Added support to reserve/enable a GPIO pin to be used from pps-gpio module (LinuxPPS).

Enable PPS modules in default config for RPi.

Author: tjko

arch/arm/configs/bcmrpi_defconfig

@@ -554,6 +554,9 @@ CONFIG_I2C_BCM2708=m
 CONFIG_SPI=y
 CONFIG_SPI_BCM2708=m
 CONFIG_SPI_SPIDEV=y
+CONFIG_PPS=m
+CONFIG_PPS_CLIENT_LDISC=m
+CONFIG_PPS_CLIENT_GPIO=m
 CONFIG_GPIO_SYSFS=y
 CONFIG_W1=m
 CONFIG_W1_MASTER_DS2490=m

arch/arm/mach-bcm2708/bcm2708.c

@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <linux/spi/spi.h>
 #include <linux/w1-gpio.h>
+#include <linux/pps-gpio.h>
 
 #include <linux/version.h>
 #include <linux/clkdev.h>
@@ -90,6 +91,7 @@ static unsigned disk_led_active_low = 1;
 static unsigned reboot_part = 0;
 static unsigned w1_gpio_pin = W1_GPIO;
 static unsigned w1_gpio_pullup = W1_PULLUP;
+static int pps_gpio_pin = -1;
 static unsigned bcm2835_mmc = 1;
 static bool vc_i2c_override = false;
 
@@ -282,6 +284,19 @@ static struct platform_device w1_device = {
 };
 #endif
 
+static struct pps_gpio_platform_data pps_gpio_info = {
+	.assert_falling_edge = false,
+	.capture_clear = false,
+	.gpio_pin = -1,
+	.gpio_label = "PPS",
+};
+
+static struct platform_device pps_gpio_device = {
+	.name = "pps-gpio",
+	.id = PLATFORM_DEVID_NONE,
+	.dev.platform_data = &pps_gpio_info,
+};
+
 static u64 fb_dmamask = DMA_BIT_MASK(DMA_MASK_BITS_COMMON);
 
 static struct platform_device bcm2708_fb_device = {
@@ -851,6 +866,12 @@ void __init bcm2708_init(void)
 	bcm_register_device(&bcm2708_vcio_device);
 #ifdef CONFIG_BCM2708_GPIO
 	bcm_register_device(&bcm2708_gpio_device);
+	if (pps_gpio_pin >= 0) {
+		pr_info("bcm2708: GPIO %d setup as pps-gpio device\n", pps_gpio_pin);
+		pps_gpio_info.gpio_pin = pps_gpio_pin;
+		pps_gpio_device.id = pps_gpio_pin;
+		bcm_register_device(&pps_gpio_device);
+	}
 #endif
 #if defined(CONFIG_W1_MASTER_GPIO) || defined(CONFIG_W1_MASTER_GPIO_MODULE)
 	w1_gpio_pdata.pin = w1_gpio_pin;
@@ -1111,6 +1132,8 @@ module_param(disk_led_active_low, uint, 0644);
 module_param(reboot_part, uint, 0644);
 module_param(w1_gpio_pin, uint, 0644);
 module_param(w1_gpio_pullup, uint, 0644);
+module_param(pps_gpio_pin, int, 0644);
+MODULE_PARM_DESC(pps_gpio_pin, "Set GPIO pin to reserve for PPS");
 module_param(bcm2835_mmc, uint, 0644);
 module_param(vc_i2c_override, bool, 0644);
 MODULE_PARM_DESC(vc_i2c_override, "Allow the use of VC's I2C peripheral.");