clk: rockchip: Export rockchip_clk_register_ddrclk()

This is used by the Rockchip clk driver, export it to allow that
driver to be compiled as a module..

Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Link: https://lore.kernel.org/r/20200914022225.23613-3-zhangqing@rock-chips.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157

Based on 3 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [kishon] [vijay] [abraham]
[i] [kishon]@[ti] [com] this program is distributed in the hope that
it will be useful but without any warranty without even the implied
warranty of merchantability or fitness for a particular purpose see
the gnu general public license for more details

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version [author] [graeme] [gregory]
[gg]@[slimlogic] [co] [uk] [author] [kishon] [vijay] [abraham] [i]
[kishon]@[ti] [com] [based] [on] [twl6030]_[usb] [c] [author] [hema]
[hk] [hemahk]@[ti] [com] this program is distributed in the hope
that it will be useful but without any warranty without even the
implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1105 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.202006027@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

clk: core: replace clk_{readl,writel} with {readl,writel}

Now that clk_{readl,writel} is just an alias for {readl,writel}, we can
switch all users of clk_* to use the accessors directly and remove the
helpers.

Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
[sboyd@kernel.org: Also convert renesas file so that this can be
compile independently]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: rockchip: Fix static checker warning in rockchip_ddrclk_get_parent call

Fixes the signedness bug returning '(-22)' on the return type by removing the
sanity checker in rockchip_ddrclk_get_parent(). The function should return
and unsigned value only and it's safe to remove the sanity checker as the
core functions that call get_parent like clk_core_get_parent_by_index already
ensures the validity of the clk index returned (index >= core->num_parents).

Fixes: a4f182bf81f18 ("clk: rockchip: add new clock-type for the ddrclk")
Cc: stable@vger.kernel.org
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

clk: rockchip: don't return NULL when failing to register ddrclk branch

rockchip_clk_register_ddrclk should not return NULL when failing
to call clk_register, otherwise rockchip_clk_register_branches
prints "unknown clock type". The actual case is that it's a known
clock type but we fail to register it, which may makes user confuse
the reason of failure. And the pr_err here is pointless as
rockchip_clk_register_branches will also print the similar message.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

clk: rockchip: add new clock-type for the ddrclk

Changing the rate of the DDR clock needs special care, as the DDR
is of course in use and will react badly if the rate changes under it.

Over time different approaches to handle that were used.

Past SoCs like the rk3288 and before would store some code in SRAM
while the rk3368 used a SCPI variant and let a coprocessor handle that.

New rockchip platforms like the rk3399 have a dcf controller to do ddr
frequency scaling, and support for this controller will be implemented
in the arm-trusted-firmware.

This new clock-type should over time handle all these methods for
handling DDR rate changes, but right now it will concentrate on the
SIP interface used to talk to ARM trusted firmware.

The SIP interface counterpart was merged from pull-request #684 [0]
into the upstream arm-trusted-firmware codebase.

[0] https://github.com/ARM-software/arm-trusted-firmware/pull/684

Signed-off-by: Lin Huang <hl@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>