This patch adds support for pandora (openpandora.org) backlight.
It might look like all this could be done using pwm_bl.c instead,
but there is a need of special programming sequence when turning
on the LED driver chip or else it will misbehave. Doing this using
pwm_bl.c would require to use some register programming and pwm
functions from platform code, and ARM maintainers are allergic to
driver-like code in /arch/arm nowadays. The PMIC PWM driver is
currently missing too, so pwm_bl.c can't be used anyway.
Signed-off-by: Grazvydas Ignotas <notasas@xxxxxxxxx>
---
changed in v2: fixed a bug where setting brightness to 0 twice
would actually turn the backlight on.
We had this driver in pandora tree for a couple of years now, but
while cleaning it up for mainline submission I've introduced this
bug, sorry for the noise.
drivers/video/backlight/Kconfig | 7 ++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/pandora_bl.c | 171 ++++++++++++++++++++++++++++++++++
3 files changed, 179 insertions(+), 0 deletions(-)
create mode 100644 drivers/video/backlight/pandora_bl.c
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 681b369..3f03954 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -334,6 +334,13 @@ config BACKLIGHT_AAT2870
If you have a AnalogicTech AAT2870 say Y to enable the
backlight driver.
+config BACKLIGHT_PANDORA
+ tristate "Backlight driver for Pandora console"
+ depends on TWL4030_CORE
+ help
+ If you have a Pandora console, say Y to enable the
+ backlight driver.
+
endif # BACKLIGHT_CLASS_DEVICE
endif # BACKLIGHT_LCD_SUPPORT
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index af5cf65..c73169c 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -38,4 +38,5 @@ obj-$(CONFIG_BACKLIGHT_ADP8870) += adp8870_bl.o
obj-$(CONFIG_BACKLIGHT_88PM860X) += 88pm860x_bl.o
obj-$(CONFIG_BACKLIGHT_PCF50633) += pcf50633-backlight.o
obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_bl.o
+obj-$(CONFIG_BACKLIGHT_PANDORA) += pandora_bl.o
diff --git a/drivers/video/backlight/pandora_bl.c b/drivers/video/backlight/pandora_bl.c
new file mode 100644
index 0000000..4ec3074
--- /dev/null
+++ b/drivers/video/backlight/pandora_bl.c
@@ -0,0 +1,171 @@
+/*
+ * Backlight driver for Pandora handheld.
+ * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
+ * Based on pwm_bl.c
+ *
+ * Copyright 2009,2012 Gražvydas Ignotas <notasas@xxxxxxxxx>
+ *
+ * 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/platform_device.h>
+#include <linux/delay.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
+#include <linux/i2c/twl.h>
+#include <linux/err.h>
+
+#define TWL_PWM0_ON 0x00
+#define TWL_PWM0_OFF 0x01
+
+#define TWL_INTBR_GPBR1 0x0c
+#define TWL_INTBR_PMBR1 0x0d
+
+#define TWL_PMBR1_PWM0_MUXMASK 0x0c
+#define TWL_PMBR1_PWM0 0x04
+#define PWM0_CLK_ENABLE BIT(0)
+#define PWM0_ENABLE BIT(2)
+
+/* range accepted by hardware */
+#define MIN_VALUE 9
+#define MAX_VALUE 63
+#define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
+
+#define PANDORABL_WAS_OFF BL_CORE_DRIVER1
+
+static int pandora_backlight_update_status(struct backlight_device *bl)
+{
+ int brightness = bl->props.brightness;
+ u8 r;
+
+ if (bl->props.power != FB_BLANK_UNBLANK)
+ brightness = 0;
+ if (bl->props.state & BL_CORE_FBBLANK)
+ brightness = 0;
+ if (bl->props.state & BL_CORE_SUSPENDED)
+ brightness = 0;
+
+ if ((unsigned int)brightness > MAX_USER_VALUE)
+ brightness = MAX_USER_VALUE;
+
+ if (brightness == 0) {
+ if (bl->props.state & PANDORABL_WAS_OFF)
+ goto done;
+
+ /* first disable PWM0 output, then clock */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_CLK_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+
+ goto done;
+ }
+
+ if (bl->props.state & PANDORABL_WAS_OFF) {
+ /*
+ * set PWM duty cycle to max. TPS61161 seems to use this
+ * to calibrate it's PWM sensitivity when it starts.
+ */
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, MAX_VALUE,
+ TWL_PWM0_OFF);
+
+ /* first enable clock, then PWM0 out */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
+ r &= ~PWM0_ENABLE;
+ r |= PWM0_CLK_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+ r |= PWM0_ENABLE;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
+
+ /*
+ * TI made it very easy to enable digital control, so easy that
+ * it often triggers unintentionally and disabes PWM control,
+ * so wait until 1 wire mode detection window ends.
+ */
+ usleep_range(2000, 10000);
+ }
+
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, MIN_VALUE + brightness,
+ TWL_PWM0_OFF);
+
+done:
+ if (brightness != 0)
+ bl->props.state &= ~PANDORABL_WAS_OFF;
+ else
+ bl->props.state |= PANDORABL_WAS_OFF;
+
+ return 0;
+}
+
+static int pandora_backlight_get_brightness(struct backlight_device *bl)
+{
+ return bl->props.brightness;
+}
+
+static const struct backlight_ops pandora_backlight_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = pandora_backlight_update_status,
+ .get_brightness = pandora_backlight_get_brightness,
+};
+
+static int pandora_backlight_probe(struct platform_device *pdev)
+{
+ struct backlight_properties props;
+ struct backlight_device *bl;
+ u8 r;
+
+ memset(&props, 0, sizeof(props));
+ props.max_brightness = MAX_USER_VALUE;
+ props.type = BACKLIGHT_RAW;
+ bl = backlight_device_register(pdev->name, &pdev->dev,
+ NULL, &pandora_backlight_ops, &props);
+ if (IS_ERR(bl)) {
+ dev_err(&pdev->dev, "failed to register backlight\n");
+ return PTR_ERR(bl);
+ }
+
+ platform_set_drvdata(pdev, bl);
+
+ /* 64 cycle period, ON position 0 */
+ twl_i2c_write_u8(TWL4030_MODULE_PWM0, 0x80, TWL_PWM0_ON);
+
+ bl->props.state |= PANDORABL_WAS_OFF;
+ bl->props.brightness = MAX_USER_VALUE;
+ backlight_update_status(bl);
+
+ /* enable PWM function in pin mux */
+ twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
+ r &= ~TWL_PMBR1_PWM0_MUXMASK;
+ r |= TWL_PMBR1_PWM0;
+ twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
+
+ return 0;
+}
+
+static int pandora_backlight_remove(struct platform_device *pdev)
+{
+ struct backlight_device *bl = platform_get_drvdata(pdev);
+ backlight_device_unregister(bl);
+ return 0;
+}
+
+static struct platform_driver pandora_backlight_driver = {
+ .driver = {
+ .name = "pandora-backlight",
+ .owner = THIS_MODULE,
+ },
+ .probe = pandora_backlight_probe,
+ .remove = pandora_backlight_remove,
+};
+
+module_platform_driver(pandora_backlight_driver);
+
+MODULE_AUTHOR("Gražvydas Ignotas <notasas@xxxxxxxxx>");
+MODULE_DESCRIPTION("Pandora Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pandora-backlight");
--
1.7.0.4
--
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