drm/panel: Add simple panel support

Add a driver for simple panels. Such panels can have a regulator that
provides the supply voltage and a separate GPIO to enable the panel.
Optionally the panels can have a backlight associated with them so it
can be enabled or disabled according to the panel's power management
mode.

Support is added for two panels: An AU Optronics 10.1" WSVGA and a
Chunghwa Picture Tubes 10.1" WXGA panel.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/Makefile

@@ -61,3 +61,4 @@ obj-$(CONFIG_DRM_QXL) += qxl/
 obj-$(CONFIG_DRM_MSM) += msm/
 obj-$(CONFIG_DRM_TEGRA) += tegra/
 obj-y			+= i2c/
+obj-y			+= panel/

drivers/gpu/drm/panel/Kconfig

@@ -3,3 +3,17 @@ config DRM_PANEL
 	depends on DRM
 	help
 	  Panel registration and lookup framework.
+
+menu "Display Panels"
+	depends on DRM_PANEL
+
+config DRM_PANEL_SIMPLE
+	tristate "support for simple panels"
+	depends on OF
+	help
+	  DRM panel driver for dumb panels that need at most a regulator and
+	  a GPIO to be powered up. Optionally a backlight can be attached so
+	  that it can be automatically turned off when the panel goes into a
+	  low power state.
+
+endmenu

