Disable 32KHz clock prior to MCU boot

Uses SPMI to disable the MCU peripheral clock.

Bug: 236890964
Test: logic analyzer
Change-Id: Ie4fe861ba5584e721b58ebaca72c3195fc5d8810
Signed-off-by: Mark Rawling <mwr@google.com>

2 files changed, 14 insertions, 0 deletions

diff --git a/main.c b/main.c
index 50c22fc..91c7509 100644
--- a/main.c
+++ b/main.c
@@ -822,6 +822,11 @@ static void __nanohub_hw_reset(struct nanohub_data *data, int boot_mode)
 	if (ret != 0)
 		pr_warn("nanohub: failed to disable afe_tx_sup ret=%x\n", ret);
 
+	// Disable 32KHz clock prior to MCU boot
+	ret = regmap_write(pdata->pmic_regmap, pdata->clk32_control_reg, 0);
+	if (ret != 0)
+		pr_warn("nanohub: failed to disable 32KHz clock ret=%x\n", ret);
+
 	// Reset MCU
 	gpio_set_value(pdata->nreset_gpio, 0);
 	usleep_range(1000, 2000);
@@ -1863,6 +1868,14 @@ static struct nanohub_platform_data *nanohub_parse_dt(struct device *dev)
 		goto free_pdata;
 	}
 
+	/* required MCU 32KHz clock control register */
+	ret = of_property_read_u32(dt, "sensorhub,clk32_control",
+				   &pdata->clk32_control_reg);
+	if (ret < 0) {
+		pr_err("nanohub: missing sensorhub,clk32_control in device tree\n");
+		goto free_pdata;
+	}
+
 #ifdef CONFIG_NANOHUB_BL_ST
 	/* optional (bl-max-frequency) */
 	pdata->bl_max_speed_hz = BL_MAX_SPEED_HZ;
diff --git a/nanohub.h b/nanohub.h
index 3b528ea..5693a91 100644
--- a/nanohub.h
+++ b/nanohub.h
@@ -16,6 +16,7 @@ struct nanohub_platform_data {
 	u32 spi_cs_gpio;
 	struct regmap *pmic_regmap;
 	u32 afe_control_reg;
+	u32 clk32_control_reg;
 #ifdef CONFIG_NANOHUB_BL_ST
 	u32 bl_max_speed_hz;
 	u32 bl_addr;