ACPI / LPSS: Add device link for CHT SD card dependency on I2C

Some Cherry Trail boards have a dependency between the SDHCI host
controller used for SD cards and an external PMIC accessed via I2C. Add a
device link between the SDHCI host controller (consumer) and the I2C
adapter (supplier).

This patch depends on a fix to devices links, namely commit 0ff26c662d5f
("driver core: Fix device link deferred probe"). And also either,
commit 126dbc6b49c8 ("PM: i2c-designware-platdrv: Clean up PM handling in
probe"), or patch "PM / runtime: Fix handling of suppliers with disabled
runtime PM".

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 7f2b02c..d78c57a 100644 (file)
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -427,6 +427,142 @@ out:
        return 0;
 }
 
+struct lpss_device_links {
+       const char *supplier_hid;
+       const char *supplier_uid;
+       const char *consumer_hid;
+       const char *consumer_uid;
+       u32 flags;
+};
+
+/*
+ * The _DEP method is used to identify dependencies but instead of creating
+ * device links for every handle in _DEP, only links in the following list are
+ * created. That is necessary because, in the general case, _DEP can refer to
+ * devices that might not have drivers, or that are on different buses, or where
+ * the supplier is not enumerated until after the consumer is probed.
+ */
+static const struct lpss_device_links lpss_device_links[] = {
+       {"808622C1", "7", "80860F14", "3", DL_FLAG_PM_RUNTIME},
+};
+
+static bool hid_uid_match(const char *hid1, const char *uid1,
+                         const char *hid2, const char *uid2)
+{
+       return !strcmp(hid1, hid2) && uid1 && uid2 && !strcmp(uid1, uid2);
+}
+
+static bool acpi_lpss_is_supplier(struct acpi_device *adev,
+                                 const struct lpss_device_links *link)
+{
+       return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
+                            link->supplier_hid, link->supplier_uid);
+}
+
+static bool acpi_lpss_is_consumer(struct acpi_device *adev,
+                                 const struct lpss_device_links *link)
+{
+       return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
+                            link->consumer_hid, link->consumer_uid);
+}
+
+struct hid_uid {
+       const char *hid;
+       const char *uid;
+};
+
+static int match_hid_uid(struct device *dev, void *data)
+{
+       struct acpi_device *adev = ACPI_COMPANION(dev);
+       struct hid_uid *id = data;
+
+       if (!adev)
+               return 0;
+
+       return hid_uid_match(acpi_device_hid(adev), acpi_device_uid(adev),
+                            id->hid, id->uid);
+}
+
+static struct device *acpi_lpss_find_device(const char *hid, const char *uid)
+{
+       struct hid_uid data = {
+               .hid = hid,
+               .uid = uid,
+       };
+
+       return bus_find_device(&platform_bus_type, NULL, &data, match_hid_uid);
+}
+
+static bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle handle)
+{
+       struct acpi_handle_list dep_devices;
+       acpi_status status;
+       int i;
+
+       if (!acpi_has_method(adev->handle, "_DEP"))
+               return false;
+
+       status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
+                                        &dep_devices);
+       if (ACPI_FAILURE(status)) {
+               dev_dbg(&adev->dev, "Failed to evaluate _DEP.\n");
+               return false;
+       }
+
+       for (i = 0; i < dep_devices.count; i++) {
+               if (dep_devices.handles[i] == handle)
+                       return true;
+       }
+
+       return false;
+}
+
+static void acpi_lpss_link_consumer(struct device *dev1,
+                                   const struct lpss_device_links *link)
+{
+       struct device *dev2;
+
+       dev2 = acpi_lpss_find_device(link->consumer_hid, link->consumer_uid);
+       if (!dev2)
+               return;
+
+       if (acpi_lpss_dep(ACPI_COMPANION(dev2), ACPI_HANDLE(dev1)))
+               device_link_add(dev2, dev1, link->flags);
+
+       put_device(dev2);
+}
+
+static void acpi_lpss_link_supplier(struct device *dev1,
+                                   const struct lpss_device_links *link)
+{
+       struct device *dev2;
+
+       dev2 = acpi_lpss_find_device(link->supplier_hid, link->supplier_uid);
+       if (!dev2)
+               return;
+
+       if (acpi_lpss_dep(ACPI_COMPANION(dev1), ACPI_HANDLE(dev2)))
+               device_link_add(dev1, dev2, link->flags);
+
+       put_device(dev2);
+}
+
+static void acpi_lpss_create_device_links(struct acpi_device *adev,
+                                         struct platform_device *pdev)
+{
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(lpss_device_links); i++) {
+               const struct lpss_device_links *link = &lpss_device_links[i];
+
+               if (acpi_lpss_is_supplier(adev, link))
+                       acpi_lpss_link_consumer(&pdev->dev, link);
+
+               if (acpi_lpss_is_consumer(adev, link))
+                       acpi_lpss_link_supplier(&pdev->dev, link);
+       }
+}
+
 static int acpi_lpss_create_device(struct acpi_device *adev,
                                   const struct acpi_device_id *id)
 {
@@ -500,6 +636,7 @@ static int acpi_lpss_create_device(struct acpi_device *adev,
        adev->driver_data = pdata;
        pdev = acpi_create_platform_device(adev, dev_desc->properties);
        if (!IS_ERR_OR_NULL(pdev)) {
+               acpi_lpss_create_device_links(adev, pdev);
                return 1;
        }