From: Robert Shearman <robert.shearman@xxxxxxx>
The behaviour, by default, to not deselect after each transfer is
unsafe when there is a device with an address that conflicts with
another device on another pca954x mux on the same parent bus, and it
may not be convenient to use the platform data or devicetree to set
the deselect mux, e.g. when running on x86_64 when ACPI is used to
discover most of the device hierarchy.
Therefore, provide the ability to set the device deselect mask using
sysfs as a complement to the method of instantiating the device via
sysfs.
Signed-off-by: Robert Shearman <robert.shearman@xxxxxxx>
---
drivers/i2c/muxes/i2c-mux-pca954x.c | 41 +++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index bfabf985e830..a425223c5c87 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -263,6 +263,40 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
return pca954x_reg_write(muxc->parent, client, data->last_chan);
}
+static ssize_t deselect_mask_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+ struct pca954x *data = i2c_mux_priv(muxc);
+
+ return sprintf(buf, "0x%x\n", data->deselect);
+}
+
+static ssize_t deselect_mask_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+ struct pca954x *data = i2c_mux_priv(muxc);
+ unsigned int val;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val >= 1 << data->chip->nchans)
+ return -EINVAL;
+
+ data->deselect = val;
+ return count;
+}
+
+static DEVICE_ATTR_RW(deselect_mask);
+
static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
{
struct pca954x *data = dev_id;
@@ -329,8 +363,11 @@ static int pca954x_irq_setup(struct i2c_mux_core *muxc)
static void pca954x_cleanup(struct i2c_mux_core *muxc)
{
struct pca954x *data = i2c_mux_priv(muxc);
+ struct i2c_client *client = data->client;
int c, irq;
+ device_remove_file(&client->dev, &dev_attr_deselect_mask);
+
if (data->irq) {
for (c = 0; c < data->chip->nchans; c++) {
irq = irq_find_mapping(data->irq, c);
@@ -453,6 +490,10 @@ static int pca954x_probe(struct i2c_client *client,
goto fail_cleanup;
}
+ ret = device_create_file(dev, &dev_attr_deselect_mask);
+ if (ret)
+ goto fail_cleanup;
+
dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
num, data->chip->muxtype == pca954x_ismux
? "mux" : "switch", client->name);
--
2.20.1
