--- /dev/null
+From 5b51284db77e6383ff438b1dd21ee83bb6eaa895 Mon Sep 17 00:00:00 2001
+From: Biwen Li <biwen.li@nxp.com>
+Date: Tue, 22 Oct 2019 12:11:51 +0800
+Subject: [PATCH] i2c: mux: pca954x: support property idle-state
+
+This supports property idle-state,if present,
+overrides i2c-mux-idle-disconnect.
+
+My use cases:
+ - Use the property idle-state to fix
+ an errata on LS2085ARDB and LS2088ARDB.
+ - Errata id: E-00013(board LS2085ARDB and
+ LS2088ARDB revision on Rev.B, Rev.C and Rev.D).
+ - About E-00013:
+ - Description: I2C1 and I2C3 buses
+ are missing pull-up.
+ - Impact: When the PCA954x device is tri-stated, the I2C bus
+ will float. This makes the I2C bus and its associated
+ downstream devices inaccessible.
+ - Hardware fix: Populate resistors R189 and R190 for I2C1
+ and resistors R228 and R229 for I2C3.
+ - Software fix: Remove the tri-state option from the PCA954x
+ driver(PCA954x always on enable status, specify a
+ channel zero in dts to fix the errata E-00013).
+
+Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
+Signed-off-by: Biwen Li <biwen.li@nxp.com>
+---
+ drivers/i2c/muxes/i2c-mux-pca954x.c | 69 ++++++++++++++++++++++++-------------
+ 1 file changed, 46 insertions(+), 23 deletions(-)
+
+--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
++++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
+@@ -87,7 +87,7 @@ struct pca954x {
+
+ u8 last_chan; /* last register value */
+ /* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
+- s8 idle_state;
++ s32 idle_state;
+
+ struct i2c_client *client;
+
+@@ -237,20 +237,23 @@ static int pca954x_reg_write(struct i2c_
+ I2C_SMBUS_BYTE, &dummy);
+ }
+
++static u8 pca954x_regval(struct pca954x *data, u8 chan)
++{
++ /* We make switches look like muxes, not sure how to be smarter. */
++ if (data->chip->muxtype == pca954x_ismux)
++ return chan | data->chip->enable;
++ else
++ return 1 << chan;
++}
++
+ static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
+ {
+ struct pca954x *data = i2c_mux_priv(muxc);
+ struct i2c_client *client = data->client;
+- const struct chip_desc *chip = data->chip;
+ u8 regval;
+ int ret = 0;
+
+- /* we make switches look like muxes, not sure how to be smarter */
+- if (chip->muxtype == pca954x_ismux)
+- regval = chan | chip->enable;
+- else
+- regval = 1 << chan;
+-
++ regval = pca954x_regval(data, chan);
+ /* Only select the channel if its different from the last channel */
+ if (data->last_chan != regval) {
+ ret = pca954x_reg_write(muxc->parent, client, regval);
+@@ -264,7 +267,7 @@ static int pca954x_deselect_mux(struct i
+ {
+ struct pca954x *data = i2c_mux_priv(muxc);
+ struct i2c_client *client = data->client;
+- s8 idle_state;
++ s32 idle_state;
+
+ idle_state = READ_ONCE(data->idle_state);
+ if (idle_state >= 0)
+@@ -410,6 +413,22 @@ static void pca954x_cleanup(struct i2c_m
+ i2c_mux_del_adapters(muxc);
+ }
+
++static int pca954x_init(struct i2c_client *client, struct pca954x *data)
++{
++ int ret;
++ if (data->idle_state >= 0) {
++ data->last_chan = pca954x_regval(data, data->idle_state);
++ } else {
++ /* Disconnect multiplexer */
++ data->last_chan = 0;
++ }
++ ret = i2c_smbus_write_byte(client, data->last_chan);
++ if (ret < 0)
++ data->last_chan = 0;
++
++ return ret;
++}
++
+ /*
+ * I2C init/probing/exit functions
+ */
+@@ -419,7 +438,6 @@ static int pca954x_probe(struct i2c_clie
+ struct i2c_adapter *adap = client->adapter;
+ struct device *dev = &client->dev;
+ struct device_node *np = dev->of_node;
+- bool idle_disconnect_dt;
+ struct gpio_desc *gpio;
+ struct i2c_mux_core *muxc;
+ struct pca954x *data;
+@@ -470,23 +488,24 @@ static int pca954x_probe(struct i2c_clie
+ }
+ }
+
+- /* Write the mux register at addr to verify
++ data->idle_state = MUX_IDLE_AS_IS;
++ if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
++ if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
++ data->idle_state = MUX_IDLE_DISCONNECT;
++ }
++
++ /*
++ * Write the mux register at addr to verify
+ * that the mux is in fact present. This also
+- * initializes the mux to disconnected state.
++ * initializes the mux to a channel
++ * or disconnected state.
+ */
+- if (i2c_smbus_write_byte(client, 0) < 0) {
++ ret = pca954x_init(client, data);
++ if (ret < 0) {
+ dev_warn(dev, "probe failed\n");
+ return -ENODEV;
+ }
+
+- 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)
+ goto fail_cleanup;
+@@ -538,9 +557,13 @@ static int pca954x_resume(struct device
+ 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 ret;
+
+- data->last_chan = 0;
+- return i2c_smbus_write_byte(client, 0);
++ ret = pca954x_init(client, data);
++ if (ret < 0)
++ dev_err(&client->dev, "failed to verify the mux, the mux maybe not present in fact\n");
++
++ return ret;
+ }
+ #endif
+
projects / openwrt / staging / wigyori.git / blobdiff