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From:   Stefan Mavrodiev <stefan@olimex.com>
To:     Stefan Mavrodiev <stefan@olimex.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        dri-devel@lists.freedesktop.org (open list:DRM PANEL DRIVERS),
        devicetree@vger.kernel.org (open list:OPEN FIRMWARE AND FLATTENED
        DEVICE TREE BINDINGS), linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3 1/1] drm/panel: Add support for Olimex LCD-OLinuXino panel
Date:   Thu, 12 Jul 2018 11:21:53 +0300
Message-Id: <1531383729-13932-1-git-send-email-stefan@olimex.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch adds Olimex Ltd. LCD-OLinuXino bridge panel driver. The
panel is used with different LCDs (currently from 480x272 to 1280x800).
Small EEPROM chip is used for identification, which holds some
factory data and timing requirements.

Signed-off-by: Stefan Mavrodiev <stefan@olimex.com>
---
Changes for v3:
  - Change module license from "GPL v2" to "GPL"
  - Make use of backlight_enable()/backlight_disable() helpers
  - Rework backlight device request
  - Remove drm_panel_detach()
  - Use module_i2c_driver() for initialization
  - Make the first mode preferred
  - If num_modes value is invalid, overwrite it with 4, which is the maximum
  - Some variable types optimizations

Changes for v2:
  - Changed lcd_olinuxino_funcs to static const

 .../display/panel/olimex,lcd-olinuxino.txt         |  42 +++
 MAINTAINERS                                        |   6 +
 drivers/gpu/drm/panel/Kconfig                      |  10 +
 drivers/gpu/drm/panel/Makefile                     |   1 +
 drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c | 331 +++++++++++++++++++++
 5 files changed, 390 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/panel/olimex,lcd-olinuxino.txt
 create mode 100644 drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c

diff --git a/Documentation/devicetree/bindings/display/panel/olimex,lcd-olinuxino.txt b/Documentation/devicetree/bindings/display/panel/olimex,lcd-olinuxino.txt
new file mode 100644
index 0000000..a89f9c8
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/panel/olimex,lcd-olinuxino.txt
@@ -0,0 +1,42 @@
+Binding for Olimex Ltd. LCD-OLinuXino bridge panel.
+
+This device can be used as bridge between a host controller and LCD panels.
+Currently supported LCDs are:
+  - LCD-OLinuXino-4.3TS
+  - LCD-OLinuXino-5
+  - LCD-OLinuXino-7
+  - LCD-OLinuXino-10
+
+The panel itself contains:
+  - AT24C16C EEPROM holding panel identification and timing requirements
+  - AR1021 resistive touch screen controller (optional)
+  - FT5x6 capacitive touch screnn controller (optional)
+  - GT911/GT928 capacitive touch screen controller (optional)
+
+The above chips share same I2C bus. The EEPROM is factory preprogrammed with
+device information (id, serial, etc.) and timing requirements.
+
+Touchscreen bingings can be found in these files:
+  - input/touchscreen/goodix.txt
+  - input/touchscreen/edt-ft5x06.txt
+  - input/touchscreen/ar1021.txt
+
+Required properties:
+  - compatible: should be "olimex,lcd-olinuxino"
+  - reg: address of the configuration EEPROM, should be <0x50>
+  - power-supply: phandle of the regulator that provides the supply voltage
+
+Optional properties:
+  - enable-gpios: GPIO pin to enable or disable the panel
+  - backlight: phandle of the backlight device attacked to the panel
+
+Example:
+&i2c2 {
+	panel@50 {
+		compatible = "olimex,lcd-olinuxino";
+		reg = <0x50>;
+		power-supply = <&reg_vcc5v0>;
+		enable-gpios = <&pio 7 8 GPIO_ACTIVE_HIGH>;
+		backlight = <&backlight>;
+	};
+};
diff --git a/MAINTAINERS b/MAINTAINERS
index 624c3fd..30343f1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4557,6 +4557,12 @@ S:	Supported
 F:	drivers/gpu/drm/nouveau/
 F:	include/uapi/drm/nouveau_drm.h
 
+DRM DRIVER FOR OLIMEX LCD-OLINUXINO PANELS
+M:	Stefan Mavrodiev <stefan@olimex.com>
+S:	Maintained
+F:	drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c
+F:	Documentation/devicetree/bindings/display/panel/olimex,lcd-olinuxino.txt
+
 DRM DRIVER FOR PERVASIVE DISPLAYS REPAPER PANELS
 M:	Noralf Trønnes <noralf@tronnes.org>
 S:	Maintained
diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
index 25682ff..0292994 100644
--- a/drivers/gpu/drm/panel/Kconfig
+++ b/drivers/gpu/drm/panel/Kconfig
@@ -81,6 +81,16 @@ config DRM_PANEL_LG_LG4573
 	  Say Y here if you want to enable support for LG4573 RGB panel.
