target/linux/layerscape/patches-4.4/7193-staging-fsl-mc-add-device-binding-path-driver_overri.patch

   1 From 0bda83c15b2ecfc45fac0656df15d4f4fa65afa9 Mon Sep 17 00:00:00 2001
   2 From: Bharat Bhushan <bharat.bhushan@freescale.com>
   3 Date: Wed, 18 Mar 2015 17:32:59 -0500
   4 Subject: [PATCH 193/226] staging: fsl-mc: add device binding path
   5  'driver_override'
   6
   7 This patch is required for vfio-fsl-mc meta driver to successfully bind
   8 layerscape container devices for device passthrough. This patch adds
   9 a mechanism to allow a layerscape device to specify a driver rather than
  10 a layerscape driver provide a device match.
  11
  12 This patch is based on following proposed patches for PCI and platform devices
  13 - https://lkml.org/lkml/2014/4/8/571  :- For Platform devices
  14 - http://lists-archives.com/linux-kernel/28030441-pci-introduce-new-device-binding-path-using-pci_dev-driver_override.html  :- For PCI devices
  15
  16 Example to allow a device (dprc.1) to specifically bind
  17 with driver (vfio-fsl-mc):-
  18 - echo vfio-fsl-mc > /sys/bus/fsl-mc/devices/dprc.1/driver_override
  19 - echo dprc.1 > /sys/bus/fsl-mc/drivers/fsl_mc_dprc/unbind
  20 - echo dprc.1 > /sys/bus/fsl-mc/drivers/vfio-fsl-mc/bind
  21
  22 Signed-off-by: J. German Rivera <German.Rivera@freescale.com>
  23 (Stuart: resolved merge conflicts)
  24 Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
  25 ---
  26  drivers/staging/fsl-mc/bus/mc-bus.c |   53 +++++++++++++++++++++++++++++++++++
  27  1 file changed, 53 insertions(+)
  28
  29 --- a/drivers/staging/fsl-mc/bus/mc-bus.c
  30 +++ b/drivers/staging/fsl-mc/bus/mc-bus.c
  31 @@ -42,6 +42,12 @@ static int fsl_mc_bus_match(struct devic
  32         if (WARN_ON(!fsl_mc_bus_exists()))
  33                 goto out;
  34
  35 +       /* When driver_override is set, only bind to the matching driver */
  36 +       if (mc_dev->driver_override) {
  37 +               found = !strcmp(mc_dev->driver_override, mc_drv->driver.name);
  38 +               goto out;
  39 +       }
  40 +
  41         if (!mc_drv->match_id_table)
  42                 goto out;
  43
  44 @@ -96,6 +102,50 @@ static ssize_t modalias_show(struct devi
  45  }
  46  static DEVICE_ATTR_RO(modalias);
  47
  48 +static ssize_t driver_override_store(struct device *dev,
  49 +                                    struct device_attribute *attr,
  50 +                                    const char *buf, size_t count)
  51 +{
  52 +       struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
  53 +       const char *driver_override, *old = mc_dev->driver_override;
  54 +       char *cp;
  55 +
  56 +       if (WARN_ON(dev->bus != &fsl_mc_bus_type))
  57 +               return -EINVAL;
  58 +
  59 +       if (count > PATH_MAX)
  60 +               return -EINVAL;
  61 +
  62 +       driver_override = kstrndup(buf, count, GFP_KERNEL);
  63 +       if (!driver_override)
  64 +               return -ENOMEM;
  65 +
  66 +       cp = strchr(driver_override, '\n');
  67 +       if (cp)
  68 +               *cp = '\0';
  69 +
  70 +       if (strlen(driver_override)) {
  71 +               mc_dev->driver_override = driver_override;
  72 +       } else {
  73 +               kfree(driver_override);
  74 +               mc_dev->driver_override = NULL;
  75 +       }
  76 +
  77 +       kfree(old);
  78 +
  79 +       return count;
  80 +}
  81 +
  82 +static ssize_t driver_override_show(struct device *dev,
  83 +                                   struct device_attribute *attr, char *buf)
  84 +{
  85 +       struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
  86 +
  87 +       return sprintf(buf, "%s\n", mc_dev->driver_override);
  88 +}
  89 +
  90 +static DEVICE_ATTR_RW(driver_override);
  91 +
  92  static ssize_t rescan_store(struct device *dev,
  93                             struct device_attribute *attr,
  94                             const char *buf, size_t count)
  95 @@ -127,6 +177,7 @@ static DEVICE_ATTR_WO(rescan);
  96  static struct attribute *fsl_mc_dev_attrs[] = {
  97         &dev_attr_modalias.attr,
  98         &dev_attr_rescan.attr,
  99 +       &dev_attr_driver_override.attr,
 100         NULL,
 101  };
 102
 103 @@ -677,6 +728,8 @@ void fsl_mc_device_remove(struct fsl_mc_
 104                 }
 105         }
 106
 107 +       kfree(mc_dev->driver_override);
 108 +       mc_dev->driver_override = NULL;
 109         if (mc_bus)
 110                 devm_kfree(mc_dev->dev.parent, mc_bus);
 111         else