Re: [PATCH 3/5] drm/amd/display: Add sysfs interface for set/get srm

[Bhawanpreet Lakha <Bhawanpreet.lakha@xxxxxxx>]

On 2020-01-17 2:23 p.m., Alex Deucher wrote:
> On Thu, Jan 16, 2020 at 3:30 PM Bhawanpreet Lakha
> <Bhawanpreet.Lakha@xxxxxxx> wrote:
> > [Why]
> > We need to set/get SRM and linux kernel is not suppose to write to the
> > storage, so we need to provide a interface.
> >
> > [How]
> > Provide interface so usermode can set/get srm
> >
> > Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@xxxxxxx>
> > Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
> > ---
> >   .../amd/display/amdgpu_dm/amdgpu_dm_hdcp.c    | 124 +++++++++++++++++-
> >   .../amd/display/amdgpu_dm/amdgpu_dm_hdcp.h    |   6 +
> >   2 files changed, 128 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c
> > index a269916f7dd6..a191c84ad8eb 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.c
> > @@ -28,6 +28,8 @@
> >   #include "amdgpu_dm.h"
> >   #include "dm_helpers.h"
> >   #include <drm/drm_hdcp.h>
> > +#include "hdcp_psp.h"
> > +
> >
> >   static bool
> >   lp_write_i2c(void *handle, uint32_t address, const uint8_t *data, uint32_t size)
> > @@ -67,6 +69,16 @@ lp_read_dpcd(void *handle, uint32_t address, uint8_t *data, uint32_t size)
> >          return dm_helpers_dp_read_dpcd(link->ctx, link, address, data, size);
> >   }
> >
> > +static uint8_t *psp_get_srm(struct psp_context *psp, uint32_t *srm_version, uint32_t *srm_size)
> > +{
> > +       return NULL;
> > +}
> > +
> > +static int psp_set_srm(struct psp_context *psp, uint8_t *srm, uint32_t srm_size, uint32_t *srm_version)
> > +{
> > +       return 0;
> > +}
> > +
> >   static void process_output(struct hdcp_workqueue *hdcp_work)
> >   {
> >          struct mod_hdcp_output output = hdcp_work->output;
> > @@ -88,6 +100,18 @@ static void process_output(struct hdcp_workqueue *hdcp_work)
> >          schedule_delayed_work(&hdcp_work->property_validate_dwork, msecs_to_jiffies(0));
> >   }
> >
> > +static void link_lock(struct hdcp_workqueue *work, bool lock)
> > +{
> > +
> > +       int i = 0;
> > +
> > +       for (i = 0; i < work->max_link; i++) {
> > +               if (lock)
> > +                       mutex_lock(&work[i].mutex);
> > +               else
> > +                       mutex_unlock(&work[i].mutex);
> > +       }
> > +}
> >   void hdcp_update_display(struct hdcp_workqueue *hdcp_work,
> >                           unsigned int link_index,
> >                           struct amdgpu_dm_connector *aconnector,
> > @@ -302,7 +326,8 @@ void hdcp_destroy(struct hdcp_workqueue *hdcp_work)
> >          }
> >
> >          kfree(hdcp_work);
> > -
> > +       kfree(hdcp_work->srm);
> > +       kfree(hdcp_work->srm_temp);
> >   }
> >
> >   static void update_config(void *handle, struct cp_psp_stream_config *config)
> > @@ -338,6 +363,84 @@ static void update_config(void *handle, struct cp_psp_stream_config *config)
> >          hdcp_update_display(hdcp_work, link_index, aconnector, DRM_MODE_HDCP_CONTENT_TYPE0, false);
> >   }
> >
> > +
> > +/*
> > + * This can be called twice, because SRM_SIZE > PAGE_SIZE.
> > + *
> > + * We set the SRM on each call, if SRM_SIZE > PAGE_SIZE, PSP will fail on the
> > + * first call but pass on the second call.
> > + *
> > + * Because of this we are not throwing any errors as it will stop the next call.
> > + * So it is a good idea to call the "read" sysfs to verify that the SRM was set
> > + *
> > + */
> Rather than using a file to get the data directly in chunks, how about
> adding a sysfs file where you can specify the path to the srm file.
> The driver can then use the path provided to call request firmware and
> just get the entire binary in one shot.
>
> Alex
I thought about using request_firmware but, since we also need to save 
the data aswell

and there is no "save_firmware" interface, we would have difference 
interfaces for reading and writing.

So to keep it consistent I used sysfs for both. Now we just cat and echo 
the raw data. vs echo file patch and cat raw data.


