target/linux/brcm2708/patches-4.4/0121-Extend-clock-timeout-fix-modprobe-baudrate-parameter.patch

   1 From 29171b2e2b69a4edb84bd228e1d9ea0451e7dcd2 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] Extend clock timeout, fix modprobe baudrate parameter.
   5
   6 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.
   7 ---
   8  drivers/i2c/busses/i2c-bcm2708.c | 45 ++++++++++++++++++++++++++--------------
   9  1 file changed, 29 insertions(+), 16 deletions(-)
  10
  11 --- a/drivers/i2c/busses/i2c-bcm2708.c
  12 +++ b/drivers/i2c/busses/i2c-bcm2708.c
  13 @@ -71,7 +71,8 @@
  14
  15  #define DRV_NAME               "bcm2708_i2c"
  16
  17 -static unsigned int baudrate = CONFIG_I2C_BCM2708_BAUDRATE;
  18 +static unsigned int baudrate_default = CONFIG_I2C_BCM2708_BAUDRATE;
  19 +static unsigned int baudrate;
  20  module_param(baudrate, uint, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
  21  MODULE_PARM_DESC(baudrate, "The I2C baudrate");
  22
  23 @@ -87,6 +88,7 @@ struct bcm2708_i2c {
  24         int irq;
  25         struct clk *clk;
  26         u32 cdiv;
  27 +       u32 clk_tout;
  28
  29         struct completion done;
  30
  31 @@ -126,7 +128,7 @@ static inline void bcm2708_bsc_fifo_fill
  32
  33  static inline int bcm2708_bsc_setup(struct bcm2708_i2c *bi)
  34  {
  35 -       u32 cdiv, s;
  36 +       u32 cdiv, s, clk_tout;
  37         u32 c = BSC_C_I2CEN | BSC_C_INTD | BSC_C_ST | BSC_C_CLEAR_1;
  38         int wait_loops = I2C_WAIT_LOOP_COUNT;
  39
  40 @@ -134,12 +136,14 @@ static inline int bcm2708_bsc_setup(stru
  41          * Use the value that we cached in the probe.
  42          */
  43         cdiv = bi->cdiv;
  44 +       clk_tout = bi->clk_tout;
  45
  46         if (bi->msg->flags & I2C_M_RD)
  47                 c |= BSC_C_INTR | BSC_C_READ;
  48         else
  49                 c |= BSC_C_INTT;
  50
  51 +       bcm2708_wr(bi, BSC_CLKT, clk_tout);
  52         bcm2708_wr(bi, BSC_DIV, cdiv);
  53         bcm2708_wr(bi, BSC_A, bi->msg->addr);
  54         bcm2708_wr(bi, BSC_DLEN, bi->msg->len);
  55 @@ -312,21 +316,24 @@ static int bcm2708_i2c_probe(struct plat
  56         struct bcm2708_i2c *bi;
  57         struct i2c_adapter *adap;
  58         unsigned long bus_hz;
  59 -       u32 cdiv;
  60 -
  61 -       if (pdev->dev.of_node) {
  62 -               u32 bus_clk_rate;
  63 -               pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
  64 -               if (pdev->id < 0) {
  65 -                       dev_err(&pdev->dev, "alias is missing\n");
  66 -                       return -EINVAL;
  67 +       u32 cdiv, clk_tout;
  68 +
  69 +       if (!baudrate) {
  70 +               baudrate = baudrate_default;
  71 +               if (pdev->dev.of_node) {
  72 +                       u32 bus_clk_rate;
  73 +                       pdev->id = of_alias_get_id(pdev->dev.of_node, "i2c");
  74 +                       if (pdev->id < 0) {
  75 +                               dev_err(&pdev->dev, "alias is missing\n");
  76 +                               return -EINVAL;
  77 +                       }
  78 +                       if (!of_property_read_u32(pdev->dev.of_node,
  79 +                                               "clock-frequency", &bus_clk_rate))
  80 +                               baudrate = bus_clk_rate;
  81 +                       else
  82 +                               dev_warn(&pdev->dev,
  83 +                                       "Could not read clock-frequency property\n");
  84                 }
  85 -               if (!of_property_read_u32(pdev->dev.of_node,
  86 -                                       "clock-frequency", &bus_clk_rate))
  87 -                       baudrate = bus_clk_rate;
  88 -               else
  89 -                       dev_warn(&pdev->dev,
  90 -                               "Could not read clock-frequency property\n");
  91         }
  92
  93         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  94 @@ -417,7 +424,13 @@ static int bcm2708_i2c_probe(struct plat
  95                 cdiv = 0xffff;
  96                 baudrate = bus_hz / cdiv;
  97         }
  98 +
  99 +       clk_tout = 35/1000*baudrate; //35ms timeout as per SMBus specs.
 100 +       if (clk_tout > 0xffff)
 101 +               clk_tout = 0xffff;
 102 +
 103         bi->cdiv = cdiv;
 104 +       bi->clk_tout = clk_tout;
 105
 106         dev_info(&pdev->dev, "BSC%d Controller at 0x%08lx (irq %d) (baudrate %d)\n",
 107                 pdev->id, (unsigned long)regs->start, irq, baudrate);