clk: at91: avoid sleeping early

[ Upstream commit 658fd65cf0b0d511de1718e48d9a28844c385ae0 ]

It is not allowed to sleep to early in the boot process and this may lead
to kernel issues if the bootloader didn't prepare the slow clock and main
clock.

This results in the following error and dump stack on the AriettaG25:
   bad: scheduling from the idle thread!

Ensure it is possible to sleep, else simply have a delay.

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lkml.kernel.org/r/20190920153906.20887-1-alexandre.belloni@bootlin.com
Fixes: 80eded6ce8bb ("clk: at91: add slow clks driver")
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/clk/at91/clk-main.c b/drivers/clk/at91/clk-main.c
index 2f97a843d6d6bcbd7a6fe7f90849dabfbbe54db6..fb5c14af8cc8d001978d602c8b775f270ecc47d9 100644 (file)
--- a/drivers/clk/at91/clk-main.c
+++ b/drivers/clk/at91/clk-main.c
@@ -354,7 +354,10 @@ static int clk_main_probe_frequency(struct regmap *regmap)
                regmap_read(regmap, AT91_CKGR_MCFR, &mcfr);
                if (mcfr & AT91_PMC_MAINRDY)
                        return 0;
-               usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT);
+               if (system_state < SYSTEM_RUNNING)
+                       udelay(MAINF_LOOP_MIN_WAIT);
+               else
+                       usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT);
        } while (time_before(prep_time, timeout));
 
        return -ETIMEDOUT;

diff --git a/drivers/clk/at91/sckc.c b/drivers/clk/at91/sckc.c
index ab6ecefc49ad85424a02dda7b3d3342d76598884..43ba2a8b03faf1bceeddbd2870deb4936b2fb451 100644 (file)
--- a/drivers/clk/at91/sckc.c
+++ b/drivers/clk/at91/sckc.c
@@ -74,7 +74,10 @@ static int clk_slow_osc_prepare(struct clk_hw *hw)
 
        writel(tmp | AT91_SCKC_OSC32EN, sckcr);
 
-       usleep_range(osc->startup_usec, osc->startup_usec + 1);
+       if (system_state < SYSTEM_RUNNING)
+               udelay(osc->startup_usec);
+       else
+               usleep_range(osc->startup_usec, osc->startup_usec + 1);
 
        return 0;
 }
@@ -197,7 +200,10 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
 
        writel(readl(sckcr) | AT91_SCKC_RCEN, sckcr);
 
-       usleep_range(osc->startup_usec, osc->startup_usec + 1);
+       if (system_state < SYSTEM_RUNNING)
+               udelay(osc->startup_usec);
+       else
+               usleep_range(osc->startup_usec, osc->startup_usec + 1);
 
        return 0;
 }
@@ -310,7 +316,10 @@ static int clk_sam9x5_slow_set_parent(struct clk_hw *hw, u8 index)
 
        writel(tmp, sckcr);
 
-       usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);
+       if (system_state < SYSTEM_RUNNING)
+               udelay(SLOWCK_SW_TIME_USEC);
+       else
+               usleep_range(SLOWCK_SW_TIME_USEC, SLOWCK_SW_TIME_USEC + 1);
 
        return 0;
 }
@@ -443,7 +452,10 @@ static int clk_sama5d4_slow_osc_prepare(struct clk_hw *hw)
                return 0;
        }
 
-       usleep_range(osc->startup_usec, osc->startup_usec + 1);
+       if (system_state < SYSTEM_RUNNING)
+               udelay(osc->startup_usec);
+       else
+               usleep_range(osc->startup_usec, osc->startup_usec + 1);
        osc->prepared = true;
 
        return 0;