[PATCH 3/6] hwrng: omap3-rom - Call clk_prepare() on init and exit only

[Tony Lindgren]

When unloading omap3-rom-rng, we'll get the following:

WARNING: CPU: 0 PID: 100 at drivers/clk/clk.c:948 clk_core_disable

This is because the clock is already disabled by omap3_rom_rng_idle().

Also, we should not call prepare and unprepare except during init, and
only call enable and disable during use.

Cc: Aaro Koskinen <aaro.koski...@iki.fi>
Cc: Adam Ford <aford...@gmail.com>
Cc: Pali Rohár <pali.ro...@gmail.com>
Cc: Tero Kristo <t-kri...@ti.com>
Fixes: 1c6b7c2108bd ("hwrng: OMAP3 ROM Random Number Generator support")
Signed-off-by: Tony Lindgren <t...@atomide.com>
---
 drivers/char/hw_random/omap3-rom-rng.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/char/hw_random/omap3-rom-rng.c 
b/drivers/char/hw_random/omap3-rom-rng.c
--- a/drivers/char/hw_random/omap3-rom-rng.c
+++ b/drivers/char/hw_random/omap3-rom-rng.c
@@ -44,7 +44,7 @@ static void omap3_rom_rng_idle(struct work_struct *work)
                pr_err("reset failed: %d\n", r);
                return;
        }
-       clk_disable_unprepare(rng_clk);
+       clk_disable(rng_clk);
        rng_idle = 1;
 }
 
@@ -55,13 +55,13 @@ static int omap3_rom_rng_get_random(void *buf, unsigned int 
count)
 
        cancel_delayed_work_sync(&idle_work);
        if (rng_idle) {
-               r = clk_prepare_enable(rng_clk);
+               r = clk_enable(rng_clk);
                if (r)
                        return r;
 
                r = omap3_rom_rng_call(0, 0, RNG_GEN_PRNG_HW_INIT);
                if (r != 0) {
-                       clk_disable_unprepare(rng_clk);
+                       clk_disable(rng_clk);
                        pr_err("HW init failed: %d\n", r);
                        return -EIO;
                }
@@ -114,20 +114,32 @@ static int omap3_rom_rng_probe(struct platform_device 
*pdev)
                return PTR_ERR(rng_clk);
        }
 
+       ret = clk_prepare(rng_clk);
+       if (ret < 0) {
+               dev_err(&pdev->dev, "clk_prepare failed: %i\n", ret);
+               return ret;
+       }
+
        /* Leave the RNG in reset state. */
-       ret = clk_prepare_enable(rng_clk);
+       ret = clk_enable(rng_clk);
        if (ret)
-               return ret;
+               goto err_unprepare;
        omap3_rom_rng_idle(0);
 
        return hwrng_register(&omap3_rom_rng_ops);
+
+err_unprepare:
+       clk_unprepare(rng_clk);
+
+       return ret;
 }
 
 static int omap3_rom_rng_remove(struct platform_device *pdev)
 {
        cancel_delayed_work_sync(&idle_work);
        hwrng_unregister(&omap3_rom_rng_ops);
-       clk_disable_unprepare(rng_clk);
+       clk_unprepare(rng_clk);
+
        return 0;
 }
 
-- 
2.23.0