166 lines
4.9 KiB
Diff
166 lines
4.9 KiB
Diff
From 5b51284db77e6383ff438b1dd21ee83bb6eaa895 Mon Sep 17 00:00:00 2001
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From: Biwen Li <biwen.li@nxp.com>
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Date: Tue, 22 Oct 2019 12:11:51 +0800
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Subject: [PATCH] i2c: mux: pca954x: support property idle-state
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This supports property idle-state,if present,
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overrides i2c-mux-idle-disconnect.
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My use cases:
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- Use the property idle-state to fix
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an errata on LS2085ARDB and LS2088ARDB.
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- Errata id: E-00013(board LS2085ARDB and
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LS2088ARDB revision on Rev.B, Rev.C and Rev.D).
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- About E-00013:
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- Description: I2C1 and I2C3 buses
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are missing pull-up.
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- Impact: When the PCA954x device is tri-stated, the I2C bus
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will float. This makes the I2C bus and its associated
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downstream devices inaccessible.
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- Hardware fix: Populate resistors R189 and R190 for I2C1
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and resistors R228 and R229 for I2C3.
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- Software fix: Remove the tri-state option from the PCA954x
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driver(PCA954x always on enable status, specify a
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channel zero in dts to fix the errata E-00013).
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Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
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Signed-off-by: Biwen Li <biwen.li@nxp.com>
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---
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drivers/i2c/muxes/i2c-mux-pca954x.c | 69 ++++++++++++++++++++++++-------------
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1 file changed, 46 insertions(+), 23 deletions(-)
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--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
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+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
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@@ -87,7 +87,7 @@ struct pca954x {
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u8 last_chan; /* last register value */
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/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
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- s8 idle_state;
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+ s32 idle_state;
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struct i2c_client *client;
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@@ -237,20 +237,23 @@ static int pca954x_reg_write(struct i2c_
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I2C_SMBUS_BYTE, &dummy);
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}
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+static u8 pca954x_regval(struct pca954x *data, u8 chan)
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+{
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+ /* We make switches look like muxes, not sure how to be smarter. */
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+ if (data->chip->muxtype == pca954x_ismux)
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+ return chan | data->chip->enable;
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+ else
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+ return 1 << chan;
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+}
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+
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static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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- const struct chip_desc *chip = data->chip;
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u8 regval;
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int ret = 0;
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- /* we make switches look like muxes, not sure how to be smarter */
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- if (chip->muxtype == pca954x_ismux)
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- regval = chan | chip->enable;
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- else
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- regval = 1 << chan;
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-
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+ regval = pca954x_regval(data, chan);
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/* Only select the channel if its different from the last channel */
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if (data->last_chan != regval) {
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ret = pca954x_reg_write(muxc->parent, client, regval);
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@@ -264,7 +267,7 @@ static int pca954x_deselect_mux(struct i
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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- s8 idle_state;
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+ s32 idle_state;
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idle_state = READ_ONCE(data->idle_state);
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if (idle_state >= 0)
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@@ -410,6 +413,22 @@ static void pca954x_cleanup(struct i2c_m
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i2c_mux_del_adapters(muxc);
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}
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+static int pca954x_init(struct i2c_client *client, struct pca954x *data)
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+{
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+ int ret;
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+ if (data->idle_state >= 0) {
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+ data->last_chan = pca954x_regval(data, data->idle_state);
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+ } else {
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+ /* Disconnect multiplexer */
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+ data->last_chan = 0;
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+ }
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+ ret = i2c_smbus_write_byte(client, data->last_chan);
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+ if (ret < 0)
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+ data->last_chan = 0;
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+
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+ return ret;
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+}
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+
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/*
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* I2C init/probing/exit functions
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*/
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@@ -419,7 +438,6 @@ static int pca954x_probe(struct i2c_clie
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struct i2c_adapter *adap = client->adapter;
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struct device *dev = &client->dev;
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struct device_node *np = dev->of_node;
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- bool idle_disconnect_dt;
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struct gpio_desc *gpio;
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struct i2c_mux_core *muxc;
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struct pca954x *data;
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@@ -470,23 +488,24 @@ static int pca954x_probe(struct i2c_clie
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}
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}
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- /* Write the mux register at addr to verify
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+ data->idle_state = MUX_IDLE_AS_IS;
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+ if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
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+ if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
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+ data->idle_state = MUX_IDLE_DISCONNECT;
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+ }
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+
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+ /*
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+ * Write the mux register at addr to verify
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* that the mux is in fact present. This also
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- * initializes the mux to disconnected state.
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+ * initializes the mux to a channel
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+ * or disconnected state.
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*/
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- if (i2c_smbus_write_byte(client, 0) < 0) {
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+ ret = pca954x_init(client, data);
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+ if (ret < 0) {
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dev_warn(dev, "probe failed\n");
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return -ENODEV;
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}
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- data->last_chan = 0; /* force the first selection */
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- data->idle_state = MUX_IDLE_AS_IS;
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-
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- idle_disconnect_dt = np &&
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- of_property_read_bool(np, "i2c-mux-idle-disconnect");
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- if (idle_disconnect_dt)
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- data->idle_state = MUX_IDLE_DISCONNECT;
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-
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ret = pca954x_irq_setup(muxc);
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if (ret)
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goto fail_cleanup;
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@@ -538,9 +557,13 @@ static int pca954x_resume(struct device
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struct i2c_client *client = to_i2c_client(dev);
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struct i2c_mux_core *muxc = i2c_get_clientdata(client);
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struct pca954x *data = i2c_mux_priv(muxc);
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+ int ret;
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- data->last_chan = 0;
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- return i2c_smbus_write_byte(client, 0);
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+ ret = pca954x_init(client, data);
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+ if (ret < 0)
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+ dev_err(&client->dev, "failed to verify the mux, the mux maybe not present in fact\n");
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+
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+ return ret;
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}
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#endif
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