linux-kernel - Re: [PATCH v13 1/4] clk: ralink: add clock driver for mt7621 SoC

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Message-ID: <161834070385.3764895.8150982536236653732@swboyd.mtv.corp.google.com>
Date:   Tue, 13 Apr 2021 12:05:03 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc:     robh+dt@...nel.org, john@...ozen.org, tsbogend@...ha.franken.de,
        gregkh@...uxfoundation.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-mips@...r.kernel.org,
        devel@...verdev.osuosl.org, neil@...wn.name,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v13 1/4] clk: ralink: add clock driver for mt7621 SoC

Quoting Sergio Paracuellos (2021-04-09 22:50:56)
> The documentation for this SOC only talks about two
> registers regarding to the clocks:
> * SYSC_REG_CPLL_CLKCFG0 - provides some information about
> boostrapped refclock. PLL and dividers used for CPU and some
> sort of BUS.
> * SYSC_REG_CPLL_CLKCFG1 - a banch of gates to enable/disable
> clocks for all or some ip cores.
> 
> Looking into driver code, and some openWRT patched there are
> another frequencies which are used in some drivers (uart, sd...).
> According to all of this information the clock plan for this
> SoC is set as follows:
> - Main top clock "xtal" from where all the rest of the world is
> derived.
> - CPU clock "cpu" derived from "xtal" frequencies and a bunch of
> register reads and predividers.
> - BUS clock "bus" derived from "cpu" and with (cpu / 4) MHz.
> - Fixed clocks from "xtal":
>     * "50m": 50 MHz.
>     * "125m": 125 MHz.
>     * "150m": 150 MHz.
>     * "250m": 250 MHz.
>     * "270m": 270 MHz.
> 
> We also have a buch of gate clocks with their parents:
>   * "hsdma": "150m"
>   * "fe": "250m"
>   * "sp_divtx": "270m"
>   * "timer": "50m"
>   * "pcm": "270m"
>   * "pio": "50m"
>   * "gdma": "bus"
>   * "nand": "125m"
>   * "i2c": "50m"
>   * "i2s": "270m"
>   * "spi": "bus"
>   * "uart1": "50m"
>   * "uart2": "50m"
>   * "uart3": "50m"
>   * "eth": "50m"
>   * "pcie0": "125m"
>   * "pcie1": "125m"
>   * "pcie2": "125m"
>   * "crypto": "250m"
>   * "shxc": "50m"
> 
> With this information the clk driver will provide clock and gates
> functionality from a a set of hardcoded clocks allowing to define
> a nice device tree without fixed clocks.
> 
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> ---

Applied to clk-next