 	  To compile this driver as a module, choose M here.
 
+config DRM_PANEL_OLIMEX_LCD_OLINUXINO
+	tristate "Olimex LCD-OLinuXino panel"
+	depends on OF
+	depends on I2C
+	depends on BACKLIGHT_CLASS_DEVICE
+	help
+	  Say Y here if you want to enable support for Olimex Ltd.
+	  LCD-OLinuXino panel. The panel is used with different sizes LCDs,
+	  from 480x272 to 1280x800, and 24 bit per pixel.
+
 config DRM_PANEL_ORISETECH_OTM8009A
 	tristate "Orise Technology otm8009a 480x800 dsi 2dl panel"
 	depends on OF
diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
index f26efc1..185027f 100644
--- a/drivers/gpu/drm/panel/Makefile
+++ b/drivers/gpu/drm/panel/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_DRM_PANEL_ILITEK_IL9322) += panel-ilitek-ili9322.o
 obj-$(CONFIG_DRM_PANEL_INNOLUX_P079ZCA) += panel-innolux-p079zca.o
 obj-$(CONFIG_DRM_PANEL_JDI_LT070ME05000) += panel-jdi-lt070me05000.o
 obj-$(CONFIG_DRM_PANEL_LG_LG4573) += panel-lg-lg4573.o
+obj-$(CONFIG_DRM_PANEL_OLIMEX_LCD_OLINUXINO) += panel-olimex-lcd-olinuxino.o
 obj-$(CONFIG_DRM_PANEL_ORISETECH_OTM8009A) += panel-orisetech-otm8009a.o
 obj-$(CONFIG_DRM_PANEL_PANASONIC_VVX10F034N00) += panel-panasonic-vvx10f034n00.o
 obj-$(CONFIG_DRM_PANEL_RASPBERRYPI_TOUCHSCREEN) += panel-raspberrypi-touchscreen.o
diff --git a/drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c b/drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c
new file mode 100644
index 0000000..16b27a4
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-olimex-lcd-olinuxino.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * LCD-OLinuXino support for panel driver
+ *
+ * Copyright (C) 2018 Olimex Ltd.
+ *   Author: Stefan Mavrodiev <stefan@olimex.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/crc32.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drmP.h>
+
+#include <video/videomode.h>
+#include <video/display_timing.h>
+
+
+#define LCD_OLINUXINO_HEADER_MAGIC	0x4F4CB727
+#define LCD_OLINUXINO_DATA_LEN		256
+
+struct lcd_olinuxino_mode {
+	u32 pixelclock;
+	u32 hactive;
+	u32 hfp;
+	u32 hbp;
+	u32 hpw;
+	u32 vactive;
+	u32 vfp;
+	u32 vbp;
+	u32 vpw;
+	u32 refresh;
+	u32 flags;
+};
+
+struct lcd_olinuxino_info {
+	char name[32];
+	u32 width_mm;
+	u32 height_mm;
+	u32 bpc;
+	u32 bus_format;
+	u32 bus_flag;
+} __attribute__((__packed__));
+
+struct lcd_olinuxino_eeprom {
+	u32 header;
+	u32 id;
+	char revision[4];
+	u32 serial;
+	struct lcd_olinuxino_info info;
+	u32 num_modes;
+	u8 reserved[180];
+	u32 checksum;
+} __attribute__((__packed__));
+
+struct lcd_olinuxino {
+	struct drm_panel panel;
+	struct device *dev;
+	struct i2c_client *client;
+	struct mutex mutex;
+
+	bool prepared;
+	bool enabled;
+
+	struct backlight_device *backlight;
+	struct regulator *supply;
+	struct gpio_desc *enable_gpio;
+
+	struct lcd_olinuxino_eeprom eeprom;
+};
+
+static inline struct lcd_olinuxino *to_lcd_olinuxino(struct drm_panel *panel)
+{
+	return container_of(panel, struct lcd_olinuxino, panel);
+}
+
+static int lcd_olinuxino_disable(struct drm_panel *panel)
+{
+	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
+
+	if (!lcd->enabled)
