target/linux/brcm2708/patches-3.10/0055-Add-bitbanging-pullups-use-them-for-w1-gpio.patch

   1 From 0a2fa5a85c2ed9599acb2215f24e06db0379a133 Mon Sep 17 00:00:00 2001
   2 From: popcornmix <popcornmix@gmail.com>
   3 Date: Wed, 1 May 2013 21:14:28 +0100
   4 Subject: [PATCH 055/196] Add bitbanging pullups, use them for w1-gpio
   5
   6 Allows parasite power to work, uses module option pullup=1
   7 ---
   8  drivers/w1/masters/w1-gpio.c | 20 ++++++++++++++++++++
   9  drivers/w1/w1.h              |  6 ++++++
  10  drivers/w1/w1_int.c          | 16 +++++++++-------
  11  drivers/w1/w1_io.c           | 18 +++++++++++++++---
  12  4 files changed, 50 insertions(+), 10 deletions(-)
  13
  14 diff --git a/drivers/w1/masters/w1-gpio.c b/drivers/w1/masters/w1-gpio.c
  15 index 46d9701..f615f80 100644
  16 --- a/drivers/w1/masters/w1-gpio.c
  17 +++ b/drivers/w1/masters/w1-gpio.c
  18 @@ -23,6 +23,9 @@
  19  #include "../w1.h"
  20  #include "../w1_int.h"
  21
  22 +static int w1_gpio_pullup = 0;
  23 +module_param_named(pullup, w1_gpio_pullup, int, 0);
  24 +
  25  static void w1_gpio_write_bit_dir(void *data, u8 bit)
  26  {
  27         struct w1_gpio_platform_data *pdata = data;
  28 @@ -47,6 +50,16 @@ static u8 w1_gpio_read_bit(void *data)
  29         return gpio_get_value(pdata->pin) ? 1 : 0;
  30  }
  31
  32 +static void w1_gpio_bitbang_pullup(void *data, u8 on)
  33 +{
  34 +       struct w1_gpio_platform_data *pdata = data;
  35 +
  36 +       if (on)
  37 +               gpio_direction_output(pdata->pin, 1);
  38 +       else
  39 +               gpio_direction_input(pdata->pin);
  40 +}
  41 +
  42  #if defined(CONFIG_OF)
  43  static struct of_device_id w1_gpio_dt_ids[] = {
  44         { .compatible = "w1-gpio" },
  45 @@ -133,6 +146,13 @@ static int w1_gpio_probe(struct platform_device *pdev)
  46                 master->write_bit = w1_gpio_write_bit_dir;
  47         }
  48
  49 +       if (w1_gpio_pullup)
  50 +               if (pdata->is_open_drain)
  51 +                       printk(KERN_ERR "w1-gpio 'pullup' option "
  52 +                              "doesn't work with open drain GPIO\n");
  53 +               else
  54 +                       master->bitbang_pullup = w1_gpio_bitbang_pullup;
  55 +
  56         err = w1_add_master_device(master);
  57         if (err) {
  58                 dev_err(&pdev->dev, "w1_add_master device failed\n");
  59 diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
  60 index 45908e5..0ba75f6 100644
  61 --- a/drivers/w1/w1.h
  62 +++ b/drivers/w1/w1.h
  63 @@ -148,6 +148,12 @@ struct w1_bus_master
  64          */
  65         u8              (*set_pullup)(void *, int);
  66
  67 +       /**
  68 +        * Turns the pullup on/off in bitbanging mode, takes an on/off argument.
  69 +        * @return -1=Error, 0=completed
  70 +        */
  71 +       void (*bitbang_pullup) (void *, u8);
  72 +
  73         /** Really nice hardware can handles the different types of ROM search
  74          *  w1_master* is passed to the slave found callback.
  75          */
  76 diff --git a/drivers/w1/w1_int.c b/drivers/w1/w1_int.c
  77 index 5a98649..a4d69b6 100644
  78 --- a/drivers/w1/w1_int.c
  79 +++ b/drivers/w1/w1_int.c
  80 @@ -117,19 +117,21 @@ int w1_add_master_device(struct w1_bus_master *master)
  81                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
  82                 return(-EINVAL);
  83          }
  84 -       /* While it would be electrically possible to make a device that
  85 -        * generated a strong pullup in bit bang mode, only hardware that
  86 -        * controls 1-wire time frames are even expected to support a strong
  87 -        * pullup.  w1_io.c would need to support calling set_pullup before
  88 -        * the last write_bit operation of a w1_write_8 which it currently
  89 -        * doesn't.
  90 -        */
  91 +
  92 +       /* bitbanging hardware uses bitbang_pullup, other hardware uses set_pullup
  93 +        * and takes care of timing itself */
  94         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
  95                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
  96                         "write_byte or touch_bit, disabling\n");
  97                 master->set_pullup = NULL;
  98         }
  99
 100 +       if (master->set_pullup && master->bitbang_pullup) {
 101 +               printk(KERN_ERR "w1_add_master_device: set_pullup should not "
 102 +                      "be set when bitbang_pullup is used, disabling\n");
 103 +               master->set_pullup = NULL;
 104 +       }
 105 +
 106         /* Lock until the device is added (or not) to w1_masters. */
 107         mutex_lock(&w1_mlock);
 108         /* Search for the first available id (starting at 1). */
 109 diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
 110 index e10acc2..667fdd5 100644
 111 --- a/drivers/w1/w1_io.c
 112 +++ b/drivers/w1/w1_io.c
 113 @@ -127,10 +127,22 @@ static void w1_pre_write(struct w1_master *dev)
 114  static void w1_post_write(struct w1_master *dev)
 115  {
 116         if (dev->pullup_duration) {
 117 -               if (dev->enable_pullup && dev->bus_master->set_pullup)
 118 -                       dev->bus_master->set_pullup(dev->bus_master->data, 0);
 119 -               else
 120 +               if (dev->enable_pullup) {
 121 +                       if (dev->bus_master->set_pullup) {
 122 +                               dev->bus_master->set_pullup(dev->
 123 +                                                           bus_master->data,
 124 +                                                           0);
 125 +                       } else if (dev->bus_master->bitbang_pullup) {
 126 +                               dev->bus_master->
 127 +                                   bitbang_pullup(dev->bus_master->data, 1);
 128 +                       msleep(dev->pullup_duration);
 129 +                               dev->bus_master->
 130 +                                   bitbang_pullup(dev->bus_master->data, 0);
 131 +                       }
 132 +               } else {
 133                         msleep(dev->pullup_duration);
 134 +               }
 135 +
 136                 dev->pullup_duration = 0;
 137         }
 138  }
 139 --
 140 1.9.1
 141