drivers/gpu/drm/panel/Makefile

+obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o

drivers/gpu/drm/panel/panel-simple.c

+/*
+ * Copyright (C) 2013, NVIDIA Corporation.  All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_panel.h>
+
+struct panel_desc {
+	const struct drm_display_mode *modes;
+	unsigned int num_modes;
+
+	struct {
+		unsigned int width;
+		unsigned int height;
+	} size;
+};
+
+/* TODO: convert to gpiod_*() API once it's been merged */
+#define GPIO_ACTIVE_LOW	(1 << 0)
+
+struct panel_simple {
+	struct drm_panel base;
+	bool enabled;
+
+	const struct panel_desc *desc;
+
+	struct backlight_device *backlight;
+	struct regulator *supply;
+	struct i2c_adapter *ddc;
+
+	unsigned long enable_gpio_flags;
+	int enable_gpio;
+};
+
+static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
+{
+	return container_of(panel, struct panel_simple, base);
+}
+
+static int panel_simple_get_fixed_modes(struct panel_simple *panel)
+{
+	struct drm_connector *connector = panel->base.connector;
+	struct drm_device *drm = panel->base.drm;
+	struct drm_display_mode *mode;
+	unsigned int i, num = 0;
+
+	if (!panel->desc)
+		return 0;
+
+	for (i = 0; i < panel->desc->num_modes; i++) {
+		const struct drm_display_mode *m = &panel->desc->modes[i];
+
+		mode = drm_mode_duplicate(drm, m);
+		if (!mode) {
+			dev_err(drm->dev, "failed to add mode %ux%u@%u\n",
+				m->hdisplay, m->vdisplay, m->vrefresh);
+			continue;
+		}
+
+		drm_mode_set_name(mode);
+
+		drm_mode_probed_add(connector, mode);
+		num++;
+	}
+
+	connector->display_info.width_mm = panel->desc->size.width;
+	connector->display_info.height_mm = panel->desc->size.height;
+
+	return num;
+}
+
+static int panel_simple_disable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+
+	if (!p->enabled)
+		return 0;
+
+	if (p->backlight) {
+		p->backlight->props.power = FB_BLANK_POWERDOWN;
+		backlight_update_status(p->backlight);
+	}
+
+	if (gpio_is_valid(p->enable_gpio)) {
+		if (p->enable_gpio_flags & GPIO_ACTIVE_LOW)
+			gpio_set_value(p->enable_gpio, 1);
+		else
+			gpio_set_value(p->enable_gpio, 0);
+	}
+
+	regulator_disable(p->supply);
+	p->enabled = false;
+
+	return 0;
+}
+
+static int panel_simple_enable(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int err;
+
+	if (p->enabled)
+		return 0;
+
+	err = regulator_enable(p->supply);
+	if (err < 0) {
+		dev_err(panel->dev, "failed to enable supply: %d\n", err);
+		return err;
+	}
+
+	if (gpio_is_valid(p->enable_gpio)) {
+		if (p->enable_gpio_flags & GPIO_ACTIVE_LOW)
+			gpio_set_value(p->enable_gpio, 0);
+		else
+			gpio_set_value(p->enable_gpio, 1);
+	}
+
+	if (p->backlight) {
+		p->backlight->props.power = FB_BLANK_UNBLANK;
+		backlight_update_status(p->backlight);
+	}
+
+	p->enabled = true;
+
+	return 0;
+}
+
+static int panel_simple_get_modes(struct drm_panel *panel)
+{
+	struct panel_simple *p = to_panel_simple(panel);
+	int num = 0;
+
+	/* probe EDID if a DDC bus is available */
+	if (p->ddc) {
+		struct edid *edid = drm_get_edid(panel->connector, p->ddc);
+		if (edid) {
+			num += drm_add_edid_modes(panel->connector, edid);
+			kfree(edid);
+		}
+	}
+
+	/* add hard-coded panel modes */
+	num += panel_simple_get_fixed_modes(p);
+
+	return num;
+}
+
+static const struct drm_panel_funcs panel_simple_funcs = {
+	.disable = panel_simple_disable,
+	.enable = panel_simple_enable,
+	.get_modes = panel_simple_get_modes,
+};
+
+static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
+{
+	struct device_node *backlight, *ddc;
+	struct panel_simple *panel;
+	enum of_gpio_flags flags;
+	int err;
+
+	panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
+	if (!panel)
+		return -ENOMEM;
+
+	panel->enabled = false;
+	panel->desc = desc;
+
+	panel->supply = devm_regulator_get(dev, "power");
+	if (IS_ERR(panel->supply))
+		return PTR_ERR(panel->supply);
+
+	panel->enable_gpio = of_get_named_gpio_flags(dev->of_node,
+						     "enable-gpios", 0,
+						     &flags);
+	if (gpio_is_valid(panel->enable_gpio)) {
+		unsigned int value;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			panel->enable_gpio_flags |= GPIO_ACTIVE_LOW;
+
+		err = gpio_request(panel->enable_gpio, "enable");
+		if (err < 0) {
+			dev_err(dev, "failed to request GPIO#%u: %d\n",
+				panel->enable_gpio, err);
+			return err;
+		}
+
+		value = (panel->enable_gpio_flags & GPIO_ACTIVE_LOW) != 0;
+
+		err = gpio_direction_output(panel->enable_gpio, value);
+		if (err < 0) {
