jornada720_bl.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *
  4 * Backlight driver for HP Jornada 700 series (710/720/728)
  5 * Copyright (C) 2006-2009 Kristoffer Ericson <kristoffer.ericson@gmail.com>
  6 */
  7
  8#include <linux/backlight.h>
  9#include <linux/device.h>
 10#include <linux/io.h>
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/platform_device.h>
 14
 15#include <mach/jornada720.h>
 16#include <mach/hardware.h>
 17
 18#include <video/s1d13xxxfb.h>
 19
 20#define BL_MAX_BRIGHT	255
 21#define BL_DEF_BRIGHT	25
 22
 23static int jornada_bl_get_brightness(struct backlight_device *bd)
 24{
 25	int ret;
 26
 27	/* check if backlight is on */
 28	if (!(PPSR & PPC_LDD1))
 29		return 0;
 30
 31	jornada_ssp_start();
 32
 33	/* cmd should return txdummy */
 34	ret = jornada_ssp_byte(GETBRIGHTNESS);
 35
 36	if (jornada_ssp_byte(GETBRIGHTNESS) != TXDUMMY) {
 37		dev_err(&bd->dev, "get brightness timeout\n");
 38		jornada_ssp_end();
 39		return -ETIMEDOUT;
 40	}
 41
 42	/* exchange txdummy for value */
 43	ret = jornada_ssp_byte(TXDUMMY);
 44
 45	jornada_ssp_end();
 46
 47	return BL_MAX_BRIGHT - ret;
 48}
 49
 50static int jornada_bl_update_status(struct backlight_device *bd)
 51{
 52	int ret = 0;
 53
 54	jornada_ssp_start();
 55
 56	/* If backlight is off then really turn it off */
 57	if (backlight_is_blank(bd)) {
 58		ret = jornada_ssp_byte(BRIGHTNESSOFF);
 59		if (ret != TXDUMMY) {
 60			dev_info(&bd->dev, "brightness off timeout\n");
 61			/* turn off backlight */
 62			PPSR &= ~PPC_LDD1;
 63			PPDR |= PPC_LDD1;
 64			ret = -ETIMEDOUT;
 65		}
 66	} else  /* turn on backlight */
 67		PPSR |= PPC_LDD1;
 68
 69	/* send command to our mcu */
 70	if (jornada_ssp_byte(SETBRIGHTNESS) != TXDUMMY) {
 71		dev_info(&bd->dev, "failed to set brightness\n");
 72		ret = -ETIMEDOUT;
 73		goto out;
 74	}
 75
 76	/*
 77	 * at this point we expect that the mcu has accepted
 78	 * our command and is waiting for our new value
 79	 * please note that maximum brightness is 255,
 80	 * but due to physical layout it is equal to 0, so we simply
 81	 * invert the value (MAX VALUE - NEW VALUE).
 82	 */
 83	if (jornada_ssp_byte(BL_MAX_BRIGHT - bd->props.brightness)
 84		!= TXDUMMY) {
 85		dev_err(&bd->dev, "set brightness failed\n");
 86		ret = -ETIMEDOUT;
 87	}
 88
 89	/*
 90	 * If infact we get an TXDUMMY as output we are happy and dont
 91	 * make any further comments about it
 92	 */
 93out:
 94	jornada_ssp_end();
 95
 96	return ret;
 97}
 98
 99static const struct backlight_ops jornada_bl_ops = {
100	.get_brightness = jornada_bl_get_brightness,
101	.update_status = jornada_bl_update_status,
102	.options = BL_CORE_SUSPENDRESUME,
103};
104
105static int jornada_bl_probe(struct platform_device *pdev)
106{
107	struct backlight_properties props;
108	int ret;
109	struct backlight_device *bd;
110
111	memset(&props, 0, sizeof(struct backlight_properties));
112	props.type = BACKLIGHT_RAW;
113	props.max_brightness = BL_MAX_BRIGHT;
114
115	bd = devm_backlight_device_register(&pdev->dev, S1D_DEVICENAME,
116					&pdev->dev, NULL, &jornada_bl_ops,
117					&props);
118	if (IS_ERR(bd)) {
119		ret = PTR_ERR(bd);
120		dev_err(&pdev->dev, "failed to register device, err=%x\n", ret);
121		return ret;
122	}
123
124	bd->props.power = BACKLIGHT_POWER_ON;
125	bd->props.brightness = BL_DEF_BRIGHT;
126	/*
127	 * note. make sure max brightness is set otherwise
128	 * you will get seemingly non-related errors when
129	 * trying to change brightness
130	 */
131	jornada_bl_update_status(bd);
132
133	platform_set_drvdata(pdev, bd);
134	dev_info(&pdev->dev, "HP Jornada 700 series backlight driver\n");
135
136	return 0;
137}
138
139static struct platform_driver jornada_bl_driver = {
140	.probe		= jornada_bl_probe,
141	.driver	= {
142		.name	= "jornada_bl",
143	},
144};
145
146module_platform_driver(jornada_bl_driver);
147
148MODULE_AUTHOR("Kristoffer Ericson <kristoffer.ericson>");
149MODULE_DESCRIPTION("HP Jornada 710/720/728 Backlight driver");
150MODULE_LICENSE("GPL");