3 files changed, 50 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
index bd9be0b5bc20..b7943f3f9995 100644
--- a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
+++ b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt
@@ -19,6 +19,9 @@ Optional properties:
     "bus-width = <1>" property.
   - sdhci,auto-cmd12: specifies that a controller can only handle auto
     CMD12.
+  - voltage-ranges : two cells are required, first cell specifies minimum
+    slot voltage (mV), second cell specifies maximum slot voltage (mV).
+    Several ranges could be specified.
 
 Example:
 
@@ -29,4 +32,5 @@ sdhci@2e000 {
         interrupt-parent = <&ipic>;
         /* Filled in by U-Boot */
         clock-frequency = <0>;
+        voltage-ranges = <3300 3300>;
 };
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 49a5bca418bd..b9b9fb6e4496 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -27,6 +27,7 @@
 #include <linux/fault-inject.h>
 #include <linux/random.h>
 #include <linux/slab.h>
+#include <linux/of.h>
 
 #include <linux/mmc/card.h>
 #include <linux/mmc/host.h>
@@ -1196,6 +1197,49 @@ u32 mmc_vddrange_to_ocrmask(int vdd_min, int vdd_max)
 }
 EXPORT_SYMBOL(mmc_vddrange_to_ocrmask);
 
+#ifdef CONFIG_OF
+
+/**
+ * mmc_of_parse_voltage - return mask of supported voltages
+ * @np: The device node need to be parsed.
+ * @mask: mask of voltages available for MMC/SD/SDIO
+ *
+ * 1. Return zero on success.
+ * 2. Return negative errno: voltage-range is invalid.
+ */
+int mmc_of_parse_voltage(struct device_node *np, u32 *mask)
+{
+        const u32 *voltage_ranges;
+        int num_ranges, i;
+
+        voltage_ranges = of_get_property(np, "voltage-ranges", &num_ranges);
+        num_ranges = num_ranges / sizeof(*voltage_ranges) / 2;
+        if (!voltage_ranges || !num_ranges) {
+                pr_info("%s: voltage-ranges unspecified\n", np->full_name);
+                return -EINVAL;
+        }
+
+        for (i = 0; i < num_ranges; i++) {
+                const int j = i * 2;
+                u32 ocr_mask;
+
+                ocr_mask = mmc_vddrange_to_ocrmask(
+                                be32_to_cpu(voltage_ranges[j]),
+                                be32_to_cpu(voltage_ranges[j + 1]));
+                if (!ocr_mask) {
+                        pr_err("%s: voltage-range #%d is invalid\n",
+                                np->full_name, i);
+                        return -EINVAL;
+                }
+                *mask |= ocr_mask;
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(mmc_of_parse_voltage);
+
+#endif /* CONFIG_OF */
+
 #ifdef CONFIG_REGULATOR
 
 /**
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 443243b241d5..da51bec578c3 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -208,6 +208,8 @@ static inline void mmc_claim_host(struct mmc_host *host)
         __mmc_claim_host(host, NULL);
 }
 
+struct device_node;
 extern u32 mmc_vddrange_to_ocrmask(int vdd_min, int vdd_max);
+extern int mmc_of_parse_voltage(struct device_node *np, u32 *mask);
 
 #endif /* LINUX_MMC_CORE_H */