Revision ab170c27361d1578b4769276ce2bbdb14394743d authored by Ondrej Jirman on 21 April 2018, 04:51:55 UTC, committed by Sean Paul on 25 April 2018, 19:03:12 UTC
The reverted commit broke LVDS output on TBS A711 Tablet. That tablet has simple-panel node that has fixed pixel clock-frequency that A83T SoC used in the tablet can't generate exactly. Requested rate is 52000000 and rounded_rate is calculated as 51857142. It's close enough for it to work in practice, but with strict check in the reverted commit, the mode is rejected needlessly in this case. DT allows to specify a range of values for simple-panel/clock-frequency, but driver doesn't respect that ATM. Given that TBS A711 is the single user of sun4i-lvds driver, let's revert that commit for now, until a better solution for the problem is found. Also see: https://patchwork.kernel.org/patch/9446385/ for relevant discussion (or search for "[RFC] drm/sun4i: rgb: Add 5% tolerance to dot clock frequency check"). Fixes: e4e4b7ad50cf ("drm/sun4i: add lvds mode_valid function") Reported-by: Ondrej Jirman <megous@megous.com> Signed-off-by: Ondrej Jirman <megous@megous.com> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180421045155.15332-1-megous@megous.com Signed-off-by: Sean Paul <seanpaul@chromium.org>
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jitterentropy-kcapi.c
/*
* Non-physical true random number generator based on timing jitter --
* Linux Kernel Crypto API specific code
*
* Copyright Stephan Mueller <smueller@chronox.de>, 2015
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU General Public License, in which case the provisions of the GPL2 are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fips.h>
#include <linux/time.h>
#include <linux/crypto.h>
#include <crypto/internal/rng.h>
struct rand_data;
int jent_read_entropy(struct rand_data *ec, unsigned char *data,
unsigned int len);
int jent_entropy_init(void);
struct rand_data *jent_entropy_collector_alloc(unsigned int osr,
unsigned int flags);
void jent_entropy_collector_free(struct rand_data *entropy_collector);
/***************************************************************************
* Helper function
***************************************************************************/
__u64 jent_rol64(__u64 word, unsigned int shift)
{
return rol64(word, shift);
}
void *jent_zalloc(unsigned int len)
{
return kzalloc(len, GFP_KERNEL);
}
void jent_zfree(void *ptr)
{
kzfree(ptr);
}
int jent_fips_enabled(void)
{
return fips_enabled;
}
void jent_panic(char *s)
{
panic("%s", s);
}
void jent_memcpy(void *dest, const void *src, unsigned int n)
{
memcpy(dest, src, n);
}
/*
* Obtain a high-resolution time stamp value. The time stamp is used to measure
* the execution time of a given code path and its variations. Hence, the time
* stamp must have a sufficiently high resolution.
*
* Note, if the function returns zero because a given architecture does not
* implement a high-resolution time stamp, the RNG code's runtime test
* will detect it and will not produce output.
*/
void jent_get_nstime(__u64 *out)
{
__u64 tmp = 0;
tmp = random_get_entropy();
/*
* If random_get_entropy does not return a value, i.e. it is not
* implemented for a given architecture, use a clock source.
* hoping that there are timers we can work with.
*/
if (tmp == 0)
tmp = ktime_get_ns();
*out = tmp;
}
/***************************************************************************
* Kernel crypto API interface
***************************************************************************/
struct jitterentropy {
spinlock_t jent_lock;
struct rand_data *entropy_collector;
};
static int jent_kcapi_init(struct crypto_tfm *tfm)
{
struct jitterentropy *rng = crypto_tfm_ctx(tfm);
int ret = 0;
rng->entropy_collector = jent_entropy_collector_alloc(1, 0);
if (!rng->entropy_collector)
ret = -ENOMEM;
spin_lock_init(&rng->jent_lock);
return ret;
}
static void jent_kcapi_cleanup(struct crypto_tfm *tfm)
{
struct jitterentropy *rng = crypto_tfm_ctx(tfm);
spin_lock(&rng->jent_lock);
if (rng->entropy_collector)
jent_entropy_collector_free(rng->entropy_collector);
rng->entropy_collector = NULL;
spin_unlock(&rng->jent_lock);
}
static int jent_kcapi_random(struct crypto_rng *tfm,
const u8 *src, unsigned int slen,
u8 *rdata, unsigned int dlen)
{
struct jitterentropy *rng = crypto_rng_ctx(tfm);
int ret = 0;
spin_lock(&rng->jent_lock);
ret = jent_read_entropy(rng->entropy_collector, rdata, dlen);
spin_unlock(&rng->jent_lock);
return ret;
}
static int jent_kcapi_reset(struct crypto_rng *tfm,
const u8 *seed, unsigned int slen)
{
return 0;
}
static struct rng_alg jent_alg = {
.generate = jent_kcapi_random,
.seed = jent_kcapi_reset,
.seedsize = 0,
.base = {
.cra_name = "jitterentropy_rng",
.cra_driver_name = "jitterentropy_rng",
.cra_priority = 100,
.cra_ctxsize = sizeof(struct jitterentropy),
.cra_module = THIS_MODULE,
.cra_init = jent_kcapi_init,
.cra_exit = jent_kcapi_cleanup,
}
};
static int __init jent_mod_init(void)
{
int ret = 0;
ret = jent_entropy_init();
if (ret) {
pr_info("jitterentropy: Initialization failed with host not compliant with requirements: %d\n", ret);
return -EFAULT;
}
return crypto_register_rng(&jent_alg);
}
static void __exit jent_mod_exit(void)
{
crypto_unregister_rng(&jent_alg);
}
module_init(jent_mod_init);
module_exit(jent_mod_exit);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
MODULE_DESCRIPTION("Non-physical True Random Number Generator based on CPU Jitter");
MODULE_ALIAS_CRYPTO("jitterentropy_rng");
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