video: tegra: Add PWM backlight driver

bug 773671

Original-Change-Id: Ib93f0dcb7e22220fe297c81d403c401548f3c649
Reviewed-on: http://git-master/r/18280
Tested-by: Joseph Lehrer <jlehrer@nvidia.com>
Reviewed-by: Thomas Cherry <tcherry@nvidia.com>
Reviewed-by: Jonathan Mayo <jmayo@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
Reviewed-by: Daniel Willemsen <dwillemsen@nvidia.com>

Rebase-Id: R3ddd56d2d3df9d9a78b2e8ccbfd0cd64e824ab2f

3 files changed, 165 insertions, 0 deletions

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 278aeaa92505..ddbe7837aff1 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -238,6 +238,15 @@ config BACKLIGHT_PWM
 	  If you have a LCD backlight adjustable by PWM, say Y to enable
 	  this driver.
 
+config BACKLIGHT_TEGRA_PWM
+	bool "Tegra2 PMx based PWM Backlight Driver"
+	depends on ARCH_TEGRA_2x_SOC && TEGRA_DC
+	help
+	  Enable support for Tegra2 DC pwm backlight.
+
+	  If you have a pwm backlight adjustable by the DC PM0 or PM1 signal
+	  control on tegra2, say Y to enable this driver.
+
 config BACKLIGHT_DA903X
 	tristate "Backlight Driver for DA9030/DA9034 using WLED"
 	depends on PMIC_DA903X
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index fdd1fc4b2770..debd41c9313e 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o
 obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o
 obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o
 obj-$(CONFIG_BACKLIGHT_PWM)	+= pwm_bl.o
+obj-$(CONFIG_BACKLIGHT_TEGRA_PWM) += tegra_pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_DA903X)	+= da903x_bl.o
 obj-$(CONFIG_BACKLIGHT_MAX8925)	+= max8925_bl.o
 obj-$(CONFIG_BACKLIGHT_APPLE)	+= apple_bl.o
diff --git a/drivers/video/backlight/tegra_pwm_bl.c b/drivers/video/backlight/tegra_pwm_bl.c
new file mode 100644
index 000000000000..4c823b5a08e8
--- /dev/null
+++ b/drivers/video/backlight/tegra_pwm_bl.c
@@ -0,0 +1,155 @@
+/*
+ * linux/drivers/video/backlight/tegra_pwm_bl.c
+ *
+ * Tegra pwm backlight driver
+ *
+ * Copyright (C) 2011 NVIDIA Corporation
+ * Author: Renuka Apte <rapte@nvidia.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/tegra_pwm_bl.h>
+#include <mach/dc.h>
+
+struct tegra_pwm_bl_data {
+	struct device *dev;
+	int which_dc;
+	struct tegra_dc_pwm_params params;
+};
+
+static int tegra_pwm_backlight_update_status(struct backlight_device *bl)
+{
+	struct tegra_pwm_bl_data *tbl = dev_get_drvdata(&bl->dev);
+	int brightness = bl->props.brightness;
+	int max = bl->props.max_brightness;
+	struct tegra_dc *dc;
+
+	if (bl->props.power != FB_BLANK_UNBLANK)
+		brightness = 0;
+
+	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
+		brightness = 0;
+
+	if (brightness > max)
+		dev_err(&bl->dev, "Invalid brightness value: %d max: %d\n",
+		brightness, max);
+
+	/* map API brightness range from (0~255) to hw range (0~128) */
+	tbl->params.duty_cycle = (brightness * 128) / 255;
+
+	/* Call tegra display controller function to update backlight */
+	dc = tegra_dc_get_dc(tbl->which_dc);
+	if (dc)
+		tegra_dc_config_pwm(dc, &tbl->params);
+	else
+		dev_err(&bl->dev, "tegra display controller not available\n");
+
+	return 0;
+}
+
+static int tegra_pwm_backlight_get_brightness(struct backlight_device *bl)
+{
+	return bl->props.brightness;
+}
+
+static const struct backlight_ops tegra_pwm_backlight_ops = {
+	.update_status	= tegra_pwm_backlight_update_status,
+	.get_brightness	= tegra_pwm_backlight_get_brightness,
+};
+
+static int tegra_pwm_backlight_probe(struct platform_device *pdev)
+{
+	struct backlight_properties props;
+	struct platform_tegra_pwm_backlight_data *data;
+	struct backlight_device *bl;
+	struct tegra_pwm_bl_data *tbl;
+	int ret;
+
+	data = pdev->dev.platform_data;
+	if (!data) {
+		dev_err(&pdev->dev, "failed to find platform data\n");
+		return -EINVAL;
+	}
+
+	tbl = kzalloc(sizeof(*tbl), GFP_KERNEL);
+	if (!tbl) {
+		dev_err(&pdev->dev, "no memory for state\n");
+		ret = -ENOMEM;
+		goto err_alloc;
+	}
+
+	tbl->dev = &pdev->dev;
+	tbl->which_dc = data->which_dc;
+	tbl->params.which_pwm = data->which_pwm;
+	tbl->params.period = data->period;
+	tbl->params.clk_div = data->clk_div;
+	tbl->params.clk_select = data->clk_select;
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.max_brightness = data->max_brightness;
+	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, tbl,
+			&tegra_pwm_backlight_ops, &props);
+	if (IS_ERR(bl)) {
+		dev_err(&pdev->dev, "failed to register backlight\n");
+		ret = PTR_ERR(bl);
+		goto err_bl;
+	}
+
+	bl->props.brightness = data->dft_brightness;
+	backlight_update_status(bl);
+
+	platform_set_drvdata(pdev, bl);
+	return 0;
+
+err_bl:
+	kfree(tbl);
+err_alloc:
+	return ret;
+}
+
+static int tegra_pwm_backlight_remove(struct platform_device *pdev)
+{
+	struct backlight_device *bl = platform_get_drvdata(pdev);
+	struct tegra_pwm_bl_data *tbl = dev_get_drvdata(&bl->dev);
+
+	backlight_device_unregister(bl);
+	kfree(tbl);
+	return 0;
+}
+
+static struct platform_driver tegra_pwm_backlight_driver = {
+	.driver		= {
+		.name	= "tegra-pwm-bl",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= tegra_pwm_backlight_probe,
+	.remove		= tegra_pwm_backlight_remove,
+};
+
+static int __init tegra_pwm_backlight_init(void)
+{
+	return platform_driver_register(&tegra_pwm_backlight_driver);
+}
+module_init(tegra_pwm_backlight_init);
+
+static void __exit tegra_pwm_backlight_exit(void)
+{
+	platform_driver_unregister(&tegra_pwm_backlight_driver);
+}
+module_exit(tegra_pwm_backlight_exit);
+
+MODULE_DESCRIPTION("Tegra PWM Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:tegra-pwm-backlight");
+