+		return 0;
+
+	backlight_disable(lcd->backlight);
+
+	lcd->enabled = false;
+
+	return 0;
+}
+
+static int lcd_olinuxino_unprepare(struct drm_panel *panel)
+{
+	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
+
+	if (!lcd->prepared)
+		return 0;
+
+	gpiod_set_value_cansleep(lcd->enable_gpio, 0);
+	regulator_disable(lcd->supply);
+
+	lcd->prepared = false;
+
+	return 0;
+}
+
+static int lcd_olinuxino_prepare(struct drm_panel *panel)
+{
+	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
+	int ret;
+
+	if (lcd->prepared)
+		return 0;
+
+	ret = regulator_enable(lcd->supply);
+	if (ret < 0)
+		return ret;
+
+	gpiod_set_value_cansleep(lcd->enable_gpio, 1);
+	lcd->prepared = true;
+
+	return 0;
+}
+
+static int lcd_olinuxino_enable(struct drm_panel *panel)
+{
+	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
+
+	if (lcd->enabled)
+		return 0;
+
+	backlight_enable(lcd->backlight);
+
+	lcd->enabled = true;
+
+	return 0;
+}
+
+static int lcd_olinuxino_get_modes(struct drm_panel *panel)
+{
+	struct lcd_olinuxino *lcd = to_lcd_olinuxino(panel);
+	struct drm_connector *connector = lcd->panel.connector;
+	struct lcd_olinuxino_info *lcd_info = &lcd->eeprom.info;
+	struct drm_device *drm = lcd->panel.drm;
+	struct lcd_olinuxino_mode *lcd_mode;
+	struct drm_display_mode *mode;
+	u32 i, num = 0;
+
+	for (i = 0; i < lcd->eeprom.num_modes; i++) {
+		lcd_mode = (struct lcd_olinuxino_mode *)
+			   &lcd->eeprom.reserved[i * sizeof(*lcd_mode)];
+
+		mode = drm_mode_create(drm);
+		if (!mode) {
+			dev_err(drm->dev, "failed to add mode %ux%u@%u\n",
+				lcd_mode->hactive,
+				lcd_mode->vactive,
+				lcd_mode->refresh);
+				continue;
+		}
+
+		mode->clock = lcd_mode->pixelclock;
+		mode->hdisplay = lcd_mode->hactive;
+		mode->hsync_start = lcd_mode->hactive + lcd_mode->hfp;
+		mode->hsync_end = lcd_mode->hactive + lcd_mode->hfp +
+				  lcd_mode->hpw;
+		mode->htotal = lcd_mode->hactive + lcd_mode->hfp +
+			       lcd_mode->hpw + lcd_mode->hbp;
+		mode->vdisplay = lcd_mode->vactive;
+		mode->vsync_start = lcd_mode->vactive + lcd_mode->vfp;
+		mode->vsync_end = lcd_mode->vactive + lcd_mode->vfp +
+				  lcd_mode->vpw;
+		mode->vtotal = lcd_mode->vactive + lcd_mode->vfp +
+			       lcd_mode->vpw + lcd_mode->vbp;
+		mode->vrefresh = lcd_mode->refresh;
+
+		/* Always make the first mode preferred */
+		if (i == 0)
+			mode->type |= DRM_MODE_TYPE_PREFERRED;
+		mode->type |= DRM_MODE_TYPE_DRIVER;
+
+		drm_mode_set_name(mode);
+		drm_mode_probed_add(connector, mode);
+
+		num++;
+	}
+
+	memcpy(connector->display_info.name, lcd_info->name, 32);
+	connector->display_info.width_mm = lcd_info->width_mm;
+	connector->display_info.height_mm = lcd_info->height_mm;
+	connector->display_info.bpc = lcd_info->bpc;
+
+	if (lcd_info->bus_format)
+		drm_display_info_set_bus_formats(&connector->display_info,
+						 &lcd_info->bus_format, 1);
+	connector->display_info.bus_flags = lcd_info->bus_flag;
+
+	return num;
+}
+
+static const struct drm_panel_funcs lcd_olinuxino_funcs = {
+	.disable = lcd_olinuxino_disable,
+	.unprepare = lcd_olinuxino_unprepare,
+	.prepare = lcd_olinuxino_prepare,
