[RFC PATCH 2/6] hwmon: axi-fan-control: add tacho devicetree properties

["Nuno Sá" <nuno.sa@analog.com>]

This core is capable to run without any user interaction and when it
does, it uses some predefined values in order to evaluate the tacho
signal from the FAN. These values depend on the attached FAN, so that
the core now exposes registers to change them accordingly. The values
are:

 * adi,tacho-25-us: Expected tacho signal when the PWM is 25%;
 * adi,tacho-50-us: Expected tacho signal when the PWM is 50%;
 * adi,tacho-75-us: Expected tacho signal when the PWM is 75%;
 * adi,tacho-100-us: Expected tacho signal when the PWM is 100%.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
---
 drivers/hwmon/axi-fan-control.c | 34 +++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/hwmon/axi-fan-control.c b/drivers/hwmon/axi-fan-control.c
index 901d1588234d..aa5a922f684d 100644
--- a/drivers/hwmon/axi-fan-control.c
+++ b/drivers/hwmon/axi-fan-control.c
@@ -23,6 +23,14 @@
 #define ADI_REG_PWM_PERIOD	0x00c0
 #define ADI_REG_TACH_MEASUR	0x00c4
 #define ADI_REG_TEMPERATURE	0x00c8
+#define ADI_REG_TACH_25		0x0140
+#define ADI_REG_TACH_50		0x0144
+#define ADI_REG_TACH_75		0x0148
+#define ADI_REG_TACH_100	0x014c
+#define ADI_REG_TACH_25_TOL	0x0150
+#define ADI_REG_TACH_50_TOL	0x0154
+#define ADI_REG_TACH_75_TOL	0x0158
+#define ADI_REG_TACH_100_TOL	0x015c
 
 #define ADI_REG_IRQ_MASK	0x0040
 #define ADI_REG_IRQ_PENDING	0x0044
@@ -328,6 +336,7 @@ static int axi_fan_control_init(struct axi_fan_control_data *ctl,
 				const struct device_node *np)
 {
 	int ret;
+	u32 tacho_val;
 
 	/* get fan pulses per revolution */
 	ret = of_property_read_u32(np, "pulses-per-revolution", &ctl->ppr);
@@ -337,6 +346,31 @@ static int axi_fan_control_init(struct axi_fan_control_data *ctl,
 	/* 1, 2 and 4 are the typical and accepted values */
 	if (ctl->ppr != 1 && ctl->ppr != 2 && ctl->ppr != 4)
 		return -EINVAL;
+
+	if (!of_property_read_u32(np, "adi,tacho-25-us", &tacho_val)) {
+		tacho_val = DIV_ROUND_CLOSEST_ULL((u64)tacho_val * ctl->clk_rate, 1000000);
+		axi_iowrite(tacho_val, ADI_REG_TACH_25, ctl);
+		axi_iowrite(DIV_ROUND_CLOSEST(tacho_val * 25, 100), ADI_REG_TACH_25_TOL, ctl);
+	}
+
+	if (!of_property_read_u32(np, "adi,tacho-50-us", &tacho_val)) {
+		tacho_val = DIV_ROUND_CLOSEST_ULL((u64)tacho_val * ctl->clk_rate, 1000000);
+		axi_iowrite(tacho_val, ADI_REG_TACH_50, ctl);
+		axi_iowrite(DIV_ROUND_CLOSEST(tacho_val * 25, 100), ADI_REG_TACH_50_TOL, ctl);
+	}
+
+	if (!of_property_read_u32(np, "adi,tacho-75-us", &tacho_val)) {
+		tacho_val = DIV_ROUND_CLOSEST_ULL((u64)tacho_val * ctl->clk_rate, 1000000);
+		axi_iowrite(tacho_val, ADI_REG_TACH_75, ctl);
+		axi_iowrite(DIV_ROUND_CLOSEST(tacho_val * 25, 100), ADI_REG_TACH_75_TOL, ctl);
+	}
+
+	if (!of_property_read_u32(np, "adi,tacho-100-us", &tacho_val)) {
+		tacho_val = DIV_ROUND_CLOSEST_ULL((u64)tacho_val * ctl->clk_rate, 1000000);
+		axi_iowrite(tacho_val, ADI_REG_TACH_100, ctl);
+		axi_iowrite(DIV_ROUND_CLOSEST(tacho_val * 25, 100), ADI_REG_TACH_100_TOL, ctl);
+	}
+
 	/*
 	 * Enable all IRQs
 	 */
-- 
2.32.0