static int hd44780_probe()

in hd44780.c [200:320]

• 96 lines of code
• 18 McCabe index (conditional complexity)

static int hd44780_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	unsigned int i, base;
	struct charlcd *lcd;
	struct hd44780_common *hdc;
	struct hd44780 *hd;
	int ifwidth, ret = -ENOMEM;

	/* Required pins */
	ifwidth = gpiod_count(dev, "data");
	if (ifwidth < 0)
		return ifwidth;

	switch (ifwidth) {
	case 4:
		base = PIN_DATA4;
		break;
	case 8:
		base = PIN_DATA0;
		break;
	default:
		return -EINVAL;
	}

	hdc = hd44780_common_alloc();
	if (!hdc)
		return -ENOMEM;

	lcd = charlcd_alloc();
	if (!lcd)
		goto fail1;

	hd = kzalloc(sizeof(struct hd44780), GFP_KERNEL);
	if (!hd)
		goto fail2;

	hdc->hd44780 = hd;
	lcd->drvdata = hdc;
	for (i = 0; i < ifwidth; i++) {
		hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i,
							  GPIOD_OUT_LOW);
		if (IS_ERR(hd->pins[base + i])) {
			ret = PTR_ERR(hd->pins[base + i]);
			goto fail3;
		}
	}

	hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_E])) {
		ret = PTR_ERR(hd->pins[PIN_CTRL_E]);
		goto fail3;
	}

	hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH);
	if (IS_ERR(hd->pins[PIN_CTRL_RS])) {
		ret = PTR_ERR(hd->pins[PIN_CTRL_RS]);
		goto fail3;
	}

	/* Optional pins */
	hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw",
							GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_RW])) {
		ret = PTR_ERR(hd->pins[PIN_CTRL_RW]);
		goto fail3;
	}

	hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight",
							GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_BL])) {
		ret = PTR_ERR(hd->pins[PIN_CTRL_BL]);
		goto fail3;
	}

	/* Required properties */
	ret = device_property_read_u32(dev, "display-height-chars",
				       &lcd->height);
	if (ret)
		goto fail3;
	ret = device_property_read_u32(dev, "display-width-chars", &lcd->width);
	if (ret)
		goto fail3;

	/*
	 * On displays with more than two rows, the internal buffer width is
	 * usually equal to the display width
	 */
	if (lcd->height > 2)
		hdc->bwidth = lcd->width;

	/* Optional properties */
	device_property_read_u32(dev, "internal-buffer-width", &hdc->bwidth);

	hdc->ifwidth = ifwidth;
	if (ifwidth == 8) {
		lcd->ops = &hd44780_ops_gpio8;
		hdc->write_data = hd44780_write_data_gpio8;
		hdc->write_cmd = hd44780_write_cmd_gpio8;
	} else {
		lcd->ops = &hd44780_ops_gpio4;
		hdc->write_data = hd44780_write_data_gpio4;
		hdc->write_cmd = hd44780_write_cmd_gpio4;
		hdc->write_cmd_raw4 = hd44780_write_cmd_raw_gpio4;
	}

	ret = charlcd_register(lcd);
	if (ret)
		goto fail3;

	platform_set_drvdata(pdev, lcd);
	return 0;

fail3:
	kfree(hd);
fail2:
	kfree(lcd);
fail1:
	kfree(hdc);
	return ret;
}