1 files changed, 79 insertions, 27 deletions

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index bfabf985e830..923aa3a5a3dc 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -46,10 +46,10 @@
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
-#include <linux/platform_data/pca954x.h>
 #include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <dt-bindings/mux/mux.h>
 
 #define PCA954X_MAX_NCHANS 8
 
@@ -85,7 +85,9 @@ struct pca954x {
 	const struct chip_desc *chip;
 
 	u8 last_chan;		/* last register value */
-	u8 deselect;
+	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
+	s8 idle_state;
+
 	struct i2c_client *client;
 
 	struct irq_domain *irq;
@@ -254,15 +256,71 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
 {
 	struct pca954x *data = i2c_mux_priv(muxc);
 	struct i2c_client *client = data->client;
+	s8 idle_state;
+
+	idle_state = READ_ONCE(data->idle_state);
+	if (idle_state >= 0)
+		/* Set the mux back to a predetermined channel */
+		return pca954x_select_chan(muxc, idle_state);
+
+	if (idle_state == MUX_IDLE_DISCONNECT) {
+		/* Deselect active channel */
+		data->last_chan = 0;
+		return pca954x_reg_write(muxc->parent, client,
+					 data->last_chan);
+	}
 
-	if (!(data->deselect & (1 << chan)))
-		return 0;
+	/* otherwise leave as-is */
 
-	/* Deselect active channel */
-	data->last_chan = 0;
-	return pca954x_reg_write(muxc->parent, client, data->last_chan);
+	return 0;
+}
+
+static ssize_t idle_state_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, "%d\n", READ_ONCE(data->idle_state));
 }
 
+static ssize_t idle_state_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);
+	int val;
+	int ret;
+
+	ret = kstrtoint(buf, 0, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
+	    (val < 0 || val >= data->chip->nchans))
+		return -EINVAL;
+
+	i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);
+
+	WRITE_ONCE(data->idle_state, val);
+	/*
+	 * Set the mux into a state consistent with the new
+	 * idle_state.
+	 */
+	if (data->last_chan || val != MUX_IDLE_DISCONNECT)
+		ret = pca954x_deselect_mux(muxc, 0);
+
+	i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);
+
+	return ret < 0 ? ret : count;
+}
+
+static DEVICE_ATTR_RW(idle_state);
+
 static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
 {
 	struct pca954x *data = dev_id;
@@ -329,8 +387,11 @@ 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_idle_state);
+
 	if (data->irq) {
 		for (c = 0; c < data->chip->nchans; c++) {
 			irq = irq_find_mapping(data->irq, c);
@@ -348,14 +409,13 @@ static int pca954x_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct i2c_adapter *adap = client->adapter;
-	struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct device *dev = &client->dev;
 	struct device_node *np = dev->of_node;
 	bool idle_disconnect_dt;
 	struct gpio_desc *gpio;
-	int num, force, class;
 	struct i2c_mux_core *muxc;
 	struct pca954x *data;
+	int num;
 	int ret;
 
 	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
@@ -412,9 +472,12 @@ static int pca954x_probe(struct i2c_client *client,
 	}
 
 	data->last_chan = 0;		   /* force the first selection */
+	data->idle_state = MUX_IDLE_AS_IS;
 
 	idle_disconnect_dt = np &&
 		of_property_read_bool(np, "i2c-mux-idle-disconnect");
+	if (idle_disconnect_dt)
+		data->idle_state = MUX_IDLE_DISCONNECT;
 
 	ret = pca954x_irq_setup(muxc);
 	if (ret)
@@ -422,24 +485,7 @@ static int pca954x_probe(struct i2c_client *client,
 
 	/* Now create an adapter for each channel */
 	for (num = 0; num < data->chip->nchans; num++) {
-		bool idle_disconnect_pd = false;
-
-		force = 0;			  /* dynamic adap number */
-		class = 0;			  /* no class by default */
-		if (pdata) {
-			if (num < pdata->num_modes) {
-				/* force static number */
-				force = pdata->modes[num].adap_id;
-				class = pdata->modes[num].class;
-			} else
-				/* discard unconfigured channels */
-				break;
-			idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
-		}
-		data->deselect |= (idle_disconnect_pd ||
-				   idle_disconnect_dt) << num;
-
-		ret = i2c_mux_add_adapter(muxc, force, num, class);
+		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
 		if (ret)
 			goto fail_cleanup;
 	}
@@ -453,6 +499,12 @@ static int pca954x_probe(struct i2c_client *client,
 			goto fail_cleanup;
 	}
 
+	/*
+	 * The attr probably isn't going to be needed in most cases,
+	 * so don't fail completely on error.
+	 */
+	device_create_file(dev, &dev_attr_idle_state);
+
 	dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
 		 num, data->chip->muxtype == pca954x_ismux
 				? "mux" : "switch", client->name);