diff options
Diffstat (limited to 'drivers/video/backlight/pandora_bl.c')
| -rw-r--r-- | drivers/video/backlight/pandora_bl.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/drivers/video/backlight/pandora_bl.c b/drivers/video/backlight/pandora_bl.c new file mode 100644 index 000000000..f946470ce --- /dev/null +++ b/drivers/video/backlight/pandora_bl.c @@ -0,0 +1,162 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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@gmail.com> + */ + +#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/mfd/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) + +struct pandora_private { + unsigned old_state; +#define PANDORABL_WAS_OFF 1 +}; + +static int pandora_backlight_update_status(struct backlight_device *bl) +{ + int brightness = bl->props.brightness; + struct pandora_private *priv = bl_get_data(bl); + 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 (priv->old_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 (priv->old_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(TWL_MODULE_PWM, 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(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF); + +done: + if (brightness != 0) + priv->old_state = 0; + else + priv->old_state = PANDORABL_WAS_OFF; + + return 0; +} + +static const struct backlight_ops pandora_backlight_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = pandora_backlight_update_status, +}; + +static int pandora_backlight_probe(struct platform_device *pdev) +{ + struct backlight_properties props; + struct backlight_device *bl; + struct pandora_private *priv; + u8 r; + + priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) { + dev_err(&pdev->dev, "failed to allocate driver private data\n"); + return -ENOMEM; + } + + memset(&props, 0, sizeof(props)); + props.max_brightness = MAX_USER_VALUE; + props.type = BACKLIGHT_RAW; + bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, + priv, &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(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON); + + priv->old_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 struct platform_driver pandora_backlight_driver = { + .driver = { + .name = "pandora-backlight", + }, + .probe = pandora_backlight_probe, +}; + +module_platform_driver(pandora_backlight_driver); + +MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>"); +MODULE_DESCRIPTION("Pandora Backlight Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:pandora-backlight"); |