From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH] of/platform: Support dynamic device tree on AMBA bus References: <1540485597-12240-1-git-send-email-jaewon02.kim@samsung.com> <1f7b35fd-7900-0c48-50a2-4f84481a208c@gmail.com> <20181106131140.GA27291@bogus> From: Jaewon Kim Message-ID: <157391f7-eb1a-982d-37fd-8255d32844cf@gmail.com> Date: Fri, 9 Nov 2018 23:55:37 +0900 MIME-Version: 1.0 In-Reply-To: <20181106131140.GA27291@bogus> Content-Type: multipart/alternative; boundary="------------98B86053D959AF7F22993E81" Content-Language: en-US To: Rob Herring Cc: Frank Rowand , jaewon02.kim@samsung.com, devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" List-ID: This is a multi-part message in MIME format. --------------98B86053D959AF7F22993E81 Content-Type: text/plain; charset=euc-kr; format=flowed Content-Transfer-Encoding: 7bit On 11/6/18 10:11 PM, Rob Herring wrote: > On Tue, Nov 06, 2018 at 01:49:05AM +0900, Jaewon Kim wrote: >> Hi Rob, >> >> On 11/1/18 3:31 AM, Rob Herring wrote: >>> On Thu, Oct 25, 2018 at 11:40 AM Jaewon Kim wrote: >>>> This patch supports dynamic device-tree for AMBA device. >>>> The AMBA device must be registered on the AMBA bus, not the platform bus. >>> I'm not convinced we should even support this. There's a limited >>> number of AMBA devices. They would almost certainly be on-chip and >>> static. I suppose in theory you could have them in an FPGA, but >>> generally the FPGA vendors have their own IP blocks and don't use ARM >>> Primecell IP. So what is the usecase? >> In my case, our target has GPIO output pin, like RPI board. And I want to >> use dt-overlay to change GPIO alternative function. But, I found that AMBA >> device not work with dt-overlay. Most AMBA devices do not require dynamic >> device-tree. But, pl022(serial) and pl011(SPI) needs dynamic device-tree. > The bootloader should apply the overlay. > >>>> Signed-off-by: Jaewon Kim >>> Your author and S-o-b emails should match. >> Okay, I will change it my gmail. >>>> --- >>>> drivers/of/platform.c | 93 ++++++++++++++++++++++++++++++++++++++++----------- >>>> 1 file changed, 73 insertions(+), 20 deletions(-) >>>> >>>> diff --git a/drivers/of/platform.c b/drivers/of/platform.c >>>> index 04ad312..b9ac105 100644 >>>> --- a/drivers/of/platform.c >>>> +++ b/drivers/of/platform.c >>>> @@ -286,6 +286,22 @@ static struct amba_device *of_amba_device_create(struct device_node *node, >>>> of_node_clear_flag(node, OF_POPULATED); >>>> return NULL; >>>> } >>>> + >>>> +/** >>>> + * of_find_amba_device_by_node - Find the amba_device associated with a node >>>> + * @np: Pointer to device tree node >>>> + * >>>> + * Returns amba_device pointer, or NULL if not found >>>> + */ >>>> +struct amba_device *of_find_amba_device_by_node(struct device_node *np) >>>> +{ >>>> + struct device *dev; >>>> + >>>> + dev = bus_find_device(&amba_bustype, NULL, np, of_dev_node_match); >>>> + return dev ? to_amba_device(dev) : NULL; >>>> +} >>>> +EXPORT_SYMBOL(of_find_amba_device_by_node); >>> I would prefer we add (or change the platform device version) an >>> of_find_device_by_node which can be extended to different bus types. >> The returned type is different. of_find_device_by_node () returns 'struct >> platform_device *', and of_find_amba_device_by_node() returns 'struct >> amba_device *'. To make this the same, It need to modify return value of >> of_find_device_by_node() function or merge amba_device to >> platform_device.of_find_device_by_node() function is a widely used kernel >> source and it requires a lot of modifications.I think it would be simpler to >> make of_find_amba_device_by_node(). > You don't have to make treewide changes. Define a new function returning > struct device. Make of_find_device_by_node() a wrapper that gets the > platform_device from the struct device. Okay, I will make a new function that returns struct device on various bus. for example) struct device *of_find_device_by_bus(struct device_node *np, struct bus_type *bus) {}; > >>>> + >>>> #else /* CONFIG_ARM_AMBA */ >>>> static struct amba_device *of_amba_device_create(struct device_node *node, >>>> const char *bus_id, >>>> @@ -294,6 +310,12 @@ static struct amba_device *of_amba_device_create(struct device_node *node, >>>> { >>>> return NULL; >>>> } >>>> + >>>> +struct amba_device *of_find_amba_device_by_node(struct device_node *np) >>>> +{ >>>> + return NULL; >>>> +} >>>> +EXPORT_SYMBOL(of_find_amba_device_by_node); >>>> #endif /* CONFIG_ARM_AMBA */ >>>> >>>> /** >>>> @@ -665,6 +687,7 @@ static int of_platform_notify(struct notifier_block *nb, >>>> { >>>> struct of_reconfig_data *rd = arg; >>>> struct platform_device *pdev_parent, *pdev; >>>> + struct amba_device *adev_p, *adev; >>>> bool children_left; >>>> >>>> switch (of_reconfig_get_state_change(action, rd)) { >>>> @@ -677,17 +700,34 @@ static int of_platform_notify(struct notifier_block *nb, >>>> if (of_node_check_flag(rd->dn, OF_POPULATED)) >>>> return NOTIFY_OK; >>>> >>>> - /* pdev_parent may be NULL when no bus platform device */ >>>> - pdev_parent = of_find_device_by_node(rd->dn->parent); >>>> - pdev = of_platform_device_create(rd->dn, NULL, >>>> - pdev_parent ? &pdev_parent->dev : NULL); >>>> - of_dev_put(pdev_parent); >>>> - >>>> - if (pdev == NULL) { >>>> - pr_err("%s: failed to create for '%pOF'\n", >>>> - __func__, rd->dn); >>>> - /* of_platform_device_create tosses the error code */ >>>> - return notifier_from_errno(-EINVAL); >>>> + if (of_device_is_compatible(rd->dn, "arm,primecell")) { >>>> + /* adev_p may be NULL when no bus amba device */ >>>> + adev_p = of_find_amba_device_by_node(rd->dn->parent); >>> An amba_device can't ever have a parent that's an amba_device. The >>> parent of an amba_device is typically a platform_device for a >>> 'simple-bus'. >> You are right. there is no parent device . >> I will remove it in v2. >> >>>> + adev = of_amba_device_create(rd->dn, NULL, NULL, >>>> + adev_p ? &adev_p->dev : NULL); >>>> + >>>> + if (adev_p) >>>> + put_device(&adev_p->dev); >>>> + >>>> + if (adev == NULL) { >>>> + pr_err("%s: failed to create for '%s'\n", >>>> + __func__, rd->dn->full_name); >>>> + /* of_amba_device_create tosses the error */ >>>> + return notifier_from_errno(-EINVAL); >>>> + } >>>> + } else { >>>> + /* pdev_parent may be NULL when no bus platform device*/ >>>> + pdev_parent = of_find_device_by_node(rd->dn->parent); >>>> + pdev = of_platform_device_create(rd->dn, NULL, >>>> + pdev_parent ? &pdev_parent->dev : NULL); >>>> + of_dev_put(pdev_parent); >>>> + >>>> + if (pdev == NULL) { >>>> + pr_err("%s: failed to create for '%pOF'\n", >>>> + __func__, rd->dn); >>>> + /* of_platform_device_create tosses the error */ >>>> + return notifier_from_errno(-EINVAL); >>>> + } >>> This all pretty much duplicates what of_platform_bus_create() does and >>> we should use it here rather than have another copy. Plus what about >>> handling of any child devices (in the platform device case). >> The code looks duplicated, but processed type of variable is >> different.(struct amba_device, struct platform_device) > of_platform_bus_create() works on both. Also, it handles some conditions > not handled here. > > Rob Okay, i got it. Thanks Jaewon Kim --------------98B86053D959AF7F22993E81 Content-Type: text/html; charset=euc-kr Content-Transfer-Encoding: 7bit 


