[PATCH 1/5] soc/tegra: pmc: Guard against uninitialised PMC clock

[Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

It is possible for the public functions, tegra_io_rail_power_on/off()
to be called before the PMC device has been probed. If this happens
then the pmc->clk member will not be initialised and the call to
clk_get_rate() in tegra_io_rail_prepare() will return zero and lead
to a divide-by-zero exception. The function clk_get_rate() will return
zero if a NULl clk pointer is passed. Therefore, rather that checking
if pmc->clk is initialised, fix this by checking the return value for
clk_get_rate() to make sure it is not zero.

Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 drivers/soc/tegra/pmc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index 7792ed88d80b..c99580aabcf6 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -931,6 +931,8 @@ static int tegra_io_rail_prepare(unsigned int id, unsigned long *request,
 	}
 
 	rate = clk_get_rate(pmc->clk);
+	if (!rate)
+		return -ENODEV;
 
 	tegra_pmc_writel(DPD_SAMPLE_ENABLE, DPD_SAMPLE);
 
-- 
1.9.1