+			dev_err(dev, "failed to setup GPIO%u: %d\n",
+				panel->enable_gpio, err);
+			goto free_gpio;
+		}
+	}
+
+	backlight = of_parse_phandle(dev->of_node, "backlight", 0);
+	if (backlight) {
+		panel->backlight = of_find_backlight_by_node(backlight);
+		of_node_put(backlight);
+
+		if (!panel->backlight) {
+			err = -EPROBE_DEFER;
+			goto free_gpio;
+		}
+	}
+
+	ddc = of_parse_phandle(dev->of_node, "ddc-i2c-bus", 0);
+	if (ddc) {
+		panel->ddc = of_find_i2c_adapter_by_node(ddc);
+		of_node_put(ddc);
+
+		if (!panel->ddc) {
+			err = -EPROBE_DEFER;
+			goto free_backlight;
+		}
+	}
+
+	drm_panel_init(&panel->base);
+	panel->base.dev = dev;
+	panel->base.funcs = &panel_simple_funcs;
+
+	err = drm_panel_add(&panel->base);
+	if (err < 0)
+		goto free_ddc;
+
+	dev_set_drvdata(dev, panel);
+
+	return 0;
+
+free_ddc:
+	if (panel->ddc)
+		put_device(&panel->ddc->dev);
+free_backlight:
+	if (panel->backlight)
+		put_device(&panel->backlight->dev);
+free_gpio:
+	if (gpio_is_valid(panel->enable_gpio))
+		gpio_free(panel->enable_gpio);
+
+	return err;
+}
+
+static int panel_simple_remove(struct device *dev)
+{
+	struct panel_simple *panel = dev_get_drvdata(dev);
+
+	drm_panel_detach(&panel->base);
+	drm_panel_remove(&panel->base);
+
+	panel_simple_disable(&panel->base);
+
+	if (panel->ddc)
+		put_device(&panel->ddc->dev);
+
+	if (panel->backlight)
+		put_device(&panel->backlight->dev);
+
+	if (gpio_is_valid(panel->enable_gpio))
+		gpio_free(panel->enable_gpio);
+
+	regulator_disable(panel->supply);
+
+	return 0;
+}
+
+static const struct drm_display_mode auo_b101aw03_mode = {
+	.clock = 51450,
+	.hdisplay = 1024,
+	.hsync_start = 1024 + 156,
+	.hsync_end = 1024 + 156 + 8,
+	.htotal = 1024 + 156 + 8 + 156,
+	.vdisplay = 600,
+	.vsync_start = 600 + 16,
+	.vsync_end = 600 + 16 + 6,
+	.vtotal = 600 + 16 + 6 + 16,
+	.vrefresh = 60,
+};
+
+static const struct panel_desc auo_b101aw03 = {
+	.modes = &auo_b101aw03_mode,
+	.num_modes = 1,
+	.size = {
+		.width = 223,
+		.height = 125,
+	},
+};
+
+static const struct drm_display_mode chunghwa_claa101wb01_mode = {
+	.clock = 69300,
+	.hdisplay = 1366,
+	.hsync_start = 1366 + 48,
+	.hsync_end = 1366 + 48 + 32,
+	.htotal = 1366 + 48 + 32 + 20,
+	.vdisplay = 768,
+	.vsync_start = 768 + 16,
+	.vsync_end = 768 + 16 + 8,
+	.vtotal = 768 + 16 + 8 + 16,
+	.vrefresh = 60,
+};
+
+static const struct panel_desc chunghwa_claa101wb01 = {
+	.modes = &chunghwa_claa101wb01_mode,
+	.num_modes = 1,
+	.size = {
+		.width = 223,
+		.height = 125,
+	},
+};
+
+static const struct of_device_id platform_of_match[] = {
+	{
+		.compatible = "auo,b101aw03",
+		.data = &auo_b101aw03,
+	}, {
+		.compatible = "chunghwa,claa101wb01",
+		.data = &chunghwa_claa101wb01
+	}, {
+		.compatible = "simple-panel",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, platform_of_match);
+
+static int panel_simple_platform_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *id;
+
+	id = of_match_node(platform_of_match, pdev->dev.of_node);
+	if (!id)
+		return -ENODEV;
+
+	return panel_simple_probe(&pdev->dev, id->data);
+}
+
+static int panel_simple_platform_remove(struct platform_device *pdev)
+{
+	return panel_simple_remove(&pdev->dev);
+}
+
+static struct platform_driver panel_simple_platform_driver = {
+	.driver = {
+		.name = "panel-simple",
+		.owner = THIS_MODULE,
+		.of_match_table = platform_of_match,
+	},
+	.probe = panel_simple_platform_probe,
+	.remove = panel_simple_platform_remove,
+};
+
+static const struct drm_display_mode panasonic_vvx10f004b00_mode = {
+	.clock = 157200,
+	.hdisplay = 1920,
+	.hsync_start = 1920 + 154,
+	.hsync_end = 1920 + 154 + 16,
+	.htotal = 1920 + 154 + 16 + 32,
+	.vdisplay = 1200,
+	.vsync_start = 1200 + 17,
+	.vsync_end = 1200 + 17 + 2,
+	.vtotal = 1200 + 17 + 2 + 16,
+	.vrefresh = 60,
+};
+
+static const struct panel_desc panasonic_vvx10f004b00 = {
+	.modes = &panasonic_vvx10f004b00_mode,
+	.num_modes = 1,
+	.size = {
+		.width = 217,
+		.height = 136,
+	},
+};
+
+static int __init panel_simple_init(void)
+{
+	return platform_driver_register(&panel_simple_platform_driver);
+}
+module_init(panel_simple_init);
+
+static void __exit panel_simple_exit(void)
+{
+	platform_driver_unregister(&panel_simple_platform_driver);
+}
+module_exit(panel_simple_exit);
+
+MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
+MODULE_DESCRIPTION("DRM Driver for Simple Panels");
+MODULE_LICENSE("GPL and additional rights");