Fwd: Re: [PATCH] Added Getentropy() support to beagle BSP

Christian Mauderer christian.mauderer at embedded-brains.de
Wed Mar 14 05:35:28 UTC 2018


Ups. Hit reply instead of reply all. This should go to the mailing list.

--- Ursprüngliche Nachricht ---
> 
> Am Mittwoch, 14. März 2018 schrieb Udit agarwal:
> > Hi,
> > @Joel This seems to be SoC specific.
> > 
> > 
> > So, here is the implementation with mutex, Do let me know if this is okay. I'll then do it for atsam also.
> 
> Atsam should be an extra patch.
> 
> > 
> > int getentropy(void *ptr, size_t n)
> > {
> > volatile am335x_trng_register *rng = (am335x_trng_register*) RNG_BASE;
> > rtems_mutex lock_trng_reg = RTEMS_MUTEX_INITIALIZER("lock_trng_reg");
> 
> If you create a local variable every thread will have it's own mutex. So they still can access the critical section in parallel. Use a global one in this case.
> 
> > 
> > while (n > 0)
> > {
> > uint64_t random;
> > size_t copy;
> > 
> > /* for mutual exclusion synchronization between multiple
> > access to TRNG register in different contexts */
> > rtems_mutex_lock(&lock_trng_reg);
> > 
> > /* wait untill RNG becomes ready with next set of random data */
> > while( ( rng->status & RNG_STATUS_RDY ) == 0 )
> > {
> > /* wait */
> > }
> > 
> > random = trng_getranddata(rng);
> > /* clear the status flag after reading to generate new random
> > value */
> > rng->status_clr = RNG_STATUS_RDY;
> > rtems_mutex_unlock(&lock_trng_reg);
> > 
> > /* checking for error by masking all bits other then error bit in
> > status register */
> > if( ((rng->status & RNG_STATUS_ERR)>>1) == 1)
> > {
> > copy = sizeof(random);
> > if ( n < copy )
> > {
> > copy = n;
> > }
> > memcpy(ptr, &random, copy);
> > n -= copy;
> > ptr = (char*)ptr + copy;
> > }
> 
> Just noted that one: What Value is returned in the error case? Can the error even happen? I think that there is a special function that should be called in that case.
> 
> > }
> > 
> > rtems_mutex_destroy(&lock_trng_reg);
> > return 0;
> > }
> > 
> > 
> > 
> > 
> > On Wed, Mar 14, 2018 at 2:15 AM, Joel Sherrill <joel at rtems.org> wrote:
> > 
> > 
> > 
> > 
> > 
> > On Mar 13, 2018 1:31 AM, "Sebastian Huber" <sebastian.huber at embedded-brains.de> wrote:
> > 
> > 
> > 
> > On 12/03/18 20:02, Udit agarwal wrote:
> > 
> > So, It looks like here's the final patch, do let me know if its ready to be pushed. Also, it would be really helpful if someone else also tests this patch before pushing(Although i have done that once).
> > 
> > Thanks,
> > Udit agarwal
> > 
> > 
> > From 454a8ff3e0ea3393818859874705a54b098c6081 Mon Sep 17 00:00:00 2001
> > 
> > From: Udit agarwal <dev.madaari at gmail.com <mailto:dev.madaari at gmail.com>>
> > 
> > Date: Tue, 13 Mar 2018 00:20:28 +0530
> > Subject: [PATCH] Added Getentropy() support to beagle BSP
> > 
> > ---
> > bsps/arm/include/libcpu/am335x.h | 37 ++++++-
> > c/src/lib/libbsp/arm/beagle/Makefile.am | 4 +-
> > .../libbsp/arm/beagle/getentropy/bbb_getentropy.c | 116 +++++++++++++++++++++
> > 3 files changed, 155 insertions(+), 2 deletions(-)
> > create mode 100644 c/src/lib/libbsp/arm/beagle/getentropy/bbb_getentropy.c
> > 
> > diff --git a/bsps/arm/include/libcpu/am335x.h b/bsps/arm/include/libcpu/am335x.h
> > index 367e97c..cedd637 100644
> > --- a/bsps/arm/include/libcpu/am335x.h
> > +++ b/bsps/arm/include/libcpu/am335x.h
> > @@ -14,11 +14,17 @@
> > 
> > * Modified by Ben Gras <beng at shrike-systems.com <mailto:beng at shrike-systems.com>> to add lots
> > 
> > * of beagleboard/beaglebone definitions, delete lpc32xx specific
> > * ones, and merge with some other header files.
> > + *
> > 
> > + * Modified by Udit agarwal <dev.madaari at gmail.com <mailto:dev.madaari at gmail.com>> to add random
> > 
> > + * number generating module definitions and TRNG register structure.
> > */
> > 
> > #if !defined(_AM335X_H_)
> > #define _AM335X_H_
> > 
> > +/* For TRNG register definition */
> > +#include <stdint.h>
> > +
> > /* Interrupt controller memory map */
> > #define OMAP3_DM37XX_INTR_BASE 0x48200000 /* INTCPS physical address */
> > 
> > @@ -701,4 +707,33 @@
> > #define AM335X_CM_PER_OCPWP_L3_CLKSTCTRL_CLKACTIVITY_OCPWP_L4_GCLK (0x00000020u)
> > #define AM335X_I2C_INT_STOP_CONDITION AM335X_I2C_IRQSTATUS_BF
> > 
> > -#endif
> > +/* TRNG Register */
> > +
> > +/* RNG base address */
> > +#define RNG_BASE 0x48310000
> > +/* RNG clock control */
> > +#define CM_PER_RNG_CLKCTRL (AM335X_CM_PER_ADDR | (9 << 4))
> > +/* rng module clock status bits */
> > +#define AM335X_CLK_RNG_BIT_MASK (0x30000)
> > +/* Offset from RNG base for output ready flag */
