Messages in this thread | | | Date | Wed, 31 Aug 2016 19:04:56 +0200 | From | Alexandre Belloni <> | Subject | Re: [PATCH 5/5] misc: sram: add Atmel securam support |
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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 <alexandre.belloni@free-electrons.com> > > --- > > Cc: Arnd Bergmann <arnd@arndb.de> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Philipp Zabel <p.zabel@pengutronix.de> > > Cc: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> > > 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
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