mmc: Add SDIO function devicetree subnode parsing

This adds SDIO devicetree subnode parsing to the mmc core. While
SDIO devices are runtime probable they sometimes need nonprobable
additional information on embedded systems, like an additional gpio
interrupt or a clock. This patch makes it possible to supply this
information from the devicetree. SDIO drivers will find a pointer
to the devicenode in their devices of_node pointer.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
[hdegoede@redhat.com: Misc. cleanups]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 9584bffa8b22..d3bfbdfab052 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1232,6 +1232,34 @@ EXPORT_SYMBOL(mmc_of_parse_voltage);
 
 #endif /* CONFIG_OF */
 
+static int mmc_of_get_func_num(struct device_node *node)
+{
+        u32 reg;
+        int ret;
+
+        ret = of_property_read_u32(node, "reg", &reg);
+        if (ret < 0)
+                return ret;
+
+        return reg;
+}
+
+struct device_node *mmc_of_find_child_device(struct mmc_host *host,
+                unsigned func_num)
+{
+        struct device_node *node;
+
+        if (!host->parent || !host->parent->of_node)
+                return NULL;
+
+        for_each_child_of_node(host->parent->of_node, node) {
+                if (mmc_of_get_func_num(node) == func_num)
+                        return node;
+        }
+
+        return NULL;
+}
+
 #ifdef CONFIG_REGULATOR
 
 /**