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 311cea0c3ae2b9b92e27c28a44ae70472f1a4d8c..54b2b2dd2bb579f4ed719a8089c26e761a667ab4 100644 (file)
--- a/drivers/clk/at91/clk-main.c
+++ b/drivers/clk/at91/clk-main.c
@@ -297,7 +297,10 @@ 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 9bfe9a28294a7ec7f5acbb38f7e21f477355839e..fac0ca56d42d92a3df623f2d3e69cb5ca380e639 100644 (file)
--- a/drivers/clk/at91/sckc.c
+++ b/drivers/clk/at91/sckc.c
@@ -76,7 +76,10 @@ static int clk_slow_osc_prepare(struct clk_hw *hw)
 
        writel(tmp | osc->bits->cr_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;
 }
@@ -187,7 +190,10 @@ static int clk_slow_rc_osc_prepare(struct clk_hw *hw)
 
        writel(readl(sckcr) | osc->bits->cr_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;
 }
@@ -288,7 +294,10 @@ 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;
 }
@@ -533,7 +542,10 @@ 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;