hwrng: atmel - add wait for ready support on read

Add wait for ready support on read.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index ecb71c4..1a48746 100644 (file)
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -13,6 +13,7 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/hw_random.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
@@ -20,6 +21,7 @@
 #define TRNG_CR                0x00
 #define TRNG_MR                0x04
 #define TRNG_ISR       0x1c
+#define TRNG_ISR_DATRDY        BIT(0)
 #define TRNG_ODATA     0x50
 
 #define TRNG_KEY       0x524e4700 /* RNG */
@@ -36,25 +38,40 @@ struct atmel_trng {
        struct hwrng rng;
 };
 
+static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait)
+{
+       int ready;
+
+       ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY;
+       if (!ready && wait)
+               readl_poll_timeout(trng->base + TRNG_ISR, ready,
+                                  ready & TRNG_ISR_DATRDY, 1000, 20000);
+
+       return !!ready;
+}
+
 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
                           bool wait)
 {
        struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
        u32 *data = buf;
+       int ret;
+
+       ret = atmel_trng_wait_ready(trng, wait);
+       if (!ret)
+               goto out;
 
-       /* data ready? */
-       if (readl(trng->base + TRNG_ISR) & 1) {
-               *data = readl(trng->base + TRNG_ODATA);
-               /*
-                 ensure data ready is only set again AFTER the next data
-                 word is ready in case it got set between checking ISR
-                 and reading ODATA, so we don't risk re-reading the
-                 same word
-               */
-               readl(trng->base + TRNG_ISR);
-               return 4;
-       } else
-               return 0;
+       *data = readl(trng->base + TRNG_ODATA);
+       /*
+        * ensure data ready is only set again AFTER the next data word is ready
+        * in case it got set between checking ISR and reading ODATA, so we
+        * don't risk re-reading the same word
+        */
+       readl(trng->base + TRNG_ISR);
+       ret = 4;
+
+out:
+       return ret;
 }
 
 static void atmel_trng_enable(struct atmel_trng *trng)