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    SubjectRe: [PATCH] cpufreq: rockchip: add driver
    Date
    Hi Feng,

    Am Freitag, 18. März 2016, 20:10:04 schrieb Feng Xiao:
    > This driver will directly use cpufreq-dt driver as backend.
    >
    > As there is not a generic devicetree board file(rockchip.c)
    > on ARM64 architecture, so remove platform_device_register_simple
    > in rockchip.c and add a new cpufreq driver to support for all
    > Rockchip SoCs.
    >
    > Signed-off-by: Feng Xiao <xf@rock-chips.com>

    [...]

    > diff --git a/drivers/cpufreq/rockchip-cpufreq.c
    > b/drivers/cpufreq/rockchip-cpufreq.c new file mode 100644
    > index 0000000..ecbadcd
    > --- /dev/null
    > +++ b/drivers/cpufreq/rockchip-cpufreq.c
    > @@ -0,0 +1,36 @@
    > +/*
    > + * Rockchip Platforms CPUFreq Support
    > + *
    > + * Copyright (C) 2016 Fuzhou Rockchip Electronics Co., Ltd
    > + *
    > + * Feng Xiao <xf@rock-chips.com>
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + *
    > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
    > + * kind, whether express or implied; without even the implied warranty
    > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + */
    > +
    > +#include <linux/err.h>
    > +#include <linux/init.h>
    > +#include <linux/kernel.h>
    > +#include <linux/module.h>
    > +#include <linux/of.h>
    > +#include <linux/platform_device.h>
    > +
    > +static int __init rockchip_cpufreq_driver_init(void)
    > +{
    > + struct platform_device *pdev;
    > +
    > + pdev = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
    > + return PTR_ERR_OR_ZERO(pdev);

    This would create that cpufreq-dt device on all non-Rockchip platforms
    compiled into the same kernel image as well - we definitly don't want that.

    Also, on both the rk3368 as well as the rk3399, you probably want the cluster-
    handling of arm-bL-cpufreq-dt.
    Contrary to its name it is _not_ limited to switching between clusters, but
    can also control frequencies of multiple cpu-clusters running at the same
    time.


    Implementation-wise, I guess doing it similar to the scpi-implementation might
    make more sense. Please take a look at drivers/clk/clk-scpi.c that registers
    the virtual cpufreq device there.

    So we could do something similar, move the cpufreq from mach-rockchip to the
    clock drivers and register the appropriate cpufreq-driver for each soc.
    cpufreq-dt for socs with a single cluster, the bL-thing for socs with multiple
    clusters.


    Heiko

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