[PATCH v3 11/19] hwmon: (mr75203) add VM pre-scaler support

Eliav Farber
2022-08-30T19:23:12Z

Add mr76006 pre-scaler support to normalize the voltage output result for
channels that use pre-scaler units to get the measurement to be within
the range that the sensor supports.

For channels that are listed in the device-tree to have a pre-scaler, the
voltage result is multiplied by a factor of 2, to represent to the user
the actual voltage source which is measured.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
V3 -> V2:
- Modify code according to new property format.

drivers/hwmon/mr75203.c | 64 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
index 6925e8490587..1cd5ff6eacce 100644
--- a/drivers/hwmon/mr75203.c
+++ b/drivers/hwmon/mr75203.c
@@ -13,10 +13,12 @@
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
+#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/reset.h>
+#include <linux/slab.h>

/* PVT Common register */
#define PVT_IP_CONFIG 0x04
@@ -108,9 +110,13 @@
#define PVT_N_CONST 90
#define PVT_R_CONST 245805

+#define PRE_SCALER_X1 1
+#define PRE_SCALER_X2 2
+
struct voltage_device {
u32 vm_map; /* Map channel number to VM index */
u32 ch_map; /* Map channel number to channel index */
+ u32 pre_scaler;
};

struct voltage_channels {
@@ -192,7 +198,7 @@ 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;
+ u32 n, stat, pre_scaler;
u8 vm_idx, ch_idx;
int ret;

@@ -217,7 +223,9 @@ 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 * n - PVT_R_CONST) >> PVT_CONV_BITS;
+ pre_scaler = pvt->vd[channel].pre_scaler;
+ *val = pre_scaler * (PVT_N_CONST * n - PVT_R_CONST) >>
+ PVT_CONV_BITS;

return 0;
default:
@@ -582,6 +590,54 @@ 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)
+{
+ const struct device_node *np = dev->of_node;
+ u32 total_channels = pvt->vm_channels.total;
+ u32 channel;
+ u8 *pre_scaler_ch_list;
+ int i, ret, num_ch;
+
+ /* Set default pre-scaler value to be 1. */
+ for (i = 0; i < total_channels; i++)
+ pvt->vd[i].pre_scaler = PRE_SCALER_X1;
+
+ /* Get number of channels configured in "moortec,vm-pre-scaler". */
+ num_ch = of_property_count_u8_elems(np, "moortec,vm-pre-scaler");
+ if (num_ch <= 0)
+ return 0;
+
+ pre_scaler_ch_list = kcalloc(total_channels,
+ 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",
+ pre_scaler_ch_list, num_ch);
+ if (ret)
+ goto out;
+
+ for (i = 0; i < num_ch; i++) {
+ channel = pre_scaler_ch_list[i];
+
+ if (channel >= total_channels) {
+ dev_err(dev,
+ "invalid channel (%u) in pre-scaler list\n",
+ channel);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ pvt->vd[channel].pre_scaler = PRE_SCALER_X2;
+ }
+
+out:
+ kfree(pre_scaler_ch_list);
+
+ return ret;
+}
+
static int mr75203_probe(struct platform_device *pdev)
{
const struct hwmon_channel_info **pvt_info;
@@ -697,6 +753,10 @@ 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