
	 * i2c-dev from userpace.
	 * In this case the slave_addr is set to -1 and won't be checked when
	 * launching a P2WI transfer.
	 */
	childnp = of_get_next_available_child(np, NULL);
	if (childnp) {
		ret = of_property_read_u32(childnp, "reg", &slave_addr);
		if (ret) {
			dev_err(dev, "invalid slave address on node %pOF\n",
				childnp);
			return -EINVAL;
		}

		p2wi->slave_addr = slave_addr;
	}

	p2wi->regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(p2wi->regs))
		return PTR_ERR(p2wi->regs);

	strscpy(p2wi->adapter.name, pdev->name, sizeof(p2wi->adapter.name));
	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	p2wi->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(p2wi->clk)) {
		ret = PTR_ERR(p2wi->clk);
		dev_err(dev, "failed to retrieve clk: %d\n", ret);
		return ret;
	}

	ret = clk_prepare_enable(p2wi->clk);
	if (ret) {
		dev_err(dev, "failed to enable clk: %d\n", ret);
		return ret;
	}

	parent_clk_freq = clk_get_rate(p2wi->clk);

	p2wi->rstc = devm_reset_control_get_exclusive(dev, NULL);
	if (IS_ERR(p2wi->rstc)) {
		ret = PTR_ERR(p2wi->rstc);
		dev_err(dev, "failed to retrieve reset controller: %d\n", ret);
		goto err_clk_disable;
	}

	ret = reset_control_deassert(p2wi->rstc);
	if (ret) {
		dev_err(dev, "failed to deassert reset line: %d\n", ret);
		goto err_clk_disable;
	}

	init_completion(&p2wi->complete);
	p2wi->adapter.dev.parent = dev;
	p2wi->adapter.algo = &p2wi_algo;
	p2wi->adapter.owner = THIS_MODULE;
	p2wi->adapter.dev.of_node = pdev->dev.of_node;
	platform_set_drvdata(pdev, p2wi);
	i2c_set_adapdata(&p2wi->adapter, p2wi);

	ret = devm_request_irq(dev, irq, p2wi_interrupt, 0, pdev->name, p2wi);
	if (ret) {
		dev_err(dev, "can't register interrupt handler irq%d: %d\n",
			irq, ret);
		goto err_reset_assert;
	}

	writel(P2WI_CTRL_SOFT_RST, p2wi->regs + P2WI_CTRL);

	clk_div = parent_clk_freq / clk_freq;
	if (!clk_div) {
		dev_warn(dev,
			 "clock-frequency is too high, setting it to %lu Hz\n",
			 parent_clk_freq);
		clk_div = 1;
	} else if (clk_div > P2WI_CCR_MAX_CLK_DIV) {
		dev_warn(dev,
			 "clock-frequency is too low, setting it to %lu Hz\n",
			 parent_clk_freq / P2WI_CCR_MAX_CLK_DIV);
		clk_div = P2WI_CCR_MAX_CLK_DIV;
	}

	writel(P2WI_CCR_SDA_OUT_DELAY(1) | P2WI_CCR_CLK_DIV(clk_div),
	       p2wi->regs + P2WI_CCR);

	ret = i2c_add_adapter(&p2wi->adapter);
	if (!ret)
		return 0;

err_reset_assert:
	reset_control_assert(p2wi->rstc);

err_clk_disable:
	clk_disable_unprepare(p2wi->clk);

	return ret;
}