target/linux/layerscape/patches-4.4/8233-i2c-pca954x-Add-option-to-skip-disabling-PCA954x-Mux.patch

   1 From a4be9046c3a3fc39a06089553df8cc19a2abd814 Mon Sep 17 00:00:00 2001
   2 From: Priyanka Jain <Priyanka.Jain@freescale.com>
   3 Date: Tue, 3 Nov 2015 11:25:24 +0530
   4 Subject: [PATCH 233/238] i2c: pca954x: Add option to skip disabling PCA954x
   5  Mux device
   6
   7 On some Layerscape boards like LS2085ARDB/LS2080ARDB,
   8 input pull-up resistors on PCA954x Mux device are
   9 missing on board. So, if mux are disabled after powered-on,
  10 input lines will float leading to incorrect functionality.
  11
  12 Hence, PCA954x Mux device should never be turned-off after
  13 power-on.
  14
  15 Add option to skip disabling PCA954x Mux device
  16 if device tree contians "i2c-mux-never-disable" property
  17 for pca954x device node.
  18
  19 Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
  20 ---
  21  drivers/i2c/muxes/i2c-mux-pca954x.c |   38 +++++++++++++++++++++++++++++++++++
  22  1 file changed, 38 insertions(+)
  23
  24 diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
  25 index acfcef3..386f86f 100644
  26 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
  27 +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
  28 @@ -63,6 +63,7 @@ struct pca954x {
  29         struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
  30
  31         u8 last_chan;           /* last register value */
  32 +       u8 disable_mux;         /* do not disable mux if val not 0 */
  33  };
  34
  35  struct chip_desc {
  36 @@ -174,6 +175,13 @@ static int pca954x_deselect_mux(struct i2c_adapter *adap,
  37  {
  38         struct pca954x *data = i2c_get_clientdata(client);
  39
  40 +#ifdef CONFIG_ARCH_LAYERSCAPE
  41 +       if (data->disable_mux != 0)
  42 +               data->last_chan = chips[data->type].nchans;
  43 +       else
  44 +               data->last_chan = 0;
  45 +       return pca954x_reg_write(adap, client, data->disable_mux);
  46 +#endif
  47         /* Deselect active channel */
  48         data->last_chan = 0;
  49         return pca954x_reg_write(adap, client, data->last_chan);
  50 @@ -201,6 +209,23 @@ static int pca954x_probe(struct i2c_client *client,
  51         if (!data)
  52                 return -ENOMEM;
  53
  54 +#ifdef CONFIG_ARCH_LAYERSCAPE
  55 +       /* The point here is that you must not disable a mux if there
  56 +        * are no pullups on the input or you mess up the I2C. This
  57 +        * needs to be put into the DTS really as the kernel cannot
  58 +        * know this otherwise.
  59 +        */
  60 +       data->type = id->driver_data;
  61 +       data->disable_mux = of_node &&
  62 +               of_property_read_bool(of_node, "i2c-mux-never-disable") &&
  63 +               chips[data->type].muxtype == pca954x_ismux ?
  64 +               chips[data->type].enable : 0;
  65 +       /* force the first selection */
  66 +       if (data->disable_mux != 0)
  67 +               data->last_chan = chips[data->type].nchans;
  68 +       else
  69 +               data->last_chan = 0;
  70 +#endif
  71         i2c_set_clientdata(client, data);
  72
  73         /* Get the mux out of reset if a reset GPIO is specified. */
  74 @@ -212,13 +237,19 @@ static int pca954x_probe(struct i2c_client *client,
  75          * that the mux is in fact present. This also
  76          * initializes the mux to disconnected state.
  77          */
  78 +#ifdef CONFIG_ARCH_LAYERSCAPE
  79 +       if (i2c_smbus_write_byte(client, data->disable_mux) < 0) {
  80 +#else
  81         if (i2c_smbus_write_byte(client, 0) < 0) {
  82 +#endif
  83                 dev_warn(&client->dev, "probe failed\n");
  84                 return -ENODEV;
  85         }
  86
  87 +#ifndef CONFIG_ARCH_LAYERSCAPE
  88         data->type = id->driver_data;
  89         data->last_chan = 0;               /* force the first selection */
  90 +#endif
  91
  92         idle_disconnect_dt = of_node &&
  93                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
  94 @@ -289,6 +320,13 @@ static int pca954x_resume(struct device *dev)
  95         struct i2c_client *client = to_i2c_client(dev);
  96         struct pca954x *data = i2c_get_clientdata(client);
  97
  98 +#ifdef CONFIG_ARCH_LAYERSCAPE
  99 +       if (data->disable_mux != 0)
 100 +               data->last_chan = chips[data->type].nchans;
 101 +       else
 102 +               data->last_chan = 0;
 103 +       return i2c_smbus_write_byte(client, data->disable_mux);
 104 +#endif
 105         data->last_chan = 0;
 106         return i2c_smbus_write_byte(client, 0);
 107  }
 108 --
 109 1.7.9.5
 110