+	.enable = lcd_olinuxino_enable,
+	.get_modes = lcd_olinuxino_get_modes,
+};
+
+static int lcd_olinuxino_probe(struct i2c_client *client,
+			       const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct lcd_olinuxino *lcd;
+	u32 checksum, i;
+	int ret = 0;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+				     I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+		return -ENODEV;
+
+	lcd = devm_kzalloc(dev, sizeof(*lcd), GFP_KERNEL);
+	if (!lcd)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, lcd);
+	lcd->dev = dev;
+	lcd->client = client;
+
+	mutex_init(&lcd->mutex);
+
+	/* Copy data into buffer */
+	for (i = 0; i < LCD_OLINUXINO_DATA_LEN; i += I2C_SMBUS_BLOCK_MAX) {
+		mutex_lock(&lcd->mutex);
+		ret = i2c_smbus_read_i2c_block_data(client,
+						    i,
+						    I2C_SMBUS_BLOCK_MAX,
+						    (u8 *)&lcd->eeprom + i);
+		mutex_unlock(&lcd->mutex);
+		if (ret < 0) {
+			dev_err(dev, "error reading from device at %02x\n", i);
+			return ret;
+		}
+	}
+
+	/* Check configuration checksum */
+	checksum = ~crc32(~0, (u8 *)&lcd->eeprom, 252);
+	if (checksum != lcd->eeprom.checksum) {
+		dev_err(dev, "configuration checksum does not match!\n");
+		return -EINVAL;
+	}
+
+	/* Check magic header */
+	if (lcd->eeprom.header != LCD_OLINUXINO_HEADER_MAGIC) {
+		dev_err(dev, "magic header does not match\n");
+		return -EINVAL;
+	}
+
+	dev_info(dev, "Detected %s, Rev. %s, Serial: %08x\n",
+		 lcd->eeprom.info.name,
+		 lcd->eeprom.revision,
+		 lcd->eeprom.serial);
+
+	/*
+	 * The eeprom can hold up to 4 modes.
+	 * If the stored value is bigger, overwrite it.
+	 */
+	if (lcd->eeprom.num_modes > 4) {
+		dev_warn(dev, "invalid number of modes, falling back to 4\n");
+		lcd->eeprom.num_modes = 4;
+	}
+
+	lcd->enabled = false;
+	lcd->prepared = false;
+
+	lcd->supply = devm_regulator_get(dev, "power");
+	if (IS_ERR(lcd->supply))
+		return PTR_ERR(lcd->supply);
+
+	lcd->enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(lcd->enable_gpio))
+		return PTR_ERR(lcd->enable_gpio);
+
+	lcd->backlight = devm_of_find_backlight(dev);
+	if (IS_ERR(lcd->backlight))
+		return PTR_ERR(lcd->backlight);
+
+	drm_panel_init(&lcd->panel);
+	lcd->panel.dev = dev;
+	lcd->panel.funcs = &lcd_olinuxino_funcs;
+
+	return drm_panel_add(&lcd->panel);
+}
+
+static int lcd_olinuxino_remove(struct i2c_client *client)
+{
+	struct lcd_olinuxino *panel = i2c_get_clientdata(client);
+
+	drm_panel_remove(&panel->panel);
+
+	lcd_olinuxino_disable(&panel->panel);
+	lcd_olinuxino_unprepare(&panel->panel);
+
+	return 0;
+}
+
+static const struct of_device_id lcd_olinuxino_of_ids[] = {
+	{ .compatible = "olimex,lcd-olinuxino" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, lcd_olinuxino_of_ids);
+
+static struct i2c_driver lcd_olinuxino_driver = {
+	.driver = {
+		.name = "lcd_olinuxino",
+		.of_match_table = lcd_olinuxino_of_ids,
+	},
+	.probe = lcd_olinuxino_probe,
+	.remove = lcd_olinuxino_remove,
+};
+
+module_i2c_driver(lcd_olinuxino_driver);
+
+MODULE_AUTHOR("Stefan Mavrodiev <stefan@olimex.com>");
+MODULE_DESCRIPTION("LCD-OLinuXino driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4