Add two sysfs files as interfaces to inspect or change UMA carveout
size. These files are:

- uma_carveout_options: a read-only file listing all the available
  UMA allocation options and their index.

- uma_carveout: a file that is both readable and writable. On read,
  it shows the index of the current setting. Writing a valid index
  into this file allows users to change the UMA carveout size to that
  option on the next boot.

Co-developed-by: Mario Limonciello (AMD) <[email protected]>
Signed-off-by: Mario Limonciello (AMD) <[email protected]>
Signed-off-by: Yo-Jung Leo Lin (AMD) <[email protected]>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 127 +++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
index 444ab4102168..b9378f34eb79 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
@@ -30,6 +30,7 @@
 #include <linux/power_supply.h>
 #include <linux/pm_runtime.h>
 #include <linux/suspend.h>
+#include <linux/device.h>
 #include <acpi/video.h>
 #include <acpi/actbl.h>
 
@@ -1247,6 +1248,125 @@ int amdgpu_acpi_get_mem_info(struct amdgpu_device 
*adev, int xcc_id,
        return -ENOENT;
 }
 
+static ssize_t uma_carveout_options_show(struct device *dev,
+                                        struct device_attribute *attr,
+                                        char *buf)
+{
+       struct amdgpu_uma_carveout_info *uma_info = 
&amdgpu_acpi_priv.atcs.uma_info;
+       ssize_t size = 0;
+
+       if (!uma_info || !uma_info->num_entries)
+               return -ENODEV;
+
+       for (int i = 0; i < uma_info->num_entries; i++) {
+               size += sysfs_emit_at(buf, size, "%d: %s (%u GB)\n",
+                                     i,
+                                     uma_info->entries[i].name,
+                                     uma_info->entries[i].memory_carved);
+       }
+
+       return size;
+}
+static DEVICE_ATTR_RO(uma_carveout_options);
+
+static ssize_t uma_carveout_show(struct device *dev,
+                                struct device_attribute *attr,
+                                char *buf)
+{
+       return sysfs_emit(buf, "%u\n", 
amdgpu_acpi_priv.atcs.uma_info.uma_option_index);
+}
+
+static ssize_t uma_carveout_store(struct device *dev,
+                                 struct device_attribute *attr,
+                                 const char *buf, size_t count)
+{
+       struct amdgpu_uma_carveout_info *uma_info = 
&amdgpu_acpi_priv.atcs.uma_info;
+       struct drm_device *ddev = dev_get_drvdata(dev);
+       struct amdgpu_device *adev = drm_to_adev(ddev);
+       struct amdgpu_uma_carveout_option *opt;
+       unsigned long val;
+       uint8_t flags;
+       int r;
+
+       r = kstrtoul(buf, 10, &val);
+       if (r)
+               return r;
+
+       if (val >= uma_info->num_entries)
+               return -EINVAL;
+
+       opt = &uma_info->entries[val];
+
+       if (!(opt->flags & AMDGPU_UMA_FLAG_AUTO) &&
+           !(opt->flags & AMDGPU_UMA_FLAG_CUSTOM)) {
+               drm_err_once(ddev, "Option %ul not supported due to lack of 
Custom/Auto flag", r);
+               return -EINVAL;
+       }
+
+       flags = opt->flags;
+       flags &= ~((flags & AMDGPU_UMA_FLAG_AUTO) >> 1);
+
+       guard(mutex)(&uma_info->update_lock);
+
+       r = amdgpu_acpi_set_uma_allocation_size(adev, val, flags);
+       if (r)
+               return r;
+
+       uma_info->uma_option_index = val;
+
+       return count;
+}
+static DEVICE_ATTR_RW(uma_carveout);
+
+static struct attribute *amdgpu_uma_attrs[] = {
+       &dev_attr_uma_carveout.attr,
+       &dev_attr_uma_carveout_options.attr,
+       NULL
+};
+
+const struct attribute_group amdgpu_uma_attr_group = {
+       .attrs = amdgpu_uma_attrs
+};
+
+static int amdgpu_acpi_uma_option_init(struct amdgpu_device *adev)
+{
+       struct amdgpu_atcs *atcs = &amdgpu_acpi_priv.atcs;
+       int rc;
+
+       if (!atcs->functions.set_uma_allocation_size)
+               return -ENODEV;
+
+       rc = amdgpu_atomfirmware_get_uma_carveout_info(adev, &atcs->uma_info);
+       if (rc) {
+               drm_dbg(adev_to_drm(adev),
+                       "Failed to parse UMA carveout info from VBIOS: %d\n", 
rc);
+               goto out_info;
+       }
+
+       mutex_init(&atcs->uma_info.update_lock);
+
+       rc = devm_device_add_group(adev->dev, &amdgpu_uma_attr_group);
+       if (rc) {
+               drm_dbg(adev_to_drm(adev), "Failed to add UMA carveout sysfs 
interfaces %d\n", rc);
+               goto out_attr;
+       }
+
+       return 0;
+
+out_attr:
+       mutex_destroy(&atcs->uma_info.update_lock);
+out_info:
+       return rc;
+}
+
+static void amdgpu_acpi_uma_option_fini(void)
+{
+       struct amdgpu_uma_carveout_info *uma_info = 
&amdgpu_acpi_priv.atcs.uma_info;
+
+       mutex_destroy(&uma_info->update_lock);
+       uma_info->num_entries = 0;
+}
+
 /**
  * amdgpu_acpi_event - handle notify events
  *
@@ -1291,6 +1411,12 @@ static int amdgpu_acpi_event(struct notifier_block *nb,
 int amdgpu_acpi_init(struct amdgpu_device *adev)
 {
        struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
+       int rc;
+
+       rc = amdgpu_acpi_uma_option_init(adev);
+
+       if (rc)
+               drm_dbg(adev_to_drm(adev), "Not creating uma carveout 
interfaces: %d", rc);
 
        if (atif->notifications.brightness_change) {
                if (adev->dc_enabled) {
@@ -1343,6 +1469,7 @@ void amdgpu_acpi_get_backlight_caps(struct 
amdgpu_dm_backlight_caps *caps)
 void amdgpu_acpi_fini(struct amdgpu_device *adev)
 {
        unregister_acpi_notifier(&adev->acpi_nb);
+       amdgpu_acpi_uma_option_fini();
 }
 
 /**

-- 
2.43.0

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