Adding Touchscreen Support [Adding Backlight & 7'' LCD]

board-am335xevm.c

Enable Backlight Support:

File Names changed :  arch/arm/mach-omap2/board-am335xevm.c
                      arch/arm/mach-omap2/mux33xx.c

File Name:  arch/arm/mach-omap2/board-am335xevm.c


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+#include <linux/pwm/pwm.h>
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Adding the PWM header file having declations of files such as 
"struct pwm_device_ops {",  
"struct pwm_config {", 
"struct pwm_device {"
"struct pwm_device *pwm_request_byname(const char *name, const char *label);"

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+/* Setup pwm-backlight for bbtoys7lcd */
+static struct platform_device bbtoys7lcd_backlight = {
+	.name           = "pwm-backlight",
+	.id             = -1,
+	.dev            = {
+		.platform_data  = &bbcape7lcd_backlight_data,
+	}
+};
+
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Adding platform device of type bbtoys7lcd_backlight to beagle bone 
platform with the structure static struct bbtoys7lcd_backlight and 
bbcape7lcd_backlight_data is defined 
in the following file


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+/* eHRPWM is used to enable LCD backlight */
+static int ehrpwm_backlight_enable;
+
+/* LCD backlight platform Data */
+#define AM335X_BACKLIGHT_MAX_BRIGHTNESS        100
+#define AM335X_BACKLIGHT_DEFAULT_BRIGHTNESS    50
+#define AM335X_PWM_PERIOD_NANO_SECONDS        (1000000 * 5)
+
+#define BBCAPE7LCD_PWM_DEVICE_ID   "ehrpwm.1:0"
+
+static struct platform_pwm_backlight_data bbcape7lcd_backlight_data = {
+	.pwm_id         = BBCAPE7LCD_PWM_DEVICE_ID,
+	.ch             = -1,
+	.max_brightness = AM335X_BACKLIGHT_MAX_BRIGHTNESS,
+	.dft_brightness = AM335X_BACKLIGHT_DEFAULT_BRIGHTNESS,
+	.pwm_period_ns  = AM335X_PWM_PERIOD_NANO_SECONDS,
+};
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ehpwrm is device of type PWM using pwm.h declarations and device specifications are 
described in the above structure 
"static struct platform_pwm_backlight_data bbcape7lcd_backlight_data" 

------------------------------------------------------------------------------------

+/* Enable ehrpwm for backlight control */
+static void enable_ehrpwm1(void)
+{
+	ehrpwm_backlight_enable = true;
+	setup_pin_mux(ehrpwm_pin_mux);
+}
+
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ehpwrm is device of type pwm providing back light capability to beagle bone cape and 
enabling function for pin muxing function

------------------------------------------------------------------------------
+/* Module pin mux for LCD backlight */
+static struct pinmux_config ehrpwm_pin_mux[] = {
+        {"gpmc_a2.ehrpwm1A", OMAP_MUX_MODE6 | AM33XX_PIN_OUTPUT},
+        {NULL, 0},
+};
+
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This function is to enable the pin muxing for the device ehpwrm


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+static struct pwmss_platform_data  pwm_pdata[3] = {
+        {
+                .version = PWM_VERSION_1,
+        },
+        {
+                .version = PWM_VERSION_1,
+        },
+        {
+                .version = PWM_VERSION_1,
+        },
+};
+
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This is the data provided to mention version number and number of PWM supported
devices by the platform [Beagle bone]

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+/* Initialize and enable ehrpwm */
+static int __init ehrpwm1_init(void)
+{
+	int status = 0;
+	if (ehrpwm_backlight_enable) {
+                am33xx_register_ehrpwm(1, &pwm_pdata[0]);
+		platform_device_register(&bbtoys7lcd_backlight);
+	}
+	return status;
+}
+late_initcall(ehrpwm1_init);
+
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Initilization of device ehpwrm where ehpwrm_backlight_enable varible is 
defined as "true" value.  

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+	am33xx_cpuidle_init();
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+	omap_serial_init();
+	am335x_rtc_init();
+	clkout2_enable();
+	omap_sdrc_init(NULL, NULL);
+	enable_ehrpwm1();

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Intilizing all data transfer activities and necessary devices to transfer the 
data to other devices


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+	/* Beagle Bone has Micro-SD slot which doesn't have Write Protect pin */
+	am335x_mmc[0].gpio_wp = -EINVAL;

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Giving support of device to MMC [Correct me if I am wrong]

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+	mii1_init();
+	am33xx_cpsw_init_generic(MII_MODE_ENABLE,gigabit_enable);
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Adding the Mode enable function.



File Name:  arch/arm/mach-omap2/mux33xx.c

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static struct omap_mux am33xx_muxmodes[] = {
 		NULL, NULL, NULL, "gpio1_17"),
 	_AM33XX_MUXENTRY(GPMC_A2, 0,
 		"gpmc_a2", "mii2_txd3", "rgmii2_td3", "mmc2_dat1",
-		NULL, NULL, NULL, "gpio1_18"),
+		NULL, NULL, "ehrpwm1A", "gpio1_18"),
 	_AM33XX_MUXENTRY(GPMC_A3, 0,
 		"gpmc_a3", "mii2_txd2", "rgmii2_td2", "mmc2_dat2",
 		NULL, NULL, NULL, "gpio1_19"),
-------------------------------------------------------------------------------------------------

Adding pin muxing modes for ehpwrm device