[nrf fromlist] drivers: clock_control nrf_lfclk: patch clock option order

The clock options used within the driver are supposed to be ordered
from lowest to highest power consumption, so the lowest/default
option is the most power efficient. The order was reversed to make
the init code of the lfclk a bit simpler, and this was accounted for
in the clock option lookup function. However, the common nrf clock
control request/release feature would request the lowest index, not
the lowest clock option, so the lfclk would default to its highest
power consumption mode.

The clock option init and lookup has been refactored to be sorted
from lowest to highest power consumption, and comments have been
adjusted accordingly.

Upstream PR #: 99382

Signed-off-by: Bjarki Arge Andreasen <[email protected]>

Author: bjarki-andreasen

drivers/clock_control/clock_control_nrf_lfclk.c

@@ -25,38 +25,25 @@ BUILD_ASSERT(DT_NUM_INST_STATUS_OKAY(DT_DRV_COMPAT) == 1,
 #define LFCLK_LFRC_STARTUP_TIME_US DT_INST_PROP(0, lfrc_startup_time_us)
 
 #define LFCLK_MAX_OPTS 4
-#define LFCLK_DEF_OPTS 2
 
 #define NRFS_CLOCK_TIMEOUT K_MSEC(CONFIG_CLOCK_CONTROL_NRF_LFCLK_CLOCK_TIMEOUT_MS)
 
 #define BICR (NRF_BICR_Type *)DT_REG_ADDR(DT_NODELABEL(bicr))
 
-/* Clock options sorted from highest to lowest power consumption.
- * - Clock synthesized from a high frequency clock
+/*
+ * Clock options sorted from lowest to highest power consumption. If clock option
+ * is not available it is not included.
+ * - External sine or square wave
+ * - XTAL low precision
+ * - XTAL high precision
  * - Internal RC oscillator
- * - External clock. These are inserted into the list at driver initialization.
- *   Set to one of the following:
- *   - XTAL. Low or High precision
- *   - External sine or square wave
+ * - Clock synthesized from a high frequency clock
  */
 static struct clock_options {
 	uint16_t accuracy : 15;
 	uint16_t precision : 1;
 	nrfs_clock_src_t src;
-} clock_options[LFCLK_MAX_OPTS] = {
-	{
-		/* NRFS will request FLL16M use HFXO in bypass mode if SYNTH src is used */
-		.accuracy = LFCLK_HFXO_ACCURACY,
-		.precision = 1,
-		.src = NRFS_CLOCK_SRC_LFCLK_SYNTH,
-	},
-	{
-		.accuracy = LFCLK_LFRC_ACCURACY,
-		.precision = 0,
-		.src = NRFS_CLOCK_SRC_LFCLK_LFRC,
-	},
-	/* Remaining options are populated on lfclk_init */
-};
+} clock_options[LFCLK_MAX_OPTS];
 
 struct lfclk_dev_data {
 	STRUCT_CLOCK_CONFIG(lfclk, ARRAY_SIZE(clock_options)) clk_cfg;
@@ -161,7 +148,7 @@ static int lfclk_resolve_spec_to_idx(const struct device *dev,
 		     ? dev_data->max_accuracy
 		     : req_spec->accuracy;
 
-	for (int i = dev_data->clock_options_cnt - 1; i >= 0; --i) {
+	for (int i = 0; i < dev_data->clock_options_cnt; i++) {
 		/* Iterate to a more power hungry and accurate clock source
 		 * If the requested accuracy is higher (lower ppm) than what
 		 * the clock source can provide.
@@ -331,24 +318,24 @@ static int api_get_rate_lfclk(const struct device *dev,
 static int lfclk_init(const struct device *dev)
 {
 	struct lfclk_dev_data *dev_data = dev->data;
-	nrf_bicr_lfosc_mode_t lfosc_mode;
 	nrfs_err_t res;
+	int ret;
+	nrf_bicr_lfosc_mode_t lfosc_mode;
+	struct clock_options *clock_option;
 
 	res = nrfs_clock_init(clock_evt_handler);
 	if (res != NRFS_SUCCESS) {
 		return -EIO;
 	}
 
-	dev_data->clock_options_cnt = LFCLK_DEF_OPTS;
+	dev_data->clock_options_cnt = 0;
 
 	lfosc_mode = nrf_bicr_lfosc_mode_get(BICR);
 
 	if (lfosc_mode == NRF_BICR_LFOSC_MODE_UNCONFIGURED ||
 	    lfosc_mode == NRF_BICR_LFOSC_MODE_DISABLED) {
 		dev_data->max_accuracy = LFCLK_HFXO_ACCURACY;
 	} else {
-		int ret;
-
 		ret = lfosc_get_accuracy(&dev_data->max_accuracy);
 		if (ret < 0) {
 			LOG_ERR("LFOSC enabled with invalid accuracy");
@@ -357,34 +344,41 @@ static int lfclk_init(const struct device *dev)
 
