8 files changed, 73 insertions, 38 deletions

diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c
index 556fd81fa815..c422e870dc52 100644
--- a/drivers/char/hw_random/amd-rng.c
+++ b/drivers/char/hw_random/amd-rng.c
@@ -28,6 +28,7 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/hw_random.h>
+#include <linux/delay.h>
 #include <asm/io.h>
 
 
@@ -52,11 +53,18 @@ MODULE_DEVICE_TABLE(pci, pci_tbl);
 static struct pci_dev *amd_pdev;
 
 
-static int amd_rng_data_present(struct hwrng *rng)
+static int amd_rng_data_present(struct hwrng *rng, int wait)
 {
         u32 pmbase = (u32)rng->priv;
+        int data, i;
 
-        return !!(inl(pmbase + 0xF4) & 1);
+        for (i = 0; i < 20; i++) {
+                data = !!(inl(pmbase + 0xF4) & 1);
+                if (data || !wait)
+                        break;
+                udelay(10);
+        }
+        return data;
 }
 
 static int amd_rng_data_read(struct hwrng *rng, u32 *data)
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 26a860adcb38..0118b9817a95 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -66,11 +66,11 @@ static inline void hwrng_cleanup(struct hwrng *rng)
                 rng->cleanup(rng);
 }
 
-static inline int hwrng_data_present(struct hwrng *rng)
+static inline int hwrng_data_present(struct hwrng *rng, int wait)
 {
         if (!rng->data_present)
                 return 1;
-        return rng->data_present(rng);
+        return rng->data_present(rng, wait);
 }
 
 static inline int hwrng_data_read(struct hwrng *rng, u32 *data)
@@ -94,8 +94,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 {
         u32 data;
         ssize_t ret = 0;
-        int i, err = 0;
-        int data_present;
+        int err = 0;
         int bytes_read;
 
         while (size) {
@@ -107,21 +106,10 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
                         err = -ENODEV;
                         goto out;
                 }
-                if (filp->f_flags & O_NONBLOCK) {
-                        data_present = hwrng_data_present(current_rng);
-                } else {
-                        /* Some RNG require some time between data_reads to gather
-                         * new entropy. Poll it.
-                         */
-                        for (i = 0; i < 20; i++) {
-                                data_present = hwrng_data_present(current_rng);
-                                if (data_present)
-                                        break;
-                                udelay(10);
-                        }
-                }
+
                 bytes_read = 0;
-                if (data_present)
+                if (hwrng_data_present(current_rng,
+                                       !(filp->f_flags & O_NONBLOCK)))
                         bytes_read = hwrng_data_read(current_rng, &data);
                 mutex_unlock(&rng_mutex);
 
diff --git a/drivers/char/hw_random/geode-rng.c b/drivers/char/hw_random/geode-rng.c
index 8e8658dcd2e3..fed4ef5569f5 100644
--- a/drivers/char/hw_random/geode-rng.c
+++ b/drivers/char/hw_random/geode-rng.c
@@ -28,6 +28,7 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/hw_random.h>
+#include <linux/delay.h>
 #include <asm/io.h>
 
 
@@ -61,11 +62,18 @@ static int geode_rng_data_read(struct hwrng *rng, u32 *data)
         return 4;
 }
 
-static int geode_rng_data_present(struct hwrng *rng)
+static int geode_rng_data_present(struct hwrng *rng, int wait)
 {
         void __iomem *mem = (void __iomem *)rng->priv;
+        int data, i;
 
-        return !!(readl(mem + GEODE_RNG_STATUS_REG));
+        for (i = 0; i < 20; i++) {
+                data = !!(readl(mem + GEODE_RNG_STATUS_REG));
+                if (data || !wait)
+                        break;
+                udelay(10);
+        }
+        return data;
 }
 
 
diff --git a/drivers/char/hw_random/intel-rng.c b/drivers/char/hw_random/intel-rng.c
index 753f46052b87..5cc651ef75eb 100644
--- a/drivers/char/hw_random/intel-rng.c
+++ b/drivers/char/hw_random/intel-rng.c
@@ -29,6 +29,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/stop_machine.h>
+#include <linux/delay.h>
 #include <asm/io.h>
 
 
@@ -162,11 +163,19 @@ static inline u8 hwstatus_set(void __iomem *mem,
         return hwstatus_get(mem);
 }
 
