Add support for mr76006 pre-scaler which provides divide-by-2 scaling
of the input voltage, so that it can be presented to the VM for
measurement within its range (the VM input range is limited from -0.1V
to 1V).
The driver reads from the device-tree all the channels that use the
mr76006 pre-scaler and multiplies the voltage result by a factor of 2,
to represent to the user with the actual voltage input source.
Channels that are not in the device-tree are multiplied by a factor
of 1.
Signed-off-by: Eliav Farber <farbere@xxxxxxxxxx>
---
V4 -> V3:
- Replace of_property_count_u8_elems() with device_property_count_u8().
- Remove unnecessary blank line.
- Remove code that validated the YAML.
V3 -> V2:
- Modify code according to new property format.
drivers/hwmon/mr75203.c | 55 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 53 insertions(+), 2 deletions(-)
diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
index 5aa694fd9118..66f151082c11 100644
--- a/drivers/hwmon/mr75203.c
+++ b/drivers/hwmon/mr75203.c
@@ -17,6 +17,7 @@
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/reset.h>
+#include <linux/slab.h>
/* PVT Common register */
#define PVT_IP_CONFIG 0x04
@@ -108,17 +109,24 @@
#define PVT_N_CONST 90
#define PVT_R_CONST 245805
+#define PRE_SCALER_X1 1
+#define PRE_SCALER_X2 2
+
/**
* struct voltage_device - VM single input parameters.
* @vm_map: Map channel number to VM index.
* @ch_map: Map channel number to channel index.
+ * @pre_scaler: Pre scaler value (1 or 2) used to normalize the voltage output
+ * result.
*
* The structure provides mapping between channel-number (0..N-1) to VM-index
* (0..num_vm-1) and channel-index (0..ch_num-1) where N = num_vm * ch_num.
+ * It also provides normalization factor for the VM equation.
*/
struct voltage_device {
u32 vm_map;
u32 ch_map;
+ u32 pre_scaler;
};
/**
@@ -207,8 +215,8 @@ static int pvt_read_in(struct device *dev, u32 attr, int channel, long *val)
{
struct pvt_device *pvt = dev_get_drvdata(dev);
struct regmap *v_map = pvt->v_map;
+ u32 n, stat, pre_scaler;
u8 vm_idx, ch_idx;
- u32 n, stat;
int ret;
if (channel >= pvt->vm_channels.total)
@@ -232,7 +240,9 @@ static int pvt_read_in(struct device *dev, u32 attr, int channel, long *val)
n &= SAMPLE_DATA_MSK;
/* Convert the N bitstream count into voltage */
- *val = (PVT_N_CONST * (long)n - PVT_R_CONST) / (1 << PVT_CONV_BITS);
+ pre_scaler = pvt->vd[channel].pre_scaler;
+ *val = pre_scaler * (PVT_N_CONST * (long)n - PVT_R_CONST) /
+ (1 << PVT_CONV_BITS);
return 0;
default:
@@ -594,6 +604,43 @@ static int pvt_get_active_channel(struct device *dev, struct pvt_device *pvt,
return 0;
}
+static int pvt_get_pre_scaler(struct device *dev, struct pvt_device *pvt)
+{
+ u8 *pre_scaler_ch_list;
+ int i, ret, num_ch;
+ u32 channel;
+
+ /* Set default pre-scaler value to be 1. */
+ for (i = 0; i < pvt->vm_channels.total; i++)
+ pvt->vd[i].pre_scaler = PRE_SCALER_X1;
+
+ /* Get number of channels configured in "moortec,vm-pre-scaler-x2". */
+ num_ch = device_property_count_u8(dev, "moortec,vm-pre-scaler-x2");
+ if (num_ch <= 0)
+ return 0;
+
+ pre_scaler_ch_list = kcalloc(num_ch, sizeof(*pre_scaler_ch_list),
+ GFP_KERNEL);
+ if (!pre_scaler_ch_list)
+ return -ENOMEM;
+
+ /* Get list of all channels that have pre-scaler of 2. */
+ ret = device_property_read_u8_array(dev, "moortec,vm-pre-scaler-x2",
+ pre_scaler_ch_list, num_ch);
+ if (ret)
+ goto out;
+
+ for (i = 0; i < num_ch; i++) {
+ channel = pre_scaler_ch_list[i];
+ pvt->vd[channel].pre_scaler = PRE_SCALER_X2;
+ }
+
+out:
+ kfree(pre_scaler_ch_list);
+
+ return ret;
+}
+
static int mr75203_probe(struct platform_device *pdev)
{
u32 ts_num, vm_num, pd_num, ch_num, val, index, i;
@@ -709,6 +756,10 @@ static int mr75203_probe(struct platform_device *pdev)
if (ret)
return ret;
+ ret = pvt_get_pre_scaler(dev, pvt);
+ if (ret)
+ return ret;
+
in_config = devm_kcalloc(dev, pvt->vm_channels.total + 1,
sizeof(*in_config), GFP_KERNEL);
if (!in_config)
--
2.37.1