On 11/6/18 10:11 PM, Rob Herring wrote:

On Tue, Nov 06, 2018 at 01:49:05AM +0900, Jaewon Kim wrote:

Hi Rob,

On 11/1/18 3:31 AM, Rob Herring wrote:

On Thu, Oct 25, 2018 at 11:40 AM Jaewon Kim <jaewon02.kim@gmail.com> wrote:

This patch supports dynamic device-tree for AMBA device.
The AMBA device must be registered on the AMBA bus, not the platform bus.

I'm not convinced we should even support this. There's a limited
number of AMBA devices. They would almost certainly be on-chip and
static. I suppose in theory you could have them in an FPGA, but
generally the FPGA vendors have their own IP blocks and don't use ARM
Primecell IP. So what is the usecase?

In my case, our target has GPIO output pin, like RPI board. And I want to
use dt-overlay to change GPIO alternative function. But, I found that AMBA
device not work with dt-overlay. Most AMBA devices do not require dynamic
device-tree. But, pl022(serial) and pl011(SPI) needs dynamic device-tree.

The bootloader should apply the overlay.



        

          

          

            
Signed-off-by: Jaewon Kim <jaewon02.kim@samsung.com>


          

          
Your author and S-o-b emails should match.


        

        
Okay, I will change it my gmail.


