Just to see how it would look, I tried doing the below. Since a board
may have more than one ad74412/ad74413, one needs to be able to
differentiate between them. So for now each module parameter channelX
(X=0,1,2,3) accepts a space-separated list of <label>:<function>,
where label is matched against the label property in device tree, but
also allowing * to match any, which is more convenient when one knows
there is only one device.
Aside from the missing documentation (MODULE_PARM_DESC), there are of
course various details to hash out. E.g., should the function be
specified with a raw integer as here, or should we take a text string
"voltage-output", "current-input-ext-power" etc. and translate those?
Should we use space or comma or semicolon as separator? And so on.
I also considered whether instead of the label one should instead
match on the OF_FULLNAME,
e.g. /soc@0/bus@30800000/spi@30840000/ad74412r@0, but that's a lot
more complicated, and I assume that anybody that has more than one of
these chips would anyway assign a label so that they can distinguish
their /sys/bus/iio/... directories.
I should also note that it is not unprecedented for modules to take
parameters that do some sort of (ad hoc) parsing to apply settings
per-device. For example:
- ignore_wake in drivers/gpio/gpiolib-acpi.c
- mtdparts in drivers/mtd/parsers/cmdlinepart.c
- pci_devs_to_hide in drivers/xen/xen-pciback/pci_stub.c
- quirks in drivers/hid/usbhid/hid-core.c
So the question is, is there any chance that anything like this could
be accepted? If so, I'll of course spin this into a real patch with
proper MODULE_PARM_DESC and commit log etc.
This has been tested doing
insmod ad74413r.ko 'channel0=*:1' 'channel1=*:3' 'channel2=*:2' 'channel3=*:4'
and seeing that the channels did indeed come up as expected, where the
device tree specified CH_FUNC_HIGH_IMPEDANCE for all of them.
---
drivers/iio/addac/ad74413r.c | 37 ++++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
index ef873737c33a..284bdb358dec 100644
--- a/drivers/iio/addac/ad74413r.c
+++ b/drivers/iio/addac/ad74413r.c
@@ -1146,6 +1146,35 @@ static const struct ad74413r_channels ad74413r_channels_map[] = {
[CH_FUNC_CURRENT_INPUT_LOOP_POWER_HART] = AD74413R_CHANNELS(current_input),
};
+static char *channel_function[AD74413R_CHANNEL_MAX];
+
+static int ad74413r_get_channel_function(struct ad74413r_state *st, u32 index,
+ struct fwnode_handle *channel_node)
+{
+ const char *s, *c, *label;
+ u32 func, label_len;
+
+ if (device_property_read_string(st->dev, "label", &label))
+ label = "";
+
+ label_len = strlen(label);
+ for (s = channel_function[index]; s; s = strchr(s, ' ')) {
+ s = skip_spaces(s);
+ c = strchr(s, ':');
+ if (!c)
+ break;
+
+ if ((c - s == label_len && !memcmp(s, label, label_len)) ||
+ (c - s == 1 && *s == '*'))
+ return simple_strtol(c + 1, NULL, 10);
+ }
+
+ func = CH_FUNC_HIGH_IMPEDANCE;
+ fwnode_property_read_u32(channel_node, "adi,ch-func", &func);
+
+ return func;
+}
+
static int ad74413r_parse_channel_config(struct iio_dev *indio_dev,
struct fwnode_handle *channel_node)
{
@@ -1171,8 +1200,7 @@ static int ad74413r_parse_channel_config(struct iio_dev *indio_dev,
return -EINVAL;
}
- config->func = CH_FUNC_HIGH_IMPEDANCE;
- fwnode_property_read_u32(channel_node, "adi,ch-func", &config->func);
+ config->func = ad74413r_get_channel_function(st, index, channel_node);
if (config->func < CH_FUNC_MIN || config->func > CH_FUNC_MAX) {
dev_err(st->dev, "Invalid channel function %u\n", config->func);
@@ -1494,6 +1522,11 @@ static struct spi_driver ad74413r_driver = {
.id_table = ad74413r_spi_id,
};
+module_param_named(channel0, channel_function[0], charp, 0444);
+module_param_named(channel1, channel_function[1], charp, 0444);
+module_param_named(channel2, channel_function[2], charp, 0444);
+module_param_named(channel3, channel_function[3], charp, 0444);
+
module_driver(ad74413r_driver,
ad74413r_register_driver,
ad74413r_unregister_driver);
--
2.37.2
