video/backlight/pandora_bl.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Backlight driver for Pandora handheld.
0004  * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight.
0005  * Based on pwm_bl.c
0006  *
0007  * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com>
0008  */
0009
0010 #include <linux/module.h>
0011 #include <linux/kernel.h>
0012 #include <linux/platform_device.h>
0013 #include <linux/delay.h>
0014 #include <linux/fb.h>
0015 #include <linux/backlight.h>
0016 #include <linux/mfd/twl.h>
0017 #include <linux/err.h>
0018
0019 #define TWL_PWM0_ON     0x00
0020 #define TWL_PWM0_OFF        0x01
0021
0022 #define TWL_INTBR_GPBR1     0x0c
0023 #define TWL_INTBR_PMBR1     0x0d
0024
0025 #define TWL_PMBR1_PWM0_MUXMASK  0x0c
0026 #define TWL_PMBR1_PWM0      0x04
0027 #define PWM0_CLK_ENABLE     BIT(0)
0028 #define PWM0_ENABLE     BIT(2)
0029
0030 /* range accepted by hardware */
0031 #define MIN_VALUE 9
0032 #define MAX_VALUE 63
0033 #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE)
0034
0035 struct pandora_private {
0036     unsigned old_state;
0037 #define PANDORABL_WAS_OFF 1
0038 };
0039
0040 static int pandora_backlight_update_status(struct backlight_device *bl)
0041 {
0042     int brightness = bl->props.brightness;
0043     struct pandora_private *priv = bl_get_data(bl);
0044     u8 r;
0045
0046     if (bl->props.power != FB_BLANK_UNBLANK)
0047         brightness = 0;
0048     if (bl->props.state & BL_CORE_FBBLANK)
0049         brightness = 0;
0050     if (bl->props.state & BL_CORE_SUSPENDED)
0051         brightness = 0;
0052
0053     if ((unsigned int)brightness > MAX_USER_VALUE)
0054         brightness = MAX_USER_VALUE;
0055
0056     if (brightness == 0) {
0057         if (priv->old_state == PANDORABL_WAS_OFF)
0058             goto done;
0059
0060         /* first disable PWM0 output, then clock */
0061         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
0062         r &= ~PWM0_ENABLE;
0063         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
0064         r &= ~PWM0_CLK_ENABLE;
0065         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
0066
0067         goto done;
0068     }
0069
0070     if (priv->old_state == PANDORABL_WAS_OFF) {
0071         /*
0072          * set PWM duty cycle to max. TPS61161 seems to use this
0073          * to calibrate it's PWM sensitivity when it starts.
0074          */
0075         twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
0076
0077         /* first enable clock, then PWM0 out */
0078         twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
0079         r &= ~PWM0_ENABLE;
0080         r |= PWM0_CLK_ENABLE;
0081         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
0082         r |= PWM0_ENABLE;
0083         twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
0084
0085         /*
0086          * TI made it very easy to enable digital control, so easy that
0087          * it often triggers unintentionally and disabes PWM control,
0088          * so wait until 1 wire mode detection window ends.
0089          */
0090         usleep_range(2000, 10000);
0091     }
0092
0093     twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF);
0094
0095 done:
0096     if (brightness != 0)
0097         priv->old_state = 0;
0098     else
0099         priv->old_state = PANDORABL_WAS_OFF;
0100
0101     return 0;
0102 }
0103
0104 static const struct backlight_ops pandora_backlight_ops = {
0105     .options    = BL_CORE_SUSPENDRESUME,
0106     .update_status  = pandora_backlight_update_status,
0107 };
0108
0109 static int pandora_backlight_probe(struct platform_device *pdev)
0110 {
0111     struct backlight_properties props;
0112     struct backlight_device *bl;
0113     struct pandora_private *priv;
0114     u8 r;
0115
0116     priv = devm_kmalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
0117     if (!priv) {
0118         dev_err(&pdev->dev, "failed to allocate driver private data\n");
0119         return -ENOMEM;
0120     }
0121
0122     memset(&props, 0, sizeof(props));
0123     props.max_brightness = MAX_USER_VALUE;
0124     props.type = BACKLIGHT_RAW;
0125     bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev,
0126                     priv, &pandora_backlight_ops, &props);
0127     if (IS_ERR(bl)) {
0128         dev_err(&pdev->dev, "failed to register backlight\n");
0129         return PTR_ERR(bl);
0130     }
0131
0132     platform_set_drvdata(pdev, bl);
0133
0134     /* 64 cycle period, ON position 0 */
0135     twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON);
0136
0137     priv->old_state = PANDORABL_WAS_OFF;
0138     bl->props.brightness = MAX_USER_VALUE;
0139     backlight_update_status(bl);
0140
0141     /* enable PWM function in pin mux */
0142     twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1);
0143     r &= ~TWL_PMBR1_PWM0_MUXMASK;
0144     r |= TWL_PMBR1_PWM0;
0145     twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1);
0146
0147     return 0;
0148 }
0149
0150 static struct platform_driver pandora_backlight_driver = {
0151     .driver     = {
0152         .name   = "pandora-backlight",
0153     },
0154     .probe      = pandora_backlight_probe,
0155 };
0156
0157 module_platform_driver(pandora_backlight_driver);
0158
0159 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>");
0160 MODULE_DESCRIPTION("Pandora Backlight Driver");
0161 MODULE_LICENSE("GPL");
0162 MODULE_ALIAS("platform:pandora-backlight");