target/linux/layerscape/patches-5.4/808-i2c-0014-i2c-mux-pca954x-support-property-idle-state.patch

   1 From 5b51284db77e6383ff438b1dd21ee83bb6eaa895 Mon Sep 17 00:00:00 2001
   2 From: Biwen Li <biwen.li@nxp.com>
   3 Date: Tue, 22 Oct 2019 12:11:51 +0800
   4 Subject: [PATCH] i2c: mux: pca954x: support property idle-state
   5
   6 This supports property idle-state,if present,
   7 overrides i2c-mux-idle-disconnect.
   8
   9 My use cases:
  10         - Use the property idle-state to fix
  11           an errata on LS2085ARDB and LS2088ARDB.
  12         - Errata id: E-00013(board LS2085ARDB and
  13           LS2088ARDB revision on Rev.B, Rev.C and Rev.D).
  14         - About E-00013:
  15           - Description: I2C1 and I2C3 buses
  16             are missing pull-up.
  17           - Impact: When the PCA954x device is tri-stated, the I2C bus
  18             will float. This makes the I2C bus and its associated
  19             downstream devices inaccessible.
  20           - Hardware fix: Populate resistors R189 and R190 for I2C1
  21             and resistors R228 and R229 for I2C3.
  22           - Software fix: Remove the tri-state option from the PCA954x
  23             driver(PCA954x always on enable status, specify a
  24             channel zero in dts to fix the errata E-00013).
  25
  26 Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
  27 Signed-off-by: Biwen Li <biwen.li@nxp.com>
  28 ---
  29  drivers/i2c/muxes/i2c-mux-pca954x.c | 69 ++++++++++++++++++++++++-------------
  30  1 file changed, 46 insertions(+), 23 deletions(-)
  31
  32 --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
  33 +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
  34 @@ -87,7 +87,7 @@ struct pca954x {
  35
  36         u8 last_chan;           /* last register value */
  37         /* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
  38 -       s8 idle_state;
  39 +       s32 idle_state;
  40
  41         struct i2c_client *client;
  42
  43 @@ -237,20 +237,23 @@ static int pca954x_reg_write(struct i2c_
  44                                 I2C_SMBUS_BYTE, &dummy);
  45  }
  46
  47 +static u8 pca954x_regval(struct pca954x *data, u8 chan)
  48 +{
  49 +       /* We make switches look like muxes, not sure how to be smarter. */
  50 +       if (data->chip->muxtype == pca954x_ismux)
  51 +               return chan | data->chip->enable;
  52 +       else
  53 +               return 1 << chan;
  54 +}
  55 +
  56  static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
  57  {
  58         struct pca954x *data = i2c_mux_priv(muxc);
  59         struct i2c_client *client = data->client;
  60 -       const struct chip_desc *chip = data->chip;
  61         u8 regval;
  62         int ret = 0;
  63
  64 -       /* we make switches look like muxes, not sure how to be smarter */
  65 -       if (chip->muxtype == pca954x_ismux)
  66 -               regval = chan | chip->enable;
  67 -       else
  68 -               regval = 1 << chan;
  69 -
  70 +       regval = pca954x_regval(data, chan);
  71         /* Only select the channel if its different from the last channel */
  72         if (data->last_chan != regval) {
  73                 ret = pca954x_reg_write(muxc->parent, client, regval);
  74 @@ -264,7 +267,7 @@ static int pca954x_deselect_mux(struct i
  75  {
  76         struct pca954x *data = i2c_mux_priv(muxc);
  77         struct i2c_client *client = data->client;
  78 -       s8 idle_state;
  79 +       s32 idle_state;
  80
  81         idle_state = READ_ONCE(data->idle_state);
  82         if (idle_state >= 0)
  83 @@ -410,6 +413,22 @@ static void pca954x_cleanup(struct i2c_m
  84         i2c_mux_del_adapters(muxc);
  85  }
  86
  87 +static int pca954x_init(struct i2c_client *client, struct pca954x *data)
  88 +{
  89 +       int ret;
  90 +       if (data->idle_state >= 0) {
  91 +               data->last_chan = pca954x_regval(data, data->idle_state);
  92 +       } else {
  93 +               /* Disconnect multiplexer */
  94 +               data->last_chan = 0;
  95 +       }
  96 +       ret = i2c_smbus_write_byte(client, data->last_chan);
  97 +       if (ret < 0)
  98 +               data->last_chan = 0;
  99 +
 100 +       return ret;
 101 +}
 102 +
 103  /*
 104   * I2C init/probing/exit functions
 105   */
 106 @@ -419,7 +438,6 @@ static int pca954x_probe(struct i2c_clie
 107         struct i2c_adapter *adap = client->adapter;
 108         struct device *dev = &client->dev;
 109         struct device_node *np = dev->of_node;
 110 -       bool idle_disconnect_dt;
 111         struct gpio_desc *gpio;
 112         struct i2c_mux_core *muxc;
 113         struct pca954x *data;
 114 @@ -470,23 +488,24 @@ static int pca954x_probe(struct i2c_clie
 115                 }
 116         }
 117
 118 -       /* Write the mux register at addr to verify
 119 +       data->idle_state = MUX_IDLE_AS_IS;
 120 +       if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
 121 +               if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
 122 +                       data->idle_state = MUX_IDLE_DISCONNECT;
 123 +       }
 124 +
 125 +       /*
 126 +        * Write the mux register at addr to verify
 127          * that the mux is in fact present. This also
 128 -        * initializes the mux to disconnected state.
 129 +        * initializes the mux to a channel
 130 +        * or disconnected state.
 131          */
 132 -       if (i2c_smbus_write_byte(client, 0) < 0) {
 133 +       ret = pca954x_init(client, data);
 134 +       if (ret < 0) {
 135                 dev_warn(dev, "probe failed\n");
 136                 return -ENODEV;
 137         }
 138
 139 -       data->last_chan = 0;               /* force the first selection */
 140 -       data->idle_state = MUX_IDLE_AS_IS;
 141 -
 142 -       idle_disconnect_dt = np &&
 143 -               of_property_read_bool(np, "i2c-mux-idle-disconnect");
 144 -       if (idle_disconnect_dt)
 145 -               data->idle_state = MUX_IDLE_DISCONNECT;
 146 -
 147         ret = pca954x_irq_setup(muxc);
 148         if (ret)
 149                 goto fail_cleanup;
 150 @@ -538,9 +557,13 @@ static int pca954x_resume(struct device
 151         struct i2c_client *client = to_i2c_client(dev);
 152         struct i2c_mux_core *muxc = i2c_get_clientdata(client);
 153         struct pca954x *data = i2c_mux_priv(muxc);
 154 +       int ret;
 155
 156 -       data->last_chan = 0;
 157 -       return i2c_smbus_write_byte(client, 0);
 158 +       ret = pca954x_init(client, data);
 159 +       if (ret < 0)
 160 +               dev_err(&client->dev, "failed to verify the mux, the mux maybe not present in fact\n");
 161 +
 162 +       return ret;
 163  }
 164  #endif
 165