target/linux/brcm2708/patches-4.4/0122-Extend-clock-timeout-fix-modprobe-baudrate-parameter.patch

   1 From ba2e42fe23631e6cf1f2e1167618ab1c13d9b3ba Mon Sep 17 00:00:00 2001
   2 From: Devon Fyson <devonfyson@gmail.com>
   3 Date: Wed, 30 Dec 2015 16:40:47 -0500
   4 Subject: [PATCH 122/127] Extend clock timeout, fix modprobe baudrate
   5  parameter.
   6
   7 Set the BSC_CLKT clock streching timeout to 35ms as per SMBus specs.\n- Increase priority of baudrate parameter passed to modprobe (in /etc/modprobe.d/*.conf or command line). Currently custom baudrates don't work because they are overridden by clock-frequency in the platform_device passed to the function.
   8 ---
   9  drivers/i2c/busses/i2c-bcm2708.c | 45 ++++++++++++++++++++++++++--------------
  10  1 file changed, 29 insertions(+), 16 deletions(-)
  11
  12 --- a/drivers/i2c/busses/i2c-bcm2708.c
  13 +++ b/drivers/i2c/busses/i2c-bcm2708.c
  14 @@ -71,7 +71,8 @@
  15
  16  #define DRV_NAME               "bcm2708_i2c"
  17
  18 -static unsigned int baudrate = CONFIG_I2C_BCM2708_BAUDRATE;
  19 +static unsigned int baudrate_default = CONFIG_I2C_BCM2708_BAUDRATE;
  20 +static unsigned int baudrate;
  21  module_param(baudrate, uint, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
  22  MODULE_PARM_DESC(baudrate, "The I2C baudrate");
  23
  24 @@ -87,6 +88,7 @@ struct bcm2708_i2c {
  25         int irq;
  26         struct clk *clk;
  27         u32 cdiv;
  28 +       u32 clk_tout;
  29
  30         struct completion done;
  31
  32 @@ -126,7 +128,7 @@ static inline void bcm2708_bsc_fifo_fill
  33
  34  static inline int bcm2708_bsc_setup(struct bcm2708_i2c *bi)
  35  {
  36 -       u32 cdiv, s;
  37 +       u32 cdiv, s, clk_tout;
  38         u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1;
  39         int wait_loops = I2C_WAIT_LOOP_COUNT;
  40
  41 @@ -134,12 +136,14 @@ static inline int bcm2708_bsc_setup(stru
  42          * Use the value that we cached in the probe.
  43          */
  44         cdiv = bi->cdiv;
  45 +       clk_tout = bi->clk_tout;
  46
  47         if (bi->msg->flags & I2C_M_RD)
  48                 c |= BSC_C_INTR | BSC_C_READ;
  49         else
  50                 c |= BSC_C_INTT;
  51
  52 +       bcm2708_wr(bi, BSC_CLKT, clk_tout);
  53         bcm2708_wr(bi, BSC_DIV, cdiv);
  54         bcm2708_wr(bi, BSC_A, bi->msg->addr);
  55         bcm2708_wr(bi, BSC_DLEN, bi->msg->len);
  56 @@ -312,21 +316,24 @@ static int bcm2708_i2c_probe(struct plat
  57         struct bcm2708_i2c *bi;
  58         struct i2c_adapter *adap;
  59         unsigned long bus_hz;
  60 -       u32 cdiv;
  61 -
  62 -       if (pdev->dev.of_node) {
  63 -               u32 bus_clk_rate;
  64 -               pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
  65 -               if (pdev->id < 0) {
  66 -                       dev_err(&pdev->dev, "alias is missing\n");
  67 -                       return -EINVAL;
  68 +       u32 cdiv, clk_tout;
  69 +
  70 +       if (!baudrate) {
  71 +               baudrate = baudrate_default;
  72 +               if (pdev->dev.of_node) {
  73 +                       u32 bus_clk_rate;
  74 +                       pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
  75 +                       if (pdev->id < 0) {
  76 +                               dev_err(&pdev->dev, "alias is missing\n");
  77 +                               return -EINVAL;
  78 +                       }
  79 +                       if (!of_property_read_u32(pdev->dev.of_node,
  80 +                                               "clock-frequency", &bus_clk_rate))
  81 +                               baudrate = bus_clk_rate;
  82 +                       else
  83 +                               dev_warn(&pdev->dev,
  84 +                                       "Could not read clock-frequency property\n");
  85                 }
  86 -               if (!of_property_read_u32(pdev->dev.of_node,
  87 -                                       "clock-frequency", &bus_clk_rate))
  88 -                       baudrate = bus_clk_rate;
  89 -               else
  90 -                       dev_warn(&pdev->dev,
  91 -                               "Could not read clock-frequency property\n");
  92         }
  93
  94         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  95 @@ -417,7 +424,13 @@ static int bcm2708_i2c_probe(struct plat
  96                 cdiv = 0xffff;
  97                 baudrate = bus_hz / cdiv;
  98         }
  99 +
 100 +       clk_tout = 35/1000*baudrate; //35ms timeout as per SMBus specs.
 101 +       if (clk_tout > 0xffff)
 102 +               clk_tout = 0xffff;
 103 +
 104         bi->cdiv = cdiv;
 105 +       bi->clk_tout = clk_tout;
 106
 107         dev_info(&pdev->dev, "BSC%d Controller at 0x%08lx (irq %d) (baudrate %d)\n",
 108                 pdev->id, (unsigned long)regs->start, irq, baudrate);