-static int intel_rng_data_present(struct hwrng *rng)
+static int intel_rng_data_present(struct hwrng *rng, int wait)
 {
         void __iomem *mem = (void __iomem *)rng->priv;
-
-        return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT);
+        int data, i;
+
+        for (i = 0; i < 20; i++) {
+                data = !!(readb(mem + INTEL_RNG_STATUS) &
+                          INTEL_RNG_DATA_PRESENT);
+                if (data || !wait)
+                        break;
+                udelay(10);
+        }
+        return data;
 }
 
 static int intel_rng_data_read(struct hwrng *rng, u32 *data)
diff --git a/drivers/char/hw_random/omap-rng.c b/drivers/char/hw_random/omap-rng.c
index 3f35a1c562b1..7e319951fa41 100644
--- a/drivers/char/hw_random/omap-rng.c
+++ b/drivers/char/hw_random/omap-rng.c
@@ -29,6 +29,7 @@
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/hw_random.h>
+#include <linux/delay.h>
 
 #include <asm/io.h>
 
@@ -65,9 +66,17 @@ static void omap_rng_write_reg(int reg, u32 val)
 }
 
 /* REVISIT: Does the status bit really work on 16xx? */
-static int omap_rng_data_present(struct hwrng *rng)
+static int omap_rng_data_present(struct hwrng *rng, int wait)
 {
-        return omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
+        int data, i;
+
+        for (i = 0; i < 20; i++) {
+                data = omap_rng_read_reg(RNG_STAT_REG) ? 0 : 1;
+                if (data || !wait)
+                        break;
+                udelay(10);
+        }
+        return data;
 }
 
 static int omap_rng_data_read(struct hwrng *rng, u32 *data)
diff --git a/drivers/char/hw_random/pasemi-rng.c b/drivers/char/hw_random/pasemi-rng.c
index fa6040b6c8f2..621adf25e580 100644
--- a/drivers/char/hw_random/pasemi-rng.c
+++ b/drivers/char/hw_random/pasemi-rng.c
@@ -23,6 +23,7 @@
 #include <linux/kernel.h>
 #include <linux/platform_device.h>
 #include <linux/hw_random.h>
+#include <linux/delay.h>
 #include <asm/of_platform.h>
 #include <asm/io.h>
 
@@ -44,9 +45,16 @@
 static int pasemi_rng_data_present(struct hwrng *rng)
 {
         void __iomem *rng_regs = (void __iomem *)rng->priv;
-
-        return (in_le32(rng_regs + SDCRNG_CTL_REG)
-                & SDCRNG_CTL_FVLD_M) ? 1 : 0;
+        int data, i;
+
+        for (i = 0; i < 20; i++) {
+                data = (in_le32(rng_regs + SDCRNG_CTL_REG)
+                        & SDCRNG_CTL_FVLD_M) ? 1 : 0;
+                if (data || !wait)
+                        break;
+                udelay(10);
+        }
+        return data;
 }
 
 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index ec435cb25c4f..868e39fd42e4 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/hw_random.h>
+#include <linux/delay.h>
 #include <asm/io.h>
 #include <asm/msr.h>
 #include <asm/cpufeature.h>
@@ -77,10 +78,11 @@ static inline u32 xstore(u32 *addr, u32 edx_in)
         return eax_out;
 }
 
-static int via_rng_data_present(struct hwrng *rng)
+static int via_rng_data_present(struct hwrng *rng, int wait)
 {
         u32 bytes_out;
         u32 *via_rng_datum = (u32 *)(&rng->priv);
+        int i;
 
         /* We choose the recommended 1-byte-per-instruction RNG rate,
          * for greater randomness at the expense of speed.  Larger
@@ -95,12 +97,15 @@ static int via_rng_data_present(struct hwrng *rng)
          * completes.
          */
 
-        *via_rng_datum = 0; /* paranoia, not really necessary */
-        bytes_out = xstore(via_rng_datum, VIA_RNG_CHUNK_1);
-        bytes_out &= VIA_XSTORE_CNT_MASK;
-        if (bytes_out == 0)
-                return 0;
-        return 1;
+        for (i = 0; i < 20; i++) {
+                *via_rng_datum = 0; /* paranoia, not really necessary */
+                bytes_out = xstore(via_rng_datum, VIA_RNG_CHUNK_1);
+                bytes_out &= VIA_XSTORE_CNT_MASK;
+                if (bytes_out || !wait)
+                        break;
+                udelay(10);
+        }
+        return bytes_out ? 1 : 0;
 }
 
 static int via_rng_data_read(struct hwrng *rng, u32 *data)
diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index 21ea7610e177..85d11916e9ea 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -33,7 +33,7 @@ struct hwrng {
         const char *name;
         int (*init)(struct hwrng *rng);
         void (*cleanup)(struct hwrng *rng);
-        int (*data_present)(struct hwrng *rng);
+        int (*data_present)(struct hwrng *rng, int wait);
         int (*data_read)(struct hwrng *rng, u32 *data);
         unsigned long priv;