board: pinephone-pro: Wait for the battery to get some charge [TODO]

We need to wait for the battery voltage to raise above some safe level
before proceeding with boot.

Signed-off-by: Ondrej Jirman <megi@xff.cz>

board/pine64/pinephone-pro-rk3399/pinephone-pro-rk3399.c

@@ -14,6 +14,7 @@
 #include <asm/arch-rockchip/hardware.h>
 #include <asm/arch-rockchip/misc.h>
 #include <power/regulator.h>
+#include <linux/delay.h>
 #include <power/rk8xx_pmic.h>
 
 #define GRF_IO_VSEL_BT565_GPIO2AB 1
@@ -62,6 +63,8 @@ static void pinephone_pro_init(void)
 	struct udevice *pmic;
 	int ret;
 
+	printf("Initializing Pinephone Pro charger\n");
+
 	ret = uclass_first_device_err(UCLASS_PMIC, &pmic);
 	if (ret) {
 		printf("ERROR: PMIC not found! (%d)\n", ret);
@@ -80,6 +83,12 @@ static void pinephone_pro_init(void)
 	 * Close charger when USB lower then 3.26V
 	 */
 	rk818_spl_configure_usb_chrg_shutdown(pmic, 3260000);
+
+	/*
+	 * Check battery voltage and wait until it's in bootable state.
+	 */
+	//TODO:
+	rk818_wait_battery(pmic);
 }
 
 void pmic_setup(void)

drivers/power/pmic/rk8xx.c

@@ -129,6 +129,11 @@ static int rk8xx_read(struct udevice *dev, uint reg, uint8_t *buff, int len)
 	return 0;
 }
 
+int rk818_wait_battery(struct udevice *dev)
+{
+	return 0;
+}
+
 #if CONFIG_IS_ENABLED(PMIC_CHILDREN)
 static int rk8xx_bind(struct udevice *dev)
 {

include/power/rk8xx_pmic.h

@@ -236,4 +236,6 @@ int rk8xx_spl_configure_buck(struct udevice *pmic, int buck, int uvolt);
 int rk818_spl_configure_usb_input_current(struct udevice *pmic, int current_ma);
 int rk818_spl_configure_usb_chrg_shutdown(struct udevice *pmic, int uvolt);
 
+int rk818_wait_battery(struct udevice *dev);
+
 #endif