From 4e67fc399793c062150ae1a5910646fc0abebe7f Mon Sep 17 00:00:00 2001
From: Rene Straub <rene.straub@netmodule.com>
Date: Wed, 23 Aug 2023 08:22:21 +0200
Subject: [PATCH] hw21/26: adapt power sequencing for NEO-M9

NEO-M9 modems sometimes boot into Safe Boot mode because of the 3.3 V
power sequencing defined by the PMIC.

Change SPL/U-Boot to
- insert LDO feeding GNSS modem in automatic power sequencing
- reset GNSS module at power on reset.

id:420663
---
 board/nm/common/da9063.h |  1 +
 board/nm/nmhw21/board.c  | 53 ++++++++++++++++++++++++++++++++++------
 2 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/board/nm/common/da9063.h b/board/nm/common/da9063.h
index 2692c98b88..0a0fd97586 100644
--- a/board/nm/common/da9063.h
+++ b/board/nm/common/da9063.h
@@ -57,6 +57,7 @@
 #define PMIC_LDOx_CONF_MASK	0x80
 
 #define PMIC_REG_ID_4_3		0x84
+#define PMIC_REG_ID_6_5		0x85
 
 #define PMIC_REG_BUCK_ILIM_A	0x9A
 #define PMIC_REG_BUCK_ILIM_B	0x9B
diff --git a/board/nm/nmhw21/board.c b/board/nm/nmhw21/board.c
index d605e5c01c..143488e7ea 100644
--- a/board/nm/nmhw21/board.c
+++ b/board/nm/nmhw21/board.c
@@ -454,6 +454,26 @@ static void pmic_disable_auto_mode(void)
 	}
 }
 
+static void pmic_gnss_pwr_sequence(void)
+{
+	int rc;
+	uint8_t val;
+
+	/* 
+	 * GNSS 3.3V needs to start at same time as board 3.3V.
+	 * Modify LDO6 configuration accordingly if not already done.
+	 */
+	rc = da9063_get_reg(PMIC_REG_ID_6_5, &val);
+	if (!rc && (val != 0x20)) {
+		(void)da9063_set_reg(PMIC_REG_ID_6_5, 0x20);	/* Add LDO6 to sequencer, slot 2 */
+		(void)da9063_set_reg(PMIC_REG_CONFIG_G, 0x64);	/* LDO6 automatic enable control by sequencer */
+	}
+
+	/* Enable +3V3_GNSS (LDO6) */
+	(void)da9063_set_reg(PMIC_REG_LDO6_CONT, PMIC_LDOx_EN_MASK);
+	mdelay(2);
+}
+
 static void init_pmic_spl(void)
 {
 	int bus;
@@ -471,9 +491,7 @@ static void init_pmic_spl(void)
 		pmic_disable_auto_mode();
 	}
 
-	/* Enable +3V3_GNSS (LDO6) */
-	(void)da9063_set_reg(PMIC_REG_LDO6_CONT, PMIC_LDOx_EN_MASK);
-	mdelay(2);
+	pmic_gnss_pwr_sequence();
 
 	/* Enable +5V_CAN (LDO11 Switch) */
 	(void)da9063_set_reg(PMIC_REG_LDO11_CONT, PMIC_LDOx_EN_MASK);
@@ -1148,12 +1166,33 @@ static void init_gsm(void)
 #endif
 }
 
-static void init_gnss(void)
+static void init_gnss(uint32_t reset_reason_shm_location)
 {
+	volatile struct reset_registers* reset_regs = (struct reset_registers*)reset_reason_shm_location;
+	bool do_reset = false;
+
 	/*
-	 * Release GNSS reset line, so that module starts up early
+	 * Release GNSS reset line, so that module starts up early.
+	 * Excpetion: If this is an initial power up, we reset the module to ensure defined operation.
+	 * Reasoning: Some NEO-M9 modems start in Safe Boot mode, due to power sequencing.
 	 */
-	REQUEST_AND_SET_GPIO(GPIO_RST_GNSS);
+	puts("GNSS:  ");
+
+	if (rr_is_start_reason_valid(reset_regs)) {
+		if ((reset_regs->sr_events & SR_POR) == SR_POR) {
+			do_reset = true;
+		}
+	}
+
+	if (do_reset) {
+		puts("reset\n");
+		REQUEST_AND_CLEAR_GPIO(GPIO_RST_GNSS);
+		mdelay(110);
+		gpio_set_value(GPIO_RST_GNSS, 1);
+	} else {
+		puts("init\n");
+		REQUEST_AND_SET_GPIO(GPIO_RST_GNSS);
+	}
 }
 
 static void init_timepulse(void)
@@ -1909,7 +1948,7 @@ int board_late_init(void)
 #endif
 	init_sim_mux();
 	init_gsm();
-	init_gnss();
+	init_gnss(RESET_REASON_SHM_LOCATION);
 	init_timepulse();
 
 	/*