 		switch (lfosc_mode) {
 		case NRF_BICR_LFOSC_MODE_CRYSTAL:
-			clock_options[LFCLK_MAX_OPTS - 1].accuracy = dev_data->max_accuracy;
-			clock_options[LFCLK_MAX_OPTS - 1].precision = 0;
-			clock_options[LFCLK_MAX_OPTS - 1].src = NRFS_CLOCK_SRC_LFCLK_XO_PIERCE;
-
-			clock_options[LFCLK_MAX_OPTS - 2].accuracy = dev_data->max_accuracy;
-			clock_options[LFCLK_MAX_OPTS - 2].precision = 1;
-			clock_options[LFCLK_MAX_OPTS - 2].src = NRFS_CLOCK_SRC_LFCLK_XO_PIERCE_HP;
-
-			dev_data->clock_options_cnt += 2;
+			clock_option = &clock_options[dev_data->clock_options_cnt];
+			clock_option->accuracy = dev_data->max_accuracy;
+			clock_option->precision = 0;
+			clock_option->src = NRFS_CLOCK_SRC_LFCLK_XO_PIERCE;
+			dev_data->clock_options_cnt++;
+
+			clock_option = &clock_options[dev_data->clock_options_cnt];
+			clock_option->accuracy = dev_data->max_accuracy;
+			clock_option->precision = 1;
+			clock_option->src = NRFS_CLOCK_SRC_LFCLK_XO_PIERCE_HP;
+			dev_data->clock_options_cnt++;
 			break;
-		case NRF_BICR_LFOSC_MODE_EXTSINE:
-			clock_options[LFCLK_MAX_OPTS - 1].accuracy = dev_data->max_accuracy;
-			clock_options[LFCLK_MAX_OPTS - 1].precision = 0;
-			clock_options[LFCLK_MAX_OPTS - 1].src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SINE;
 
-			clock_options[LFCLK_MAX_OPTS - 2].accuracy = dev_data->max_accuracy;
-			clock_options[LFCLK_MAX_OPTS - 2].precision = 1;
-			clock_options[LFCLK_MAX_OPTS - 2].src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SINE_HP;
-
-			dev_data->clock_options_cnt += 2;
+		case NRF_BICR_LFOSC_MODE_EXTSINE:
+			clock_option = &clock_options[dev_data->clock_options_cnt];
+			clock_option->accuracy = dev_data->max_accuracy;
+			clock_option->precision = 0;
+			clock_option->src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SINE;
+			dev_data->clock_options_cnt++;
+
+			clock_option = &clock_options[dev_data->clock_options_cnt];
+			clock_option->accuracy = dev_data->max_accuracy;
+			clock_option->precision = 1;
+			clock_option->src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SINE_HP;
+			dev_data->clock_options_cnt++;
 			break;
-		case NRF_BICR_LFOSC_MODE_EXTSQUARE:
-			clock_options[LFCLK_MAX_OPTS - 2].accuracy = dev_data->max_accuracy;
-			clock_options[LFCLK_MAX_OPTS - 2].precision = 0;
-			clock_options[LFCLK_MAX_OPTS - 2].src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SQUARE;
 
-			dev_data->clock_options_cnt += 1;
+		case NRF_BICR_LFOSC_MODE_EXTSQUARE:
+			clock_option = &clock_options[dev_data->clock_options_cnt];
+			clock_option->accuracy = dev_data->max_accuracy;
+			clock_option->precision = 0;
+			clock_option->src = NRFS_CLOCK_SRC_LFCLK_XO_EXT_SQUARE;
+			dev_data->clock_options_cnt++;
 			break;
+
 		default:
 			LOG_ERR("Unexpected LFOSC mode");
 			return -EINVAL;
@@ -398,6 +392,18 @@ static int lfclk_init(const struct device *dev)
 		}
 	}
 
+	clock_option = &clock_options[dev_data->clock_options_cnt];
+	clock_option->accuracy = LFCLK_LFRC_ACCURACY;
+	clock_option->precision = 0;
+	clock_option->src = NRFS_CLOCK_SRC_LFCLK_LFRC;
+	dev_data->clock_options_cnt++;
+
+	clock_option = &clock_options[dev_data->clock_options_cnt];
+	clock_option->accuracy = LFCLK_HFXO_ACCURACY;
+	clock_option->precision = 1;
+	clock_option->src = NRFS_CLOCK_SRC_LFCLK_SYNTH;
+	dev_data->clock_options_cnt++;
+
 	dev_data->hfxo_startup_time_us = nrf_bicr_hfxo_startup_time_us_get(BICR);
 	if (dev_data->hfxo_startup_time_us == NRF_BICR_HFXO_STARTUP_TIME_UNCONFIGURED) {
 		LOG_ERR("BICR HFXO startup time invalid");