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>

1 files changed, 137 insertions, 0 deletions

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index 7f2b02cc8ea1..d78c57a95b86 100644
--- 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;
         }