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- From a4be9046c3a3fc39a06089553df8cc19a2abd814 Mon Sep 17 00:00:00 2001
- From: Priyanka Jain <Priyanka.Jain@freescale.com>
- Date: Tue, 3 Nov 2015 11:25:24 +0530
- Subject: [PATCH 233/238] i2c: pca954x: Add option to skip disabling PCA954x
- Mux device
- On some Layerscape boards like LS2085ARDB/LS2080ARDB,
- input pull-up resistors on PCA954x Mux device are
- missing on board. So, if mux are disabled after powered-on,
- input lines will float leading to incorrect functionality.
- Hence, PCA954x Mux device should never be turned-off after
- power-on.
- Add option to skip disabling PCA954x Mux device
- if device tree contians "i2c-mux-never-disable" property
- for pca954x device node.
- Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
- ---
- drivers/i2c/muxes/i2c-mux-pca954x.c | 38 +++++++++++++++++++++++++++++++++++
- 1 file changed, 38 insertions(+)
- --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
- +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
- @@ -63,6 +63,7 @@ struct pca954x {
- struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
-
- u8 last_chan; /* last register value */
- + u8 disable_mux; /* do not disable mux if val not 0 */
- };
-
- struct chip_desc {
- @@ -174,6 +175,13 @@ static int pca954x_deselect_mux(struct i
- {
- struct pca954x *data = i2c_get_clientdata(client);
-
- +#ifdef CONFIG_ARCH_LAYERSCAPE
- + if (data->disable_mux != 0)
- + data->last_chan = chips[data->type].nchans;
- + else
- + data->last_chan = 0;
- + return pca954x_reg_write(adap, client, data->disable_mux);
- +#endif
- /* Deselect active channel */
- data->last_chan = 0;
- return pca954x_reg_write(adap, client, data->last_chan);
- @@ -201,6 +209,23 @@ static int pca954x_probe(struct i2c_clie
- if (!data)
- return -ENOMEM;
-
- +#ifdef CONFIG_ARCH_LAYERSCAPE
- + /* The point here is that you must not disable a mux if there
- + * are no pullups on the input or you mess up the I2C. This
- + * needs to be put into the DTS really as the kernel cannot
- + * know this otherwise.
- + */
- + data->type = id->driver_data;
- + data->disable_mux = of_node &&
- + of_property_read_bool(of_node, "i2c-mux-never-disable") &&
- + chips[data->type].muxtype == pca954x_ismux ?
- + chips[data->type].enable : 0;
- + /* force the first selection */
- + if (data->disable_mux != 0)
- + data->last_chan = chips[data->type].nchans;
- + else
- + data->last_chan = 0;
- +#endif
- i2c_set_clientdata(client, data);
-
- /* Get the mux out of reset if a reset GPIO is specified. */
- @@ -212,13 +237,19 @@ static int pca954x_probe(struct i2c_clie
- * that the mux is in fact present. This also
- * initializes the mux to disconnected state.
- */
- +#ifdef CONFIG_ARCH_LAYERSCAPE
- + if (i2c_smbus_write_byte(client, data->disable_mux) < 0) {
- +#else
- if (i2c_smbus_write_byte(client, 0) < 0) {
- +#endif
- dev_warn(&client->dev, "probe failed\n");
- return -ENODEV;
- }
-
- +#ifndef CONFIG_ARCH_LAYERSCAPE
- data->type = id->driver_data;
- data->last_chan = 0; /* force the first selection */
- +#endif
-
- idle_disconnect_dt = of_node &&
- of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
- @@ -289,6 +320,13 @@ static int pca954x_resume(struct device
- struct i2c_client *client = to_i2c_client(dev);
- struct pca954x *data = i2c_get_clientdata(client);
-
- +#ifdef CONFIG_ARCH_LAYERSCAPE
- + if (data->disable_mux != 0)
- + data->last_chan = chips[data->type].nchans;
- + else
- + data->last_chan = 0;
- + return i2c_smbus_write_byte(client, data->disable_mux);
- +#endif
- data->last_chan = 0;
- return i2c_smbus_write_byte(client, 0);
- }
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