> > +#define RNG_STATUS_RDY (1u << 0)
> > +/* Offset from RNG base for FRO related error */
> > +#define RNG_STATUS_ERR (1u << 1)
> > +/* Offset from RNG base for clock status */
> > +#define RNG_STATUS_CLK (1u << 31)
> > +/* enable module */
> > +#define AM335X_RNG_ENABLE (1 << 10)
> > +
> > +/* TRNG register structure */
> > +struct bbb_trng_register
> > +{
> > + uint64_t output; /* 00 */
> > + uint32_t status; /* 08 */
> > + uint32_t irq_en; /* 0c */
> > + uint32_t status_clr; /* 10 */
> > + uint32_t control; /* 14 */
> > + uint32_t config; /* 18 */
> > +};
> > +typedef struct bbb_trng_register bbb_trng_register;
> > 
> > 
> > The bbb (Beagle Bone Black) is a particular board and the AM335X is a SoC family. This should be something like this
> > 
> > typedef struct {
> > ...
> > } am335x_trng;
> > 
> > 
> > 
> > +
> > +#endif
> > \ No newline at end of file
> > 
> > 
> > 
> > Git thinks that files should have a newline at the end of the file.
> > 
> > 
> > 
> > diff --git a/c/src/lib/libbsp/arm/beagle/Makefile.am b/c/src/lib/libbsp/arm/beagle/Makefile.am
> > index 8251660..5d5ade3 100644
> > --- a/c/src/lib/libbsp/arm/beagle/Makefile.am
> > +++ b/c/src/lib/libbsp/arm/beagle/Makefile.am
> > @@ -40,7 +40,6 @@ libbsp_a_LIBADD =
> > 
> > # Shared
> > libbsp_a_SOURCES += ../../shared/bootcard.c
> > -libbsp_a_SOURCES += ../../shared/getentropy-cpucounter.c
> > libbsp_a_SOURCES += ../../shared/src/bsp-fdt.c
> > libbsp_a_SOURCES += ../../shared/bspclean.c
> > libbsp_a_SOURCES += ../../shared/bspgetworkarea.c
> > @@ -88,6 +87,9 @@ libbsp_a_SOURCES += gpio/bbb-gpio.c
> > #pwm
> > libbsp_a_SOURCES += pwm/pwm.c
> > 
> > +#getentropy
> > +libbsp_a_SOURCES += getentropy/bbb_getentropy.c
> > +
> > 
> > 
> > 
> > With the new BSP source structure
> > 
> > https://devel.rtems.org/ticket/3285
> > 
> > this new file could be also placed at
> > 
> > bsps/arm/beagle/dev/getentropy.c
> > 
> > 
> > 
> > Is this specific to the Beagle or the SoC? Or a combination? Earlier you said the structure was SoC specific?
> > 
> > 
> > [...]
> > 
> > +int getentropy(void *ptr, size_t n)
> > +{
> > + volatile bbb_trng_register *rng = (bbb_trng_register*) RNG_BASE;
> > + am335x_rng_enable(rng);
> > + while (n > 0)
> > + {
> > + uint64_t random;
> > + size_t copy;
> > +
> > + /* wait untill RNG becomes ready with next set of random data */
> > + while( ( rng->status & RNG_STATUS_RDY ) == 0 )
> > + {
> > + /* wait */
> > + }
> > 
> > 
> > What happens if you call this function in parallel on different processors?
> > 
> > 
> > +
> > + random = trng_getranddata(rng);
> > +
> > + /* Checking for error by masking all bits other then error bit in
> > + status register */
> > + if( ((rng->status & RNG_STATUS_ERR)>>1) == 1)
> > + {
> > + /* clear the status flag after reading to generate new random
> > + value */
> > + rng->status_clr = RNG_STATUS_RDY;
> > + copy = sizeof(random);
> > + if ( n < copy )
> > + {
> > + copy = n;
> > + }
> > + memcpy(ptr, &random, copy);
> > + n -= copy;
> > + ptr = (char*)ptr + copy;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +RTEMS_SYSINIT_ITEM(
> > + am335x_rng_clock_enable,
> > + RTEMS_SYSINIT_DEVICE_DRIVERS,
> > + RTEMS_SYSINIT_ORDER_LAST
> > +);
> > \ No newline at end of file
> > -- 
> > 1.9.1
> > 
> > 
> > 
> > 
> > 
> > _______________________________________________
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
> > 
> > 
> > -- 
> > Sebastian Huber, embedded brains GmbH
> > 
> > Address : Dornierstr. 4, D-82178 Puchheim, Germany
> > Phone : +49 89 189 47 41-16
> > Fax : +49 89 189 47 41-09
> > E-Mail : sebastian.huber at embedded-brains.de
> > PGP : Public key available on request.
> > 
> > Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
> > 
> > 
> > _______________________________________________
> > devel mailing list
> > devel at rtems.org
> > http://lists.rtems.org/mailman/listinfo/devel
> > 
> > 
> > 
> >
> 
> -- 
> --------------------------------------------
> embedded brains GmbH
> Christian Mauderer
> Dornierstr. 4
> D-82178 Puchheim
> Germany
> email: christian.mauderer at embedded-brains.de
> Phone: +49-89-18 94 741 - 18
> Fax: +49-89-18 94 741 - 08
> PGP: Public key available on request.
> 
> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG

-- 
--------------------------------------------
embedded brains GmbH
Christian Mauderer
Dornierstr. 4
D-82178 Puchheim
Germany
email: christian.mauderer at embedded-brains.de
Phone: +49-89-18 94 741 - 18
Fax:   +49-89-18 94 741 - 08
PGP: Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.


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