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 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
  25 +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
  26 @@ -63,6 +63,7 @@ struct pca954x {
  27         struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
  28
  29         u8 last_chan;           /* last register value */
  30 +       u8 disable_mux;         /* do not disable mux if val not 0 */
  31  };
  32
  33  struct chip_desc {
  34 @@ -174,6 +175,13 @@ static int pca954x_deselect_mux(struct i
  35  {
  36         struct pca954x *data = i2c_get_clientdata(client);
  37
  38 +#ifdef CONFIG_ARCH_LAYERSCAPE
  39 +       if (data->disable_mux != 0)
  40 +               data->last_chan = chips[data->type].nchans;
  41 +       else
  42 +               data->last_chan = 0;
  43 +       return pca954x_reg_write(adap, client, data->disable_mux);
  44 +#endif
  45         /* Deselect active channel */
  46         data->last_chan = 0;
  47         return pca954x_reg_write(adap, client, data->last_chan);
  48 @@ -201,6 +209,23 @@ static int pca954x_probe(struct i2c_clie
  49         if (!data)
  50                 return -ENOMEM;
  51
  52 +#ifdef CONFIG_ARCH_LAYERSCAPE
  53 +       /* The point here is that you must not disable a mux if there
  54 +        * are no pullups on the input or you mess up the I2C. This
  55 +        * needs to be put into the DTS really as the kernel cannot
  56 +        * know this otherwise.
  57 +        */
  58 +       data->type = id->driver_data;
  59 +       data->disable_mux = of_node &&
  60 +               of_property_read_bool(of_node, "i2c-mux-never-disable") &&
  61 +               chips[data->type].muxtype == pca954x_ismux ?
  62 +               chips[data->type].enable : 0;
  63 +       /* force the first selection */
  64 +       if (data->disable_mux != 0)
  65 +               data->last_chan = chips[data->type].nchans;
  66 +       else
  67 +               data->last_chan = 0;
  68 +#endif
  69         i2c_set_clientdata(client, data);
  70
  71         /* Get the mux out of reset if a reset GPIO is specified. */
  72 @@ -212,13 +237,19 @@ static int pca954x_probe(struct i2c_clie
  73          * that the mux is in fact present. This also
  74          * initializes the mux to disconnected state.
  75          */
  76 +#ifdef CONFIG_ARCH_LAYERSCAPE
  77 +       if (i2c_smbus_write_byte(client, data->disable_mux) < 0) {
  78 +#else
  79         if (i2c_smbus_write_byte(client, 0) < 0) {
  80 +#endif
  81                 dev_warn(&client->dev, "probe failed\n");
  82                 return -ENODEV;
  83         }
  84
  85 +#ifndef CONFIG_ARCH_LAYERSCAPE
  86         data->type = id->driver_data;
  87         data->last_chan = 0;               /* force the first selection */
  88 +#endif
  89
  90         idle_disconnect_dt = of_node &&
  91                 of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
  92 @@ -289,6 +320,13 @@ static int pca954x_resume(struct device
  93         struct i2c_client *client = to_i2c_client(dev);
  94         struct pca954x *data = i2c_get_clientdata(client);
  95
  96 +#ifdef CONFIG_ARCH_LAYERSCAPE
  97 +       if (data->disable_mux != 0)
  98 +               data->last_chan = chips[data->type].nchans;
  99 +       else
 100 +               data->last_chan = 0;
 101 +       return i2c_smbus_write_byte(client, data->disable_mux);
 102 +#endif
 103         data->last_chan = 0;
 104         return i2c_smbus_write_byte(client, 0);
 105  }