        

          

          

            
---
  drivers/of/platform.c | 93 ++++++++++++++++++++++++++++++++++++++++-----------
  1 file changed, 73 insertions(+), 20 deletions(-)

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 04ad312..b9ac105 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -286,6 +286,22 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
         of_node_clear_flag(node, OF_POPULATED);
         return NULL;
  }
+
+/**
+ * of_find_amba_device_by_node - Find the amba_device associated with a node
+ * @np: Pointer to device tree node
+ *
+ * Returns amba_device pointer, or NULL if not found
+ */
+struct amba_device *of_find_amba_device_by_node(struct device_node *np)
+{
+       struct device *dev;
+
+       dev = bus_find_device(&amba_bustype, NULL, np, of_dev_node_match);
+       return dev ? to_amba_device(dev) : NULL;
+}
+EXPORT_SYMBOL(of_find_amba_device_by_node);


          

          
I would prefer we add (or change the platform device version) an
of_find_device_by_node which can be extended to different bus types.


        

        
The returned type is different. of_find_device_by_node () returns 'struct
platform_device *', and of_find_amba_device_by_node() returns 'struct
amba_device *'. To make this the same, It need to modify return value of
of_find_device_by_node() function or merge amba_device to
platform_device.of_find_device_by_node() function is a widely used kernel
source and it requires a lot of modifications.I think it would be simpler to
make of_find_amba_device_by_node().


      

      
You don't have to make treewide changes. Define a new function returning 
struct device. Make of_find_device_by_node() a wrapper that gets the 
platform_device from the struct device.

    

    
Okay, I will make a new function that returns struct device on various bus.

for example)


    
struct device *of_find_device_by_bus(struct device_node *np, struct bus_type *bus) {};


    

      



      

        

        

          

          

            
+
  #else /* CONFIG_ARM_AMBA */
  static struct amba_device *of_amba_device_create(struct device_node *node,
                                                  const char *bus_id,
@@ -294,6 +310,12 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
  {
         return NULL;
  }
+
+struct amba_device *of_find_amba_device_by_node(struct device_node *np)
+{
+       return NULL;
+}
+EXPORT_SYMBOL(of_find_amba_device_by_node);
  #endif /* CONFIG_ARM_AMBA */

  /**
@@ -665,6 +687,7 @@ static int of_platform_notify(struct notifier_block *nb,
  {
         struct of_reconfig_data *rd = arg;
         struct platform_device *pdev_parent, *pdev;
+       struct amba_device *adev_p, *adev;
         bool children_left;

         switch (of_reconfig_get_state_change(action, rd)) {
@@ -677,17 +700,34 @@ static int of_platform_notify(struct notifier_block *nb,
                 if (of_node_check_flag(rd->dn, OF_POPULATED))
                         return NOTIFY_OK;

-               /* pdev_parent may be NULL when no bus platform device */
-               pdev_parent = of_find_device_by_node(rd->dn->parent);
-               pdev = of_platform_device_create(rd->dn, NULL,
-                               pdev_parent ? &pdev_parent->dev : NULL);
-               of_dev_put(pdev_parent);
-
-               if (pdev == NULL) {
-                       pr_err("%s: failed to create for '%pOF'\n",
-                                       __func__, rd->dn);
-                       /* of_platform_device_create tosses the error code */
-                       return notifier_from_errno(-EINVAL);
+               if (of_device_is_compatible(rd->dn, "arm,primecell")) {
+                       /* adev_p may be NULL when no bus amba device */
+                       adev_p = of_find_amba_device_by_node(rd->dn->parent);


          

          
An amba_device can't ever have a parent that's an amba_device. The
parent of an amba_device is typically a platform_device for a
'simple-bus'.


        

        
You are right. there is no parent device .
I will remove it in v2.



        

          

          

            
+                       adev = of_amba_device_create(rd->dn, NULL, NULL,
+                                       adev_p ? &adev_p->dev : NULL);
+
+                       if (adev_p)
+                               put_device(&adev_p->dev);
+
+                       if (adev == NULL) {
+                               pr_err("%s: failed to create for '%s'\n",
+                                               __func__, rd->dn->full_name);
+                               /* of_amba_device_create tosses the error */
+                               return notifier_from_errno(-EINVAL);
+                       }
+               } else {
+                       /* pdev_parent may be NULL when no bus platform device*/
+                       pdev_parent = of_find_device_by_node(rd->dn->parent);
+                       pdev = of_platform_device_create(rd->dn, NULL,
+                                       pdev_parent ? &pdev_parent->dev : NULL);
+                       of_dev_put(pdev_parent);
+
+                       if (pdev == NULL) {
+                               pr_err("%s: failed to create for '%pOF'\n",
+                                               __func__, rd->dn);
+                               /* of_platform_device_create tosses the error */
+                               return notifier_from_errno(-EINVAL);
+                       }


          

          
This all pretty much duplicates what of_platform_bus_create() does and
we should use it here rather than have another copy. Plus what about
handling of any child devices (in the platform device case).


        

        
The code looks duplicated, but processed type of variable is
different.(struct amba_device, struct platform_device)


      

      
of_platform_bus_create() works on both. Also, it handles some conditions 
not handled here.

Rob


    

    
Okay, i got it.

    
Thanks
Jaewon Kim


  


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