[PATCH] backlight: lcd: add driver for raster-type lcd's with gpio controlled panel reset
From: lars@metafoo.de (Lars-Peter Clausen)
Date: 2012-01-05 19:09:14
Also in:
linux-samsung-soc, lkml
quoted hunk ↗ jump to hunk
[...]diff --git a/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt b/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt new file mode 100644 index 0000000..941e2ff --- /dev/null +++ b/Documentation/devicetree/bindings/lcd/lcd-pwrctrl.txt@@ -0,0 +1,39 @@ +* Power controller for simple lcd panels + +Some LCD panels provide a simple control interface for the host system. The +control mechanism would include a nRESET line connected to a gpio of the host +system and a Vcc supply line which the host can optionally be controlled using +a voltage regulator. Such simple panels do not support serial command +interface (such as i2c or spi) or memory-mapped-io interface. + +Required properties: +- compatible: should be 'lcd,powerctrl' +- gpios: The GPIO number of the host system used to control the nRESET line. + The format of the gpio specifier depends on the gpio controller of the + host system. + +Optional properties: +- lcd,pwrctrl-nreset-gpio-invert: When the nRESET line is asserted low, the + lcd panel is reset and stays in reset mode as long as the nRESET line is + asserted low. This is the default behaviour of most lcd panels. If a lcd + panel requires the nRESET line to be asserted high for panel reset, then + this property is used.
Maybe use OF_GPIO_ACTIVE_LOW here instead. That would make active high the default but be a bit more consistent.
+- lcd,pwrctrl-min-uV: If a regulator controls the Vcc voltage of the lcd panel, + this property specifies the minimum voltage the regulator should supply. + The value of this property should in in micro-volts. +- lcd,pwrctrl-max-uV: If a regulator controls the Vcc voltage of the lcd panel, + this property specifies the maximum voltage the regulator should limit to + on the Vcc line. The value of this property should in in micro-volts.
The min and max voltage should rather be specified through the regulator constraints.
+- vcc-lcd-supply: phandle of the regulator that controls the vcc supply to + the lcd panel. +
[...]
quoted hunk ↗ jump to hunk
diff --git a/drivers/video/backlight/lcd_pwrctrl.c b/drivers/video/backlight/lcd_pwrctrl.c new file mode 100644 index 0000000..6f3110b --- /dev/null +++ b/drivers/video/backlight/lcd_pwrctrl.c@@ -0,0 +1,231 @@[...] +static int lcd_pwrctrl_set_power(struct lcd_device *lcd, int power) +{ + struct lcd_pwrctrl *lp = lcd_get_data(lcd); + struct lcd_pwrctrl_data *pd = lp->pdata; + int lcd_enable, lcd_reset; + + lcd_enable = (power == FB_BLANK_POWERDOWN || lp->suspended) ? 0 : 1; + lcd_reset = (pd->invert) ? !lcd_enable : lcd_enable; + + if (IS_ERR(lp->regulator)) + goto no_regulator;
I wouldn't use a goto here.
+
+ if (lcd_enable) {
+ if ((pd->min_uV || pd->max_uV) &&
+ regulator_set_voltage(lp->regulator,
+ pd->min_uV, pd->max_uV))
+ dev_info(lp->dev,
+ "regulator voltage set failed\n");
+ if (regulator_enable(lp->regulator))
+ dev_info(lp->dev, "failed to enable regulator\n");
+ } else {
+ regulator_disable(lp->regulator);
+ }I think you have to make sure that the regulator enable and disable calls are balanced.
+ + no_regulator: + gpio_direction_output(lp->pdata->gpio, lcd_reset); + lp->power = power; + return 0; +} +
[...]
+ +#ifdef CONFIG_OF
I think you can remove all the CONFIG_OF ifdefs, the of API should stub itself out.
+static void __devinit lcd_pwrctrl_parse_dt(struct device *dev,
+ struct lcd_pwrctrl_data *pdata)
+{
+ struct device_node *np = dev->of_node;
+
+ pdata->gpio = of_get_gpio(np, 0);
+ if (of_get_property(np, "lcd,pwrctrl-nreset-gpio-invert", NULL))
+ pdata->invert = true;
+ of_property_read_u32(np, "lcd,pwrctrl-min-uV", &pdata->min_uV);
+ of_property_read_u32(np, "lcd,pwrctrl-max-uV", &pdata->max_uV);
+}
+#endif
+
+static int __devinit lcd_pwrctrl_probe(struct platform_device *pdev)
+{
+ struct lcd_pwrctrl *lp;
+ struct lcd_pwrctrl_data *pdata = pdev->dev.platform_data;
+ struct device *dev = &pdev->dev;
+ int err;
+
+#ifdef CONFIG_OF
+ if (dev->of_node) {
+ pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+ if (!pdata) {
+ dev_err(dev, "memory allocation for pdata failed\n");
+ return -ENOMEM;
+ }
+ lcd_pwrctrl_parse_dt(dev, pdata);
+ }
+#endif
+
+ if (!pdata) {
+ dev_err(dev, "platform data not available\n");
+ return -EINVAL;
+ }
+
+ err = gpio_request(pdata->gpio, "LCD-nRESET");
+ if (err) {
+ dev_err(dev, "gpio [%d] request failed\n", pdata->gpio);
+ return err;
+ }
+
+ lp = devm_kzalloc(dev, sizeof(struct lcd_pwrctrl), GFP_KERNEL);
+ if (!lp) {
+ dev_err(dev, "memory allocation failed for private data\n");
+ return -ENOMEM;You are leaking the gpio here.
+ }
+
+ /*
+ * If power to lcd and/or lcd interface is controlled using a regulator,
+ * get the handle to the regulator for later use during power switching.
+ */
+ lp->regulator = regulator_get(dev, "vcc-lcd");
+ if (IS_ERR(lp->regulator))
+ dev_info(dev, "could not find regulator\n");
+
+ lp->dev = dev;
+ lp->pdata = pdata;
+ lp->lcd = lcd_device_register(dev_name(dev), dev, lp, &lcd_pwrctrl_ops);
+ if (IS_ERR(lp->lcd)) {
+ dev_err(dev, "cannot register lcd device\n");
+ regulator_put(lp->regulator);And here.
+ return PTR_ERR(lp->lcd);
+ }
+
+ platform_set_drvdata(pdev, lp);
+ lcd_pwrctrl_set_power(lp->lcd, FB_BLANK_NORMAL);
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id lcd_pwrctrl_match[] = {
+ { .compatible = "lcd,powerctrl", },
+ {},
+};MODULE_DEVICE_TABLE(...)
+#endif
+static struct platform_driver lcd_pwrctrl_driver = {
+ .driver = {
+ .name = "lcd-pwrctrl",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(lcd_pwrctrl_match),
+ },
+ .probe = lcd_pwrctrl_probe,
+ .remove = lcd_pwrctrl_remove,
+ .suspend = lcd_pwrctrl_suspend,
+ .resume = lcd_pwrctrl_resume,please use dev_pm_ops instead of the legacy callbacks
+};
+
+static int __init lcd_pwrctrl_init(void)
+{
+ return platform_driver_register(&lcd_pwrctrl_driver);
+}
+
+static void __exit lcd_pwrctrl_cleanup(void)
+{
+ platform_driver_unregister(&lcd_pwrctrl_driver);
+}
+
+module_init(lcd_pwrctrl_init);
+module_exit(lcd_pwrctrl_cleanup);module_platform_driver(&lcd_pwrctrl_driver);
+
+MODULE_AUTHOR("Thomas Abraham [off-list ref]");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:lcd-pwrctrl");