hwrng: meson - add support for S4

For some Amlogic SOC's, mechanism to obtain random number
has been changed. For example, S4 now uses status bit waiting algo.

Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/meson-rng.c b/drivers/char/hw_random/meson-rng.c
index a4eb8e3..75225eb 100644 (file)
--- a/drivers/char/hw_random/meson-rng.c
+++ b/drivers/char/hw_random/meson-rng.c
@@ -13,12 +13,23 @@
 #include <linux/types.h>
 #include <linux/of.h>
 #include <linux/clk.h>
+#include <linux/iopoll.h>
 
-#define RNG_DATA 0x00
+#define RNG_DATA       0x00
+#define RNG_S4_DATA    0x08
+#define RNG_S4_CFG     0x00
+
+#define RUN_BIT                BIT(0)
+#define SEED_READY_STS_BIT     BIT(31)
+
+struct meson_rng_priv {
+       int (*read)(struct hwrng *rng, void *buf, size_t max, bool wait);
+};
 
 struct meson_rng_data {
        void __iomem *base;
        struct hwrng rng;
+       struct device *dev;
 };
 
 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
@@ -31,16 +42,62 @@ static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
        return sizeof(u32);
 }
 
+static int meson_rng_wait_status(void __iomem *cfg_addr, int bit)
+{
+       u32 status = 0;
+       int ret;
+
+       ret = readl_relaxed_poll_timeout_atomic(cfg_addr,
+                                               status, !(status & bit),
+                                               10, 10000);
+       if (ret)
+               return -EBUSY;
+
+       return 0;
+}
+
+static int meson_s4_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+       struct meson_rng_data *data =
+                       container_of(rng, struct meson_rng_data, rng);
+
+       void __iomem *cfg_addr = data->base + RNG_S4_CFG;
+       int err;
+
+       writel_relaxed(readl_relaxed(cfg_addr) | SEED_READY_STS_BIT, cfg_addr);
+
+       err = meson_rng_wait_status(cfg_addr, SEED_READY_STS_BIT);
+       if (err) {
+               dev_err(data->dev, "Seed isn't ready, try again\n");
+               return err;
+       }
+
+       err = meson_rng_wait_status(cfg_addr, RUN_BIT);
+       if (err) {
+               dev_err(data->dev, "Can't get random number, try again\n");
+               return err;
+       }
+
+       *(u32 *)buf = readl_relaxed(data->base + RNG_S4_DATA);
+
+       return sizeof(u32);
+}
+
 static int meson_rng_probe(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
        struct meson_rng_data *data;
        struct clk *core_clk;
+       const struct meson_rng_priv *priv;
 
        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;
 
+       priv = device_get_match_data(&pdev->dev);
+       if (!priv)
+               return -ENODEV;
+
        data->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(data->base))
                return PTR_ERR(data->base);
@@ -51,13 +108,30 @@ static int meson_rng_probe(struct platform_device *pdev)
                                     "Failed to get core clock\n");
 
        data->rng.name = pdev->name;
-       data->rng.read = meson_rng_read;
+       data->rng.read = priv->read;
+
+       data->dev = &pdev->dev;
 
        return devm_hwrng_register(dev, &data->rng);
 }
 
+static const struct meson_rng_priv meson_rng_priv = {
+       .read = meson_rng_read,
+};
+
+static const struct meson_rng_priv meson_rng_priv_s4 = {
+       .read = meson_s4_rng_read,
+};
+
 static const struct of_device_id meson_rng_of_match[] = {
-       { .compatible = "amlogic,meson-rng", },
+       {
+               .compatible = "amlogic,meson-rng",
+               .data = (void *)&meson_rng_priv,
+       },
+       {
+               .compatible = "amlogic,meson-s4-rng",
+               .data = (void *)&meson_rng_priv_s4,
+       },
        {},
 };
 MODULE_DEVICE_TABLE(of, meson_rng_of_match);