board: asus: grouper: add Google Nexus 7 (2012) support

Nexus 7 is a mini tablet computer co-developed by Google and Asus
that runs the Android operating system. The Nexus 7 features a 7"
display, an Nvidia Tegra 3 quad-core chip, 1 GB of RAM and 8/16 GB
of internal storage.

This patch brings support for all 3 known ASUS/Google devices:
- Nexus 7 (2012) E1565
- Nexus 7 (2012) PM269
- Nexus 7 (2012) 3G - tilapia

Tested-by: Andreas Westman Dorcsak <hedmoo@yahoo.com> # ASUS Grouper E1565
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # ASUS Grouper E1565
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/board/asus/grouper/grouper-spl-max.c b/board/asus/grouper/grouper-spl-max.c
new file mode 100644
index 0000000..8443837
--- /dev/null
+++ b/board/asus/grouper/grouper-spl-max.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  T30 Grouper MAX SPL stage configuration
+ *
+ *  (C) Copyright 2010-2013
+ *  NVIDIA Corporation <www.nvidia.com>
+ *
+ *  (C) Copyright 2022
+ *  Svyatoslav Ryhel <clamor95@gmail.com>
+ */
+
+#include <common.h>
+#include <asm/arch-tegra/tegra_i2c.h>
+#include <linux/delay.h>
+
+#define MAX77663_I2C_ADDR		(0x3C << 1)
+
+#define MAX77663_REG_SD0		0x16
+#define MAX77663_REG_SD0_DATA		(0x2100 | MAX77663_REG_SD0)
+#define MAX77663_REG_SD1		0x17
+#define MAX77663_REG_SD1_DATA		(0x3000 | MAX77663_REG_SD1)
+#define MAX77663_REG_LDO4		0x2B
+#define MAX77663_REG_LDO4_DATA		(0xE000 | MAX77663_REG_LDO4)
+
+#define MAX77663_REG_GPIO4		0x3A
+#define MAX77663_REG_GPIO4_DATA		(0x0100 | MAX77663_REG_GPIO4)
+
+void pmic_enable_cpu_vdd(void)
+{
+	/* Set VDD_CORE to 1.200V. */
+	tegra_i2c_ll_write(MAX77663_I2C_ADDR, MAX77663_REG_SD1_DATA);
+
+	udelay(1000);
+
+	/* Bring up VDD_CPU to 1.0125V. */
+	tegra_i2c_ll_write(MAX77663_I2C_ADDR, MAX77663_REG_SD0_DATA);
+	udelay(1000);
+
+	/* Bring up VDD_RTC to 1.200V. */
+	tegra_i2c_ll_write(MAX77663_I2C_ADDR, MAX77663_REG_LDO4_DATA);
+	udelay(10 * 1000);
+
+	/* Set 32k-out gpio state */
+	tegra_i2c_ll_write(MAX77663_I2C_ADDR, MAX77663_REG_GPIO4_DATA);
+}