On 31/08/2016 at 18:45:37 +0200, Philipp Zabel wrote : > Hi Alexandre, > > Am Mittwoch, den 31.08.2016, 18:11 +0200 schrieb Alexandre Belloni: > > The Atmel secure SRAM is connected to a security module and may be erased > > automatically under certain conditions. For that reason, it is necessary to > > wait for the security module to flag that SRAM accesses are allowed before > > accessing it. > > > > Signed-off-by: Alexandre Belloni <[email protected]> > > --- > > Cc: Arnd Bergmann <[email protected]> > > Cc: Greg Kroah-Hartman <[email protected]> > > Cc: Philipp Zabel <[email protected]> > > Cc: Vladimir Zapolskiy <[email protected]> > > drivers/misc/sram.c | 52 > > +++++++++++++++++++++++++++++++++++++++++++++------- > > 1 file changed, 45 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c > > index f84b53d6ce50..8d411c64d07f 100644 > > --- a/drivers/misc/sram.c > > +++ b/drivers/misc/sram.c > > @@ -19,12 +19,16 @@ > > */ > > > > #include <linux/clk.h> > > +#include <linux/delay.h> > > #include <linux/genalloc.h> > > #include <linux/io.h> > > #include <linux/list_sort.h> > > #include <linux/of_address.h> > > #include <linux/platform_device.h> > > +#include <linux/regmap.h> > > #include <linux/slab.h> > > +#include <linux/mfd/syscon.h> > > +#include <soc/at91/atmel-secumod.h> > > > > #define SRAM_GRANULARITY 32 > > > > @@ -334,12 +338,43 @@ static int sram_reserve_regions(struct sram_dev > > *sram, struct resource *res) > > return ret; > > } > > > > +static int atmel_securam_wait(void) > > +{ > > + struct regmap *regmap; > > + unsigned long timeout = jiffies + HZ; > > Can this really take up to a second? >
Well, probably not but it can take some time. My understanding is that it can take up to almost half a second (4096 bytes at 8kHz). But quite frankly, by the time linux is starting, the delay has probably already expired so the while loop is unlikely to run. -- Alexandre Belloni, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
