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

   1 From 28ca85a46bbdae4152b48a669872ac205d053856 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 055/174] 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 --- a/drivers/w1/masters/w1-gpio.c
  15 +++ b/drivers/w1/masters/w1-gpio.c
  16 @@ -23,6 +23,9 @@
  17  #include "../w1.h"
  18  #include "../w1_int.h"
  19
  20 +static int w1_gpio_pullup = 0;
  21 +module_param_named(pullup, w1_gpio_pullup, int, 0);
  22 +
  23  static void w1_gpio_write_bit_dir(void *data, u8 bit)
  24  {
  25         struct w1_gpio_platform_data *pdata = data;
  26 @@ -47,6 +50,16 @@ static u8 w1_gpio_read_bit(void *data)
  27         return gpio_get_value(pdata->pin) ? 1 : 0;
  28  }
  29
  30 +static void w1_gpio_bitbang_pullup(void *data, u8 on)
  31 +{
  32 +       struct w1_gpio_platform_data *pdata = data;
  33 +
  34 +       if (on)
  35 +               gpio_direction_output(pdata->pin, 1);
  36 +       else
  37 +               gpio_direction_input(pdata->pin);
  38 +}
  39 +
  40  #if defined(CONFIG_OF)
  41  static struct of_device_id w1_gpio_dt_ids[] = {
  42         { .compatible = "w1-gpio" },
  43 @@ -133,6 +146,13 @@ static int w1_gpio_probe(struct platform
  44                 master->write_bit = w1_gpio_write_bit_dir;
  45         }
  46
  47 +       if (w1_gpio_pullup)
  48 +               if (pdata->is_open_drain)
  49 +                       printk(KERN_ERR "w1-gpio 'pullup' option "
  50 +                              "doesn't work with open drain GPIO\n");
  51 +               else
  52 +                       master->bitbang_pullup = w1_gpio_bitbang_pullup;
  53 +
  54         err = w1_add_master_device(master);
  55         if (err) {
  56                 dev_err(&pdev->dev, "w1_add_master device failed\n");
  57 --- a/drivers/w1/w1.h
  58 +++ b/drivers/w1/w1.h
  59 @@ -148,6 +148,12 @@ struct w1_bus_master
  60          */
  61         u8              (*set_pullup)(void *, int);
  62
  63 +       /**
  64 +        * Turns the pullup on/off in bitbanging mode, takes an on/off argument.
  65 +        * @return -1=Error, 0=completed
  66 +        */
  67 +       void (*bitbang_pullup) (void *, u8);
  68 +
  69         /** Really nice hardware can handles the different types of ROM search
  70          *  w1_master* is passed to the slave found callback.
  71          */
  72 --- a/drivers/w1/w1_int.c
  73 +++ b/drivers/w1/w1_int.c
  74 @@ -117,19 +117,21 @@ int w1_add_master_device(struct w1_bus_m
  75                 printk(KERN_ERR "w1_add_master_device: invalid function set\n");
  76                 return(-EINVAL);
  77          }
  78 -       /* While it would be electrically possible to make a device that
  79 -        * generated a strong pullup in bit bang mode, only hardware that
  80 -        * controls 1-wire time frames are even expected to support a strong
  81 -        * pullup.  w1_io.c would need to support calling set_pullup before
  82 -        * the last write_bit operation of a w1_write_8 which it currently
  83 -        * doesn't.
  84 -        */
  85 +
  86 +       /* bitbanging hardware uses bitbang_pullup, other hardware uses set_pullup
  87 +        * and takes care of timing itself */
  88         if (!master->write_byte && !master->touch_bit && master->set_pullup) {
  89                 printk(KERN_ERR "w1_add_master_device: set_pullup requires "
  90                         "write_byte or touch_bit, disabling\n");
  91                 master->set_pullup = NULL;
  92         }
  93
  94 +       if (master->set_pullup && master->bitbang_pullup) {
  95 +               printk(KERN_ERR "w1_add_master_device: set_pullup should not "
  96 +                      "be set when bitbang_pullup is used, disabling\n");
  97 +               master->set_pullup = NULL;
  98 +       }
  99 +
 100         /* Lock until the device is added (or not) to w1_masters. */
 101         mutex_lock(&w1_mlock);
 102         /* Search for the first available id (starting at 1). */
 103 --- a/drivers/w1/w1_io.c
 104 +++ b/drivers/w1/w1_io.c
 105 @@ -127,10 +127,22 @@ static void w1_pre_write(struct w1_maste
 106  static void w1_post_write(struct w1_master *dev)
 107  {
 108         if (dev->pullup_duration) {
 109 -               if (dev->enable_pullup && dev->bus_master->set_pullup)
 110 -                       dev->bus_master->set_pullup(dev->bus_master->data, 0);
 111 -               else
 112 +               if (dev->enable_pullup) {
 113 +                       if (dev->bus_master->set_pullup) {
 114 +                               dev->bus_master->set_pullup(dev->
 115 +                                                           bus_master->data,
 116 +                                                           0);
 117 +                       } else if (dev->bus_master->bitbang_pullup) {
 118 +                               dev->bus_master->
 119 +                                   bitbang_pullup(dev->bus_master->data, 1);
 120                         msleep(dev->pullup_duration);
 121 +                               dev->bus_master->
 122 +                                   bitbang_pullup(dev->bus_master->data, 0);
 123 +                       }
 124 +               } else {
 125 +                       msleep(dev->pullup_duration);
 126 +               }
 127 +
 128                 dev->pullup_duration = 0;
 129         }
 130  }