Bhawan

> > +static ssize_t srm_data_write(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, char *buffer,
> > +                             loff_t pos, size_t count)
> > +{
> > +       struct hdcp_workqueue *work;
> > +       uint32_t srm_version = 0;
> > +
> > +       work = container_of(bin_attr, struct hdcp_workqueue, attr);
> > +       link_lock(work, true);
> > +
> > +       memcpy(work->srm_temp + pos, buffer, count);
> > +
> > +       if (!psp_set_srm(work->hdcp.config.psp.handle, work->srm_temp, pos + count, &srm_version)) {
> > +               DRM_DEBUG_DRIVER("HDCP SRM SET version 0x%X", srm_version);
> > +               memcpy(work->srm, work->srm_temp, pos + count);
> > +               work->srm_size = pos + count;
> > +               work->srm_version = srm_version;
> > +       }
> > +
> > +
> > +       link_lock(work, false);
> > +
> > +       return count;
> > +}
> > +
> > +static ssize_t srm_data_read(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, char *buffer,
> > +                            loff_t pos, size_t count)
> > +{
> > +       struct hdcp_workqueue *work;
> > +       uint8_t *srm = NULL;
> > +       uint32_t srm_version;
> > +       uint32_t srm_size;
> > +       size_t ret = count;
> > +
> > +       work = container_of(bin_attr, struct hdcp_workqueue, attr);
> > +
> > +       link_lock(work, true);
> > +
> > +       srm = psp_get_srm(work->hdcp.config.psp.handle, &srm_version, &srm_size);
> > +
> > +       if (!srm)
> > +               return -EINVAL;
> > +
> > +       if (pos >= srm_size)
> > +               ret = 0;
> > +
> > +       if (srm_size - pos < count) {
> > +               memcpy(buffer, srm + pos, srm_size - pos);
> > +               ret = srm_size - pos;
> > +               goto ret;
> > +       }
> > +
> > +       memcpy(buffer, srm + pos, count);
> > +
> > +ret:
> > +       link_lock(work, false);
> > +       return ret;
> > +}
> > +
> > +
> > +static const struct bin_attribute data_attr = {
> > +       .attr = {.name = "hdcp_srm", .mode = 0664},
> > +       .size = PSP_HDCP_SRM_FIRST_GEN_MAX_SIZE, /* Limit SRM size */
> > +       .write = srm_data_write,
> > +       .read = srm_data_read,
> > +};
> > +
> > +
> >   struct hdcp_workqueue *hdcp_create_workqueue(struct amdgpu_device *adev, struct cp_psp *cp_psp, struct dc *dc)
> >   {
> >
> > @@ -348,10 +451,19 @@ struct hdcp_workqueue *hdcp_create_workqueue(struct amdgpu_device *adev, struct
> >          if (hdcp_work == NULL)
> >                  goto fail_alloc_context;
> >
> > +       hdcp_work->srm = kcalloc(PSP_HDCP_SRM_FIRST_GEN_MAX_SIZE, sizeof(*hdcp_work->srm), GFP_KERNEL);
> > +
> > +       if (hdcp_work->srm == NULL)
> > +               goto fail_alloc_context;
> > +
> > +       hdcp_work->srm_temp = kcalloc(PSP_HDCP_SRM_FIRST_GEN_MAX_SIZE, sizeof(*hdcp_work->srm_temp), GFP_KERNEL);
> > +
> > +       if (hdcp_work->srm_temp == NULL)
> > +               goto fail_alloc_context;
> > +
> >          hdcp_work->max_link = max_caps;
> >
> >          for (i = 0; i < max_caps; i++) {
> > -
> >                  mutex_init(&hdcp_work[i].mutex);
> >
> >                  INIT_WORK(&hdcp_work[i].cpirq_work, event_cpirq);
> > @@ -371,10 +483,18 @@ struct hdcp_workqueue *hdcp_create_workqueue(struct amdgpu_device *adev, struct
> >          cp_psp->funcs.update_stream_config = update_config;
> >          cp_psp->handle = hdcp_work;
> >
> > +       /* File created at /sys/class/drm/card0/device/hdcp_srm*/
> > +       hdcp_work[0].attr = data_attr;
> > +
> > +       if (sysfs_create_bin_file(&adev->dev->kobj, &hdcp_work[0].attr))
> > +               DRM_WARN("Failed to create device file hdcp_srm");
> > +
> >          return hdcp_work;
> >
> >   fail_alloc_context:
> >          kfree(hdcp_work);
> > +       kfree(hdcp_work->srm);
> > +       kfree(hdcp_work->srm_temp);
> >
> >          return NULL;
> >
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.h
> > index 331b50825510..5159b3a5e5b0 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.h
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.h
> > @@ -53,6 +53,12 @@ struct hdcp_workqueue {
> >
> >          enum mod_hdcp_encryption_status encryption_status;
> >          uint8_t max_link;
> > +
> > +       uint8_t *srm;
> > +       uint8_t *srm_temp;
> > +       uint32_t srm_version;
> > +       uint32_t srm_size;
> > +       struct bin_attribute attr;
> >   };
> >
> >   void hdcp_update_display(struct hdcp_workqueue *hdcp_work,
> > --
> > 2.17.1
> >
> > _______________________________________________
> > amd-gfx mailing list
> > amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> > https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.freedesktop.org%2Fmailman%2Flistinfo%2Famd-gfx&amp;data=02%7C01%7CBhawanpreet.Lakha%40amd.com%7C31850cb2894b4459b6cf08d79b82b6af%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637148858026280913&amp;sdata=%2BncbIbzgws%2BKPbTAqzARNGAZWM66UoxzjDeJm6vvXlg%3D&amp;reserved=0
_______________________________________________
amd-gfx mailing list
amd-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/amd-gfx